Jean-Louis Latil

Etienne Jaillard
email: etienne.jaillard@univ-grenoble-alpes.fr

Nathalie Bardet
email: nathalie.bardet@mnhn.fr

Naser Raissossadat
email: snraeisosadat@birjand.ac.ir

Peggy Vincent
email: peggy.vincent@mnhn.fr

Crowhurst, S.J W J Kennedy

In Gale

The Albian-Cenomanian transition in a shelf-basin transect: Biostratigraphy, sedimentology and paleontology of Jebel Mghila, Central Tunisia

Keywords: Biostratigraphy, sequence stratigraphy, ammonite paleontology, elasmosaurid plesiosaur, Albian-Cenomanian transition Cretaceous Research 25, 865-905

Twenty-two ammonite species are identified in the upper Albian Mortoniceras (Subschloenbachia) rostratum, Mortoniceras (Subschloenbachia) perinflatum and Stoliczkaia (Shumarinaia) africana Zones, and in the lower Cenomanian Mantelliceras mantelli Zone. The species Placenticeras Saadensis Thomas and Peron, 1890 is revised, including Engonoceras Thomasi Pervinquière, 1907, and is placed within the genus Hypengonoceras Spath, 1922. This accurate biostratigraphic framework allowed to evidence, at the Albian-Cenomanian transition (S. (S.) africana Zone), a significant sea level drop, responsible for emergence and erosion to the SE, and for deposition of a Lowstand wedge to the NW, fed by erosional channels on the shelf slope. Plesiosaur remains found in the upper Albian series (base of M. (S.) rostratum Zone) represent one of the few elasmosaurids known worldwide in the Albian, and the first plesiosaurian reported from Tunisia.

Introduction

The Albian stage is one of the longest stages in Mesozoic times (≈ 12 Ma), and records many sedimentological and geodynamic events, such as a major marine transgression [START_REF] Haq | Cretaceous eustasy revisited[END_REF], the widespread demise of carbonate shelves [START_REF] Skelton | The Cretaceous World[END_REF], Oceanic Anoxic Events (OAE) (e.g., [START_REF] Schlanger | Cretaceous oceanic anoxic events: Causes and consequences[END_REF][START_REF] Luciani | The regional record of Albian oceanic anoxic events at the Apulian Platform Margin (Gargano Promontory, southern Italy)[END_REF], local synsedimentary tectonic events, and the opening of the equatorial Atlantic Ocean [START_REF] Klingelhoefer | Crustal structure variations along the NW-African continental margin: a comparison of new and existing models from wide-angle and reflection seismic data[END_REF]. In spite of these important features, this period is still poorly known and understood, mainly because of its thick and monotonous, chiefly argillaceous succession, which rarely offers good exposures.

The south-Tethyan margin of Tunisia offers the opportunity of studying the sedimentary record of the Albian stage, thanks to good outcrops, to fossiliferous successions, and to good exposures along the shelf to basin transition, in the central and northern parts of the country. In this work, we present a study of the uppermost Albian deposits and their transition to the Cenomanian sediments in Jebel Mghila, which is located in Central Tunisia, and presents an outer shelf succession of marls and thin limestone beds. The collection of about fifteen ammonite levels and the sedimentological study of three 20 to 50 m thick sections, make possible to refine the latest Albian ammonite succession, to explore the transition between the Albian and Cenomanian stages, and to describe the first plesiosaurian specimen discovered in Tunisia.

Geological and historical background

During Mesozoic times, Tunisia is part of the South-Tethyan passive continental margin, the rifting of which occurred in Triassic times. The Mesogean sea is assumed to open in the Cretaceous [START_REF] Dercourt | Geological evolution of the Tethys belt from the Atlantic to the Pamir since the Lias[END_REF], reactivating the extensional rifting structures. From the late Eocene onwards, the Alpine compression deformed the Mesozoic series into NE-trending folds, giving way to the present-day structural domains. These are the Tellian nappes in northernmost Tunisia, the intracontinental folded belt of the Atlas chain in Northern and Central Tunisia, and the almost undeformed Saharan platform to the South. The northern part of the Atlas domain is marked by numerous diapirs, and is sometimes referred to as the diapir zone (e.g., [START_REF] Snoke | Structural evolution of djebel Debadib anticline: A clue to the regional tectonic style of the Tunisian Atlas[END_REF]Amri et al., in press). The Atlas domain is separated from the eastern lowlands around Kairouan by a complex zone of folds and faults, the North-South Axis, which also acted as a major normal fault (Fig. 1).

During the Cretaceous, Tunisia comprised four paleogeographic domains (Fig. 1; [START_REF] Fournié | Esquisses sédimentologiques et paléogéographiques sur le Crétacé inférieur de Tunisie du Berriasien au Barrêmien[END_REF][START_REF] Zghal | The Lower Cretaceous of Central Tunisia[END_REF][START_REF] Soua | Cretaceous oceanic anoxic events (OAEs) recorded in the northern margin of Africa as possible oil and gas shale potential in Tunisia: an overview[END_REF]. The southern Saharan platform is a stable domain, which received a thin, incomplete sedimentary succession. It is separated from Central Tunisia, by the subsident Chott depression. The Central Tunisian platform is a little subsident zone, marked by the deposition of abundant Cretaceous shelf carbonates and by a long lasting hiatus that encompasses part of the Albian stage. The North Tunisian Basin corresponds to the Northern Atlas and the Tell nappes. It received mainly outer shelf marls and shales during the Cretaceous.

After pioneer exploratory works by French geologists in the late 19 th century, [START_REF] Pervinquière | Étude géologique de la Tunisie centrale[END_REF][START_REF] Pervinquière | Étude de paléontologie tunisienne. 1 : Céphalopodes des terrains secondaires[END_REF] was the first to establish a stratigraphy of the Mesozoic strata of Tunisia, based on detailed paleontological studies. This synthesis has been then used for the publication of numerous geological maps, and enlarged by [START_REF] Burollet | Contribution à l'étude stratigraphique de la Tunisie Centrale[END_REF] to Central and Northern Tunisia, by means of numerous field sections, and the collection of abundant fauna. At the same time, [START_REF] Dubourdieu | Etude géologique de la région de l'Ouenza (Confins Algéro-tunisiens)[END_REF] stated the geology and stratigraphy of northeastern Algeria and northwestern Tunisia. Since then, many sedimentological works have been carried out, leading to a better understanding of the Cretaceous evolution of the Tunisian margin. Regarding the Albian-Cenomanian succession, detailed stratigraphic works on the Cretaceous succession in Tunisia have been published by [START_REF] Bismuth | Réflexions stratigraphiques sur l'Albo-Aptien dans la région des djebels Douleb et Semmama et son environnement (Tunisie du Centre-Nord)[END_REF], [START_REF] Bismuth | Le Crétacé moyen et supérieur du djebel Semmama (Tunisie du Centre-Nord) : microstratigraphie et évolution sédimentologique[END_REF][START_REF] Bismuth | Etude sédimentologique et biostratigraphique du Crétacé moyen et supérieur du Djebel Semmama (Tunisie du Centre Nord)[END_REF], [START_REF] M'rabet | Stratigraphie, sédimentation et diagenèse carbonatée des séries du Crétacé inférieur de Tunisie Centrale[END_REF], [START_REF] Philip | Organisation et évolution sédimentaires d'une marge de plate-forme carbonatée : l'Albien-Cénomanien de Tunisie centrale[END_REF], Robaszynski et al. (1993aRobaszynski et al. ( , 1993b[START_REF] Robaszynski | The Albian (Vraconnian)-Cenomanian boundary at the western Tethyan margin (central Tunisia and southeastern France)[END_REF], [START_REF] M'rabet | Catalog of Type Sections in Tunisia: Cretaceous, 8. Entreprise Tunisienne des Activités Pétrolières-ETAP Mémoir[END_REF], [START_REF] Zghal | Foraminifères et Ostracodes de l'Aptien-Albien du Jebel Hameima (région de Tadjerouine, Tunisie): Biostratigraphie, paleoécologie[END_REF], [START_REF] Jaillard | Albian sedimentation in the Tadjerouine area. Livret-guide excursion, Aptian-Turonian events in Central Tunisia[END_REF], [START_REF] Lehmann | Aptian (Lower Cretaceous) biostratigraphy and cephalopods from north central Tunisia[END_REF], [START_REF] Chihaoui | Stratigraphy of the Hameima and lower Fahdene formations in the Tajerouine area (Northern Tunisia)[END_REF], [START_REF] Latil | Lower Albian ammonites from Central Tunisia and adjacent areas of Algeria[END_REF]), Ben Fahdel et al. (2011), [START_REF] Layeb | Thrombolitic and coral buildups in the Upper Albian of the Fahdene basin (North Tunisia): stratigraphy, sedimentology and genesis[END_REF], [START_REF] Meister | Les ammonites du Cénomanien-Turonien de la région de Kasserine, Tunisie centrale[END_REF] and Kennedy and Gale (2015). According to these works, the Aptian carbonate shelf became emergent in most of Central Tunisia, around the Aptian-Albian boundary [START_REF] Burollet | Contribution à l'étude stratigraphique de la Tunisie Centrale[END_REF][START_REF] M'rabet | Catalog of Type Sections in Tunisia: Cretaceous, 8. Entreprise Tunisienne des Activités Pétrolières-ETAP Mémoir[END_REF][START_REF] Touir | Microstratigraphy and interpretation of the karst sedimentary fillings associated to the Aptian-Albian unconformity in Jebel Semmama (central Tunisia)[END_REF]. Subsequently, the Albian marine transgression progressively overwhelmed the emergent part of Central Tunisia. It began in earliest Albian times around Tajerouine [START_REF] Chihaoui | Stratigraphy of the Hameima and lower Fahdene formations in the Tajerouine area (Northern Tunisia)[END_REF][START_REF] Latil | Lower Albian ammonites from Central Tunisia and adjacent areas of Algeria[END_REF], and in late Albian times in most of Central Tunisia [START_REF] Bismuth | Etude sédimentologique et biostratigraphique du Crétacé moyen et supérieur du Djebel Semmama (Tunisie du Centre Nord)[END_REF][START_REF] M'rabet | Catalog of Type Sections in Tunisia: Cretaceous, 8. Entreprise Tunisienne des Activités Pétrolières-ETAP Mémoir[END_REF][START_REF] Touir | Microstratigraphy and interpretation of the karst sedimentary fillings associated to the Aptian-Albian unconformity in Jebel Semmama (central Tunisia)[END_REF]. The latest Albian time-span is marked by a shallowing upward trend, which triggered the northward progradation of shelf carbonates [START_REF] Bismuth | Etude sédimentologique et biostratigraphique du Crétacé moyen et supérieur du Djebel Semmama (Tunisie du Centre Nord)[END_REF]. The Albian-Cenomanian boundary is poorly constrained in Southern and Central Tunisia, where it is usually merged into a single Zebbag Formation, made of massive shelf limestones with evaporite intercalations [START_REF] M'rabet | Catalog of Type Sections in Tunisia: Cretaceous, 8. Entreprise Tunisienne des Activités Pétrolières-ETAP Mémoir[END_REF][START_REF] Jaballah | Stratigraphical and sedimentary charcaters of Late Cretaceous formations outcropping in central and southern Tunisia, Tethyan southern margin[END_REF]. Farther North, the Albian-Cenomanian boundary is marked by a limestone intercalation within the shaly marls of the Fahdene Formation [START_REF] Burollet | Contribution à l'étude stratigraphique de la Tunisie Centrale[END_REF]Robaszynski et al., 1993b;[START_REF] Jaillard | Albian sedimentation in the Tadjerouine area. Livret-guide excursion, Aptian-Turonian events in Central Tunisia[END_REF].

Jebel Mghila is a NE-trending anticline, the axis of which plunges to the SW toward the city of Sbeitla (Fig. 2). Because it is comprised between the underlying Aptian shelf carbonates and the overlying Turonian shelf limestone, the Albian and Cenomanian marls are well exposed in a "U" shaped depression crossed by a road joining the localities of Jilma to the SE, and Sbiba to the NW. [START_REF] Pervinquière | Étude géologique de la Tunisie centrale[END_REF] was the first to describe the Albian-Cenomanian succession in this locality. Then, [START_REF] Touir | Biostratigraphie et sédimentologie des séquences du Crétacé supérieur du Jebel Mrhila -Tunisie centrale[END_REF] summarized the upper Albian-Campanian sedimentation of Jebel Mghila, and Kennedy and Gale (2015) described the ammonite succession of the Cenomanian series of this area, following a work by Hancock.

Here, we present three sections of the upper Albian-lowermost Cenomanian succession (Fahdene Formation) studied in Jebel Mghila. Two sections have been studied on the western flank of the anticline (MR and MHC, Fig. 2B) and one on the eastern flank of the structure (MH, Fig. 2B). The lower part of the upper Albian marly succession and its lower contact with the Aptian massive dolomites (Serdj Formation) is difficult to observed, due to abundant soil and cultivated fields. [START_REF] Pervinquière | Étude géologique de la Tunisie centrale[END_REF] described two outcrops at the South-East (South of Foum el Guelta) and at the South (Kef Si Abd el Kader) of Jebel Mghila. He did recognize the "Vraconnien" stage, also called "zone à Mortoniceras inflatum" at the base of his Cenomanian (units 1-3 of [START_REF] Pervinquière | Étude géologique de la Tunisie centrale[END_REF] with "Stoliczkaia dispar d'Orb., Mortoniceras inflatum Sow." and "Turrilites Bergeri Brong.".

Biostratigraphy

Hancock, Kennedy and Gale (Kennedy and Gale, 2015) investigated the Cenomanian to lowermost Turonian successions, which were originally described in [START_REF] Pervinquière | Étude géologique de la Tunisie centrale[END_REF], but they did not investigate the uppermost Albian interval, providing only new descriptions of the material collected by Pervinquière.

As pointed out by Kennedy and Gale (2015), the uppermost Albian zonal succession developed in western Europe (Amedro, 1992(Amedro, , 2002;;Amedro et al., 2004;[START_REF] Latil | The Dispar zone in South-East France and comments about the biozonation of Albian in the Tethyan realm : biostratigraphy and paleontology (Ammonites)[END_REF]Kennedy and Latil, 2007) can be used in Tunisia, keeping in mind that [START_REF] Robaszynski | The Albian (Vraconnian)-Cenomanian boundary at the western Tethyan margin (central Tunisia and southeastern France)[END_REF] interpreted the Stoliczkaia africana Zone as a regional equivalent of the West-European Pleurohoplites briacensis Zone, which is supported by our field observations. The biostratigraphic scheme herein adopted for the uppermost Albian comprises three lineage zones [Mortoniceras (M.) fallax, Mortoniceras (S.) rostratum, M. (S.) perinflatum Zones] and one interval zone [Stoliczkaia (S.) africana Zone].

Our measured sections correspond to units 1-4 of [START_REF] Pervinquière | Étude géologique de la Tunisie centrale[END_REF], and the massive beds located at their top correspond to the "laterally extensive dolomitic limestone" of Kennedy and Gale (2015). They allow us to provide a detailed biostratigraphic scheme for the uppermost Albian (Fig. 3).

The Mortoniceras (M.) fallax Zone has not been recognized in the absence of fossil material, even though this zone is most probably represented in the lower part of the Mghila East section (MH.1-11, Fig. 3).

The Mortoniceras (Subschloenbachia) rostratum Zone has been identified at the base of the Mghila West section (beds MR.1 and 2) and in the Mghila East section Fig. 3) The Mortoniceras (Subschloenbachia) perinflatum Zone is well expressed in the three sections Fig. 3), yielding the following assemblage : Desmoceras (Desmoceras) latidorsatum [START_REF] Michelin | Note sur une argile dépendant du Gault, observée au Gaty, commune de Gérodot, département de l'Aube[END_REF] Hypengonoceras saadense [START_REF] Thomas | Description des mollusques fossiles des terrains crétacés de la région sud des hauts plateaux de la Tunisie recueillis en 1885 et 1886 par M. Philippe Thomas[END_REF])

Stoliczkaia (Stoliczkaia) clavigera Neumayr, 1875
Mortoniceras (Mortoniceras) pachys [START_REF] Seeley | On Ammonites from the Cambridge Greensand[END_REF] Mortoniceras (Subschloenbachia) perinflatum [START_REF] Spath | On Cretaceous ammonites from Angola, collected by Prof[END_REF] Cantabrigites spinosum [START_REF] Pervinquière | Étude de paléontologie tunisienne. 1 : Céphalopodes des terrains secondaires[END_REF] Scaphites aff. meriani Pictet and Campiche, 1861 In the absence of the index species, the Stoliczkaia (S.) africana Zone is herein defined by default between the last Mortoniceras occurrence and the first occurrence of true Cenomanian ammonites, below the discontinuity at the base of the laterally extensive sandy dolomitic bed (beds MH.22-24 and MR.3-5). The following assemblage has been collected within this interval (Fig. 3) : Puzosia aff. mayoriana (Orbigny, 1841) (large specimen) Hypengonoceras saadense [START_REF] Thomas | Description des mollusques fossiles des terrains crétacés de la région sud des hauts plateaux de la Tunisie recueillis en 1885 et 1886 par M. Philippe Thomas[END_REF]) Mariella (Mariella) bergeri [START_REF] Brongniart | Description Géologique des Environs de Paris[END_REF] The Albian-Cenomanian boundary in Mont Risou, Southeastern France, given by [START_REF] Kennedy | Ammonites from the Pawpaw Shale (Upper Albian) in northeast Texas[END_REF], see also Petrizzo et al., 2015), is defined by "the level 36 m below the top of the Marnes Bleues, which corresponds to first occurrence of the planktonic foraminiferan Rotalipora globotruncanoides." This boundary lies within the west-European Pleurohoplites briacensis Zone [START_REF] Kennedy | Ammonites from the Pawpaw Shale (Upper Albian) in northeast Texas[END_REF]. The occurrence of evolved morphologies of Mariella (M.) bergeri in the Stoliczkaia (S.) africana Zone of the eastern MH section, strongly suggests that the Albian-Cenomanian boundary lies within the latter ammonite zone.

The lower Cenomanian Neostlingoceras carcitanense Subzone of the Mantelliceras mantelli Zone is possibly known in the Mghila Centre section (Bed MHC.4-10) with the occurrence of the following assemblage (Fig. 3) :

Stoliczkaia (Stoliczkaia) aff. clavigera [START_REF] Neumayr | Die Ammoniten der Kreide und die Systematik der Ammonitiden[END_REF]Mantelliceras couloni (d'Orbigny, 1850) Mariella (Mariella) dorsetensis [START_REF] Spath | On the Zones of the Cenomanian and Uppermost Albian[END_REF].

The upper Mantelliceras mantelli Zone is well expressed in the three studied sections (above beds MH.25, MR.7 and MHC.10), yielding the following assemblage :

Pachydesmoceras aff. denisonianum [START_REF] Stoliczka | On the Character of the Cephalopoda of the South-Indian Cretaceous Rocks[END_REF] Sharpeiceras florencae [START_REF] Spath | On Upper Albian Ammonoidea from Portuguese East Africa, with an appendix on Upper Cretaceous ammonites from Maputoland[END_REF]Mantelliceras couloni (d'Orbigny, 1850) Mantelliceras lymense [START_REF] Spath | On the Zones of the Cenomanian and Uppermost Albian[END_REF] Graysonites cobbani (Amedro, 1994) Mariella (Mariella) dorsetensis [START_REF] Spath | On the Zones of the Cenomanian and Uppermost Albian[END_REF] Mariella (Mariella) lewesiensis [START_REF] Spath | On the Zones of the Cenomanian and Uppermost Albian[END_REF] 4. Sedimentology

Jebel Mghila

Four major discontinuities have been identified in Jebel Mghila sections (Fig. 4).

The first one (D1) corresponds to the contact with the Aptian dolomites (Serdj Formation). The top of the latter is partly brecciated, mineralized and karstified. Karst cavities are filled up with yellow, dolomitic sandstone, presenting bioturbation, ferruginous bivalves and gastropods, and locally, cross bedding. The iron rich cap contains aeolian quartz grains, lithoclasts and marine fauna (brachiopods, sea-urchins), indicating a marine transgression that follows a long-lasting emergence. The latter corresponds to the post-Aptian hiatus known in most of Central Tunisia [START_REF] Burollet | Contribution à l'étude stratigraphique de la Tunisie Centrale[END_REF]. This discontinuity likely contains several amalgamated surfaces.

The second discontinuity (D2) is marked by an erosional surface overlain by dolomitic sandstone containing aeolian quartz and sandstone lithoclasts. In section MR (Fig. 4), a small channel is infilled with biogenic calcarenite containing rounded quartz, lithoclasts, gastropods, nautilus and ammonites. Plesiosaur vertebrae, found loose close to this outcrop, most likely proceed from the infilling of this channel, interpreted as a small-scale incised valley. No evidence of emergence has been found, but the lithoclasts, channelized deposits and reworking evidence indicate an erosional hiatus.

The third discontinuity (D3) is well marked in the three studied sections. In sections MR and MH, it is marked by an erosional surface at the base of a set of yellow/orange, massive, coarsely sandy, dolomitic beds, which can be followed all along the outcrop of Jebel Mghila (unit 2 of [START_REF] Pervinquière | Étude géologique de la Tunisie centrale[END_REF]; base of the sections described by Kennedy and Gale, 2015). In section MHC, it is marked, 5 m below the sandy dolomitic beds, by an erosional surface overlain by sandy dolomitic marls containing coarse quartz grains and reworked pebbles of calcareous marl, up to 12 cm large. In all sections, it marks an abrupt lithologic change, with respect to the mainly shaly-marly, underlying series. The fifth discontinuity (D5) resembles the forth one. It is located at the top of a second well marked massive sandy dolomite bed (top of unit 2 of [START_REF] Pervinquière | Étude géologique de la Tunisie centrale[END_REF]; top of the "laterally extensive dolomitic limestone" of Kennedy and Gale, 2015). It is a thin, glauconiteand phosphate-rich bed, containing bioclasts, ammonites and sea-urchins. The base of the underlying dolomitic and sandy bed is interpreted either as a sequence or parasequence boundary, the phosphate bed (D5) corresponding to a transgressive surface. These sedimentary discontinuities define three third order depositional sequences (Fig. 4 and5).

The first one is poorly exposed. In the eastern section (MH), it consists of a succession of sandy dolomitic beds, with few marl interbeds. The occurrence of gastropods, pectinids and fragments of other bivalves, as well as abundant glauconite, indicate a marine environment. Bioturbation is also present. Sedimentary features consist of some cross bedding and current ripples near the base, and of horizontal laminae in the upper part, suggesting a shallow marine deposition. The last sandy dolomite bed presents iron-rich mineralization and stromatolithic laminae, suggesting an intertidal environment and a subsequent emergence period. Available data allow to ascribe this sequence to the M. (M.) fallax (?) and the very base of the M. (S.) rostratum ammonite zones. The base of the second depositional sequence (S2) is exposed in the western (MR) and eastern section (MH), where it is affected by minor faults that may disturb the observed succession. To the East (MH section), it begins with white, slightly sandy, calcareous marl beds bearing fish remains (vertebrae and teeth) oysters and pectinids, indicating a shallow marine environment. They are overlain by white calcareous marls and green clayey marl containing benthic fauna (oysters, pectinids and other bivalves, scarce fish remains) and abundant ammonites, suggesting a transgressive trend. To the West (MR section), above the plesiosaurian-bearing channel, the lower part of the sequence contains both benthic (brachiopods, echinoids, scarce bivalves) and pelagic fauna (ammonites, belemnites), while the upper part only contains ammonites, indicating an outer shelf environment and supporting the transgressive trend. Pyrite is locally abundant. The top of this sequence seems to have been eroded below the overlying erosional discontinuity. It has been deposited during the late M. (S.) rostratum, the M. (S.) perinflatum and part of the S. (S.) africana ammonite zones.

The base of the third sequence (S3) presents variable successions. In the western and eastern sections, S3 begins with a bed of yellow to reddish, sandy dolomite or limestone, which presents an erosional base and contains quartz gravels and lithoclasts up to 1 cm in diameter (D3). This bed is overlain by the phosphate-rich bioturbated, sandy marls with sandy dolomitic marl bed, interpreted as D4. The faunal content (irregular sea-urchins, rudistids (Sauvagesia nicaisei of [START_REF] Pervinquière | Étude géologique de la Tunisie centrale[END_REF] and ammonites) suggests a shallow, open marine environment.

In the MHC section, the succession is more complete. It begins (bed 4, Fig. 4) with some beds of clayey, dolomitic sandstone, which contains reworked pebbles of the underlying nodular calcareous marl and quartz gravels, and is capped by a Fe-Mg rich crust (hard ground). These are overlain by coarse sandstone rich in phosphate, grading upward into sandy and dolomitic marls containing scarce regular sea-urchins, rudistids and ammonites (beds 5 and 6). They are overlain by massive beds of coarse grained to gravelly dolomitic sandstone (beds 7-11, Fig. 4), capped by D4.

In all sections, the phosphate-and glauconite-rich marl bed capped by D4 is overlain by bioturbated, sandy marl beds still rich in phosphate and glauconite, bearing irregular urchins, bioclasts, serpulids and ammonites, suggesting a submarine condensed sedimentation. These phosphate-rich layers are overlain by a massive bed of bioturbated sandy dolostone, showing locally laminae and ripples. The top of the sandy dolomite is capped by a glauconite-and phosphate-rich marly layer, locally bearing bioclasts and ammonites (D5). Overlying this thin layer interpreted as a Transgressive Surface, is a thick succession of green clayey marl, the base of which yields scarce oysters and ammonites (unit 3 of [START_REF] Pervinquière | Étude géologique de la Tunisie centrale[END_REF]; see also Kennedy and Gale, 2015). None of the late Albian ammonites described by [START_REF] Touir | Biostratigraphie et sédimentologie des séquences du Crétacé supérieur du Jebel Mrhila -Tunisie centrale[END_REF] above D5 have been found, and in agreement with Kennedy and Gale (2015), we consider the overlying sequence as early Cenomanian in age (Fig. 5).

In total, the D3-D5 interval is 12 m thick in section MHC, whereas it is 3 to 3.5 m in the other sections. Therefore, combined with the biostratigraphic data that evidence an erosion of the upper part of sequence 2 in section MHC, the base of sequence 3 in the latter section is interpreted as the infilling of a channel caved in sequence 2, and infilled by lowstand deposits. In this interpretation, a significant erosion occurred during the Albian-Cenomanian transition period (S. (S.) africana ammonite zone) in the area of Jebel Mghila. No evidence of an emergence period has been found (karst, desiccation, paleosols …) in Jebel Mghila, which can be due to the marly nature of the underlying deposits. Therefore, it is not possible to specify certainly whether erosion took place in a submarine or subaerial environment.

Comparison with neighbouring areas

In Central Tunisia, uppermost Albian deposits bear evidences of a shallowing upward trend. In Jebels Selloum and Semmama (Fig. 2), the upper Albian marls grade upward into locally cross-bedded, coarse-grained bioclastic limestones [START_REF] Bismuth | Réflexions stratigraphiques sur l'Albo-Aptien dans la région des djebels Douleb et Semmama et son environnement (Tunisie du Centre-Nord)[END_REF][START_REF] Bismuth | Etude sédimentologique et biostratigraphique du Crétacé moyen et supérieur du Djebel Semmama (Tunisie du Centre Nord)[END_REF][START_REF] Philip | Organisation et évolution sédimentaires d'une marge de plate-forme carbonatée : l'Albien-Cénomanien de Tunisie centrale[END_REF]Fig. 6). The latter were deposited in a high energy, very shallow marine environment, and their top is marked by emergence features [START_REF] Bismuth | Etude sédimentologique et biostratigraphique du Crétacé moyen et supérieur du Djebel Semmama (Tunisie du Centre Nord)[END_REF][START_REF] Philip | Organisation et évolution sédimentaires d'une marge de plate-forme carbonatée : l'Albien-Cénomanien de Tunisie centrale[END_REF]. The high lateral thickness variations of the bioclastic limestones suggest that either they are deeply channelized, or more probably, they were strongly eroded. These observations show that a subaerial erosion at the top of the upper Albian marls of Jebel Mghila is likely.

In Jebel Semmama, the top of the bioclastic limestones yielded "Submantelliceras sp.", associated with poorly preserved specimens of "Paraturrilites", "Mortoniceras" and "?Knemiceras" [START_REF] Philip | Organisation et évolution sédimentaires d'une marge de plate-forme carbonatée : l'Albien-Cénomanien de Tunisie centrale[END_REF]. Since "Submantelliceras" is a Cenomanian genus and the other ones are late Albian in age, either the latter are reworked, or Submantelliceras sp." has been misidentified. In Jebel Selloum, the shallow marine bioclastic limestones are overlain by limestone of open marine environment, in turn overlain by shallow marine rudistid-rich limestones. This open marine limestone yielded "Submantelliceras gr. couloni" and "Mantelliceras cf. picteti" [START_REF] Philip | Organisation et évolution sédimentaires d'une marge de plate-forme carbonatée : l'Albien-Cénomanien de Tunisie centrale[END_REF], which indicate the upper part of the "Mantelliceras mantelli" Zone of early Cenomanian age. In Jebel Zaouïa (Fig. 2 and6), the Aptian dolomites are overlain by a comparable sequence, which yielded ammonites of the M. mantelli Zone ("Submantelliceras martinpreyi", "Mantelliceras lymense", "M. saxbii", "M. gr. Dixoni", "M. cf. mantelli", "M. tenue"; [START_REF] Philip | Organisation et évolution sédimentaires d'une marge de plate-forme carbonatée : l'Albien-Cénomanien de Tunisie centrale[END_REF]. The overlying, oyster-rich marls yielded "Sharpeiceras laticlavium" and "Mantelliceras lymense" of early Cenomanian age [START_REF] Philip | Organisation et évolution sédimentaires d'une marge de plate-forme carbonatée : l'Albien-Cénomanien de Tunisie centrale[END_REF]. In Northern Tunisia, uppermost Albian marls also record a shallowing upward trend, since mud mounds and isolated corals and rudistids have been mentioned [START_REF] Layeb | Thrombolitic and coral buildups in the Upper Albian of the Fahdene basin (North Tunisia): stratigraphy, sedimentology and genesis[END_REF]Robaszynski et al., 1993b;[START_REF] Jaillard | Albian sedimentation in the Tadjerouine area. Livret-guide excursion, Aptian-Turonian events in Central Tunisia[END_REF]. East of Jebel Jerissa (Oued Azreg, Fig. 2), Robaszynski et al. (1993a;1993b;2008) described at the top of the upper Albian marls, a 20 m thick, thickening upward succession marked by shallow erosional channels, interpreted as a lowstand deposits (Shelf margin wedge), which contains the Albian-Cenomanian boundary defined by foraminifera (Fig. 6). It is capped by three phosphate-and ammonite-rich channelized beds, which were ascribed to two local, newly defined ammonite zones (G. azregensis and G. cobbani Zones) of earliest Cenomanian age (Robaszynski et al., 1993a;2008). Kennedy and Gale (2015) consider the G. cobbani ammonite zone as corresponding to the Sharpeicears schlueteri Subzone (earliest Cenomanian) of the M. mantelli Zone.

Farther northwest (Oued Segui, Fig. 2; erroneously named Oued Zerga in [START_REF] Jaillard | Albian sedimentation in the Tadjerouine area. Livret-guide excursion, Aptian-Turonian events in Central Tunisia[END_REF], the "Late Albian" marls are overlain by a 30 m thick thickening-and shallowingupward sequence culminating with sandy limestones showing current features and shallow marine fauna (isolated rudistids, echinoids) [START_REF] Jaillard | Albian sedimentation in the Tadjerouine area. Livret-guide excursion, Aptian-Turonian events in Central Tunisia[END_REF]Fig. 6). This sequence yielded latest Albian ammonites and contains the Albian-Cenomanian boundary defined by foraminifera (Fig. 5). It is first overlain by a ≈ 20 m thick aggrading strata set, in which appear the first typical Cenomanian ammonites. Above, a thinning-upward succession yielded ammonites from both the G. azregensis and G. cobbani Zones, and is interpreted as a transgressive (retrogradational) sedimentary body [START_REF] Jaillard | Albian sedimentation in the Tadjerouine area. Livret-guide excursion, Aptian-Turonian events in Central Tunisia[END_REF].

Correlations and interpretation

These data make possible the following correlations and interpretations (Fig. 6). During the late Albian (S2), a shallowing upward trend is indicated in the southeastern sections by the appearance of biogenic limestones and in the northeastern sections by the occurrence of benthic fauna (rudistids, corals, mudmounds …). This shallowing upward succession is interrupted to the Northwest by the abrupt contact of relatively shallow deposits resting on deep outershelf marl, and to the Southeast by emergence features. In agreement with Robaszynski et al. (1993a;1993b), we interpret this contact as a Sequence boundary of late Albian age (D3 in Fig. 6) that caps our S2 depositional sequence.

The latter is overlain in the northwestern sections by Lowstand deposits (LST), well expressed in the Oued Segui section by a first prograding (thickening upward), then aggrading succession bearing benthic fauna of outer shelf environment. This part of the succession contains the Albian-Cenomanian boundary defined by planktic foraminifera (Robaszynski et al., 1993a;1993b;[START_REF] Jaillard | Albian sedimentation in the Tadjerouine area. Livret-guide excursion, Aptian-Turonian events in Central Tunisia[END_REF]. In Oued Segui, the aggrading strata set is overlain by a thinning upward series that may likely represent a transgressive deposit that evolves into deep outer shelf marls (Fig. 6). The top of the aggrading succession is interpreted as a Transgressive surface, which seems to grade laterally southeastward into condensed, phosphate-rich beds. In this interpretation, on one hand the superimposed phosphate-rich beds identified in the Oued Azreg and Jebel Mghila sections would correspond to transgressive parasequences at the base of a third order Transgressive Systems Tract (TST). On the other hand, the channels filled by the phosphate-rich marls in Oued Azreg and Jebel Mghila were carved during the LST on the slope joining the southeastern emergent areas to the northwestern basin domain. This erosion was likely due to the transport of products resulting from the erosion of the emergent areas. These products may be represented by the limestone beds of the LST deposits in the Oued Segui section, and by the lens shaped limestone beds locally identified in Oued Azreg (Robaszynski et al., 1993a;1993b).

The first transgressive deposits are of earliest Cenomanian age (N. carcitanense Subzone, Fig. 5), while the late part of the TST seems to mainly correspond to the Sharpeiceras schlueteri Subzone. The Early Cenomanian transgression may have reached the southeastern areas (Jebel Selloum and Jebel Zaouia) during the S. schlueteri Subzone. In the latter sections, the transgressive deposits are overlain by shallow marine, rudistid-bearing limestones [START_REF] Philip | Organisation et évolution sédimentaires d'une marge de plate-forme carbonatée : l'Albien-Cénomanien de Tunisie centrale[END_REF] interpreted as the Highstand Systems Tract (HST) of the third order sequence S3. Data are lacking so far in the northwestern sections to document such evolution. Order: Ammonoidea Zittel, 1884 Suborder: Ammonitina Hyatt, 1889 Superfamily: Desmoceratoidea Zittel, 1895 Family: Puzosiidae [START_REF] Spath | On Cretaceous ammonites from Angola, collected by Prof[END_REF]Subfamily: Puzosiinae Spath, 1922 Genus Puzosia Bayle, 1878 Subgenus Puzosia [START_REF] Bayle | Explication de la Carte Géologique de la France[END_REF](= Matsumotoceras Hoepen,1968;?Hyperpuzosia Matsumoto, 1988) Type species. Ammonites planulatus J. de C. Sowerby, 1827, p. 38, by subsequent designation of H. Douvillé, 1879, p. 91. Puzosia sp. juv. Fig. 7.n Material. UJF-ID.15003 from the bed MR.2 from the Mghila West section, upper Albian, Mortoniceras (Subschloenbachia) rostratum Zone.

Systematic paleontology

Description and remarks.

A tiny limonitic nucleus (Fig. 7.n), 10 mm in diameter, with rather evolute coiling (U/D= 0.3), a whorl section as high as broad, low vertical umbilical wall, rounded umbilical shoulders, feebly convex flanks and rounded venter. There are four sigmoidal constrictions on the last preserved whorl and no indication of ribs. This specimen cannot be identified at a specific level. Pervinquière (1907, pl. 6, figs 25-32) figured several small pyritized specimens from the latest Albian of Pont du Fahs and Guern Er Rhezal, northern Tunisia, which do not show the strongly sigmoidal constrictions of our specimen.

Genus Pachydesmoceras Spath, 1922 Material. UJF-ID. 15050 from the bed MR.7 from the Mghila West section, early Cenomanian, Mantelliceras mantelli Zone.

Description and remarks.

A poorly preserved internal mould of an incomplete phragmocone, about 160 mm in diameter (Figs 8.c,d). The coiling is evolute, the umbilicus comprising about 30% of the total preserved diameter. The umbilicus is deep, with a broadly rounded umbilical shoulder. The oval whorl section is too distorted to be measured. The weathered flanks show numerous, slightly flexuous, narrow, widely spaced ribs.

This specimen differs from the material described by Matsumoto (1988, p. 109, figs 48, 49) from the Cenomanian of Japan, by its denser ribbing and by its intercalatory ribs that arise lower on the flanks. Our specimen seems to be closer to the specimen figured by Collignon (1961, pl. 8

Description and remarks.

A poorly preserved 90° sector of phragmocone, with a whorl height of 60 mm (Figs 8.a,b). Although strongly weathered, the whorl section is subelliptical and slightly compressed (Wb/Wh = 0.9), with a maximum of width at the inner third of the flanks. The flanks are smooth and convex, converging to a narrowly rounded venter.

Superfamily: Engonoceratoidea [START_REF] Hyatt | Textbook of Palaeontology[END_REF]Family: Knemiceratidae Hyatt, 1903Genus Hypengonoceras Spath, 1922 Type species. Placenticeras Warthii Kossmat, 1895, by the original designation of Spath, 1922, p. 112.

Hypengonoceras saadense [START_REF] Thomas | Description des mollusques fossiles des terrains crétacés de la région sud des hauts plateaux de la Tunisie recueillis en 1885 et 1886 par M. Philippe Thomas[END_REF] Even though Engonoceras Thomasi Pervinquière and Placenticeras Saadensis Thomas and Peron are very difficult to compare because of their different preservations (juvenile pyritized for the first species, calcareous subadult and adults for the second one), these two species are herein placed in synonymy as a result of the position of the pyritized faunas, which are interposed between the first calcareous faunas of the Mortoniceras (Subschloenbachia) rostratum Zone and the last calcareous specimen of the Stoliczkaia (Shumarinaia) africana Zone, strongly suggesting that Engonoceras Thomasi represents the juvenile growth stages of Hypengonoceras saadense.

Neotype. [START_REF] Thomas | Description des mollusques fossiles des terrains crétacés de la région sud des hauts plateaux de la Tunisie recueillis en 1885 et 1886 par M. Philippe Thomas[END_REF], described the species Placenticeras saadensis on the basis of several fragments from Bou Saada (Algeria), Jebel Mghila and Jebel Roumana (Tunisia) and they figured only two fragments from Jebel Mghila. Breistroffer (1940b, p. 131 h,i). At this stage of the ontogeny, the coiling is moderately involute (U/D = 0.33), the flanks and the venter are convex, the whorl section is still almost circular and the last preserved whorl shows 6 radially elongated latero-umbilical tubercles, which most probably disappear soon after.

At a diameter of 10 mm and beyond, the coiling is involute (UD = 0.13), with shallow steep umbilical wall, narrowly rounded umbilical edge, the whorl section is subtriangular and compressed (Wb/D = 0.58), with smooth flattened flanks ending with a sharp ventrolateral edge, and the venter is narrow, smooth and flat (e.g. UJF-ID.15025, Figs 9.e-g).

The largest known pyritized specimen from Jebel Mghila is the holoype of Engonoceras Thomasi Pervinquière, 1907 (unregistered MNHN specimen, Figs 9.a-d).

It is a well preserved pyritized internal mould, 32 mm in diameter. The shell is discoidal, high-whorled (Wh/D = 0.59), with a compressed subtriangular whorl section (Wb/Wh = 0.5), feebly convex flanks with a maximum breadth just above the umbilicus. Coiling is very involute, the umbilicus comprising 8% of the diameter. The umbilical wall is shallow and the umbilical edge is broadly rounded. The flanks converge to a narrow and flat venter (v/D = 0.11). The ornament is made of few sigmoidal striae on the adapical part of the last preserved whorl, which are visible only on the upper half of the flanks (Figs 9.a,d).

Additional material from the Mortoniceras (Subschloenbachia) perinflatum Zone of the Azreg section, Tajerouine area, Central Tunisia, allowed us to follow the early sutural ontogeny (Fig. 11.a-e). It should be noted that the saddles are exceptionally indented in Fig. 11.d (UJF-ID. 15085). The suture line figured by Pervinquière (1907, fig. 77) is herein refigured (Fig. 11.e).

The growth stages between the larger pyritized specimen, 32 mm of diameter, and the smaller known calcareous fragments, with an estimated diameter of 70 mm, are not known.

Beyond a diameter of 70 mm, the species is known from numerous fragments preserved as slightly weathered calcareous internal moulds. At that stage of the growth, the whorl section is always compressed (Wb/Wh ranging from 0.47 to 0.57), subtriangular, with very narrow umbilicus, shallow umbilical wall, narrowly rounded umbilical edge, slightly convex flanks, converging to a rather sharp ventrolateral edge. The venter is generally flat, rarely slightly concave or slightly convex, more of less narrow (the ratio of venter thickness to whorl height ranging from 0.05 to 0.15). There are spirally elongated ventrolateral tubercles, alternating across the venter, which are more or less expressed depending on the state of preservation and the thickness of the venter. The flanks are generally smooth (e.g. UJF-ID.15043, Figs 9.m-o) but some specimens show radially elongated periumbilical swellings giving rise to feeble, coarse ribs on the inner half of the flanks (UJF-ID.15038, Figs 9.j-k).

A large specimen (UJF-ID.15047, Figs 10.a, b), 370 mm in diameter is preserved as an internal mould of a phragmocone. The coiling is very involute, the whorl section is becoming more elliptical, with smooth, convex flanks and a maximum of thickness on the inner third of the flanks. The umbilicus is shallow, the umbilical edge is broadly rounded. The venter is very narrow (v/Wh = 0.06), retaining ventrolateral tubercles up to a diameter of about 180 mm. Beyond this diameter, the venter becomes smooth, narrow and convex. The body chamber is unknown.

Remarks. The fragment figured by Latil (1989, p. 57, pl. 1, fig. 3) as Engonoceras sp., from the Mortoniceras (Subschloenbachia) perinflatum Zone of Salazac (Gard, France), which was identified as Engonhoplitoides cf. vicorpense Basse by Breistroffer (1983, p. 56), does not differ in any way from the Tunisian fragment UJF-ID.15038 (Figs 9.j-k).

The fragment identified as Hypengonoceras sp. in Latil (1989, p. 54, pl. 1, fig. 4), from just above the phosphatized level of the Mortoniceras (Mortoniceras) fallax Zone of Salazac, Gard, France, is very probably an adult phragmocone of Hypengonoceras duboisi [START_REF] Latil | Les genres Engonoceras Neumayr and Uhlig, 1881 et Hypengonoceras Spath, 1922 dans l'Albien supérieur (z. à Dispar) de Salazac[END_REF].

As suggested by [START_REF] Latil | Knemiceras gracile Douvillé, 1916: a misunderstood Early Albian ammonite from north Sinai (Egypt), and considerations on the genus Platiknemiceras Bataller[END_REF], the present species is closely related to Hypengonoceras warthii [START_REF] Kossmat | Untersuchungen über die südindische Kreideformation[END_REF]. [START_REF] Roy | A note on Placenticeras warthi Kossmat, 1895 (Ammonoidea), the type species of the genus Hypengonoceras Spath[END_REF] recently re-figured the type material of Hypengonoceras warthi [START_REF] Kossmat | Untersuchungen über die südindische Kreideformation[END_REF] from the late Albian of India. Our species is closely allied to H. warthi, from which it differs mainly by its much larger size and its non-vertical umbilical wall. Kennedy (2015) has placed the Tunisian species in the genus Placenticeras Meek, 1876, but as shown by Roy and Bardhan, Hypengonoceras warthi, and then H. saadense, clearly belong to the Engonoceratoidea. Occurence. The species is known from the uppermost Albian, Mortoniceras (Subschloenbachia) rostratum to Stoliczkaia (Shumarinaia) africana Zones of Jebel Mghila. It has also been recorded in Tunisia from Jebel Roumana and the area of Jebel Adira and Jebel el Hamra. Pervinquière (1903, p. 80) and we found it farther north, in the Tajerouine area. We were unable to trace the Algerian material from Bou Saada and Khenchela, in Algeria, mentionned by [START_REF] Thomas | Description des mollusques fossiles des terrains crétacés de la région sud des hauts plateaux de la Tunisie recueillis en 1885 et 1886 par M. Philippe Thomas[END_REF]. Type. The holotype, SMC B54 from the reworked upper Albian phosphates at the base of the Cenomanian Cambridge Greensand in eastern England [START_REF] Seeley | On Ammonites from the Cambridge Greensand[END_REF][START_REF] Spath | A monograph of the Ammonoidea of the Gault[END_REF], redescribed by Kennedy et al. (2008, p. 42;pl. 10, figs. 9-11).

Material. Two fragments from Bed 3b of Mghila West section (UJF-ID.15007-08), one fragment from Bed 16 of Mghila East section (UJF-ID.15086), late Albian, Mortoniceras (Subschloenbachia) perinflatum Zone.

Description. UJF-ID.15007 is a fragment of a juvenile specimen, 29 mm long, preserved as calcareous internal mould with a diameter of about 25 mm. Coiling is moderately evolute. The umbilical wall is feebly convex, the umbilical shoulder broadly rounded. The intercostal whorl section is as broad as high, trapezoidal, the ventrolateral shoulders broadly rounded, the venter flattened, with a strong siphonal keel. Coarse ribs arise on the umbilical wall and strenghten into minute, umbilical radially elongated clavi. The tubercles give rise to generally two, rarely one, radial to slightly prorsiradiate ribs. The ribs bear inconspicuous ventrolateral bullae, from which the ribs become slightly projected forward on the venter. A narrow smooth zone separates the ribs from the siphonal keel.

UJF-ID.15008 (Fig. 12.j, k) is a larger fragment of phragmocone, with a whorl height of 31 mm, that has a slightly higher than broad, trapezoidal whorl section The ribs are slightly flexuous, arising at the base of the umbilical wall, bifurcates above the umbilical shoulder from an only slight, radially elongated swelling, decline on the inner third of the flanks, become coarser on the outer part of the flanks, developing tiny inner ventrolateral tubercles that tend to disappear with age, and are slightly projected forward on the venter. UJF-ID.15086, a fragment of phragmocone preserved as calcareous internal mould, is more characteristic of the species, with radially elongated umbilical tubercles, depression on the inner third of the flanks, minute lateral tubercle and a well marked ventrolateral tubercle. Remarks. Our material differs from Mortoniceras (Mortoniceras) pachys only by its almost inconspicuous tuberculation, which is tentatively interpretated as an unexpected survivor of the species at the base of the Mortoniceras (Subschloenbachia) perinflatum Zone.

Occurrence. Mortoniceras (Subschloenbachia) perinflatum Zone of Jebel Mghila, Tunisia.

The species was previously known in the Mortoniceras (Mortoniceras) fallax Zone of France, Belgium, England, Hungary, Poland, Morocco and Madagascar.

Subgenus Subschloenbachia [START_REF] Spath | On Cretaceous Cephalopoda from Zululand[END_REF](= Durnovarites Spath, 1932, p. 380;Reyreiceras Collignon, 1979, p. 34).

Type species. Ammonites rostratus J. Sowerby, 1817, p. 163, pl. 173, by original designation by Spath, 1921, p. 284. Vraconne, Saint Croix, Switzerland. It was refigured by Renz (1968, pl. 9, fig. 1), Wiedmann and Dieni (1968, pl. 14, fig. 4) and Meister et al. (2011, text-fig. 5a, b).

Mortoniceras (Subschloenbachia) rostratum (J.
Material. Fifteen fragments from Bed 3 of Mghila West section, four fragments from Bed 16A, two fragments from Bed 16B of Mghila East section, late Albian, Mortoniceras (Subschloenbachia) perinflatum Zone (unit 1 of Pervinquière, 1903, text-fig. 14).

Description. Kennedy (2015, pl. 4, figs 3, 4, 6) has described and figured the three unregistered specimens in the Sorbonne Collections, mentioned by Pervinquière [1903, p. 64;1907, p. 229 (pars)], from Foum el Guelta and Kef et Tella. Our material is made of fragments of juvenile and adult phragmocones preserved as calcareous internal moulds. The whorl section is variable, from slightly compressed to strongly depressed (Wb/Wh between 0.90 and 1.40) (Figs 13.a-f). The flanks are flat to slightly convex, the ornament is characteristic of the species, with low to elevated, coarse ribs, week to strong, radially elongated periumbical tubercles, rather small, conical, lateral tubercles, week to strong, radially elongated inner ventrolateral tubercles and weak to rather strong conical, outer ventrolateral tubercles. It should be noted that the strenght of the ornament is not correlated with the shape of the section. At the end of the phragmocone, the ribs tend to become single, bearing coarse, radially elongated periumbilical swellings, strong, coarse outer lateral tubercles and strong inner ventrolateral tubercles, which tend to merge with attenuated, coarse, outer ventrolateral bulges. A small distorted and strongly weathered piece of body chamber is known from a single fragment and seems to show coarse, single ribs bearing strong lateral tubercles and probly merged inner and outer ventrolateral tubercles.

Remarks.

Our material comes from the base of the Mortoniceras (Subschloenbachia) perinflatum Zone in both Mhrila East and Mhrila West sections. The absence of the species in higher stratigraphic levels is very probably due to the scarcity of the species in marly levels: Mortoniceras (S.) rostratum represents only 3-5% of the mortoniceratids fauna in underlying beds with pyritized fossils and the beds of the upper part of the Mortoniceras (Subschloenbachia) perinflatum Zone are very poor in pyritized fossils.

Our material shows a high morphological variability, the more compressed morphologies being very similar to Mortoniceras (S.) rostratum when only phragmocones are preserved.

Occurrence. Mortoniceras (Subschloenbachia) perinflatum Zone of Jebel Mghila, Tunisia. The species is also known from southern England, southeastern France, Hungary, Poland, Romania, Sardinia, ?northern Spain, Switzerland, Crimea, the Lesser Caucasus, Iran, USA (Texas), Angola, Nigeria, Tunisia, and South Africa.

Genus Cantabrigites [START_REF] Spath | A monograph of the Ammonoidea of the Gault[END_REF] Type species. Mortoniceras (Cantabrigites) cantabrigense Spath, 1932, p. 380, pl. 41 appearing very early in the ontogeny, prior to a diameter of 5 mm. At about 6 mm, fine, sharp ribs are appearing on the ventrolateral edge, bearing inner and outer ventrolateral minute tubercles. At a diameter of 6-7 mm, the ribs are extending on the outer half of the flanks. At a diameter of 9 mm, all the ribs have reached the umbilical shoulder, developing a minute umbilical tubercle. Beyond a diameter of 10 mm, the ribs arise from a periumbilical, conical tubercle, alone of by two, are coarse and somewhat effaced on the inner part of the flanks, strenghten into an inner ventrolateral conical tubercle, which is linked to an outer ventrolateral tubercle by a coarse, rather strong rib, which is perpendicular to the keel of slightly projected forward. The tubercles generally become stronger with age and the ribs tend to become single on the adult body chamber. The whorl section is subquadratic, only slightly higher than broad (Wb/Wh between 0.93 and 1.00). UJF-ID.15095 (Fig. 14.j) is an adult 90° sector of bodychamber, with a well marked depression of the ribs on the inner half of the flanks, develops minute lateral tubercles. Two specimens show a radical change on the body chamber, where the ribs are sharp and always bifurcating and the tubercles become minute, tending to disappear with age.

Remarks. The morphological variability of our material does not seem to be considerable. It should be noted that there are four, poorly preserved, juvenile specimens, less than 16 mm in diameter, with compressed whorl section, that show dense, fine ribbing and minute tubercles.

As pointed out by Kennedy (2004, p. 879), 'There are a number of species from western Europe that have the same basic style of ribbing and tuberculation, but all come from condensed units, and limits of intraspecific variation are unclear'. Our material, close to the one figured by [START_REF] Kennedy | Ammonites from the Pawpaw Shale (Upper Albian) in northeast Texas[END_REF] l-o) is a fragment of a micromorph ammonite preserved as a pyritized internald mould, comprising the very end of the phragmocone and a 130° sector of body chamber, with an estimated diameter of 15 mm. The coiling is evolute. The intercostal whorl section is subquadrangular. The umbilical wall is shallow et rounded. The ribs arise on the umbilical wall, develop small conical bullae on the umbilical shoulder, giving one or two straight, slightly prorsiradiate, coarse ribs, which all bear a small inner conical ventrolateral tubercles and a small, slightly spirally elongated, outer ventrolateral tubercle. Every four ribs, a rib is strongly projected backward and then forward on the outer part of the flanks, colliding the preceeding rib, developing a characteristic v-shape bulge, and ending like the other ribs with an outer ventrolateral tubercle, the inner ventrolateral tubercle being present or not. The ribs are projected forward on the phragmocone and the beginning of the body chamber, and tend to be perpendicular to the keel on the outer part of the body chamber.

The suture is simple.

Remarks. This enigmatic specimen shows all the characteristics of Cantabrigites spinosum, except that it periodically develops outer lateral bulges. The regularity of their apparitions and their presence on both sides exclude any kind of teratology. This specimen is herein interpretated as a potential new species of the genus Cantabrigites.

Occurrence. Late Albian, Mortoniceras (Subschloenbachia) rostratum Zone, of Jebel Mghila, Tunisia.

Family: Acanthoceratidae Grossouvre, 1894 Subfamily: Stoliczkaiinae Breistroffer, 1953 Remarks. As previously suggested (Latil, 1995, p. 348), the stoliczkaiinae are very probably not phylogenetically connected with the lyelliceratids, the suture of early Stoliczkaiinae (e.g., Neophlycticeras [START_REF] Spath | On Cretaceous ammonites from Angola, collected by Prof[END_REF], rather suggesting a rooting among the Desmoceratoidea Zittel, 1895. On the other hand, the lineage Stoliczkaiinae-Mantelliceratinae is now well documented. Consequently, the Stoliczkaiinae is herein interpretated as a subfamily of the Acanthoceratidae Grossouvre, 1894.

Genus and Subgenus Stoliczkaia [START_REF] Neumayr | Die Ammoniten der Kreide und die Systematik der Ammonitiden[END_REF](= Stoliczkaiella Cooper, 2012) Type species. Ammonites dispar d 'Orbigny, 1841, p. 142, pl. 45, figs 1, 2, by the subsequent designation of Diener, 1925, p. 179.

Remarks. Cooper (2012, p. 185) Type. The holotype, by monotypy, is the original of Stoliczka, 1865, pl. 45, fig. 1 only, GSI. 191 from the Uttatur Group of Moraviatoor, India. A cast of this specimen was figured by Delanoy and Latil (1988, pl. 5, fig. 1).

Material. Description. The early whorls, prior to a diameter of 5 mm, are unknown. Coiling is moderately involute, the umbilicus of moderate depth, with a feebly convex wall and narrowly rounded umbilical shoulder. The whorl section is compressed, with Wb/Wh between 0.68 and 0.84 and a maximum of width at about mid-flanks. The flanks are flattened and subparallel, tending to be slightly convex with age, the ventrolateral shoulders broadly rounded, the venter very feebly convex. The ornament appears very early in the ontogeny. Up to a diameter of 10 mm (Figs 15.g-r), the ribs are regularly alternating, one primary for one intercalatory rib, the primaries arising on the periumbilical shoulder, the intercalatories on the inner third of the flanks. The ribs are slightly flexuous and rectiradiate, ending with a more or less expressed ventrolateral tubercle, and the siphonal area is smooth. Beyond a diameter of 10 mm 7.i,j), the primary ribs are less numerous and stronger than the intercalatories, arising on the umbilical wall and strenghtening on the periumbilical shoulder, developping radially elongated swellings. All the ribs are crossing the venter without interruption. The ventrolateral tubercles are present at a diameter of 18-20 mm and then tend to disappear.

The adult phragmocone, about 65 mm in diameter, is known from 3 poorly preserved fragments preserved as calcareous internal moulds, having a compressed whorl section with Wb/Wh at about 0.75, slightly convex flanks, a rather narrow convex venter, and showing irregular, fine and dense ribbing. UJF-ID.15020 (Figs 15.c,d), about 80 mm in diameter, shows the beginning of the body chamber. Two other fragments, UJF-ID.15021-22 (Figs 15.a, b, e, f) both comprise 100° sectors of body chamber, for an estimated diameter of 110 mm. On the body chamber, the ornament is made of regularly alternating primary and intercalatory ribs. The primaries arise on the umbilical seam, are slightly flexuous on the flanks and streghten on the upper half of the flanks and the venter where they are coarse. The intercalatories arise at mid-flank or on the upper third of the flanks. The whorl section is slightly less compressed. At the very end of the body chamber, the ornament disappears suddendly and the whorl section is becoming narrower toward the aperture.

UJF-ID.15083 is a 180° sector of body chamber, 95 mm in diameter, preserved as a weathered calcareous internal mould of a body chamber. The ornament is poorly preserved, but the subscaphitoid coiling in relation with the narrowing of the whorl section close to the aperture, and the apparent attenuation of the ribbing on the flanks toward the aperture, suggest that this specimen is closely related to Stoliczkaia (S.) clavigera.

Remarks. The two fragments figured by Kennedy (2015, p. 258, pl. 3. fig. 4, Pl. 4, fig. 1) as Stoliczkaiella (Stoliczkaiella) dispar (d [START_REF] Orbigny | Paléontologie française : Terrains crétacés[END_REF] from the late Albian of Mghila (Pervinquière Collection), are strongly weathered. Since the true Stoliczkaia (S.) dispar is not known from us in Tunisia, we merely refer these specimens to S. (S.) clavigera.

As pointed out by Kennedy and Klinger (2013b): « Stoliczkaia (S.) dorsetensis Spath, 1931 (p. 337, pl. 31, figs 2, 3, 10, 13, 14;pl. 32, fig. 7;pl. 33, fig. 1 (including var. compressa), originaly described from the condensed perinflatum Zone of south Dorset, was regarded as a synonym of clavigera by Wright and Kennedy (1994, p. 576), and some juveniles are very similar; however, the adult stages are not known from the type area. ». After a re-examination of the type material, S. (S.) dorsetensis, with its wide venter, flattened flanks, and its wide, low ribs on the venter, where they are slightly curved forward, is herein regarded as a valid species. Wright and Kennedy also suggest that the juveniles of S. (S.) clavigera are less compressed than the juveniles of S. (S.) dispar, which, from our experience, does not seem to be supported by the facts. Everywhere, the juveniles are very difficult to identify at a specific level when the adult stages are lacking and the synonymies should be revised.

Occurrence. Late Albian, Mortoniceras (Subschloenbachia) rostratum Zone and Mortoniceras (Subschloenbachia) perinflatum Zone of Jebel Mghila, Tunisia.

Stoliczkaia (Stoliczkaia) sp. juv. Description. The early whorls, prior to a diameter of 5 mm, are known only from UJF-ID.15011 (Fig. 7.c-e), and are almost smooth with only well-expressed oblique ventrolateral tubercles. The ventrolateral tubercles disappear early in the ontogeny, probably at a diameter of 10-15 mm. At about 20 mm in diameter, the flanks are convex, the ventrolateral shoulders are narrowly rounded and the venter is rather broad.

Remarks. At the same size, at about 20 mm in diameter, this juvenile material differs from S. (S.) clavigera by its more convex flanks, its broader venter and an earlier loss of the ventrolateral tubercles. This kind of morphology is known only by juvenile fragments preserved as pyritized internal moulds and a small calcareous fragment, which are twice less numerous than the juveniles of S. (S.) clavigera. It should be noted that these morphologies do not seem to occur further north, in the Tajerouine area. Our material differs from S. (S.) dorsetensis by its narrower and more convex venter, its more convex flanks and its ribs that are not curved on the venter.

Occurrence. Late Albian, Mortoniceras (Subschloenbachia) rostratum Zone and Mortoniceras (Subschloenbachia) perinflatum Zone of Jebel Mghila, Tunisia.

Subfamily: Mantelliceratinae [START_REF] Hyatt | Pseudoceratites of the Cretaceous[END_REF]Genus Mantelliceras Hyatt, 1903 Type Species. Ammonites mantelli J. Sowerby, 1814, p. 199, by the original designation of [START_REF] Hyatt | Pseudoceratites of the Cretaceous[END_REF], p. 113 (ICZN Specific Name No. 1634).

Mantelliceras lymense [START_REF] Spath | On the Zones of the Cenomanian and Uppermost Albian[END_REF] ) is a small sector of body chamber, preserved as calcareous internal mould, with a maximum preserved whorl height of 57 mm. The intercostal whorl section is compressed (Wb/Wh = 0.90), subquadrangular with feebly convex flanks, broadly rounded umbilical edge and broadly rounded ventrolateral shoulders. The venter broad and feebly convex. There are six parts of ribs on the fragment, three primaries and three intercalatories. The primaries arise at the umbilical seam, and are low and sharp on the umbilical wall, with inconspicuous clavate bullae on the ventrolateral shoulder. The ribs are broadening on the venter. Description. UJF-ID.15084 is a 90° sector of phragmocone, preserved as a slightly crushed internal mould, with a maximum preserved whorl height of 50 mm. The whorl section is subogival, with a maximum of width above the umbilical edge. The umbilical wall is low and broadly rounded, the flanks are flattened, converging to broadly rounded ventrolateral shoulders. The venter is narrow and flattened. The ornament is made of regularly alternating primary and intercalatory ribs. The primaries arise on the umbilical seam, developing radially elongated swellings at the umbical edge. The intercalatories arise on the inner third of the flanks. All the ribs bear coarse, rounded, inner ventrolateral tubercles, and strong outer ventrolateral clavi. The venter is smooth between the tubercles UJF-ID.15089, differs only by its ribs crossing the venter (Fig. 16.c, d).

Discussion

Discussion. Our specimen is closely related to Mantelliceras couloni, differing only by the persistence of the inner ventrolateral tubercles.

Occurrence. Early Cenomanian of England, France, Iran, ?Romania, Central Tunisia, Japan, and South Africa.

Genus Graysonites [START_REF] Young | Graysonites, a Cretaceous ammonite in Texas[END_REF] Type species. Graysonites lozoi Young, 1958, p. 172, pl. 27 Graysonites cobbani (Amedro, 1994) Fig. 16.e, f 1994 Mantelliceras cobbani Amédro,p. 424,pl. 10,figs 8,10,11;pl. 11,fig. 5;text fig. 34b.

Type. Holotype: MNHN.F.R62636 from Kef el Azreg section (KZ.21, 20 and KZ.26), early Cenomanian, Graysonites cobbani Zone of Amedro, 1994.

Material.

A fragment (UJF-ID.15079) from Bed 27 of Mghila East section, early Cenomanian, Mantelliceras mantelli Zone of the standard zonation, Graysonites cobbani Zone of Amedro, 1994.

Description. UJF-ID.15079 (Fig. 16.e, f) is a small sector of phragmocone, preserved as a slightly crushed calcareous internal mould, with a maximum preserved whorl height of 24 mm. The whorl section is distorted. There are five ribs on the fragment preserved, three primaries and two intercalatories. The primaries arise on the umbilical seam, develops small radially elongated bullae at the umbical edge, almost inconspicuous lateral swellings, stronger inner ventrolateral conical tubercles (spines) and strong outer ventrolateral tubercles (spines). The venter is almost smooth. The intercalatories differs only from the primaries by the lack of periumbilical bullae.

Discussion. Our fragment differs in no respect from the holotype figured by Amédro (1994, pl. 10, fig. 11.

Occurrence. The species is known from the early Cenomanian of central Tunisia, Mantelliceras mantelli Zone of the standard zonation, regional Graysonites cobbani Zone of [START_REF] Amédro | Ammonites[END_REF]. Genus Sharpeiceras Hyatt, 1903 Type species. Ammonites laticlavius Sharpe, 1855, p. 31, pl. 14, fig. 1, by the original designation of Hyatt, 1903, p. 111.

Sharpeiceras florencae [START_REF] Spath | On Upper Albian Ammonoidea from Portuguese East Africa, with an appendix on Upper Cretaceous ammonites from Maputoland[END_REF]Fig. 16.g, h 1925 Sharpeiceras florencae Spath, p. 198, pl. 37. 2015Sharpeiceras florencae Spath, 1925: Kennedy et al., p. 14, text-figs 7g-j, p, q, u, w;12j, k, p, q;16f-h;17f-I;[START_REF] Douvillé | ?1955 Pervinquieria spinosa (Adkins): Eristavi[END_REF]20;21;22c-e (with full synonymy). 2015 Sharpeiceras florencae Spath, 1925: Kennedy, in Kennedy and Gale, p. 276, pl. 11, fig. 3;text-fig. 19 (with synonymy). 2019 Sharpeiceras florencae Spath, 1925: Kennedy, in Gale et al., p. 226.

Type. The holotype, by monotypy, is the original of Spath, 1925, p. 19, pl. 37, in Description. UJF-ID.15080 (Fig. 16.g, h) is a 190° sector of phragmocone, preserved as slightly crushed internal mould, with a maximum preserved whorl height of 42 mm. The intercostal whorl section is compressed, with feebly convex flanks, broadly rounded umbilical edge and broadly rounded ventrolateral shoulders. The venter relatively narrow, and flattened to very feebly convex. There are five widely separated primary ribs on the fragment. They arise at the umbilical seam, and are low and broad on the umbilical wall, with inconspicuous bullae on the umbilical shoulder. The ribs on the flanks are low, broad and coarse, bearing coarse mid-lateral tubercles, strong conical inner ventrolateral tubercles and smaller outer ventrolateral clavi. The venter is smooth between the clavi. UJF-ID.15081 is a strongly weathered fragment, comprising a 120° sector of body chamber, with a maximum preserved whorl height of 65 mm. Parts of six ribs are preserved on the fragment, with well-developed mid-lateral tubercles (the umbilical area is too weathered), strong, coarse inner ventrolateral tubercles and outer ventrolateral tubercles.

Occurrence. Early Cenomanian of northeastern KwaZulu-Natal, South Africa ('Maputo land'), Madagascar, India, Angola, Peru, and northern Mexico.

Family: Flickiidae [START_REF] Adkins | Handbook of Texas fossils[END_REF] Subfamily: Salaziceratinae [START_REF] Kennedy | Ammonites from the Pawpaw Shale (Upper Albian) in northeast Texas[END_REF]Wright, 1984 Genus Metascaphites Wiedmann, 1962 Type species. Scaphites (?) Thomasi Pervinquière, 1907, p. 121, pl. 4, fig. 30, 31;text-fig. 39, by the original designation of Wiedmann, 1962, p. 212.

Remarks. According to Wright et al. (1996, p. 261), Scaphites (?) thomasi Pervinquière, appears to be a fragment of a late form of Scaphites equalis J. Sowerby, 1813. This statement is not supported by the facts: Metascaphites thomasi is older than Scaphites equalis and is a micromorph ammonite that have no shaft and no hook.

Type. The holotype, by monotypy, is the original of Brongniart (1822, pl. 7, fig. 3), from the Montagne de Fiz, Savoie, France. The specimen has not been traced. Spath, pp. 429, 431. 1996 Mariella (Mariella) dorsetensis Spath, 1926: Wright and Kennedy, p. 344, pl. 100, figs 5, 11, 17, 19, 22, 25;pl. 102, fig. 7;text-fig. 136b, e (with full synonymy).

Material

2015 Mariella (Mariella) aff. dorsetensis [START_REF] Spath | On the Zones of the Cenomanian and Uppermost Albian[END_REF]: Kennedy, p. 312, pl. 24, fig. 15. 2016Mariella dorsetensis Spath, 1926: Klein, p. 141 (with additional synonymy).

Type. The holotype, by monotypy, is BMNH C3834, the original of Sharpe, 1857, pl. 26, fig. 11, refigured by Wright andKennedy, 1996, pl. 100, fig. 5 Description. (UJF-ID.15067-72) are juvenile, preserved as calcareous internal moulds, with a maximum preserved whorl height of 10 mm (Fig. 17.i, j). There are four rows of tubercles, the tubercles of successive rows displace adaperturally. The tubercles of the upper row and the second row are subequal, and rounded to slightly transversely elongated. The first row is above the middle of the exposed whorl face, the second row is in the middle part. The tubercles of the the third row are subequal to those of the previous rows, and lie towards the bottom of the exposed whorl face. The tubercles of the fourth row are smaller, and partially concealed in the notches in the inter-whorl contact zone. A very juvenile specimen, with a maximum preserved whorl height of 6 mm, with a broad smooth area between the first and the second row of tubercles, seems to be transitional to Mariella (Mariella) lewesiensis [START_REF] Spath | On the Zones of the Cenomanian and Uppermost Albian[END_REF].

The calcareous fragments are strongly weathered. UJF-ID.15066 is an adult, consisting of four whorls, including the phragmocone and part of the body chamber, with a maximum preserved whorl height of 35 mm (Fig. 17.k). This specimen is as described by Kennedy (2015, p. 312).

Occurrence. Mariella (Mariella) Wright and Kennedy (1996, pl. 101, fig. 3).

Material. Two badly preserved fragments (UJF-ID.15077-78) from Bed 30 of Mghila East section; early Cenomanian, Mantelliceras mantelli Zone.

Description. UJF-ID.15077 is an adult, preserved as a weathered calcareous internal mould, consisting of two whorls, with a maximum preserved whorl height of 30 mm (Figs 17.l). The outer whorl face is convex in intercostal section, the junction of outer and lower whorl faces rounded, the lower whorl face flattened. There are four rows of tubercles, four in a distance equal to the whorl height, the tubercles of successive rows displace adaperturally. The tubercles of the upper row are strong and conical, and are separated from the second row by a broad smooth zone. The tubercles of the upper row are slightly less numerous than those of the second row. The second row have slightly smaller conical tubercles, and a narrow smooth zone separates the second and third rows, the latter lying just above the junction of the outer and lower whorl faces. A fourth row of tubercles, close to the third one is located in the interwhorl suture and the tubercles are slightly smaller and conical; they give rise to weak radial ribs that extend across the base of the whorl.

Remarks. This species differs from Mariella (M.) dorsetensis by its conical, less numerous tubercles, its broader smooth area between the first and second row of tubercles, and less numerous tubercles of the first row. Lectotype. The adult specimen figured by Pictet andCampiche (1861, pl. 44, fig.1, designed andrefigured by Wiedmann (1965, p. 426, pl. 54, fig. 6).

Occurrence

Material. UJF-ID.15002, from Bed 19 of Mghila East section, late Albian, Mortoniceras (Subschloenbachia) perinflatum Zone.

Description. UJF-ID.15002 (Fig. 17.g, h) is a 11.5 mm fragment, preserved as a pyritized internal mould, comprising the initial whorls until the very beginning of the shaft. The whorl section is depressed, with rounded ventrolateral margins and broad feebly convex venter. The ribs are very fine, tending to be divided into 2-3 ribs on the venter from minute ventrolateral bullae.

Remarks. Cooper (1990) considers that S. meriani is a synonym of Scaphites hugardianus d'Orbigny, 1842, on the basis of a study of morphological intraspecific variation of the species without taking into account the biostratigraphic range of both taxa. [START_REF] Scholz | Die Ammoniten des Vracon (Oberalb, dispar Zone) des Bakony-Gebirges (Westungarn) und eine revision der wichtigsten Vracon-arten der West-medirranen faunenprovinz[END_REF] mentions that S. meriani could be younger than S. hugardianus. We herein regard both species as independent and valid pending a revision on the basis of stratigraphically well documented material.

Occurence. South Tunisia, late Albian, Mortoniceras (Subschloenbachia) perinflatum Zone. The species is also known from the latest Albian of France, Hungary, Romania, Sardinia, Switzerland and ?Madagascar.

Plesiosaur

The repositeries of specimens is UJF-ID: ISTerre, Université

General preservation

Five incomplete vertebrae have been discovered. They have been found at the surface, near a small erosive channel filled with fine sandstone. So, they probably have been reworked during a transgressive phase in a channel, firstly dug during an emersion and then flooded during the transgression and acting temporarily as a tidal channel. As a result of both action (current exposure in desert environment and syn-sedimentary reworking), the bones are poorly preserved, with very few of the original periostic surface bone kept, revealing a highly spongious internal structure. The centra exhibit also some distorsion, indicating that a synsedimentary compression probably occurred during diagenesis. Only the centra are preserved and none is complete, rending their identification along the vertebral column difficult. However, the fact that these centra have been found all close together, combined with their similar size, indicate that they most probably belong to the same individual and from an adjacent part of the vertebral column.

Description

Cervical centrum (H=9,5 cm, W=8,5 cm, L=7 cm) (Fig. 18 A-D) -This centrum is slightly laterally compressed and partially preserved. It is slightly higher than wide than long but these measurements remain approximate due to its poor preservation. The articular surfaces are almost amphiplate and bear a large horizontally oval (2x1 cm) notochordal pit. In dorsal view, the typically hourglass-shaped neural canal is well visible, flanked laterally in its median part by two oval foramina. Laterally to the neural canal, there is a large ovoid surface (better preserved on left side), which sutural zone is still visible, and corresponding to the neural arch insertion. The right lateral surface preserves on its posteroventral part a pronounced knob that probably corresponds to the transverse process of the rib. The ventral surface is regularly rounded without any keel and bears two almost central nutritive foramina. Two larger and more laterally located foramina are also present. On the basis of all these characters, this centrum could correspond to one of the last cervical vertebra (see for example [START_REF] Welles | Elasmosaurid plesiosaurs with a description of new material from California[END_REF].

Pectoral centrum (H=9,5 cm, W=8 cm, L=6 cm) (Fig. 18 E-H) -This centrum is distorted and broken, so that the median plane of symmetry was difficult to determine. In anterior/posterior view, the centrum has a roughly triangular shape. The articular surfaces, though eroded, were most probably almost amphiplate with a large horizontally oval (2x1cm) notochordal pit. In dorsal view, only one part of the neural canal with a median foramen is preserved. Laterally to the neural canal, a large roughly oval rugous surface and protuberance indicate that the rib transverse process was probably located on both the centrum and the neural arch, as usual in pectoral vertebrae [START_REF] Brown | The English Upper Jurassic Plesiosauroidea (Reptilia) and a review of the phylogeny and classification of the Plesiosauria[END_REF]. The lateral surfaces of the centrum are regularly convex and bear at least three pairs of nutritive foramina, regularly spaces.

Because the rib process is highly situated and located on both the centrum and neural arch, this centrum could be one of the latest pectoral vertebra.

Dorsal centrum (H=9 cm, W=9 cm, L=6 cm) (Fig. 18 I-K) -Though also partially preserved, this centrum is the best preserved. The proportions are mostly similar to the pectoral centrum but the articular surfaces are rounded. They are almost amphiplate with a large and distinct horizontally oval (2x1cm) notochordal pit. The dorsal surface bears the trace of the neural canal flanked laterally by two oval foramina, and laterally by a large ovoid surface corresponding to the neural arch insertion which suture is visible. The lateral surfaces of the centrum, though badly preserved seems regularly convex and bear ventrally three nutritive foramina regularly spaced. This centrum whose lateral surfaces lacks any rib facet is interpreted as a dorsal one [START_REF] Brown | The English Upper Jurassic Plesiosauroidea (Reptilia) and a review of the phylogeny and classification of the Plesiosauria[END_REF]. ? Cervical centrum fragment (L=8,5 cm) (Fig. 18 L) -Only the dorsal surface, exhibiting the neural canal and the neural arch insertion suture is relatively well preserved. The length of this centrum could however be appreciated as parts of both amphiplate articular surfaces are preserved, showing that it is longer than the other centra here described. This, combined to the occurrence of two close nutritive foramina preserved on the midline of the bone, could indicate an anterior cervical centrum. The other surfaces are all damaged, precluding any detailed description.

Unidentified centrum -A bone fragment probably corresponds to a centrum because of its internal microstructure, very similar to the other described centra. A zone could correspond to the neural canal and a rounded surface to transverse process insertion zone, so that it could correspond either to one of the last pectorals, or to one of the first dorsals.

Systematical attribution

Despite their poor state of preservation, these centra exhibit at least three characteristics permitting to refer them to the clade Plesiosauria (i.e. [START_REF] Brown | The English Upper Jurassic Plesiosauroidea (Reptilia) and a review of the phylogeny and classification of the Plesiosauria[END_REF][START_REF] Storrs | Anatomy and relationships of Corosaurus alcovensis (Diapsida: Sauropterygia) and the Triassic Alcova Limestone of Wyoming[END_REF][START_REF] Storrs | Function and phylogeny in sauropterygian (Diapsida) evolution[END_REF]: 1) amphicoelous articular surfaces; 2) occurrence of paired nutritive foramina subcentralia on the ventral and lateral surfaces of the centra; 3) highly spongious microanatomy. The amphiplate (or acoelous) articular surfaces, as well as elongated cervical vertebrae are typical of Cretaceous long-necked forms, more especially of Elasmosauridae (i.e. [START_REF] Druckenmiller | A phylogeny of Plesiosauria (Sauropterygia) and its bearing on the systematic status of Leptocleidus Andrews[END_REF]Ketchum and Benson, 2010). In pliosauroids and polycotylid plesiosauroids on the contrary, the centra are always distinctively amphicoelous and shorter (L<H). The proportions of the cervical centrum described here, broader than long and high, are usually found in the posterior cervicals of elasmosaurids (e.g., SGO.PV.6506, Lagenanectes richterae, Albertonectes vanderveldei; [START_REF] Kubo | Albertonectes vanderveldei, a new elasmosaur (Reptilia, Sauropterygia) from the Upper Cretaceous of Alberta[END_REF][START_REF] Otero | A new postcranial skeleton of an elasmosaurid plesiosaur from the Upper Cretaceous of central Chile and reassessment of the historic species Cimoliasaurus andium Deecke[END_REF]Sachs et al., 2017). As a result, these vertebrae could tentatively be referred to as an indeterminate elasmosaurid. Moreover, the occurrence of a large notochordal pit probably indicates an immature state of ontogenetic growth [START_REF] Brown | The English Upper Jurassic Plesiosauroidea (Reptilia) and a review of the phylogeny and classification of the Plesiosauria[END_REF]. Unfortunately, the poor preservation and lack of any specific diagnostical character preserved on the material preclude for a more precise systematical determination at the infra-familial level.

Palaeobiogeographical implications

Plesiosaurs were widespread during Cretaceous time, having being found in all continents, including in high latitude environments like those of Antarctica and Australia [START_REF] Gasparini | Systematical review of Aristonectes and Morturneria (Plesiosauria) from the latest Cretaceous of South America and Antarctica[END_REF][START_REF] Kear | Marine reptiles from the Lower Cretaceous of South Australia: elements of a highlatitude cold-water assemblage[END_REF][START_REF] Bardet | Mesozoic marine palaeobiogeography in response to drifting plate[END_REF]. They were mainly represented by numerous genera belonging to Plesiosauroidea (short-necked polycotylids and leptocleidids, as well as longnecked elasmosaurids) and by scarcer Pliosauroidea (short-necked pliosaurids). As far as elasmosaurids are concerned, they are mainly known during the Late Cretaceous whereas they remain scarcer in the Early Cretaceous [START_REF] Bardet | Mesozoic marine palaeobiogeography in response to drifting plate[END_REF]Ketchum and Benson, 2010;[START_REF] Benson | Faunal turnover of marine tetrapods during the Jurassic-Cretaceous transition[END_REF][START_REF] Serratos | A new elasmosaurid (Sauropterygia, Plesiosauria) from the Bearpaw Shale (Late Cretaceous, Maastrichtian) of Montana demonstrates multiple evolutionary reductions of neck length within Elasmosauridae[END_REF]Sachs et al., 2017).

During Albian time, elasmosaurids remain scarce but were widely expanded, having being reported from Canada by Wapuskanectes betsynichollsae [START_REF] Druckenmiller | A new elasmosaurid plesiosaur (Reptilia: Sauropterygia) from the Lower Cretaceous Clearwater formation, northeastern Alberta, Canada[END_REF] and an indetermined specimen [START_REF] Druckenmiller | A new elasmosaurid plesiosaur (Reptilia: Sauropterygia) from the Lower Cretaceous Clearwater formation, northeastern Alberta, Canada[END_REF], Venezuela by Alzadasaurus tropicus [START_REF] Colbert | A new Cretaceous Plesiosaur from Venezuela[END_REF][START_REF] Colbert | A new Cretaceous Plesiosaur from Venezuela[END_REF], Australia by Eromangasaurus australis [START_REF] Sachs | Tuarangisaurus australis sp. nov. (Plesiosauria: Elasmosauridae) from the Lower Cretaceous of northeastern Queensland, with additional notes on the phylogeny of the Elasmosauridae[END_REF] and an indeterminated specimen [START_REF] Sachs | Tuarangisaurus australis sp. nov. (Plesiosauria: Elasmosauridae) from the Lower Cretaceous of northeastern Queensland, with additional notes on the phylogeny of the Elasmosauridae[END_REF][START_REF] Kear | Marine reptiles from the Lower Cretaceous of South Australia: elements of a highlatitude cold-water assemblage[END_REF][START_REF] Kear | Taxonomic clarification of the Australian elasmosaurid genus Eromangasaurus, with reference to other austral elasmosaur taxa[END_REF], and Europe by several indetermined or partial specimens (e.g., [START_REF] Persson | A revision of the classification of the Plesiosauria with a synopsis of the stratigraphical and geographical distribution of the group. Lunds Universitets Årsskrift[END_REF][START_REF] Bardet | Large predatory marine reptiles from the Albian-Cenomanian of Annopol, Poland[END_REF][START_REF] Vincent | Paleoenvironmental context and significance of a partial elasmosaurid skeleton from the Albian of Haute-Provence, France[END_REF].

Plesiosaurs are known in Africa by leptocleidids in the Valanginian of South Africa [START_REF] Andrews | Description of a new plesiosaur (Plesiosaurus capensis, sp. nov.) from the Uitenhage Beds of Cape Colony[END_REF][START_REF] Cruickshank | A Lower Cretaceous pliosauroid from South Africa[END_REF], pliosaurids [START_REF] Angst | A new record of the pliosaur Brachauchenius lucasi Williston, 1903 (Reptilia: Sauropterygia) of Turonian (Late Cretaceous) age, Morocco[END_REF] and polycotylids [START_REF] Bardet | A new polycotylid plesiosaur from the Late Cretaceous (Turonian) of Morocco[END_REF][START_REF] Buchy | Osteology of Manemergus anguirostris n. gen. et sp., a new plesiosaur (Reptilia, Sauropterygia) from the Upper Cretaceous of Morocco[END_REF][START_REF] Allemand | New plesiosaurian specimens (Reptilia, Plesiosauria) from the Late Cretaceous (Turonian) of Goulmima (Southern Morocco)[END_REF][START_REF] Allemand | Endocranial anatomy of plesiosaurians (Reptilia, Plesiosauria) from the Late Cretaceous (Turonian) of Goulmima (southern Morocco)[END_REF] in the Turonian of Morocco. As far as they are concerned, African elasmosaurids are known in Morocco, both in the Turonian [START_REF] Buchy | An Elasmosaur (Reptilia: Sauropterygia) from the Turonian (Upper Cretaceous) of Morocco[END_REF]Sachs and Kear, 2017;[START_REF] Allemand | Virtual re-examination of a plesiosaurian specimen (Reptilia, Plesiosauria) from the Late Cretaceous (Turonian) of Goulmima (Southern Morocco) thanks to computed tomography[END_REF][START_REF] Allemand | New plesiosaurian specimens (Reptilia, Plesiosauria) from the Late Cretaceous (Turonian) of Goulmima (Southern Morocco)[END_REF][START_REF] Allemand | Endocranial anatomy of plesiosaurians (Reptilia, Plesiosauria) from the Late Cretaceous (Turonian) of Goulmima (southern Morocco)[END_REF] and the Maastrichtian [START_REF] Vincent | Zarafasaura oceanis, a new elasmosaurid (Reptilian: Sauropterygia) from the Maastrichtian Phosphates of Morocco and the palaeobiogeography of latest Cretaceous plesiosaurs[END_REF][START_REF] Vincent | New plesiosaur specimens from the Maastrichtian Phosphates of Morocco: implications for niche partitioning in the latest Cretaceous marine top-predators[END_REF], as well as in the Maastrichtian of Angola [START_REF] Araújo | A new elasmosaurid from the early Maastrichtian of Angola and the implications of girdle morphology on swimming style in plesiosaurs[END_REF] and the Maastrichtian of Egypt [START_REF] Werner | First record of elasmosaurs (Reptilia, Plesiosauria) in the Maastrichtian of the Western Desert of Egypt[END_REF] (see [START_REF] Vincent | Zarafasaura oceanis, a new elasmosaurid (Reptilian: Sauropterygia) from the Maastrichtian Phosphates of Morocco and the palaeobiogeography of latest Cretaceous plesiosaurs[END_REF] for details).

The plesiosaur remains from the Albian of Tunisia here described, though being fragmentary, thus represent one of the few occurrences of elasmosaurids from the Albian worldwide and the first plesiosaurian specimen described from Tunisia.

Concluding remarks

-Based on our new collections, twenty-two ammonite species are recognised in the uppermost Albian and lowermost Cenomanian of Djebel Mghila. The Mortoniceras (Subschloenbachia) rostratum and the Mortoniceras (Subschloenbachia) perinflatum Zones of latest Albian age, are recognised on the basis of the occurrence of their key marker species. At the Albian-Cenomanian transition, despite the lack of the index species, the Stoliczkaia (Shumarinaia) africana Zone is also identified by the disappearance of the mortoniceratids.

The Neostlingoceras carcitanense Subzone of the Lower Cenomanian Mantelliceras mantelli Zone is doubtfully recorded in Mghila Centre section, while the Sharpeiceras schlueteri Subzone of the Lower Cenomanian Mantelliceras mantelli Zone is recognised everywhere, on the basis of the occurence of key marker species.

-The species Placenticeras saadensis Thomas and Peron, 1890 is revised, including Engonoceras thomasi [START_REF] Pervinquière | Étude de paléontologie tunisienne. 1 : Céphalopodes des terrains secondaires[END_REF], and is placed within the genus Hypengonoceras [START_REF] Spath | On Cretaceous ammonites from Angola, collected by Prof[END_REF] -The definition of an accurate biostratigraphic framework and identification of sedimentary discontinuities allowed to define 3 depositional sequences in the latest Albian and earliest Cenomanian. Correlation with other well-dated sections shows that the Albian-Cenomanian transition (S. (S.) africana Zone) is marked by major sea level drop. The latter triggered the emergence of the southeastern areas and the deposition of a lowstand wedge to the NW, fed by erosional channels in the intermediate bypass zone that includes Jebel Mghila.

-The subsequent earliest Cenomanian transgression (N.s carcitanense Subzone) is associated with diachronous, condensed, phosphate-rich deposits in the bypass zone that represents the shelf slope.

-Five vertebrae found at the base of Sequence 2 (base of the M.s (S.) rostratum Zone) are ascribed to an undetermined plesiosaur. They constitute the first plesiosaurian remains reported from Tunisia, and represent one of the few elasmosaurids known in the Albian world.

Fig. 1 .

 1 Fig. 1. Main Cretaceous sedimentary domains in Tunisia, and location of Fig. 2.

Fig. 2 .

 2 Fig. 2. Geological sketch of Central Tunisia (A), and location of the studied sections (B).

Fig. 3 .

 3 Fig. 3. Ammonite distribution along the Albian-Cenomanian transition in Jebel Mghila (location on Fig. 2B)

Fig. 4 .

 4 Fig. 4. Sedimentological sections of the Albian-Cenomanian transition in Jebel Mghila (location on Fig. 2B)

Fig. 5 .

 5 Fig. 5. Sequence stratigraphy interpretation and age of the Albian-Cenomanian transition in Jebel Mghila.

Fig. 6 .

 6 Fig. 6. Correlation and interpretation of the Albian-Cenomanian transition in Central Tunisia. Location of the sections on Fig. 2B. Data are from Philip et al. (1989) for jebels Zaouia and Selloum, from Robaszynski et al. (1993a, 1993b) for Oued Azreg, and from Jaillard et al. (2005) for oued Segui.

  in millimetres: D = diameter; Wb = whorl breadth; Wh = whorl height; U = umbilicus; v = width of the venter. Figures in parentheses are dimensions as a percentage of the diameter. The suture terminology is that of Korn et al. (2003): E = external lobe; A = adventive lobe (= lateral lobe, L, of Kullmann and Wiedmann, 1970); U = umbilical lobe; I = internal lobe. The repositeries of specimens are: UJF-ID: ISTerre, Université of Grenoble Alpes, ex Institut Dolomieu collections. MNHN: Laboratoire de Paléontologie of the Muséum National d'Histoire Naturelle, Paris. BMNH: British Museum of Natural History, London.

Fig. 7 .

 7 Fig. 7. (a, b) Stoliczkaia (Stoliczkaia) sp. juv. indet., UJF-ID.15010, from Bed 2 of Mghila West section, late Albian, Mortoniceras (Subschloenbachia) rostratum Zone ; (c-e) Stoliczkaia (Stoliczkaia) sp. juv., UJF-ID.15011, from Bed 2 of Mghila West section, late Albian, Mortoniceras (Subschloenbachia) rostratum Zone ; (f-h) Stoliczkaia (Stoliczkaia) sp. juv., from Bed 19 of Mghila East section, late Albian, Mortoniceras (Subschloenbachia) perinflatum Zone ; (i, j) Stoliczkaia (Stoliczkaia) clavigera Neumayr, 1875, from Bed 2 of Mghila West section, late Albian, Mortoniceras (Subschloenbachia) rostratum Zone ; (k-m) Metascaphites thomasi Pervinquière, 1907, UJF-ID.15009, from Bed 2 of Mghila West section, late Albian, Mortoniceras (Subschloenbachia) rostratum Zone ; (n) Puzosia sp. juv., UJF-ID.15003 from Bed MR.2 of Mghila West section, late Albian, Mortoniceras (Subschloenbachia) rostratum Zone. Scale bar is 10 mm.

Fig. 8 .

 8 Fig. 8. (a, b) Desmoceras (Desmoceras) latidorsatum (Michelin, 1838), UJF-ID. 15051 from the bed 3 of the Mghila West section, late Albian, Mortoniceras (Subschloenbachia) perinflatum Zone ; (c, d) Pachydesmoceras aff. denisonianum (Stoliczka, 1865), UJF-ID. 15050 from the bed 7 of the Mghila West section, early Cenomanian, Mantelliceras mantelli Zone. Scale bar is 10 mm.

Fig. 10

 10 Fig. 10. (a, b) Hypengonoceras saadense (Thomas and Peron, 1890), UJF-ID.15047, from MR.3, Mortoniceras (Subschloenbachia) perinflatum Zone. Scale bar is 50 mm.

Fig. 11 .

 11 Fig. 11. Hypengonoceras saadense (Thomas and Peron, 1890) ; (a-c) suture of the early whorls of a destroyed specimen from AG.6, Azreg section, central Tunisia, Mortoniceras (Subschloenbachia) perinflatum Zone ; (d) UJF-ID.15085, an atypical specimen with deeply indented saddles, from AG.6, Azreg section, central Tunisia, Mortoniceras (Subschloenbachia) perinflatum Zone ; (e) The holotype of Engonoceras Thomasi Pervinquière, 1907 (text-fig. 77), unregistered specimen from the Sorbonne collections, now housed in the Museum d'Histoire Naturelle de Paris, from the late Albian of Foum El Guelta, Jebel Mghila. Scale bar is 1 mm.

Fig. 12 .

 12 Fig. 12. (a-i) Mortoniceras (Subschloenbachia) rostratum (J. Sowerby, 1817). (a, b) UJF-ID.15006, (c) UJF-ID.15008, (d) UJF-ID.15007, (e) UJF-ID.15009 from bed MR.1, Mghila West section ; (f, g) UJF-ID.15004, (h, i) UJF-ID.15005 from bed MR.2, Mghila West section, late Albian, Mortoniceras (Subschloenbachia) rostratum Zone. (j, k) Mortoniceras (Mortoniceras) pachys (Seeley, 1865), UJF-ID.15008 from bed MR. 3, Mghila West section, late Albian, Mortoniceras (Subschloenbachia) perinflatum Zone ; (l-o) ?Cantabrigites sp. nov., UJF-ID.15006 from Bed 2 of Mghila West section, late Albian, Mortoniceras (Subschloenbachia) rostratum Zone. Scale bar is 10 mm.

Fig. 13 .

 13 Fig.13. Mortoniceras (Subschloenbachia) perinflatum[START_REF] Spath | On Cretaceous ammonites from Angola, collected by Prof[END_REF]. (a-b) UJF-ID.15087, (c, d) UJF-ID.15087, from bed MR. 3, Mghila West section, late Albian, Mortoniceras (Subschloenbachia) perinflatum Zone ; (e, f) UJF-ID.15088, from Bed 16A of Mghila east section, late Albian, Mortoniceras (Subschloenbachia) perinflatum Zone. Scale bar is 10 mm.

Fig. 14 .

 14 Fig. 14. Cantabrigites spinosum (Pervinquière, 1907). (a) UJF-ID.15089, (b-d) UJF-ID.15090, (e) UJF-ID.15091, (f) UJF-ID.15092, (g-i) UJF-ID.15093, (j) UJF-ID.15094, (k, l) UJF-ID.15095, from Bed 2 of Mghila West section, late Albian, Mortoniceras (Subschloenbachia) rostratum Zone ; (m, n) UJF-ID.15096, from Bed 19 of Mghila East section, (o, p) UJF-ID.15097 from Bed 15-17 of Mghila East section, (q) UJF-ID.15098 from Bed 3b of Mghila West section, late Albian, Mortoniceras (Subschloenbachia) perinflatum Zone. Scale bar is 10 mm. Description. The inner whorls are characterized by smooth flanks (Figs 14.c, e, f, o), the keel

Fig

  Five pyritized and one calcareous specimens from Bed 2 of Mghila West section, late Albian, Mortoniceras (Subschloenbachia) rostratum Zone, three pyritized specimens from Bed 19 of Mghila East section, late Albian, Mortoniceras (Subschloenbachia) perinflatum Zone.

Fig. 16 .

 16 Fig. 16. (a, b) Mantelliceras lymense[START_REF] Spath | On the Zones of the Cenomanian and Uppermost Albian[END_REF], UJF-ID.15082) from above Bed 5 in Mghila West section, early Cenomanian, Neostlingoceras carcitanense Subzone or Sharpeiceras schlueteri Subzone

  , figs1-11; text-fig 1b, c, d, f, by original designation = Mantelliceras wacoenseBöse, 1928, p. 215, pl. 5, figs 9-25, pl. 6, figs 1-4.

Figure 18 .

 18 Figure 18. Indeterminate elasmosaurid from the base of the Sequence 2, Mghila West section, late Albian, UJF-ID.16000. A-D: posterior cervical centrum in anterior (A), dorsal (B), ventral (C) and left lateral (D) views; E-H: pectoral centrum in anterior (E), dorsal (F), ventral (G) and left lateral (H) views; I-K: dorsal centrum in anterior (I), dorsal (J), and left lateral (K) views; L: ? cervical centrum in dorsal view. Scale is 5 cm.

  , fig.1) from the late Albian of Sakondry (Madagascar).

Family: Desmoceratidae Zittel, 1895 Subfamily: Desmoceratinae Zittel, 1895 Genus and subgenus Desmoceras Zittel, 1884 Type species. Ammonites latidorsatus

Michelin, 1838, p. 101, pl. 12, fig. 9

, by the subsequent designation of

Böhm, 1895, p. 364

. Desmoceras (Desmoceras) latidorsatum (Michelin, 1838) Figs 8.a, b 1838 Ammonites latidorsatus Michelin, p. 101, pl. 12, fig. 9. 2011 Desmoceras (Desmoceras) latidorsatum (Michelin, 1838): Klein and Vašiček, p. 144 (with full synonymy). 2013a Desmoceras (Desmoceras) latidorsatum (Michelin, 1838): Kennedy and Klinger, p. 40, figs 1-5. 2014 (Desmoceras) latidorsatum (Michelin, 1838): Kennedy and Fatmi, p. 58, text-figs 11a-h. 2015 Desmoceras (Desmoceras) cf. latidorsatum (Michelin, 1838): Kennedy, p. 252, pl. 3, fig. 5. Material. UJF-ID. 15051 from the bed MR.3 from the Mghila West section, upper Albian, Mortoniceras (Subschloenbachia) perinflatum Zone.

  EngonocerasThomasiPervinquière, 1907 (p. 202, pl. 9, fig. 6, text-fig. 77), unregistered specimen from the Sorbonne collections, now housed in the Museum d'Histoire Naturelle de Paris, from the late Albian of Foum El Guelta, Jebel Mghila ; (e-g) UJF-ID.15025, from MH.19, Mortoniceras (Subschloenbachia) perinflatum Zone ; (h, i) UJF-ID.15032, from MR.2, Mortoniceras (Subschloenbachia) rostratum Zone ; (j-l) UJF-ID.15038, from MR.3, Mortoniceras (Subschloenbachia) perinflatum Zone ; (m-o) UJF-ID.15043, from MR.3, Mortoniceras (Subschloenbachia) perinflatum Zone. Scale bar is 10 mm. Two fragments from Bed 1, five specimens from Bed 2 of Mghila West section, late Albian, Mortoniceras (Subschloenbachia) rostratum Zone; eleven fragments from Bed 3 of Mghila West section, late Albian, Mortoniceras (Subschloenbachia) perinflatum Zone; one fragment from Bed 4 of Mghila West section, late Albian, Stoliczkaia (Shumarinaia) africana Zone; one fragment from Bed 3 of Mghila Centre section, late Albian, Stoliczkaia (Shumarinaia) africana Zone; two fragments from interval 15-17, and 4 specimens from Bed 19 of Mghila East section, late Albian, Mortoniceras (Subschloenbachia) perinflatum Zone; The original material figured by Thomas and Peron, and the holotype of Engonoceras thomasi Pervinquière, 1907 from the late Albian of Foum El Guelta, Jebel Mghila.

	Measurements.
	16, figs 5, 7, refigured
	by Latil, 1989, p. 54, pl. 1, fig. 1). The original material figured by Thomas and Peron has
	been refigured by Latil (1989, pl. 1, fig. 1, 2), by Kennedy (2015, pl.1, fig. 5, 7), and is

) designated as the holotype, one of the fragments from the type locality of Bou Saada : 'Quoi qu'il en soit, il s'agit d'une forme au moins très voisine de l'espèce du Vraconien sup. (à Mariella Bergeri Brgn. sp.) ou du Cénomanien basal (à Hypoturrilites carcitanensis Mather. sp.) d'Algérie (Bou Saada = local.-typ. : holotype non fig., Khenchela) et de Tunisie (Dj. Meghila, Dj. Roumana, Dj. Meghila, D. Adira).' In the 1980', one of us (J.-L.L) tried to trace the Algerian material in the Sorbonne collections, unsuccessfully. Consequently, Latil (1989, p. 54) designated a neotype from the two Tunisian fragments figured by Thomas and Peron: MNHN.R52073, the original figured by Thomas and Peron (1890, pl. available online on the website of the Museum National d'Histoire Naturelle de Paris. (https://science.mnhn.fr/institution/mnhn/collection/f/item/r52073?listIndex=2&listCount=13) Fig. 9. Hypengonoceras saadense (Thomas and Peron, 1890). (a-d) The holotype of Material. UJF-ID.15032: D: 6.0; Wh: 2.5 (0.42); Wb: 2.5 (0.42); U: 2.0 (0.33); Wb/Wh: 1.00 UJF-ID.15025: D: 18.0; Wh: 10.0 (0.56); Wb: 5.8 (0.32); U: 2.4 (0.13); Wb/Wh: 0.58 The holotype of Engonoceras Thomasi Pervinquière, MNHN unregistered specimen: D: 32; Wh: 18.5 (0.58); Wb: 9.3 (0.29); U: 2.7 (0.08); Wb/Wh: 0.50 UJF-ID.15047: D: 360; Wh: 200 (0.55); Wb: 100 (0.28); U: ? (?); Wb/Wh: 0.50 Description. The early stages of the ontogeny are known by the inner whorls of a wellpreserved juvenile pyritized specimen, 6 mm in diameter (UJF-ID.15032: Figs 9.

  Ammonites vespertinusMorton, 1834, p. 40, pl. 17, fig. 1, by the original designation of Meek, 1876, p. 448. Mortoniceras (Pervinquieria) inflatum (Sowerby): Besairie, p. 555, pl. 16 fig. 1. 1932 Mortoniceras (Pervinquieria) pachys (Seeley): Spath, p. 405; text-fig. 130d, 138-139. 1979 Pervinquieria (Pervinquieria) pachys (Seeley): Scholz, p. 110, pl. 29, fig. 9a, 9b 1997 Mortoniceras groupe pachys (Seeley): Delamette et al., pl. 36, fig. 2, 3 2008 Mortoniceras (Mortoniceras) pachys (Seeley): Kennedy et al., p. 43.

	Subgenus Mortoniceras Meek, 1876
	Mortoniceras (Mortoniceras) pachys (Seeley, 1865)
	Figs 12.j, k
	1865 Ammonites pachys Seeley, p. 227; pl. 9, fig. 4.
	1930

Superfamily: Acanthoceratoidea De Grossouvre, 1894 Family: Brancoceratidae Spath, 1934 Subfamily: Mortoniceratinae H. Douvillé, 1912 Genus Mortoniceras Meek, 1876 Type species. 2017 Mortoniceras (Mortoniceras) pachys (Seeley, 1865): Benzaggagh et al., p. 90, fig. 12I1, 12I2, 12I3. 2018. Mortoniceras (Mortoniceras) pachys pachys (Seeley, 1865): Klein, p. 118 (with additional synonymy).

  The holotype, by monotypy, is OUM K 835, the original of Ammonites rostratus J.Sowerby, 1817, p. 163, pl. 173, from the Upper Greensand of Roke, 1.5 km NNE ofBenson, Oxfordshire, refigured by Latil (1995, pl. 1, fig. 1). Nine fragments from Bed 1 and two fragments from Bed 2 of Mghila West section, two fragments from Bed 11b of Mghila East section, late Albian, Mortoniceras (Subschloenbachia) rostratum Zone.Description.UJF-ID.15004 and 15005 (Figs 12.f-i) are juvenile specimens preserved as pyritized internal mould with a diameter of about 25 mm. Coiling is moderately evolute. The umbilical wall is feebly convex, the umbilical shoulder broadly rounded. The intercostal whorl section is depressed (Wb/Wh at about 1.05) trapezoidal, the ventrolateral shoulders broadly rounded, the venter flattened, with a strong siphonal keel. Coarse ribs arise on the umbilical wall and strenghten into strong, conical umbilical tubercle. The tubercles give rise to generally two, rarely one, radial to slightly prorsiradiate ribs. The ribs bear inconspicuous outer lateral bullae, a small inner ventrolateral conical tubercle, from which the ribs become slightly projected forward, giving rise to a small outer ventrolateral conical tubercle and declining on the venter. A narrow smooth zone separates the ribs from the siphonal keel.The material from Bed 1 of Mghila West section and Bed 11b of Mghila East section comprises weathered fragments of subadult and adult specimens, preserved as limestone internal moulds (Figs 12.a-e). At a diameter of about 40 mm, the lateral bullae become stronger and migrate to the mid-flanks. At a larger diameter, the ribs are regularly alternating, one primary for one intercalatory, the lateral tubercles are stronger, tending to become radially elongated, and the inner and outer ventrolateral tubercles tend to merge in a single bulge. The adult body chamber (Wh at about 40 mm and more) is characterized by the lack of umbilical tubercles, the lack of intercalatory ribs, the presence of radially elongated lateral tubercles and the presence of coarse, ventrolateral bulge/tubercle. Close to the aperture (Wh at about 50 mm), the tubercles are disappearing and the ribs are strongly projected forward on the venter.

	fig. 150. 1979 Mortoniceras (Durnovarites) perinflatum (Spath, 1922): Cooper and Kennedy, p. 269, figs 3g, 61, 62d-i, 63, 64 (with synonymy). Material. 238; text-2005 Mortoniceras (Durnovarites) perinflatum (Spath, 1922): Kennedy et al., p. 365, text-figs
	10a, 11a-f (with additional synonymy).
	2007 Mortoniceras (Subschloenbachia) perinflatum (Spath, 1922): Kennedy and Latil, p. 465,
	pl. 3, figs 2, 4, 5 (with additional synonymy).
	2011 Mortoniceras (Subschloenbachia) perinflatum (Spath, 1922): Kennedy in Gale et al., p.
	76, text-figs 28a, f, g, 29f.

[START_REF] Sowerby | The Mineral Conchology of Great Britain, 1-4[END_REF]

Figs 12.a-i 1817 Ammonites rostratus J.

Sowerby, p. 163, p1. 173.

1898 Schloenbachia inflata Sow. Typische form;

Kossmat, p. 190 (40) (pars), pl. 23 (19), fig. 2; pl. 24, fig. 1. 1995

Mortoniceras rostratum (J. Sowerby, 1817):

Latil, pl. 1, fig. 1 (= specimen of Sowerby, 1817, pl. 173), pl. 2, fig. 1. 2007

Mortoniceras (Subschloenbachia) rostratum (J. Sowerby, 1817):

Kennedy and Latil, p. 463, pl. 3, fig. 2; pl. 3, figs 3,[6][7][8][START_REF]et Peron: Pervinquière[END_REF] pl. 4, figs 7, 8 (with additional synonymy)

. 2010 Mortoniceras (Mortoniceras) rostratum (J. de C. Sowerby):

Owen et al., p. 190, pl. 35

, fig. 1. Non 2018 Mortoniceras (Subschloenbachia) cf. rostratum (J. Sowerby, 1817): El Qot, p. 38, fig. 11F, 11G, 11H. 2018 Mortoniceras (Mortoniceras) rostratum (J. Sowerby, 1817): Klein, pp. 101, 122 (with additional synonymy). 2019. Pervinquieria (Subschloenbachia) rostrata (J. Sowerby, 1817), Kennedy, p. 214, pl. 13, pl. 14, figs 1, 2. Type. Remarks. The specimen figured by El Qot (2018, p. 163, fig 11F-H) from the late Albian of Wadi El Karm (Sinai, Egypt) is merely a Mortoniceras (Mortoniceras) inflatum). At that size, M. (S.) rostratum still shows strong lateral tubercles.

Occurrence. Mortoniceras (Subschloenbachia) rostratum Zone of south Tunisia. The species is widespread in the late Albian of Bulgaria, Caucasus, Crimea (Ukraine), France, England, Germany, Hungary, Poland, ?Romania, Spain, Switzerland, Angola, Madagascar, Iran, Texas (United States), India and Japan.

Mortoniceras (Subschloenbachia) perinflatum

(Spath, 1922a)

Figs 13.a-f 1860 Ammonites inflatus

Pictet and Campiche (non J. Sowerby): p. 178, pl. 21, fig. 5; pl. 22, fig. 3. 1903 Mortoniceras inflatum Sow: Pervinquière, p. 66. 1907 Mortoniceras inflatum Sowerby: Pervinquière, p. 229 (pars)

. 1922 Inflaticeras (Subschloenbachia) perinflata

Spath, p. 113. 1933

Mortoniceras (Durnovarites) perinflata

Sowerby: Spath, p. 430, pl. 40, fig. 2011

Mortoniceras (Subschloenbachia) perinflatum

[START_REF] Spath | On Cretaceous ammonites from Angola, collected by Prof[END_REF]

:

Meister et al., p. 690, textfig. 5a, b. 2013

Mortoniceras (Subschloenbachia) cf. perinflatum

[START_REF] Spath | On Cretaceous ammonites from Angola, collected by Prof[END_REF]

:

Wilmsen et al., p. 501, text-fig. 7a-c. 2015

Mortoniceras (Subschloenbachia) perinflatum

[START_REF] Spath | On Cretaceous ammonites from Angola, collected by Prof[END_REF]

:

Kennedy, p. 256, pl. 4, figs 3, 4, 6. 2018

Mortoniceras (Durnovarites) perinflatum

[START_REF] Spath | On Cretaceous Cephalopoda from Zululand[END_REF]

: Klein, p. 140 (with additional synonymy).

  The lectotype, designated byKennedy, 2004, p. 877, is the original of Mortoniceras inflatum Var. spinosaPervinquière, p. 229, pl. 11, fig. 3a, 3b of Jebel Zrissa (Djerissa), central Tunisia, an unregistered specimen in the Sorbonne collections, now housed in the Museum Nationale d'Histoire naturelle, Paris with the number MNHN.F.J04325.

	Material. One specimen from Bed 1, seventy-two pyritized specimens from Bed 2 of Mghila
	West section, late Albian, Mortoniceras (Subschloenbachia) rostratum Zone; six pyritized
	, fig. 3, specimens from Bed 3b of Mghila West section; six pyritized specimens from Bed 13-15, two
	by the original designation of Spath, 1933, p. 436. pyritized specimens from Bed 15-17, eight specimens from Bed 19 of Mghila East section;

Cantabrigites spinosum

[START_REF] Pervinquière | Étude de paléontologie tunisienne. 1 : Céphalopodes des terrains secondaires[END_REF]

Figs 14.a-q 1907 Mortoniceras inflatum Var. spinosa

Pervinquière, p. 229, pl. 11, fig. 3. 1920 Schloenbachia sp.: Adkins, pl. 1, fig. 5; pl. 4, fig. 1.

Type. late Albian, Mortoniceras (Subschloenbachia) perinflatum Zone.

  Ten pyritized specimens from Bed 2 of Mghila West section, two pyritized specimens from Bed 13-15 of Mghila East section, late Albian, Mortoniceras (Subschloenbachia) rostratum Zone, four fragments from Bed 3, and one pyritized specimens from Bed 3b of Mghila West section, one fragment from bed 3 of Mghila Centre section, and three pyritized specimens from bed 19 of Mghila East section, late Albian, Mortoniceras (Subschloenbachia) perinflatum Zone. A specimen (UJF-ID.15083), from Bed 10 of Mghila Centre section, early Cenomanian, Neostlingoceras carcitanense Subzone?, is closely related to this species.

	Measurements.
	0.72
	UJF-ID. 15015: D: 17.9 mm; Wh: 9.0 (.50); Wb: 6.5 (.36); U: 3.0 (.17); Wb/Wh: 0.72
	UJF-ID. 15016: D: 21.5 mm; Wh: 11.2 (.52); Wb: 7.6 (.35); U: 2.7 (.13); Wb/Wh: .68
	UJF-ID. 15017: D: 18.7 mm; Wh: 9.6 (.51); Wb: 7.4 (.40); U: 2.7 (.14); Wb/Wh: .77
	UJF-ID. 15018: D: 21.2 mm; Wh: 10.7 (.50); Wb: 9.0 (.42); U: 3.0 (.14); Wb/Wh: .84
	UJF-ID. 15019: D: 22.0 mm; Wh: 10.5 (.47); Wb: 7.8 (.35); U: 3.4 (.15); Wb/Wh: .74

UJF-ID. 15013: D: 15.0 mm; Wh: 7.0 (.47); Wb: 5.4 (.36); U: 2.5 (.17); Wb/Wh: 0.77 UJF-ID. 15014: D: 13.5 mm; Wh: 6.9 (.51); Wb: 5.0 (.37); U: 2.4 (.17); Wb/Wh:

  The lectotype, by the subsequent designation of[START_REF] Wright | The Ammonoidea of the Lower Chalk. Part 1[END_REF], p. 102, is the original of Pervinquière 1907, pl. 16, fig. 16, refigured by Wright and Kennedy 1984, textfig. 24a, b, from south of Bargou, Tunisia, an unregistered specimen in the collections of the École des Mines, Paris, currently housed in the collections of the Université de Lyon 1-Villeurbanne.

	)
	Figs 16.a, b
	1926 Eucalycoceras lymense Spath, pp. 427, 431.
	1984 Mantelliceras lymense (Spath, 1926): Wright and Kennedy, p. 102, pl. 10, fig. 9, pl. 22,
	figs 1-6, pl. 23, figs 1-3, pl. 31, figs 1, 2, pl. 36, fig. 4, text-figs 19, 24a, b, 26d, 28f-j (with
	full synonymy).
	2004 Mantelliceras lymense (Spath, 1926): Amédro, in Robaszynski et al., p. 406, pl. 10, figs
	1, 2.
	2011 Mantelliceras lymense (Spath, 1926): Mosavina and Wilmsen, p. 182, text-figs 4d, e
	(with additional synonymy).
	2015 Mantelliceras lymense (Spath, 1926): Kennedy, in Kennedy and Gale, p. 265, pl. 3, fig.
	1; pl. 7, figs 1, 6; pl. 8, figs 2, 6; pl. 23, fig. 2; text-fig. 14.
	2019 Mantelliceras lymense (Spath, 1926): Kennedy, in Gale et al., p. 223, pl. 21, figs 1, 8; pl.
	22, Figs 3, 4.
	Type.

Material.

A loose fragment (UJF-ID.15082) from above Bed 5 in Mghila West section, early Cenomanian, Neostlingoceras carcitanense Subzone or Sharpeiceras schlueteri Subzone of the Mantelliceras mantelli Zone.

.

  See Kennedy, in Kennedy and Gale, 2015, p. 265. Occurrence. Early Cenomanian, southern England, Northern Ireland, France, Algeria, Tunisia, Madagascar, Tamil Nadu, and possibly Germany and Iran. The lectotype, by the subsequent designation ofJuignet and Kennedy (1976, p. 95) is R8011 (collections of the Laboratoire de Paléontologie of the Muséum National d'Histoire Naturelle, Paris), from the early Cenomanian of Lamnay, Sarthe, France, refigured byWright and Kennedy (1984, text-fig. 20G-I) andKennedy and Juignet in Gauthier (2006, pl. 51, fig. 1).

	Mantelliceras couloni (d'Orbigny, 1850)
	Fig. 16.c, d
	1841 Ammonites Mantelli Sowerby, Orbigny, p. 340 (pars), pl. 104, figs 1-4.
	1850 Ammonites Couloni d'Orbigny, p. 147.
	1984 Mantelliceras couloni (d'Orbigny, 1850): Wright and Kennedy, p. 119, pl. 21, fig. 1, pl.
	23, figs 5, 6, pl. 29, figs 1-3, pl. 30, figs 1, 2, pl. 31, figs 3-5, pl. 36, fig. 5, textfigs 25f, h, 27a-
	d (with full synonymy).
	2015 Mantelliceras couloni (d'Orbigny, 1850): Kennedy, in Kennedy and Gale, p. 268, pl. 7,
	figs 2, 5; Pl. 8, fig. 3 (with synonymy).
	Material. A fragment (UJF-ID.15084) from Bed 10 of Mghila Centre section, and one
	fragment (UJF-ID.15089) from Bed 30 of Mghila East section, early Cenomanian,
	Mantelliceras mantelli Zone.

Type.

  the collections of the Ditsong Museum of Natural History (formerly the Transvaal Museum), Pretoria, from northeastern KwaZulu-Natal, South Africa ('Pondoland').

	Material. A loose fragment (UJF-ID.15080) from above Bed 25 in Mghila East section and a
	loose fragment (UJF-ID.15081) from above Bed 12 of Mghila Centre section, early
	Cenomanian, Mantelliceras mantelli Zone.

  Description. UJF-ID.15052-53 are juvenile, preserved as crushed, pyritized internal moulds, with a maximum preserved whorl height of about 10 mm. On the upper part of the flanks, they are feeble prorsiradiate ribs, ending to small transversely elongated tubercles. A smooth zone separates them from a second row of feebly transversely elongated tubercles, displaced adaperturally at mid-flank. Another smooth zone separates this row from a third row of conical to feebly transversely elongated tubercles, again displaced adaperturally. A third smooth zone separates this row from the fourth row of smaller tubercles, again displaced aperturally, and housed in notches in the junction of the outer and upper whorl faces of the succeeding whorl. They give rise to single radial ribs on the lower whorl face (Fig.17.c). UJF-ID.15054-58 are slightly distorted fragments, preserved as weathered internal moulds, with a maximum preserved whorl height of about 37 mm. At this stage of growth, the upper row of tubercles has moved at just above mid-flanks and the two lower rows of tubercles are closer each other(Fig. 17.d, e). Widespread in the uppermost Albian Mortoniceras (S.) perinflatum and Arrhaphoceras briacensis Zones. Southern England, France, Switzerland, Germany, Spain, Italy, Hungary, Romania, Crimea, Caucasus, Turkmenistan, Kopet Dag, Iran, Morocco, Algeria, Tunisia, India, South Africa, Venezuela and California.

	Occurrence. Mariella (Mariella) dorsetensis Spath, 1926
	Fig. 17.i-k
	1857 Turrilites bergeri Brongniart: Sharpe, p. 65 (pars), pl. 26, figs 9, 11 only.
	1926 Turrilites dorsetensis
	. Two fragments (UJF-ID.15052-53) from the interval 22-24 and 5 fragments from
	Bed 23 (UJF-ID.15054-58) of Mghila East section, late Albian, Stoliczkaia (Shumarinaia)
	africana Zone.

  , from Chardstock, Devon. Neostlingoceras carcitanense Subzone and Sharpeiceras schlueteri Subzone of the Mantelliceras mantelli Zone.

	Material. A series of badly preserved fragments: 3 fragments (UJF-ID.15061-63) from Bed 7
	(UJF-ID.15054-58) of Mghila West section; 3 fragments (UJF-ID.15064-66) from Bed 26 of
	Mghila East section; 5 fragments (UJF-ID.15067-71) from bed 5, 2 fragments (UJF-
	ID.15059-60) from Bed 10, and 4 fragments (UJF-ID.15054-58) from Bed 12-13 of Mghila
	Centre section; early Cenomanian,

  dorsetensis is known from the lower part of early Cenomanian of southern England, northern France, Poland, Turkmenistan, Iran, Madagascar and Peru. The holotype, by monotypy, is BMNH 33558, the original of Sharpe 1857, pl. 26, fig. 10, from the Chalk Marl near Lewes, Sussex, refigured by

	Mariella (Mariella) lewesiensis (Spath, 1926)
	Figs 17.l
	1857 Turrilites bergeri Sharpe, p. 65 (pars), pl. 26, fig. 110 only.
	1926 Turrilites lewesiensis Spath, pp. 429, 431.
	1996 Mariella (Mariella) lewesiensis (Spath, 1926): Wright and Kennedy, p. 339, pl. 100, fig.
	4; pl. 101, figs 2, 3; pl. 103, figs 6-8 (with synonymy).
	2015 Cenomariella lewesiensis lewesiensis (Spath, 1926): Klein, p. 153 (with full synonymy).
	2017 Mariella lewesiensis (Spath, 1926): Mosavina and Wilmsen, p. 118, text-fig. 4b, g (with
	additional synonymy).
	2019 Mariella (Mariella) lewesiensis (Spath, 1926): Kennedy, p. 287, pl. 52, figs 7, 12.
	Type.

.

  Early Cenomanian, Mantelliceras mantelli Zone of Jebel Mghila, Tunisia. The species is also known from the early Cenomanian, southern England, France, Germany, Switzerland, Poland, Iran, Turkmenistan, South Africa, Madagascar, India, Japan, and Peru. UJF-ID.15000 (Figs 17.f) is a 17 mm long fragment, preserved as a crushed pyritized internal mould. The whorl section oval, with a maximum preserved whorl height of 10 mm. The ribs are feeble, effaced on the dorsum, narrow and widely spaced on the flanks, where they are straight and prorsiradiate, crossing the venter without interruption. Scaphites equalis J.Sowerby, 1813, p. 53, by subsequent designation ofMeek, 1876, p. 413. Scaphites) meriani Pictet and Campiche:Scholz, p. 44, pl. 1, figs 26-28. 1981 Scaphites meriani tenuisChiriac, p. 75, pl. 7, fig. 8. 2008 Scaphites meriani Pictet and Campiche: Joly and Delamette, fig. 8G. 2016b Scaphites meriani meriani Pictet and Campiche, 1861: Klein, p. 84 (with full synonymy).

	Family: Baculitidae Gill, 1871 Type species. Scaphites aff. meriani Pictet et Campiche, 1861
	Genus Lechites Nowak, 1908. Fig. 17.g, h
	1861 Scaphites meriani Pictet and Campiche, p. 16, pl. 44, figs 1-4, 8 only. Type species. Baculites gaudini Pictet and Campiche, 1861, p. 112, pl. 55, figs 5-9, by the 1965 Scaphites (Scaphites) meriani Pictet and Campiche: Wiedmann, p. 426, pl. 54, fig. 6; pl. original designation of Nowak, 1908, p. 350. 57, figs 3-4 (with synonymy).
	1968 Scaphites (Scaphites) meriani Pictet and Campiche: Wiedmann and Dieni, p. 84, pl. 7,
	Lechites gaudini (Pictet et Campiche, 1861) fig. 4; pl. 8, fig. 4; pl. 15, fig. 8.
	Fig. 17.f 1968 Scaphites (Scaphites) n. sp.: Renz, p. 94, pl. 18, fig. 19; textfig. 33b.
	1861 Baculites gaudini Pictet and Campiche, p. 112, pl. 55, figs 5-9. 1979 Scaphites (
	1977 Lechites gaudini (Pictet and Campiche): Cooper and Kennedy, p. 644, text-figs 1.1-
	1.38; 2.1-2.30; 3; 4.1-4.18; 5.115; 6; 7; 8.16-26 (with synonymy).
	2016a Lechites (Lechites) gaudini (Pictet and Campiche, 1861): Klein, pp. 2, 4 (with
	synonymy).
	2016a Lechites (Lechites) communis Spath, 1941: Klein, pp. 2, 3 (with synonymy).
	2016a Lechites (Lechites) campichei Renz, 1968: Klein, pp. 2, 3 (with synonymy).
	Lectotype. The original of Pictet and Campiche 1861, p. 112, pl. 55, fig. 5, by the subsequent
	designation of Spath 1941, p. 663, refigured by Renz 1968, pl. 17, fig. 3 (collections of the
	Musée Geologique, Lausanne, GEOLREG: 40012, 2A, 2/2, 3349) from the condensed
	uppermost Albian of Sainte-Croix, Vaud, Switzerland.
	Occurrence. Late Albian, Mortoniceras (Subschloenbachia) rostratum Zone of Mhrila area,
	South Tunisia.The species is known from the late Albian of southern England, France,
	Switzerland, Hungary, Romania, Sardinia, Iran, Algeria, Central Tunisia, Madagascar, South
	Africa, Madagascar, South India, Japan, Mexico, Australia and Alexander Island, Antarctica.
	Superfamily: Scaphitoidea
	Family: Scaphitinae Gill, 1871
	Genus Scaphites Parkinson, 1811

2016a Lechites (Lechites) italicus

Wiedmann and Dieni, 1968: Klein, pp. 2, 6 (with synonymy)

. 2016a Lechites (Lechites) raricostatus

Breistroffer, 1947: Klein, pp. 2, 3 (with synonymy)

. 2016a Lechites (Lechites) vraconensis

Renz, 1968: Klein, pp. 2, 8 (with synonymy)

. 2019 Lechites (Lechites) gaudini

(Pictet and Campiche, 1861)

: Kennedy, in Gale,

Kennedy and Walaszczyk, p. 291, pl. 58, Fig. 5

.

Material. UJF-ID.15000, from Bed 2 of Mghila West section, late Albian, Mortoniceras (Subschloenbachia) rostratum Zone.

Description.

  UJF-ID.16000, five vertebrae found at the Mghila West section, late Albian, base of the Sequence 2, base of the Mortoniceras (Subschloenbachia) rostratum Zone.

	Genus et species indeterminated
	Material.
	Grenoble Alpes, formerly
	Institut Dolomieu collections.
	Order: Sauropterygia Owen, 1860
	Plesiosauria Blainville de, 1835
	Superfamily: Plesiosauroidea (Williston) Welles, 1943
	Family: Elasmosauridae Cope, 1869

Acknowledgements

The authors thank Waleed Hassanein Kassab (Cairo, Egypt) and Fabienne Giraud (Grenoble, France) for their help during field work. This research hase been funded by the ISTerre laboratory (Grenoble) and the French Institut de Recherche pour le Développement (IRD, Marseille). Serge Ferry and Josep Moreno Bedmar are warmly thanked for their helpful reviews, as well as Prof. E. Koutsoukos for his editing work.

Metascaphites thomasi

 [START_REF] Pervinquière | Étude de paléontologie tunisienne. 1 : Céphalopodes des terrains secondaires[END_REF]Scaphites (?) Thomasi Pervinquière, p. 121, pl. 4, fig. 30, 31; text-fig. 39. 1962 Scaphites (Metascaphites) thomasi Pervinquière : Wiedmann, p. 212, 213, 219. 1965 Scaphites (Metascaphites) thomasi Pervinquière : Wiedmann, p. 427, pl. 58, fig. 1. 1979 Salaziceras (Noskytes) thomasi (Pervinquière, 1907): Scholz, p. 101, pl. 22, fig. 6; textfig. 27T. 1982 Salaziceras (Noskytes) thomasi (Pervinquière): Braga et al., p. 709, pl. 3, fig. 2. 1984 Metascaphites thomasi (Pervinquière, 1907): Kennedy and Wright, p. 163, text-fig. 1A-F. 1990 Metascaphites thomasi (Pervinquière, 1907) : Latil, p. 33 1992 Salaziceras (Metascaphites) thomasi (Pervinquière): Cooper, fig. 1H. 1994 Metascaphites thomasi (Pervinquière, 1907): Wright and Kennedy, p. 558, fig. 3. 1996 Scaphites (?) thomasi Pervinquière: Wright et al., p. 261. Non 2007 Metascaphites thomasi Pervinquière, 1907: Szives, p. 119, pl. 16, fig. 16. Non 2017 Metascaphites thomasi (Pervinquière, 1907): Kennedy and Morris, p. 9, fig. 4B, 7O-T. 2018 Metascaphites thomasi (Pervinquière, 1907): Klein, p. 249.

Type. The holotype by monotypy is the specimen figured and described by Pervinquière (1907, p. 121, pl. 4, fig. 30, 31, text-fig. 39) from the latest Albian of Jebel Mghila, Tunisia. The origin of the specimen is given by Pervinquière (1907, p. 122): 'recueilli par M. Ph. Thomas à la base du Cénomanien du Dj. Mghila, en dessous du Kef Si Abd el Kader'. It should be noted that according to Pervinquière (1903, p. 70, fig. 15) the base of the Cenomanian corresponds to the units 1 and 2 of the Kef Si Abd el Kader section, which are an equivalent of his Vraconian stage. The holotype has been very probably collected in the upper part of the Albian.

Material. A single pyritized specimens, UJF-ID. 15009 from Bed 2 of Mghila West section, late Albian, Mortoniceras (Subschloenbachia) rostratum Zone.

Measurements.

Holotype: D: 14.0 mm; Wh: 7.5 (.54); Wb: 6.0 (.43); U: 1.5 (.11); Wb/Wh: .80 UJF-ID. 15009: D: 12.5 mm; Wh: 7.0 (.56); Wb: 5.2 (.42); U: 1.2 (.10); Wb/Wh: .75 Description. This is a wholly septate specimen, 12.5 mm in diameter (Fig. 7.k-m). Coiling is very involute, the umbilicus comprising 10 per cent of the diameter, with a shallow, convex umbilical wall. The whorl section is compressed subquandrangular, with whorl breadth to height ratios of 0.75 and maximum of width at about mid-flanks. The flanks are feebly convex, the outer flanks converging to broadly rounded ventrolateral shoulders, and the venter is convex on the juvenile, becoming feebly convex with age. Up to a diameter of 9 mm, the internal mould is totally smooth, then feeble, prorsiradiate, slightly flexuous, primary ribs arise on the umbilical shoulder and are slightly projected forward on the ventrolateral shoulder. Intercalatoy ribs (one between each primary ribs), arise on the inner third of the flanks. At this stage of the ontogeny, both ribs cross the venter without interruption. The first ventrolateral bullae appear on the last preserved rib, at a diameter of 12.5 mm. Kennedy and Morris (2017, p. 10), 'The Metascaphites thomasi of Szives (2007, p. 119, pl. 16, fig. 16) has flank tubercles, linked over the venter by relatively strong ribs and belongs to some other taxon.' The specimens figured by Kennedy and Morris (2017, p. 9, fig. 4B, 7O-T) from the early Cenomanian of Tanzania are younger than the present species, they are more evolute at the same size (the ratio U/D given by Pervinquière is erroneous) and develop an ornementation at an earlier ontogenetic stage. The Tanzanian material is herein assigned to a new species: Metascaphites morrisi nov. sp., holotype specimen n° OUM KX15754 figured by Kennedy and Morris (2017, fig. 4B, 7O-Q). Occurrence. Late Albian, Mortoniceras (Subschloenbachia) rostratum Zone of Jebel Mhrila, South Tunisia. The species is also known from the latest Albian of Hungary and Spain. Suborder: Ancyloceratina Wiedmann, 1966 Superfamily: Turrilitoidea Gill, 1871 Family: Anisoceratidae Hyatt, 1900 Genus Anisoceras Pictet, 1854 Type species. Hamites saussureanus Pictet, 1847, p. 118, pl. 13, figs 1-4, by the original designation of Pictet, 1854, p. 374 Anisoceras armatum (J. Sowerby, 1817) Fig. 17.a, b 1817 Hamites armatus J. Sowerby, p. 153, pl. 168. 1908 Anisoceras armatum var. Živkovići Petković, p. 99, pl. II, fig. 3. 1965 Anisoceras armatum (J. Sowerby): Clark, p. 25, pl. 5, fig. 4; pl. 6, fig. 6; text-fig. 7a. 1979 Anisoceras (Anisoceras) armatum (J. Sowerby, 1817): Cooper and Kennedy, p. 200, figs. 13a, b, 14d, e, 16z, c, e, i, 17-19 (with full synonymy). 1979 Anisoceras (Anisoceras) armatum (J. Sowerby): Scholz, p. 25 (pars), pl. 2, figs. 1, 5, 7 only. Non 1979 Anisoceras sp. aff. armatum J. Sow.: Collignon, p. 7, pl. 1, fig. 1. 1996 Anisoceras armatum (J. Sowerby, 1817): Kennedy, p. 573, figs. 24d-f, h. 1998 Anisoceras armatum (J. Sowerby, 1817): Kennedy et al., p. 34, figs. 30, 31, 32a-c, 33df, 36f. 2004 Anisoceras armatum (J. Sowerby, 1817): Kennedy, p. 890, figs. 25G, H, Q, R, Y-D1, 26. 2007 Anisoceras armatum (J. Sowerby, 1817): Kennedy and Latil, p. 467, pl. 7, fig. 7, pl. 10, fig. 11, 14. 2015 Anisoceras armatum (J. Sowerby, 1817): Klein, p. 35, with synonymy. 2015 Anisoceras jacobi Breistroffer, 1947: Klein, p. 35, with synonymy. Type. Holotype, by monotypy, is the original of J. Sowerby, 1817, pl. 168, refigured by Kennedy et al. (1998, fig. 30). no. K673a, b in the collections of the Oxford University Museum of Natural History, from the late Albian, Upper Greensand of Roke, 1.5 km NNE of Benson, Oxfordshire, England. Fig. 17. (a, b) Anisoceras armatum (J. Sowerby, 1817), UJF-ID.15001, from Bed 2 of Mghila West section, late Albian, Mortoniceras (Subschloenbachia) rostratum Zone ; (c) Mariella (Mariella) bergeri (Brongniart, 1822), UJF-ID.15052 from the interval 22-24 of Mghila East section, late Albian, Stoliczkaia (Shumarinaia) africana Zone ; (d, e) Mariella (Mariella) bergeri (Brongniart, 1822), UJF-ID.15054, from Bed 23 of Mghila East section, late Albian, Stoliczkaia (Shumarinaia) africana Zone ; (f) Lechites gaudini (Pictet et Campiche, 1861), UJF-ID.15000, from Bed 2 of Mghila West section, late Albian, Mortoniceras (Subschloenbachia) rostratum Zone ; (g, h) Scaphites aff. meriani Pictet et Campiche, 1861, UJF-ID.15002, from Bed 19 of Mghila East section, late Albian, Mortoniceras (Subschloenbachia) perinflatum Zone ; (i, j) Mariella (Mariella) dorsetensis Spath, 1926, UJF-ID.15067, from bed 5 of Mghila Centre section; early Cenomanian, ?Neostlingoceras carcitanense Subzone of the Mantelliceras mantelli Zone ; (k) Mariella (Mariella) dorsetensis Spath, 1926, UJF-ID.15067, from Bed 26 of Mghila East section, early Cenomanian, ?Neostlingoceras carcitanense Subzone of the Mantelliceras mantelli Zone ; (l) Mariella (Mariella) lewesiensis (Spath, 1926), UJF-ID.15077, from Bed 30 of Mghila East section; early Cenomanian, Mantelliceras mantelli Zone. Scale bar is 10 mm.

Remarks. As pointed out by

Remarks. This small fragment is very similar to the type specimen of Anisoceras picteti Spath, 1926, but we follow Cooper and Kennedy (1979), considering that Anisoceras picteti is a junior synonym of A. armatum. Occurrence. Late Albian, Mortoniceras (Subschloenbachia) rostratum Zone of Mhrila area, South Tunisia.The species is known from the latest Albian of Belgium, southern England, France, Germany, Switzerland, Hungary, Serbia, Spain, South Africa, Mozambique, Texas, Georgia and South India. Family: Turrilitidae Gill, 1871 Genus and subgenus Mariella Nowak, 1916 Type species. Turrilites bergeri Brongniart, 1822, p. 395, pl. 7, fig. 3, by the original designation of Nowak, 1916, p. 10. Mariella (Mariella) bergeri (Brongniart, 1822) Fig. 17.c-e 1822 Turrilites bergeri Brongniart, p. 395, pl. 7, fig. 3. 1985 Mariella (Mariella) bergeri (Brongniart, 1822): Atabekian, p. 27, pl. 2, figs 4, 5; pl. 3, figs 1-11; pl. 4, figs 1-7 (with synonymy). 2009 Mariella (Mariella) bergeri (Brongniart, 1822): Kennedy and Bilotte, p. 62, pl. 6, figs 31-44, ?45; pl. 7, figs 1-8, 10 (with additional synonymy). 2014 Mariella (Mariella) bergeri (Brongniart, 1822): Mosavinia et al., p. 84, fig. 8C1, 8C2, 8C3. 2015 Mariella (Mariella) bergeri (Brongniart, 1822): Kennedy, p. 311, pl. 24, figs 14, 17. 2016 Mariella bergeri bergeri (Brongniart, 1822): Klein, p. 133 (with additional synonymy). 2017 Mariella bergeri (Brongniart, 1822): Tajika et al., p. 42, fig. 11D, I, K. 2019 Mariella (Mariella) bergeri (Brongniart, 1822): Gautam et al., p. 25, figs 7D-F.

Material. UJF-ID.15001, from Bed 2 of Mghila West section, late Albian, Mortoniceras (Subschloenbachia) rostratum Zone.

Description. UJF-ID.15001 (Fig. 17.a, b) is a small fragment of recurvated sector, preserved as a pyritized internal mould. The whorl section is compressed oval, with a maximum preserved whorl height of 8 mm. The ribs are unconspicuous, single and coarse on the dorsum. There is one primary for one intercalatory rib. The primary ribs develop strong conical dorsolateral tubercles, elongated parallel to the shaft, tend to be divided into two ribs on the flanks which are linked to strong clavate ventrolateral tubercles; the ventrolateral tubercles are linked across the venter by a wide coarse rib. The intercalatory ribs are single and non tuberculated.