Eduardo Villalobos-Segura

Jürgen Kriwet

Romain Vullo

Sebastian Stumpf

David J Ward

Charlie J Underwood

The skeletal remains of the euryhaline sclerorhynchoid †Onchopristis (Elasmobranchii, Batoidea) from the 'mid' Cretaceous and their palaeontological implications by

We present the first known cranial remains of the fossil batoid †Onchopristis numidus. Based on two exceptionally well preserved specimens collected from the "Kem Kem Beds" (Albian-Cenomanian), South-East of Morocco, an almost complete description of the rostral and cranial portions of the genus †Onchopristis is provided, together with new observations regarding the development and arrangement of the rostral denticle series for this genus. The comparison between the rostrum length of the specimens of †Onchopristis numidus with those of extant pristids revealed a relatively large batoid species with an estimated total length between two to four meters. Overall, the cranial morphology of †Onchopristis resembles that of other sclerorhynchoids. Its robust hypertrophied rostrum with the characteristic wood-like mineralisation covering the inner layer of tessellate cartilage at the centre of the rostrum, in addition to the thick lateral layers of densely porous cartilage on the sides of the rostral cartilages, resembles that observed in †Ischyrhiza and †Shizorhiza, and differentiates †Onchopristis from other sclerorhynchoid (e.g. †Micropristis, †Sclerorhynchus and †Libanopristis). Aiming to determinate a phylogenetic relations of †Onchopristis within sclerorhynchoids a cladistic analysis carried out based on the remains described here, its results suggest a new taxonomic arrangement within sclerorhynchoids.

INTRODUCTION †Onchopristis [START_REF] Stromer | Ergebnisse der Forschungsreisen Prof. E. Stromers in den Wiisten Agyptens. 11. Wirbeltier-Reste der Baharije-Stufe (Unterstes Cenoman). 4: Die Sage des Pristiden Onchopristis[END_REF] is a puzzling Cretaceous batoid taxon, with most of its fossil record being recorded from many 'mid' Cretaceous sites in coastal and fluvial settings.

The taxon was first described based only on rostral fragments and denticles [START_REF] Haug | Paléontologie. Documents scientifiques de la Mission saharienne (Mission Foureau-Lamy)[END_REF][START_REF] Stromer | Ergebnisse der Forschungsreisen Prof. E. Stromers in den Wiisten Agyptens. 11. Wirbeltier-Reste der Baharije-Stufe (Unterstes Cenoman). 4: Die Sage des Pristiden Onchopristis[END_REF][START_REF] Stromer | Ergebnisse der Forschungsreisen Prof. E. Stromers in den Wiisten Agyptens. 11. Wirbeltier-Reste der Baharije-Stufe (Unterstes Cenoman). 8. Ein Skelettrest des Pristiden Onchopristis numidus Haug sp[END_REF] (Fig. 1) with the teeth being described as †Squatina aegyptiaca by [START_REF] Stromer | Ergebnisse der Forschungsreisen Prof. E. Stromers in den Wiisten Agyptens. 11. Wirbeltier-Reste der Baharije-Stufe (Unterstes Cenoman). 9. Die Plagiostomen mit einem Anhangiiber kano und mesozoische Riickenflossenstacheln von Elasmobranchiern[END_REF], but later assigned to †Onchopristis by [START_REF] Slaughter | A Lower Cenomanian (Cretaceous) ichthyofauna from the Bahariya Formation of Egypt[END_REF] (see also [START_REF] Cappetta | Chondrichthyes II. Mesozoic and Cenozoic Elasmobranchii. Handbook of Paleoichthyology[END_REF]. [START_REF] Werner | Die Elasmobranchier-Fauna des Gebel Dist Member der Bahariya Formation (Obercenoman) der Oase Bahariya, Agypten[END_REF] rejected this interpretation and assigned the teeth associated with †Onchopristis numidus erroneously to a new taxon, †Sechmetia aegyptiaca. Currently, †Onchopristis is placed systematically in the suborder †Sclerorhynchoidei within the family †Sclerorhynchidae [START_REF] Cappetta | Chondrichthyes: Mesozoic and Cenozoic Elasmobrachii: Teeth[END_REF], although this affiliation has not been tested phylogenetically. The genus is restricted to the Barremian-Cenomanian [START_REF] Kriwet | Neoselachier (Pisces, Elasmobranchii) aus der Unterkreide (unteres Barremium) von Galve und Alcaine (Spanien, Provinz Teruel)[END_REF] and presently includes only two valid species ( †Onchopristis numidus and †O. dunklei, see Table 1). †Onchopristis numidus [START_REF] Haug | Paléontologie. Documents scientifiques de la Mission saharienne (Mission Foureau-Lamy)[END_REF] occurs in the Albian of Djoua, Algeria [START_REF] Cappetta | Chondrichthyes II. Mesozoic and Cenozoic Elasmobranchii. Handbook of Paleoichthyology[END_REF], the Cenomanian of Egypt [START_REF] Stromer | Ergebnisse der Forschungsreisen Prof. E. Stromers in den Wiisten Agyptens. 11. Wirbeltier-Reste der Baharije-Stufe (Unterstes Cenoman). 9. Die Plagiostomen mit einem Anhangiiber kano und mesozoische Riickenflossenstacheln von Elasmobranchiern[END_REF][START_REF] Slaughter | A Lower Cenomanian (Cretaceous) ichthyofauna from the Bahariya Formation of Egypt[END_REF][START_REF] Werner | Die Elasmobranchier-Fauna des Gebel Dist Member der Bahariya Formation (Obercenoman) der Oase Bahariya, Agypten[END_REF], the Albian-Cenomanian of Morocco [START_REF] Cappetta | Les sélaciens du Crétacé supérieur du Liban. II. Batoïdes[END_REF]. It should, however, be noted that the exact stratigraphic age of many of the North African sites is still in debate. †Onchopristis dunklei [START_REF] Mcnulty | A new sawfish from the Woodbine Formation (Cretaceous) of Texas[END_REF] is reported from the Cenomanian and middle-upper Albian of Texas. However, the specimens collected from the Lower Cretaceous (Aptian-Albian), Trinity Group of Texas, U.S.A. are considered a subspecies by [START_REF] Thurmond | Cartilaginous fishes of the Trinity Group and related rocks (lower Cretaceous) of north central Texas[END_REF], who introduced the name †Onchopristis dunklei/praecursor. †Onchopristis dunklei is also reported from the Albian of Tunisia, although this record is based on incomplete material [START_REF] Cuny | Fossil sharks from the Early Cretaceous of Tunisia[END_REF], and from the Cenomanian of Spain and France [START_REF] Bernardez | Los dientes de seláceos del Cretácico de la Depresión Central Asturiana[END_REF][START_REF] Vullo | Un faciès de type falun dans le Cénomanien basal de Charente-Maritime (France)[END_REF][START_REF] Néraudeau | Stratigraphie et paléontologie (plantes, vertébrés) de la série paralique Albien terminal-Cénomanien basal de Tonnay-Charente (Charente-Maritime, France)[END_REF]. In addition, an unnamed older species exists, which was recovered from Barremian deposits of north-eastern Spain [START_REF] Kriwet | Neoselachier (Pisces, Elasmobranchii) aus der Unterkreide (unteres Barremium) von Galve und Alcaine (Spanien, Provinz Teruel)[END_REF]. †Onchopristis dunklei/praecursor also occurs in the Upper Cretaceous (Campanian-Maastrichtian) of New Zealand by [START_REF] Keyes | Records of the northern hemisphere Cretaceous Sawfish genus Onchopristis (order Batoidea) from New Zealand[END_REF]. [START_REF] Martill | Aberrant rostral teeth of the sawfish Onchopristis numidus from the Kem Kem Beds (? early late cretaceous) of Morocco and a reappraisal of Onchopristis in New Zealand[END_REF] revised this taxon and redescribed it as †Australopristis wiffeni. Based on the differences between the specimens figured by [START_REF] Keyes | Records of the northern hemisphere Cretaceous Sawfish genus Onchopristis (order Batoidea) from New Zealand[END_REF] and the teeth of typical †Onchopristis, [START_REF] Cappetta | Chondrichthyes: Mesozoic and Cenozoic Elasmobrachii: Teeth[END_REF] proposed that the sclerorhynchid rostral teeth from New Zealand might be close to †Sclerorhynchus and might have acquired convergently morphologies with posterior barbs resembling that of †Onchopristis. Alternatively, †Australopristis maybe a sawshark belonging to Pristiophoridae, similar to †Pliotrema.

Table 1. List of species assigned to †Onchopristis with their currently accepted taxonomic status.

The genus †Onchopristis can be differentiated from other sclerorhynchoids in the shape and size of its rostral denticles (reaching 7 cm in length). The presence of barbs (hook-like protuberances directed backwards) situated on the posterior margin, along with numerous rectilinear folds along the posterior and anterior margins of the rostral denticles, are key features for their identification. Currently, the two valid species of †Onchopristis are differentiated from each other by the number of barbs associated with their rostral denticles: one in †O. numidus and several in †O. dunklei [START_REF] Cappetta | Chondrichthyes: Mesozoic and Cenozoic Elasmobrachii: Teeth[END_REF]. Numerous hypotheses have been proposed to explain the development of this feature. [START_REF] Slaughter | Notes on Rostral Teeth of Ganopristine Sawfishes, with Special Reference to Texas Material[END_REF] suggested that there is an evolutionary tendency to increase the number of barbs associated with the rostral denticles. However, a secondary loss cannot be discarded (i.e. the plesiomorphic state could be additional (more than one) barbs associated with the rostral denticles). [START_REF] Mcnulty | A new sawfish from the Woodbine Formation (Cretaceous) of Texas[END_REF] proposed that the number of barbs is related to the size of the rostral denticles, and as the denticles grow the number of barbs also increases. The presence of multiple barbed denticles (usually two) in specimens from Morocco and Egypt (Stromer, 1917, plate 1;Martill & Ibrahim, 2012, text-fig. 3A-B and 5) (Fig. 7B) renders the use of the barb numbers as a valid character for species determination within †Onchopristis problematic. Despite this, the presence of multiple barbs is typical for North American specimens of †O. dunklei, but it is a rare feature observed in North African specimens assigned to †O. numidus, where these denticles comprise less than 1% of the rostral denticles.

Here, we describe previously unknown features for †Onchopristis numidus based on several specimens recently collected from the "Kem Kem Beds" (Albian-Cenomanian) of SE Morocco and analysed their characters with those described for †O. dunklei. The new "Kem Kem" material reveals a peculiar arrangement of the enlarged lateral rostral denticle series with intercalations of various sizes, as well as the morphology of the synarcual and other cranial remains of the genus †Onchopristis for the first time.

STUDY AREA AND TAPHONOMY

Geological setting-In North Africa, the 'Continental Intercalaire' comprises an extensive non-marine succession of fluvial and fluvial-deltaic facies of Late Jurassic to 'middle' Cretaceous age [START_REF] Kilian | Des principaux complexes continentaux du Sahara[END_REF][START_REF] Lapparent | The dinosaurs of the "Continental Intercalaire" of the central Sahara[END_REF][START_REF] Cavin | Vertebrate assemblages from the Early-Late Cretaceous of southeastern Morocco: an overview[END_REF][START_REF] Ibrahim | Geology and paleontology of the Upper Cretaceous Kem Kem Group of eastern Morocco[END_REF]. In Morocco, the 'Continental Intercalaire' is informally known as the "Kem Kem Beds" [START_REF] Sereno | Predatory Dinosaurs from the Sahara and Late Cretaceous Faunal Differentiation[END_REF]; this term subsequently was later restricted to deposits of mid-Cretaceous age Albian and/or Cenomanian age [START_REF] Cavin | Vertebrate assemblages from the Early-Late Cretaceous of southeastern Morocco: an overview[END_REF]. The fluvial sandstone-dominated facies contain an abundant and diverse vertebrate fauna and are the source of extensive smallscale commercial fossil mining operations. The known fauna is dominated by diverse aquatic and semi-aquatic taxa, with facultatively terrestrial forms being rare. These faunas have been the subject of several studies (e.g. [START_REF] Dutheil | An overview of the freshwater fish fauna from the Kem Kem Beds (Late Cretaceous: Cenomanian) of Southeastern Morocco[END_REF][START_REF] Cavin | New mawsoniid coelacanth (Sarcopterygii: Actinistia) remains from the Cretaceous of the Kem Kem Beds, Southern Morocco[END_REF][START_REF] Rage | Amphibians and squamates from the Cretaceous (Cenomanian) of Morocco. A preliminary study, with description of a new genus of pipid frog[END_REF]Belverde et al., 2013;Mannion & Barret, 2013;[START_REF] Ibrahim | Geology and paleontology of the Upper Cretaceous Kem Kem Group of eastern Morocco[END_REF].

The "Kem Kem Beds" are present along an escarpment at the north-eastern, eastern and south-eastern margins of the Moroccan Anti-Atlas, and are underlain by folded Palaeozoic rocks and overlain by Cretaceous marine limestones that also form the top of the escarpments. This unit is typically divided into two units: the sandstone-dominated Ifezouane and the overlying mudstone-dominated Aoufous formations [START_REF] Cavin | Vertebrate assemblages from the Early-Late Cretaceous of southeastern Morocco: an overview[END_REF][START_REF] Ettachfini | Le cénomanien et le turonien de la plateforme préafricaine du Maroc[END_REF]. Most vertebrate fossils from the southern part of the area come from the Ifezouane Formation. In the northern part of the area, close to the mouth of the River Ziz gorge, well preserved fish fossils, and amphibian and squamate remains are known from the Aoufous Formation [START_REF] Dutheil | An overview of the freshwater fish fauna from the Kem Kem Beds (Late Cretaceous: Cenomanian) of Southeastern Morocco[END_REF]. Within the Ifezouane Formation, there is no formalised internal stratigraphy, and there is no stratigraphic control on the fossil assemblages.

Consequently, it is unknown whether the faunas found in the region have the same time age or are an assemblage of multiple ages. Despite this lack of stratigraphic detail, the Ifezouane Formation in the South of the area rests unconformably on the basement and comprises two channelised sandstone units separated by a major channel base surface. Most fossils are known from the channel lag at the base of the upper unit. In the North, there are two channelised sandstones separated by a heterolithic unit of siltstones and rippled sandstones. A gypsum rich mudstone separates these sandstones from the basement below. Fossils are common in both the channelised sandstones and the heterolithic unit, with the specimens described here being collected from the heterolithic unit.

The majority of the publications describing fossils from the "Kem Kem Beds" utilise commercially collected material with relatively few publications dealing with material collected in situ [START_REF] Dutheil | An overview of the freshwater fish fauna from the Kem Kem Beds (Late Cretaceous: Cenomanian) of Southeastern Morocco[END_REF][START_REF] Rage | Amphibians and squamates from the Cretaceous (Cenomanian) of Morocco. A preliminary study, with description of a new genus of pipid frog[END_REF]. As a result, palaeoecology studies of the unit are biased by collection procedures (e.g. higher value specimens) and taphonomic aspects (e.g. merging of stratigraphically, environmentally and geographically isolated faunas). Some studies have assumed a rather homogeneous palaeoenvironment [START_REF] Cavin | Vertebrate assemblages from the Early-Late Cretaceous of southeastern Morocco: an overview[END_REF] or noted some stratigraphical variation in the faunas but did not link that to palaeoenvironments [START_REF] Läng | Unbalanced food web in a Late Cretaceous dinosaur assemblage[END_REF]. There is a general dominance of small remains (vertebrae, teeth and scales fish) of actinopterygian fishes at all field sites, although these are of low commercial value and small size and hence are underrepresented in many collections. Lungfish toothplates and remains of coelacanths are found more irregularly. Chondrichthyan remains are common and composed mainly of †Onchopristis numidus rostral denticles, along with vertebral centra and fragments of rostral cartilages. †Onchopristis numidus teeth and smaller denticles are also common but typically only are recovered by screen-washing due to their small size. Hybodont fin spines are frequent macroscopic finds, with small hybodont teeth of several genera being abundant in many sieved samples.

Lamniform and other elasmobranch shark teeth are present but rare. Tetrapod bone fragments are also prevalent (especially chelonian carapace fragments, crocodilian bone fragments and spinosaurid teeth) and a vast diversity of large and small tetrapods are known.

Non-vertebrate remains include multiple gastropod species, small bivalves and carapace fragments of decapod crustaceans, which are rarely recorded. Ferruginised pieces of wood occur in some localities, especially in northern localities of the channel sandstone facies (e.g. Aghanbou). These fossil assemblages and the sedimentology suggest a fluvial association, with little evidence of marine influences. However, the frequent presence of †Onchopristis numidus (present within coastal and brackish water facies in Egypt) may suggest a link to coastal facies within which it is known elsewhere [START_REF] Werner | Die Elasmobranchier-Fauna des Gebel Dist Member der Bahariya Formation (Obercenoman) der Oase Bahariya, Agypten[END_REF], and the occurrence of several species of lamniform sharks (typically considered as marine) may suggest a direct and possibly close connection to the marine environments.

The channel structures within the fluvial facies in some localities (e.g. Boufaddouz) are immense, suggesting a considerable extension of the channels, which might have been part of a meandering river system, as very large and sinuous channels persist in both Morocco and Libya, indicating the continuity of an extensive river system.

MATERIAL

All specimens described here were obtained from Morocco-based commercial sources, with one of them (NHMUK PV P 75502) brought directly at the site of Boufza (UTM Easting 353973, UTM Northing 3509602, Zone 30), which facies are not exploited (i.e. commercially used) elsewhere (pers. observ. C. Underwood). Specimen IPUW 353500 presents an almost complete rostrum and an almost complete neurocranium, with only the left nasal cavity, hyomandibula, and some jaw elements missing. Specimen IGR 2818 shows an almost complete rostrum with only the tip and the complete left side of the rostrum missing. 4A-C). †Micropristis solomonis (Cappetta, 1980, pl. 1, fig. 1-4;pl. 2, fig. 1). †Libanopristis hiram (Cappetta, 1980, pl. 1, fig. 4;NHMUK PV P 108705, 108706, 13858, 63610, 75075). †Onchopristis numidus (NHMUK PV P 75502, 75503, 1, 74045, 74047, 74050, 74051, 74052, 74053, 74054;IPUW 353500;IGR 2818IGR , 2819IGR , 2820IGR , 2821)). †Ptychotrygon rostrispatula (NHMUK PV P 73630,75496,75496,75497,75500). †Sclerorhynchus atavus (Slaughter & Steiner, 1968, text-fig. 4D;NHMUK PV P 4017, 4776, 49546, 49518, 49533, 49547). †Shizorhiza stromeri [START_REF] Smith | Early development of rostrum saw-teeth in a fossil ray tests classical theory of the evolution of vertebrate dentitions[END_REF]text-fig. 1a-l; 2a-f; NHMUK PV P 73625). †Spathobatis bugesicus (NHMUK PV P 6010, 2099 (2); BSP AS I 505, 1952 I 82).

Abbreviations used in the figures

METHODS

Smaller specimens were field-collected from several sites along the main Kem Kem escarpment. Despite the extensive outcrops, exposures are restricted, and fossiliferous sites are commercially exploited. Spoil is exposed to wind ablation and (rare) rain exposing fossils therein allowing the surface collection of larger specimens and enabling dry sieving through 0.5 or 1mm mesh sieves to collect small specimens. Sieved residues were later additionally wet sieved and picked under a microscope.

Mechanical preparation was carried out in all larger specimens to remove sediment and reveal features concealed by it, for the smaller disarticulated specimens the lab work involved the sagittal and axial cutting and polishing of rostral denticles in order to check their internal morphological features.

Further histology patterns of isolated rostral denticles and teeth were examined at the Department of Palaeontology of the University of Vienna using a desktop micro-computed tomography (micro-CT) device (Bruker SkyScan 1173). The software packages DataViewer (Bruker, version 1.5.1.2) and Amira (FEI Visualization, version 5.4.g) to generate 3D volume renderings of the generated micro-CT slice file stacks from the fossil material and to digitally dissect it using clipping planes of different angles.

To determinate the phylogenetic implications of these newly discovered remains of †Onchopristis and to test their phylogenetic relations within sclerorhynchoids, a matrix of 14 taxa and 29 characters based on previous works [START_REF] Aschliman | Phylogeny of Batoidea[END_REF][START_REF] Claeson | †Tingitanius tenuimandibulus, a new platyrhinid batoid from the Turonian (Cretaceous) of Morocco and the Cretaceous radiation of the Platyrhinidae[END_REF][START_REF] Underwood | The Late Jurassic ray Kimmerobatis etchesi gen. et sp. nov. and the Jurassic radiation of the Batoidea[END_REF]Villalobos et al., 2019a;b) with modifications to account for the morphological variation added by the specimens described here was assembled in Mesquite 3.31 [START_REF] Maddison | Mesquite: A Modular System for Evolutionary Analysis[END_REF]) (Supplementary materials) and analysed. As batoids monophyly is well-established by molecular and morphological analyses (e.g. [START_REF] Douady | Molecular phylogenetic evidence refuting the hypothesis of Batoidea (rays and skates) as derived sharks[END_REF][START_REF] Naylor | Elasmobranch phylogeny: A mitochondrial estimate based on 595 species[END_REF][START_REF] Mceachran | Phylogeny of Batoidea[END_REF][START_REF] Aschliman | Phylogeny of Batoidea[END_REF], and not being the objective of the present study to test this, the selection of the outgroups included only batoids. To properly test the affiliation of †Onchopristis within sclerorhynchoids and the monophyly of sclerorhynchoids, the outgroup was composed by taxa that have been previously found in a sister relation to sclerorhynchoids by other phylogenetic analyses (e.g. Pristis by [START_REF] Kriwet | The systematic position of the Cretaceous sclerorhynchid sawfishes (Elasmobranchii, Pristiorajea)[END_REF][START_REF] Underwood | The Late Jurassic ray Kimmerobatis etchesi gen. et sp. nov. and the Jurassic radiation of the Batoidea[END_REF], Spathobatis by Claeson et al., 2013, and rajoids (Raja and Bathyraja) by Villalobos et al., 2019a;b). It is worth mention that the proximity of these taxa to sclerorhynchoids variates depending on the analysis (i.e. they are not always in immediate proximity to sclerorhynchoids). The outgroup also included Anoxypristis to contain all Pristidae genera [START_REF] Fricke | Eschmeyer's catalog of fishes: genera, species[END_REF], and Rhinobatos a genus that no previous analysis has placed in proximity to sclerorhynchoids, but present similarities with the other outgroup taxa in the analysis.

As the specimens described here are mostly composed of rostral and neurocranium remains, the selection of character was focused heavily on these structures, trying to avoid the uncertainty associated with the extensive inclusion of missing data. However, some postcranial skeletal features like the enlargement and shape of the proximal pectoral elements were kept (Char. 1, see supporting information for character discussion), as they provide key features that distinguish sclerorhynchoids from other batoids. For the comparison of the specimens described here, eight sclerorhynchoid genera from which skeletal remains are known are included and compose the ingroup in the analysis. Some tooth features were used, although not extensively, because they would involve further preparation and possible damage to the specimens within the museums. Contingent or reductive coding [START_REF] Brazeau | Problematic character coding methods in morphology and their effects[END_REF] was used as the coding method. Finally, the matrix was analysed using the recently published algorithm of [START_REF] Brazeau | An algorithm for Morphological Phylogenetic Analysis with Inapplicable Data[END_REF] in the R package TreeSearch and compared with the tree resulted from a heuristic search using TNT 1.5 [START_REF] Goloboff | TNT: Tree Analysis Using New Technology[END_REF].

For the TNT analysis, the command line was used to perform a heuristic search with unweighted characters, which included TBR (tree bisection and reconnection) as search algorithm and stepwise addition of 1000 random replications (see, supplementary material).

While for the TreeSearch analysis a script available at 'https://cran.rproject.org/web/packages/TreeSearch/vignettes/inapplicable.html', was followed (see supplementary material for the R script). The clade support was estimated using Jackknife analysis with 1000 iterations was performed in TreeSearch supplementary the group support was also estimated for the TNT analysis using frequency differences [START_REF] Goloboff | TNT: Tree Analysis Using New Technology[END_REF].

Two uninformative characters (Chars. 3 and 11) were kept in the analyses, and although they do not provide grouping information, they were map in the resulting phylogenetic tree as they offer interesting discussion points. All character optimisations were mapped on TreeSearch and discussed in the Supplementary material.

RESULTS

SYSTEMATIC PALAEONTOLOGY

CHONDRICHTHYES Huxley,1880 BATOMORPHII Cappetta, 1980 RAJIFORMES SENSU [START_REF] Naylor | Elasmobranch phylogeny: A mitochondrial estimate based on 595 species[END_REF]†SCLERORHYNCHOIDEI Cappetta, 1980†ONCHOPRISTIS Stromer, 1917 Type species: †Onchopristis numidus [START_REF] Haug | Paléontologie. Documents scientifiques de la Mission saharienne (Mission Foureau-Lamy)[END_REF] DESCRIPTION †ONCHOPRISTIS NUMIDUS [START_REF] Haug | Paléontologie. Documents scientifiques de la Mission saharienne (Mission Foureau-Lamy)[END_REF] (Figs.

Temporal and spatial distribution

Albian-Cenomanian of Africa (Egypt by Werner, 1989: plate 19-20, 23, 35-38) and

Morocco by [START_REF] Cappetta | Les sélaciens du Crétacé supérieur du Liban. II. Batoïdes[END_REF] and the present study).

Etymology

Genus: From the Latin ὄγκος (oncos) referring to the protuberance of on the lateral rostral teeth (barb) and πρίστης (pristis) = saw.

Species: From Numidia the old kingdom bereber, that comprehended (Algeria and part of Tunisia)

Rostrum

The hypertrophied rostrum is robust and triangular-shaped, reaching its widest point at the base and narrowing towards the tip (length: width at base ratio 0.0186) (Figs. 23). The base of the rostrum progresses smoothly into the neurocranium. After removal of the sediment, the specimens revealed the presence of a layer of 'wood-like' cartilage layer, covering the inner tessellate (mosaic-like) cartilage along the central part of the rostrum. This layer was first observed in †Onchopristis by [START_REF] Stromer | Ergebnisse der Forschungsreisen Prof. E. Stromers in den Wiisten Agyptens. 11. Wirbeltier-Reste der Baharije-Stufe (Unterstes Cenoman). 4: Die Sage des Pristiden Onchopristis[END_REF] and characterised as possible fossilised skin.

Later it was described by [START_REF] Cappetta | Les sélaciens du Crétacé supérieur du Liban. II. Batoïdes[END_REF] as the cartilage covering the canals for the ophthalmic nerves in the rostrum. [START_REF] Sternes | Paleobiology of the Late Cretaceous sclerorhynchid sawfish, Ischyrhiza mira (Elasmobranchii: Rajiformes), from North America based on new anatomical data[END_REF]fig. 2c) describe a similar cartilage type located at the sides of the rostrum of †Ischyrhiza next to slight thinker cartilage on the periphery of the rostrum were the lateral rostral denticles are attached.

From the description of the specimens presented here the presence of this wood-like layer seems to be not restricted only the superficial ophthalmic nerve canals, but rather is more widely extended in the rostrum, similar to that observed in †Schizorhiza (see Kirkland & Aguillόn-Martίnez, 2002;fig 8). All three genera present a thick layer of heavily porous cartilage on the sides of the rostrum supporting the lateral series of enlarged of denticles.

However, in †Schizorhiza, this layer is much less porous on the rostrum margins.

Based on the presence of fully functional (erect) enlarged denticles of different sizes on the sides of the rostrum of †Onchopristis, we hypothesise a constant addition of rostral denticles. While †Schizorhiza, a rather peculiar sclerorhynchoid, presents a similar rostral morphology which comprises a thin layer of 'wood-like' cartilage and a thick lateral layer of cartilage. The differences in the addition-replacement of lateral rostral denticles and rostral anatomy of †Onchopristis and †Schizorhiza, suggest differences with other sclerorhynchoids in the use of them (i.e. possibly as a hunting tool or a defence mechanism in †Onchopristis and †Schizorhiza).

Towards the centrum of the rostral cartilages and next to the highly porous lateral layer of cartilage, on both the dorsal and ventral surfaces are two canals, one on each side (Fig. 4A-C). The superficial ophthalmic nerve canal runs on the dorsal surface covered by a layer of cartilage and seems to terminate in a cavity next to the supraorbital crest. On the ventral side, the buccopharyngeal nerve canal terminates at the base of the nasal capsules. Both canals become narrower towards the tip of the rostrum, and in several places, are covered by the 'wood-like' cartilage suggesting that this cartilage entirely covered the canals.

Lateral enlarged rostral denticles

All lateral rostral denticles in specimens NHMUK PV P 75502, IPUW 353500 and IGR 2818, as well as disarticulated denticles recovered from various sites in the "Kem Kem Beds", display a small flat base composed mostly of osteodentine and a large-cap composed entirely of orthodentine, with an external layer of enamel, and a characteristic barb on the apical posterior margin of the denticle. Strongly marked cutting edges, accompanied by rectilinear crests, are developed on both anterior and posterior faces of the denticles (Fig. 5). The presence of these cutting edges and the lack of abrasion patterns on the denticles cap suggest that these denticles were not used to probe in the sediment.

. The presence of different enlarged series of denticles in †Onchopristis numidus that vary according to their position in the rostral and cephalic regions is similar to that of other sclerorhynchoids (e.g. †Sclerorhynchus [START_REF] Welten | Evolutionary origins and development of saw-teeth on the sawfish and saw shark rostrum (Elasmobranchii; Chondrichthyes)[END_REF][START_REF] Underwood | Sclerorhynchus atavus and the convergent evolution of rostrum-bearing chondrichthyans[END_REF].

Furthermore, the subsequent lateral section of differently shaped free denticles found in the localities showed no evidence of any projection on their posterior margins (Fig. 8B-C),

suggests that the development of the barb is restricted only to the lateral series of the rostrum.

Replacement of enlarged rostral denticles:

We identified three different size classes plus a replacement one in the lateral series of enlarged denticles of the rostrum of †Onchopristis numidus. With large denticles intercalated with smaller ones and vice versa (i.e. large denticles intercalated with smaller ones) in a single line. This type of arrangement is new in batoids, including Pristidae, in which the single lateral rostral series is composed of a single line of continuously growing rostral denticles. [START_REF] Miller | Observations on the Developing Rostrum and Rostral Teeth of Sawfish: Pristis perotteti and P. cuspidatus[END_REF] observed that the size arrangement and number of rostral teeth are established during the embryological stages in Anoxypristis cuspidata and Pristis pristis [START_REF] Welten | Evolutionary origins and development of saw-teeth on the sawfish and saw shark rostrum (Elasmobranchii; Chondrichthyes)[END_REF] propose a similar observation regarding the arrangement and number of rostral denticles in pristioids. However, this last work suggests that if denticles are added, it will be caudally near the base of the rostrum or closer to the tip, but only more pristioids embryonic material will confirm this.

Based on the presence of highly porous cartilages along the sides of the rostrum, and the presence of fully functional denticles of different size classes in †Onchopristis numidus, we hypothesise that in this species the denticles are periodically added across the rostrum as it grows and develops over time (Fig. 9). The presence of fully erect small denticles followed by larger ones, as observed in specimen IPUW 353500 and IGR 2818, suggests a seriated appearance of the rostral denticles beginning with smaller denticles and subsequently followed by larger ones (Fig. 9A-B). The three-size cluster of rostral denticles with a mirrored arrangement (i.e. similar-sized denticles placed on opposite sides in dorsal view) recognised in IGR 2818, is interpreted to be the result of synchronised development on both sides of the rostral denticles. This mirroring pattern is unnoticeable or less conspicuous at the tip of the rostrum, probably because it is a more fragile region and denticles in this area could be more susceptible to fracture due to taphonomic processes. The presence in both specimens (IPUW 353500; IGR 2818) of small denticles (G1) and larger denticles (G2 and G3) with fully enamelled caps suggest that denticles do not gradually grow, but instead that larger denticles are periodically added as the animal grows (Fig. 9C). Both the arrangement and addition sequence are different from other sclerorhynchoids (e.g. [START_REF] Sternes | Paleobiology of the Late Cretaceous sclerorhynchid sawfish, Ischyrhiza mira (Elasmobranchii: Rajiformes), from North America based on new anatomical data[END_REF]Welten et al., 2015;[START_REF] Underwood | Sclerorhynchus atavus and the convergent evolution of rostrum-bearing chondrichthyans[END_REF][START_REF] Smith | Early development of rostrum saw-teeth in a fossil ray tests classical theory of the evolution of vertebrate dentitions[END_REF].

Overall this arrangement is somewhat similar to that observed in Pristiophorus [START_REF] Welten | Evolutionary origins and development of saw-teeth on the sawfish and saw shark rostrum (Elasmobranchii; Chondrichthyes)[END_REF][START_REF] Underwood | Sclerorhynchus atavus and the convergent evolution of rostrum-bearing chondrichthyans[END_REF]. With some notable differences: In †Onchopristis numidus both small and large rostral denticles seems to lack a differentiated degree of mineralisation and present a cap densely filled with orthodentine, whereas rostral denticles in Pliotrema warreni differ in the mineralisation pattern between older (larger) and younger (smaller) denticles [START_REF] Welten | Evolutionary origins and development of saw-teeth on the sawfish and saw shark rostrum (Elasmobranchii; Chondrichthyes)[END_REF]. In addition, the triplet arrangement observed in the rostral denticles of Pliotrema warreni is not always present in †Onchopristis numidus in which denticles of the same size as those of the functional generation replace or occupy the available space. This arrangement is similar organisation to that reported for other sclerorhynchoid species (e.g. †Sclerorhynchus, [START_REF] Welten | Evolutionary origins and development of saw-teeth on the sawfish and saw shark rostrum (Elasmobranchii; Chondrichthyes)[END_REF], in which some replacement denticles are so closely associated with the existing functional ones that they seem to appear in pairs (Fig. 2, denticles marked with an arrow)".

Neurocranium

Only the postnasal region and part of the posterior edge of the nasal capsules can be addressed here, as the most anterior part of the nasal capsules is missing. The neurocranium is box-like and rectangular shaped, with an oval-shaped precerebral fenestra located near the base of the rostrum at the centre of the anterior part of the neurocranium (Fig. 10). The dorsal surface of the left nasal capsules is not discernible, because it is heavily crushed. In ventral view, the posterior region of the right nasal capsule is preserved and presents a deep nasal fenestra that smoothly progresses into the rostrum. The buccopharyngeal nerves cavities are located on the ventral surface anterior to the nasal capsules (Fig, 11 A-B).

The profile of the antorbital cartilage is triangular, with its narrow distal edge pointing posteriorly and its wide proximal edge articulating with the nasal capsule (Fig. 11 A-B). Even though the neurocranium presents some crushing dorsoventrally, the supraorbital crest stands above the dorsal surface of the chondrocranium and does not cover the eye cavity. The orbital cavity is large and houses a well mineralized optic peduncle; additional nerve foramina were not observed (Fig. 11 C-D). Next to the supraorbital crest is the cavity for the superficial ophthalmic nerve (Fig. 10 B). The postorbital region is rectangular and narrow with a small triangular postorbital process. In the otic region, the orbital fissure is above the lateral

Hyomandibula

The hyomandibula is triangular shaped (length: width at base ratio = 0.51, length: width at tip ratio = 0.018), with its proximal end articulating to the neurocranium, and its narrow distal end connected between the palatoquadrate and Meckel's cartilages. A section of the dorsal surface of the hyomandibula is missing; however, the remaining parts are slightly

Jaw cartilages

Only part of the Meckel's and palatoquadrate cartilages are observable in ventral view (Fig. 11 A-B). The palatoquadrate is thin and narrows progressively towards the symphysis (Fig. 11 A-B). In ventral view, there is no clear articulation with the neurocranium, the Meckel's cartilage and palatoquadrate are present, and both jaw elements seem to be supported by the hyomandibula. The palatoquadrate and Meckel's cartilage antimeres are not fused and connected at the symphysis. The Meckel's cartilage is wider than the palatoquadrate but also becomes narrower towards the symphysis (Fig. 11 A-B).

Oral teeth: Teeth of †Onchopristis numidus have been figured multiple times (e.g. by [START_REF] Stromer | Ergebnisse der Forschungsreisen Prof. E. Stromers in den Wiisten Agyptens. 11. Wirbeltier-Reste der Baharije-Stufe (Unterstes Cenoman). 9. Die Plagiostomen mit einem Anhangiiber kano und mesozoische Riickenflossenstacheln von Elasmobranchiern[END_REF] (1989) and described as †Onchopristis, probably belong to a different sclerorhynchoid such as †Renpetia) and are similar to those of †O. dunklei [START_REF] Welton | The collector's guide to the fossil sharks and rays from the Cretaceous of Texas[END_REF]Kriwet & Kussius, 2001,text-fig. 4;[START_REF] Cappetta | Chondrichthyes: Mesozoic and Cenozoic Elasmobrachii: Teeth[END_REF]Fig. 370M-R;Vullo et al., 2003: pl. 2, fig. 6).

Both species have teeth with a sharp and acute cusp, that bent lingually (Fig. 12 C, G, K; Fig. 13 J,L). The labial apron is narrow, with a blunt distal edge that projects anteriorly and surpasses the root and present pair of incipient lateral cusplets (Fig. 12 A, E; Fig. 13 O,K,S).

Several teeth collected in Morocco present a double-lobed labial apron (Fig. 12 A,E,D,H).

Some teeth also have a cutting edge on the labial and lingula crown faces (Fig. 13 A-E). All teeth display well developed cutting edges, which are continuous between the cusp and lateral cusplets (Fig. 12; Fig. 13 J,L). The lingual uvula is absent (Fig 12 C, G), and the root is bilobed and laterally projected (Fig. 12 B, F; Fig. 13 P).

Cross-sections of the oral teeth revealed the presence of a large pulp cavity in the root that extends apically into the crow where it becomes narrower as it progresses towards the apex (Fig. 13 G, K, R.).

Synarcual

Only the anterior part of the synarcual is preserved, which presents a well-developed odontoid process (synarcual lip) that forms part of the articulation surface for the synarcual with the neurocranium along with the extensive anterior lateral process that mirrors the odontoid processes in the neurocranium. This process and the depth of the odontoid process suggest a close and not very mobile articulation with the neurocranium (Fig. 14). The central portion of the synarcual is well developed displays some spino-occipital foramina (the actual number remains unknown as only a portion of the synarcual is preserved). The medial crest anterior part is missing; however, is remaining portions are thin and well developed, and seems to have been folded during taphonomic processes. Only the right lateral stay is visible, and it becomes progressively narrower backwards. Its distal end is well developed and flattened, and it probably was dorsally directed during life (Fig. 14 A-B). In ventral view, no vertebral centra are observable, which suggests that the vertebra centra did not pass the midpoint of the synarcual (Fig. 14

Vertebrae

The vertebral centra of †Onchopristis consist of the corpus calcareum and the intermedialia as in other chondrichthyans. The corpus calcareum is well mineralized and shows clear and opaque bands suggesting a cyclical deposition of mineral. Whether this pattern was seasonal as in other chondrichthyans, remain ambiguous for the moment (Fig. 15).

Dermal denticles

The rostrum also presents a small series of denticles at the base of the enlarged rostral denticles and on the ventral surface (Fig. 16 G). Two morphologies are present, both with a rounded well enamelled cap and a stellated base with fringes that projects just out below the cap and can be distinguished by the presence of a central cusp (Fig. 16 A-F). As in other fossil assemblages [START_REF] Werner | Die Elasmobranchier-Fauna des Gebel Dist Member der Bahariya Formation (Obercenoman) der Oase Bahariya, Agypten[END_REF], the occurrence of †Onchopristis in the "Kem Kem Beds" coincides with that of "Peyeria-like" denticles (Fig. 17). [START_REF] Cappetta | Chondrichthyes: Mesozoic and Cenozoic Elasmobrachii: Teeth[END_REF] noted that these two batoids are commonly found together, proposing that †Peyeria [START_REF] Werner | Die Elasmobranchier-Fauna des Gebel Dist Member der Bahariya Formation (Obercenoman) der Oase Bahariya, Agypten[END_REF] was, a synonym of †Onchopristis and the †Peyeria remains were, in fact, dermal denticles of †Onchopristis. Recently, similar enlarged dermal denticles were reported for †Ischyrhiza mira Leidy, 1856 by [START_REF] Sternes | Paleobiology of the Late Cretaceous sclerorhynchid sawfish, Ischyrhiza mira (Elasmobranchii: Rajiformes), from North America based on new anatomical data[END_REF] 4e-f). They present a thick enameloid layer on the anterior edge of the denticles. Additional cross-sections revealed a small pulp cavity followed by a thin, not very porous laminar layer, on which a thick layer of highly vascularised osteodentine that reaches the tip of the denticle is deposited (Fig. 17 C). The character matrix for the phylogenetic analysis used here is a modified version from that used by Villalobos et al. (2019b). The main changes include recoding of the polymorphic characters 5, 6 and 9, which were changed for Raja and Amblyraja (see supplement material;

Character discussion). These features refer to the absence/presence of malar thorns, which are developed only in male rays [START_REF] Aschliman | Phylogeny of Batoidea[END_REF]. Three different coding schemes were considered for these characters, that included removing those characters, leaving them as a polymorphic character and coding them as presence, small topological changes resulted from these different codifications (supplement material). However, we consider that regardless of the sexual dimorphism link of these characters, the malar thorns are features that correspond to the genera and should be coded as present.

Character 20 (absence/presence of a differentiated lateral uvula on the teeth), was changed for Anoxypristis to present as its teeth show a variably developed lateral uvula (e.g. [START_REF] Underwood | Shark and ray faunas in the Middle and Late Eocene of the Fayum Area, Egypt[END_REF][START_REF] Cappetta | Chondrichthyes: Mesozoic and Cenozoic Elasmobrachii: Teeth[END_REF], but in general, seems to be present.

Character 24 (absence/presence of a lingual uvula in the teeth) was changed for †Ptychotrygon, following the observations made on †Ptychotrygon rostrispatula by Villalobos et al. (2019b) and four characters were included (Chrs. 25-29) to increase the morphological variance observed within sclerorhynchoids.

The TNT analysis recovers 13 most parsimonious trees of 41 steps with a consistency index of 0.78 and a retention index of 0.85, whereas the TreeSearch analysis recovered a 41 steps tree. Both strict consensus trees (Treesearch and TNT) place all sclerorhynchoids taxa, including †Schizorhiza into a polytomy (Fig. 18 A-B, clade support Cs (strict) = 74%, Cs (majority) = 40%). In both strict consensus and majority rule trees this clade is supported by one shared feature, the lack of a rostral appendix (Fig. 18 A, Character (Chr.) = 25, 0, Consistency index (Ci) = 1) which refers to the absence of thin cartilage attached to the rostrum (see, character discussion in supplementary material). However, the compared anatomy of the process occurring within sclerorhynchoids is unique. In Myliobatiformes, the rostral appendix is polymorphic, some groups present it (e.g. Urotrygon and Potamotrygon) and others do not (e.g. Rhinoptera and Zanobatus). The development of this structure in Myliobatiformes corresponds to the anteromedial growth of the trabecula (i.e. the rostral shaft or rostral cartilage) [START_REF] Miyake | Development and morphology of rostral cartilages in batoid fishes (Chondrichthyes: Batoidea), with comments on homology within vertebrates[END_REF]. In platyrhinoids the trabecula does not present mid growth, as a result the appendix is absent, also these taxa develop as similar structure which is referred as a rostral process by [START_REF] Mceachran | Phylogeny of Batoidea[END_REF] and [START_REF] Aschliman | Phylogeny of Batoidea[END_REF]. Within torpedinids, the development of the rostrum varies with different embryonic cartilages participating in its formation (e.g. In Torpedo the rostral cartilages develop from the lamina orbitonasalis, whereas in Narcine the rostral cartilages derive from the trabecula, which also presents different chondrification periods) [START_REF] Miyake | Development and morphology of rostral cartilages in batoid fishes (Chondrichthyes: Batoidea), with comments on homology within vertebrates[END_REF]. In comparison, the development of rostral cartilages in sclerorhynchoids appears simpler, as they present a good anteromedial growth with no apparent rostral appendix (similar to that of sawsharks), suggesting a convergence between sclerorhynchoids and sawsharks, considering the anatomical differences between these shark and batoid groups (i.e. presence of synarcual and antorbital cartilages). The sclerorhynchoid clade is placed in a sister relation to the Rajidae (Amblyraja and Raja, Fig. 18 A-B, Cs = 80%). The monophyletic group Rajidae + Sclerorhynchoids (Fig. 18 A-B, Cs (strict) = 90%, Cs (majority) = 44%), is supported by four shared features in the majority rule tree and one in the strict consensus (Fig. 18 A). Both trees place the lack of differentiated lateral uvula in teeth (Fig. 18 A, Character (Char.) = 20, 0, Ci = 1) as a shared synapomorphy (see, character discussion in supplementary material). It is worth mention that sclerorhynchoids are not the only batoids lacking these projections. All sclerorhynchoids dentitions reviewed here lack these structures, suggesting more than just a diet adaptation.

Within the sclerorhynchoids clade, two monophyletic groups are recovered by the strict consensus tree estimated with TreeSearch and one with TNT analyses (Fig. 18 A). Both analyses coincide in the grouping of †Onchopristis, and †Ischyrhiza as a monophyletic group (Fig. 18 A-B, Cs (strict) = 81%, Cs (majority) = 91%). This relation is supported by one common synapomorphy in both strict consensus and majority rule trees, that is the presence of smaller denticles with a round cap associated with the base of the enlarged rostral denticles (Fig. 18 A, Character (Char.) = 28, 1, Ci = 1). The majority tree rule recovered two more shared features for the †Onchopristis and †Ischyrhiza clade, the reason why these characters are not considered a synapomorphy and do not appear in the strict consensus tree (Fig. 18 A) is the presence of ambiguity; for character 18 (Ci = 1) the coding of †Schizorhiza (?) creates ambiguity. While, for character 6 (Ci = 1) the uncertainty comes from the collapse of the †Libanopristis, †Micropristis, †Sclerorhynchus, †Ptychotrygon and †Asflapristis clade (Fig. 18 A-B, Cs (majority) = 74%). Of the features, the presence of large denticles associated with the body (Char. 18, 1) is significant as †Onchopristis and †Ischyrhiza, as they are currently the only sclerorhynchoids presenting this feature, supporting the closer relationships found between these taxa by the present analysis.

The strict consensus tree estimated with the TreeSearch analysis is better resolved than that of the TNT analysis, recovering another monophyletic group that includes †Asflapristis + †Ptychotrygon (Fig. 18 B, Cs (strict) = 91%, Cs (majority) = 81%). Three features support the relation (see MRT, Fig. 18 A); (1) lack of enlarged denticle series associated to the rostral cartilages (Char. 7, 0, Ci = 1), (2) presence of a transversal crest on teeth (Char. 17, 1, Ci = 1) and (3) lack of calcified suprascapula (Char. 22, 0, Ci = 0.5) (see, character discussion in supplementary material).

DISCUSSION

Measurements established from other studies on Pristidae (e.g. [START_REF] Morgan | North-western Australia as a hotspot for endangered Elasmobranchs with particular reference to sawfishes and the Northern river Shark[END_REF][START_REF] Whitty | Utility of rostra in the identification of Australian sawfishes (Chondrichthyes: Pristidae)[END_REF] and those made on †Libanopristis hiram (NHMUK PV P 75075) and †Ptychotrygon rostrispatula (NHMUK PV P 73630, 75496), suggest an approximate proportion between the length of the rostrum and the standard length to range from 21-30% in sclerorhynchoids. This scaling suggests that the specimens of †Onchopristis described here had an estimated total body length of 2.94 -4.25 metres (m) for IPUW 353500 and 2.21-3.15 m for IGR 2818. This size in comparisons to modern Pristidae and Rhynchobatidae of similar post rostral lengths suggest a weight of 70-150 kg.

The present study aimed to evaluate the phylogenetic relations of †Onchopristis within sclerorhynchoids. As such, some batoid groups were not included (e.g. torpedinoids, platyrhinoids and myliobatoids). We ignore these groups in the analysis because no previous phylogenetic analysis has established a close relationship between them and sclerorhynchoids [START_REF] Claeson | †Tingitanius tenuimandibulus, a new platyrhinid batoid from the Turonian (Cretaceous) of Morocco and the Cretaceous radiation of the Platyrhinidae[END_REF][START_REF] Underwood | The Late Jurassic ray Kimmerobatis etchesi gen. et sp. nov. and the Jurassic radiation of the Batoidea[END_REF]Villalobos et al., 2019a). However, when interpreting the main features that distinguish †Onchopristis and sclerorhynchoids, we include them to give a broader perspective (see, phylogenetic analysis section). The sawsharks were not included in the present analysis, because morphological features like the presence synarcual and antorbital cartilages suggest a clear batoid affiliation for †Onchopristis.

As both specimens described here are mainly composed of rostral and cranial characters, the selection of features focused on these structures to avoid uncertainties in the phylogenetic analysis, related to the extensive inclusion of missing characters (?) that will ultimately affect the resolution of the analysis. Thus, the use of other anatomical features (e.g. pelvic and pectoral girdles) was avoided.

The topologies recovered by the present analyses suggest that a different taxonomic affiliation for †Onchopristis and †Ischyrhiza could be proposed. Both analyses place these genera previously associated with †Sclerorhynchidae [START_REF] Cappetta | Chondrichthyes: Mesozoic and Cenozoic Elasmobrachii: Teeth[END_REF] Whether ptychotrygonoids are considered a separate family or not makes no difference phylogenetically. The same could be said for †Onchopristidae, as both clades form part different groups which shares no immediate ancestor with †Sclerorhynchidae. However, their taxonomic identification is needed, as it helps the definition of sclerorhynchoids, facilitates the approach for future studies, and improves the current understanding of the group. Furthermore, we believe that there is enough evidence to support the taxonomical differentiation of the two groups into two families.

According to the present analyses, the genera †Schizorhiza and †Ischyrhiza should be placed within the Sclerorhynchoidei. The presence of a thick lateral layer of cartilage on the sides and the external layer of "wood-like" cartilage in their rostrum suggests its classification within †Onchopristidae. However, considering that no cranial remains are known for both genera and that no enlarge body denticles are known for †Schizorhiza, and its highly specialised replacement pattern of the lateral series of rostral denticles, their phylogenetic relationships within Sclerorhynchoidei remain uncertain for the moment.

TAXONOMIC IMPLICATIONS

Following these results, three families are suggested within Sclerorhynchoidei ( †Sclerorhynchidae, †Onchopristidae and †Ptychotrygonidae) based on the differences in their rostral cartilages and dental morphologies. Within this arrangement the family †Onchopristidae is proposed, leaving the taxonomic classification for †Onchopristis numidus as follows. CHONDRICHTHYES Huxley,1880BATOMORPHII Cappetta, 1980RAJIFORMES SENSU Naylor et al., 2012†SCLERORHYNCHOIDEI Cappetta, 1980†ONCHOPRISTIDAE fam. nov. †ONCHOPRISTIS Stromer, 1917 †Onchopristis numidus [START_REF] Haug | Paléontologie. Documents scientifiques de la Mission saharienne (Mission Foureau-Lamy)[END_REF]) Diagnosis of †Onchopristidae: Sclerorhynchoid group with a very peculiar rostral morphology, that includes a thick lateral layer of porous cartilage on the sides of the rostral cartilages, where the enlarge denticle lateral series attach. Rostral centre and superficial ophthalmic nerve canals covered with an external layer of "wood-like". Two series of enlarged denticles with acute cap associated with the lateral regions of the rostrum and head, of which the lateral rostrum series shows smaller denticles with a round cap associated with their base. Symmetric addition of rostral denticles with denticles of different sizes being periodically added. Rostral denticles with a cap of filled with orthodentine. Large denticles are associated with the body (also see, [START_REF] Sternes | Paleobiology of the Late Cretaceous sclerorhynchid sawfish, Ischyrhiza mira (Elasmobranchii: Rajiformes), from North America based on new anatomical data[END_REF] for †Ischyrhiza).

CONCLUSION

Currently, two species are assigned to †Onchopristis: †O. numidus and †O. dunklei, both of which seem to be restricted to the Early to 'mid' Cretaceous (Barremian-Cenomanian).

These two species possess remarkably similar oral tooth morphologies but are differentiated by the internal structure of the enlarge rostral denticles. The rostral denticles of †Onchopristis numidus have an orthodentine filled cap, with a smaller pulp cavity that extends into the denticle cap, whereas the rostral of †O. dunklei presents a larger pulp cavity that extends well into the denticles cap and a thin orthodentine layer (McNulty & Slaughter, 1962, text-fig. 1c).

The peculiar neurocranial and rostral anatomy of the †Onchopristis remains described here, with their rectangular shape of the post-nasal region, a reduced post-orbital process, an anterior fenestra located at the base of the rostral cartilages, and the lack of foramina or cavities at the base of the rostral cartilages for the supra ophthalmic nerve, confirm previous hypotheses that include the placement of †Onchopristis within the Sclerorhynchoidei [START_REF] Cappetta | Chondrichthyes II. Mesozoic and Cenozoic Elasmobranchii. Handbook of Paleoichthyology[END_REF][START_REF] Cappetta | Fossilium Catalogus, I: Animalia[END_REF][START_REF] Cappetta | Chondrichthyes: Mesozoic and Cenozoic Elasmobrachii: Teeth[END_REF]. However, previous genus affiliations to the family Sclerorhynchidae are doubtful and not supported here, as the rostral anatomy and the addition and arrangement of the enlarge rostral denticle series are different from other members of the group (e.g. †Sclerorhynchus and †Libanopristis) and resembles that of †Ischyrhiza. Following the phylogenetic analysis, three monophyletic clades are recognised within Sclerorhynchoidei, which based on their differences in their rostral cartilages and dental morphologies are interpreted as families by the present study: †Sclerorhynchidae, †Onchopristidae and †Ptychotrygonidae. Recognising a new group within the Sclerorhynchoidei, the family †Onchopristidae that includes a single the genus †Onchopristis.

Figure 1 .

 1 Figure 1. A. Rostral remains figured in Stromer (1925; TL 1450 mm). B-C. Rostral remains

  2-15)DiagnosisSclerorhynchoids of relatively large size (TL ~ 4 m). Rostrum massive and with reinforcements having a triangular shapes. Rostrum consists of tessellated cartilage formed by a layer of small of prismatic ( tessellate or mosaic-like) calcified cartilage blocks covered by a layer of fibrous cartilage similar to wood cortex with several vertical, parallel and well mineralised ridges (i.e. 'wood-like' cartilage layer), along the central part of the rostrum and covering the grooves of the ophthalmic nerves. The periphery of the rostrum presents a thick layer of porous cartilage, where enlarge lateral series of rostral denticles attach. Rostral denticles on the lateral series of the rostrum are slender their caps are larger than the peduncle and its apical posterior region present hook-like projections (barbs). The number of barbs varies for 1-3 (one being the most common). The posterior surface of the enlarged rostral denticles presents several well marked ridges (~11) extending from the base and converging at the base of the barb. The denticles anterior face ornamented with smaller ridges that reach the lower third of the cap. The basal bulge is well marked. The peduncle is small with flat and strongly grooved lateral faces. The denticles on the lateral cephalic series do not present barbs and are smaller and wider than the rostrum series and do not present a pulp cavity. Lateral rostral denticles with a large pulp cavity at their base that becomes extremely narrow almost undetectable at the cap. Tooth crown with a large medial cusp and laterally expanded by the lateral shoulders (cusplets). The acute cusp is triangular-shaped bent lingually. On lateral view the labial profile is convex, and the long apron projects anteriorly surpassing the root. The lingual profile is concave with an almost incipient uvula. The root is more prominent than the crown and protrudes laterally, and its vascularisation is holaulacorhize. Large denticles with an enameloid crest on the anterior surface are associated with the body.Differential diagnosis: Rostral denticles of †Onchopristis numidus have an orthodentine filled cap, with a smaller pulp cavity that extends into the denticle cap, whereas the rostral denticles of †O. dunklei possess a larger pulp cavity that extends well into the denticle cap with a thin orthodentine layer.

Figure 2 .

 2 Figure 2. A, Cranial and rostral remains of †Onchopristis numidus (IPUW 353500). B,

Figure 3 .

 3 Figure 3. A, Cranial and rostral remains of †Onchopristis numidus (IGR 2818). B, line

Figure 4 .

 4 Figure 4. A-C, Rostrum of †Onchopristis numidus. A, Ventral surface of IPUW 353500. B,

Figure 5 .

 5 Figure 5. Enlarged rostral denticles of †Onchopristis. A-C, micro-CT-based volume rendering

Figure 6 .

 6 Figure 6. A and C Rostral denticles with multiple barbs bought in Morocco. A, Denticle

Figure 7 .

 7 Figure 7. Rostral denticles of †Onchopristis numidus found in the "Kem Kem Beds" NHMUK

Figure 8 .

 8 Figure 8. A, Mouth of †Onchopristis numidus (IPUW 353500). B, Close up view of enlarged

Figure 9 .

 9 Figure 9. Fragment of the rostrum of †Onchopristis numidus. A, IPUW 353500 (scale bar:

Figure 10 .

 10 Figure 10. A-B, Neurocranium of †Onchopristis numidus. A, picture of IPUW 353500. B, line

  commissure and below the postorbital crest. The lateral commissure covers part of the hyomandibular branch of the facial nerve foramen (Fig.11 C-D). The lymphatic foramina are present in the posterior part of the neurocranium. The jugal arches follow the otic region and are located anteriorly to the occipital condyles which are well developed and expanded laterally forming a broad and deep articulation facet for the anterior lateral process of the synarcual (Fig.10).

  elevated, which could indicate the presence of a process for muscle articulation. (Fig 10).

Figure 11 .

 11 Figure 11. Neurocranium of †Onchopristis numidus (IPUW 353500). A, Ventral view. B,

Figure 12 .

 12 Figure 12. A-L. Oral teeth of †Onchopristis numidus found in the "Kem Kem Beds",

Figure 13 .

 13 Figure 13. Micro-CT-based volume renderings and virtual sections of oral teeth of

Figure 14 .

 14 Figure 14. Synarcual of †Onchopristis numidus (IPUW 353500). A, dorsal view. B, line draw.

Figure 15 .

 15 Figure 15. A-B. Vertebral centra of †Onchopristis numidus from the "Kem Kem Beds"

Figure 16 .

 16 Figure 16. A-F Ventral rostral denticles from the section of the rostrum of †Onchopristis

Figure 17 .Figure 18 .

 1718 Figure 17. Enlarged dermal denticles of †Onchopristis numidus from the "Kem Kem Beds".

  in a monophyletic group separated from the reaming sclerorhynchoids with relatively good group support (TreeSearch: Fig. 18 B, Cs (strict) = 81% and Cs (majority) = 91%; TNT: Fig 18 A, Cs = 82)(see, TNT log in supplementary material). However, while there is a strong phylogenetic support for accommodating †Onchopristis and †Ischyrhiza in a single family (i.e. †Ischyrhizidae Cope, 1875), we argue for the formation of the family †Onchopristidae, as resurrecting[START_REF] Cope | The vertebrata of the Cretaceous formations of the west: Report of the United States Geological Survey of Territories[END_REF] †Ischyrhizidae would be taxonomically risky because the genus with the most complete fossil record is †Onchopristis. Consequently, it is expected that both taxa would be differentiated if more complete material of †Ischyrhiza turns up resulting in excluding †Onchopristis from the family it diagnoses. As such †Onchopristidae is diagnosed by the presence of the following characters: (proposed characterised by the following features:(1) a very peculiar rostral morphology with a thick lateral layer of porous cartilage on the sides of the rostral cartilages, where the enlarge denticle lateral series attach (Character (Char) = 4, 1, Consistency index (Ci) = 1); (2) an external layer of "wood-like" cartilage in the centre of the rostrum (Char = 2, 1, Ci = 1 and Char = 3,1, Ci = 1); (3) the presence of large denticles in the body (also see,[START_REF] Sternes | Paleobiology of the Late Cretaceous sclerorhynchid sawfish, Ischyrhiza mira (Elasmobranchii: Rajiformes), from North America based on new anatomical data[END_REF]) (Char = 18, 1, Ci = 1); (4) the presence of smaller denticles with a round cap associated with the base of the rostral denticles (Char = 28, 1, Ci = 1); and (5) two series of enlarged denticles with acute cap associated with the latera regions of the rostrum and head (Char 6, 1, Ci = 1); (6) a symmetric addition of rostral denticles with denticles of different sizes being periodically added (Char = 11, 2, Ci = 1); and (7) rostral denticles with a cap of filled with orthodentine (Char = 24, 0, Ci = 1). This combination of characters is unique compared to other sclerorhynchoids and differentiates †Onchopristidae from any other taxon tentatively assigned to it ( †Schizorhiza and †Ischyrhiza). Therefore, the similarities in rostral morphology similarities (e.g. wood-like mineralization and the presence of a lateral layer of porous cartilage on the sides of the rostrum) seems more likely to be a convergent development since the addition and replacement of their rostral denticles seems radically different (Character 11) and requires more complete material of †Ischyrhiza to evaluate the status of this character in more detail.There are some other uncertainties concerning the taxonomic hierarchy of the ptychotrygonoids.Villalobos et al. (2019b) suggest a placement within the Sclerorhynchidae family, based on similarities in their tooth morphology with those of †Libanopristis (i.e. present transverse crests in the labial apron, seeCappetta, 1980b, text-fig 7 B; 2012, text-fig. 368 I, in present analysis character 17). However, the teeth of †Libanopristis present a more prominent cusp, and the labial apron is less ornamented than that of ptychotrygonoids. In †Ptychotrygon there is a deep central interlocking depression.[START_REF] Cappetta | Les sélaciens du Crétacé supérieur du Liban. II. Batoïdes[END_REF] also indicated a lingual depression for some teeth of †Libanopristis hiram, but there are no clear illustrations, and we were unable to determinate if he refers to the lingual profile of the cusp below the apex or a region on the lingual uvula. Considering the present results, where ptychotrygonoids form a monophyletic group in by the strict consensus of TreeSearch with relatively high support (Fig.18B, Cs (strict) = 91% and Cs(majority) = 81%), a similar arrangement to †Onchopristidae is proposed for the †Ptychotrygon and †Asflapristis clade resurrecting the family †Ptychotrygonidae sensu[START_REF] Kriwet | Neoselachians (Chondrichthyes, Elasmobranchii) from the Lower and lower Upper Cretaceous of north-eastern Spain[END_REF]. The TNT majority rule tree and the clade support analysis corroborates this placement (Fig.18A Cs = 31). Members of †Sclerorhynchidae are differentiated form †Ptychotrygonidae in the presence of enlarged denticle series associated with the rostrum (lateral and both ventral (lateral and central) series (Char = 7, Ci = 1, Char = 8, Ci = 1) and the presence of highly ornamented teeth with transversal crests in members of †Ptychotrygonidae, (Char = 17, 1, Ci = 1).

  plate I, figs 1-4, under the name †Squatina aegyptiaca; by Werner (1989, plates 35-37), under the name †Sechmetia aegyptiaca. The teeth figured on plates 21 & 22 by Werner

  in Campanian-lower Maastrichtian of Tennessee and Alabama, U.S.A, suggesting that this feature might be even more common among sclerorhynchoids. The presence of these types of enlarged body denticles in Morocco agrees with Cappetta (2012) and Sternes & Shimada (2019) interpretations. †O. numidus dermal denticles found in Morocco are unique among sclerorhynchoids

(Werner, 1989, plate 41, figs. 1-4; Sternes & Shimada, 2019, text-fig.

ACKNOWLEDGEMENTS

We thank the NHMUK for the use of their facilities and equipment for the preparation of the specimens, and M. Graham for the training in the use of the equipment. We also thank Emma Bernard at the NHMUK for her help with access to and curation of fossil specimens. We also thank the preparation team at the Institute of Palaeontological Research at the University of Vienna for their curation work. We are particularly indebted to Brahim Tahiri, Moha Ouhouiss, Hamad and Moha Segaoui who let us purchase the specimens at very reasonable prices and guide us through the localities. We also thank Bernard Hogrel kindly providing the Rennes specimen and Damien Gendry for the photographs of the Rennes specimen. We also want to thank Tyler Greenfield for his observation regarding the taxonomic classification proposed here. Thanks to the CONACYT for the PhD Scholarship. Finally, we want to thank Todd Cook, an anonymous reviewer and editor for their comments and guidance on the early draft of this paper.

LITERATURE CITED