Didier Bert

Stéphane Bersac

Léon Canut

Implications of the 'hemihoplitid-like' ammonites iterative morphology in the context of the late Tethyan Barremian (Early Cretaceous)

Keywords: ammonites, Early Cretaceous, homeomorphy, competition, systematics, Paretooptimal solution

Resemblance of Lenicostites rusticus with Hemihoplitidae is a case of homeomorphy.

• The numerous reported occurrences of Hemihoplitinae over the world are reviewed.

• Pareto-optimal solution explains homeomorphy of the 'hemihoplitid-like' morphology.

• Homeomorphitinae subfam. nov. and Shasticrioceratidae fam. nov. are proposed.

• Lenicostites is a victim of the Gause Principle in favour of the Hemihoplitinae.

Introduction

The family Hemihoplitidae Spath, 1924a is a key element of the marine early late Barremian ammonite fauna because of its very rapid evolution and diversification, to the extent that successive representatives of this family are used in the definition of a number of stratigraphic horizons (Fig. 1). In the context of the North Tethyan margin, this family develops three major trends, materialized into three subfamilies: (1) the Gassendiceratinae Bert et al., 2006 appear in the Toxancyloceras vandenhenckei Subzone and represent the stem of the whole group (following [START_REF] Bert | Origin of the Tethyan Hemihoplitidae tested with cladistics (Ancyloceratina, Ammonoidea, Early Cretaceous): an immigration event?[END_REF] subfamilly actually would appear in the early Barremian in the proto-Altantic context of the Essaouira Basin, Morocco, with Gassendiceras essaouirae [START_REF] Bert | Origin of the Tethyan Hemihoplitidae tested with cladistics (Ancyloceratina, Ammonoidea, Early Cretaceous): an immigration event?[END_REF]; (2) the Peirescinae Bert et al., 2006, which connect with the Douvilleiceratoidea Parona and Bonarelli, 1897 (spanning the Gassendiceras alpinum to Imerites giraudi subzones); and (3) the Hemihoplitinae Spath, 1924a, which are derived from the genus Gassendiceras Bert et al., 2006 (Gassendiceratinae) at the top of the Gassendiceras alpinum Subzone. The older Hemihoplitinae species [Camereiceras breistrofferi [START_REF] Sarkar | Révision des ammonites déroulées du Crétacé inférieur du Sud-Est de la France[END_REF] and C. marchandi Bert et al., 2006] retain some characters from the Gassendiceras: (1) the ontogenetic stages (the Heberti, Barremense and Camereiceras stages -see Bert et al., 2013 for an extensive description); (2) ornamentation with differentiated ribs; (3) trituberculate main ribs; (4) general morphology with uncoiled shell. Later, in the Camereiceras limentinus Subzone, the dimorphic genus Camereiceras Delanoy, 1990a has always its whorls in contact. It gives rise to the genera Pachyhemihoplites [START_REF] Delanoy | Les ammonites du Barrémien supérieur de Saint-Laurent-de-l'Escarène (Alpes-Maritimes, sud-est de la France)[END_REF]Hemihoplites Spath, 1924a. The evolution of Hemihoplites shows a progressive reduction of the tubercles with, in stratigraphic order, H. cornagoae Bert et al., 2006, H. astarte [START_REF] Fallot | Ammonites nouvelles des Iles Baléares[END_REF] and finally, H. feraudianus (d [START_REF] Orbigny | Paléontologie française -Terrains crétacés -Tome 1[END_REF]. The latter is morphologically simplified with weak tubercles (two rows only) in the H. feraudianus Subzone, where the Hemihoplitinae disappear. This systematic and evolutionary framework is now relatively well known and restricted to the northern Tethyan margin between the G. alpinum and H. feraudianus subzones (early late Barremian -see Bert, 2012aBert, , 2014aBert, , 2014b;;Bert andBersac, 2013, 2014;Bert et al., 2013).

In this context, the discovery of new ammonite specimens with simplified morphology very close to Hemihoplites feraudianus in the lower part of the upper Barremian of the Vocontian Basin (Barremian stratotype area, southeastern France), is totally unexpected. These are not only present two ammonites subzones (three if considering their appearance) before the appearance of the first H. feraudianus, but their appearance is also clearly anterior to the oldest known Tethyan Hemihoplitinae. These ammonites are described here in detail; they are related to the hitherto poorly known species Hemihoplites rusticus [START_REF] Vermeulen | Le Barrémien de Saint-Martin, Escragnolles[END_REF] Their study suggests that they probably do not belong to Hemihoplitidae and we propose the new genus Lenicostites gen. nov. and the new family Lenicostitidae nov. fam.

A review of the literature shows that this type of situation is not exceptional in the Lower Cretaceous: many occurrences of Hemihoplitinae have been reported all around the world, always with specimens of simplified morphology, while their geographical occurrence are sometimes very far between them and the Tethyan domain in disparate stages from Valanginian to Aptian. Systematics, based on relationships between morphology, ontogeny, stratigraphy and paleobiogeographical data helps reframe their taxonomy; it appears that most of them are not Hemihoplitidae. Hypothesis about phylogenetic relationships and paleoecology of these ammonites are considered and several new taxa have to be introduced: the Homeomorphitinae subfam. nov., with Homeomorphites gen. nov. (type-species: Ho. aguirreurretae gen. nov. et sp. nov.), and Shasticrioceradidae fam. nov.

Finally, several hypotheses about the phyletic position of Lenicostites gen. nov. are discussed, which rise questions about homeomorphy and its causes (convergence, parallelism or iterative evolution), interspecific competition, competitive replacement, and Red Queen theory applied to these ammonites.

Material

This study focuses on the discovery of new material of the extremely rare genus Lenicostites gen. nov. These fossils are from four bed-by-bed sampled stratigraphic sections in the southeast of France (Alpes de Haute-Provence and Alpes-Maritimes), two of them located in the immediate vicinity of the Barremian historical stratotype of the Angles road (sections A' and A*), and the others located in the Arc of Castellane between Rougon and Vence (sections MAN and TAI). Part of this area belongs to the protected perimeter of the Geological National Nature Reserve of Haute-Provence (RNNGHP), managed by the Departmental Council of the Alpes de Haute-Provence on behalf of the French State. All the collected material is curated by the RNNGHP.

The stratigraphic framework used for the North Tethyan Barremian in this work was proposed by the I.U.G.S Lower Cretaceous ammonite working group (the Kilian Group - [START_REF] Reboulet | Report on the 6th International Meeting of the IUGS Lower Cretaceous Ammonite Working Group, the Kilian Group[END_REF]. This framework is completed by several works, which helped to reach a high stratigraphic precision level (Fig. 1): for the Barremian [START_REF] Bert | Nouveaux biohorizons et propositions pour le découpage biozonal ammonitique du Barrémien supérieur du Sud-Est de la France[END_REF]Bert and Delanoy 2009;[START_REF] Bert | Problems in the identity of "Crioceras" barremense Kilian, 1895, (Ancyloceratida, Late Barremian), and their proposed resolution[END_REF][START_REF] Bert | The Dichotomus Horizon: proposal for a new biochronologic unit of the Giraudi Zone of the Upper Barremian of southeastern France, and considerations regarding the genus Imerites Rouchadzé (Ammonoidea, Gassendiceratinae)[END_REF][START_REF] Bert | Size reduction and ornamental oscillation within a Barremian lineage of giant heteromorphic ammonites (Early Cretaceous, northwestern Tethyan margin)[END_REF], Hauterivian [START_REF] Company | Ammonite biostratigraphy of the uppermost Hauterivian in the Betic Cordillera (SE Spain)[END_REF][START_REF] Matamales-Andreu | Morphological variability patterns in the Balearites-Pseudothurmannia genera boundary (Ammonoidea, late Hauterivian): taxonomic and biostratigraphic implications[END_REF] and Aptian [START_REF] Bersac | Ontogenesis, variability and evolution of the Lower Greensand Deshayesitidae (Ammonoidea, Lower Cretaceous, Southern England): reinterpretation of literature data; taxonomic and biostratigraphic implications[END_REF]. For local zonations, the following works were used to make correlations: Aguirre-Urreta et al. 2007a (Chile and Argentina), [START_REF] Aguirre-Urreta | Hemihoplitid Ammonoids from the Austral Basin of Argentina and Chile[END_REF], Aguirre-Urreta et al., 2007b[START_REF] Riccardi | The Cretaceous system of southern South America[END_REF]and Riccardi and Medina, 2008 (Patagonia), Murphy, 1975 (California). The terminologies used in this paper (biostratigraphy and chronostratigraphy vs. geochronology) respect the standards of the International Commission on Stratigraphy [START_REF] Salvador | International stratigraphic guide: a guide to stratigraphic classification, terminology, and procedure[END_REF].

Geological setting and sections studied

During the Mesozoic Era, the Vocontian Basin (south-east of France) was a large subsident intracratonic area opened towards the Alpine ocean. The sedimentary basin is now bordered by the Mediterranean Sea (south), the Jura (north), the Massif Central (west) and the Alps (east). The Barremian, in the stratotype area (Angles, department of the Alpes de Haute-Provence), is characterized by pelagic sedimentation with an alternation of 0.10-1m thick marlstones and limestones. The outcrops are usually of good quality with continuous sedimentation and abundant fossils, with dominance of the ammonites. However, the lower upper Barremian in this area, and especially the Toxancyloceras vandenheckei Zone and the most part of the Gassendiceras alpinum Subzone, contain very few macrofossils and the beds require long time sampling.

Pelagic sections A* and A'

The section A* was described and figured by Bert (2012b) and [START_REF] Bert | Size reduction and ornamental oscillation within a Barremian lineage of giant heteromorphic ammonites (Early Cretaceous, northwestern Tethyan margin)[END_REF]. It corresponds to the complementary section to the Barremian historical stratotype of the Angles road (section A). In section A, the lower part of the upper Barremian (T. vandenheckei and Gerhardtia sartousiana zones) is poorly exposed because of growth faults that disrupt the bed successions (see more explanations in Bert, 2012b, p. 4). Given these difficulties the new reference section A*, in the immediate lateral continuity of the stratotype, allows to make good study of these beds. Section A' is another complementary section in the adjacent hill to the Barremian stratotype. For the T. vandenheckei Subzone, the bed succession is the same in the both sections A' and A*.

Neritic sections MAN and TAI

Section MAN was reported by [START_REF] Cotillon | Le Crétacé inférieur de l'arc subalpin de Castellane entre l'Asse et le Varstratigraphie et sédimentologie[END_REF]. It is close to the section SO in the Rougon area, which was described previously (Bert et al., 2013, p. 359-361, text-fig. 8). Section TAI was described and figured in a previous work (Bert et al., 2013, p. 361-362, text-fig. 9). This area is part of the neritic domain in the southern Vocontian platform border, which is rich in glauconite, benthic faunas and cephalopods. Sedimentation rates are usually low and discontinuous with some episodes of condensation and sedimentary gaps (sedimentation in a system of tilted blocks); despite of this, the beds benefit from a good stratigraphic attribution given their abundant ammonite content.

Descriptive palaeontology

Class: Cephalopoda [START_REF] Cuvier | Tableau élémentaire de l'histoire naturelle des animaux[END_REF] Order: Ammonoidea [START_REF] Agassiz | Nomina systematica generum molluscorum tam viventium quam fossilium[END_REF] Suborder: Ancyloceratina Gill, 1871 Superfamily: Ancyloceratoidea [START_REF] Gill | Arrangement of the families of mollusks[END_REF] Family: Lenicostitidae fam. nov.

Type genus. This family is currently monotypic, with Lenicostites gen. nov.

Discussion. It is undeniable that Lenicostitidae fam. nov. are morphologically very close to Hemihoplitinae, and especially to Hemihoplites feraudianus (d [START_REF] Orbigny | Paléontologie française -Terrains crétacés -Tome 1[END_REF] and the adult microconchs of Camereiceras marchandi and C. limentinus with smooth simple ribbed ontogenetic stage on body chamber. However, the total absence of the ontogenetic stages common to all Hemihoplitidae, which are lacking here (see description below), but also the stratigraphic position of the oldest representatives of the genus Lenicostites gen. nov. is problematic. Lenicostites gen. nov. appears long before the cladogenesis between the first Camereiceras (the direct ancestor of Hemihoplites) and the genus Gassendiceras, which occurs in the late part of the Gassendiceras alpinum Subzone (Fig. 1). Lenicostites rusticus [START_REF] Vermeulen | Le Barrémien de Saint-Martin, Escragnolles[END_REF] gen. nov. appears in southeastern France from the middle part of the T.

vandenheckei Subzone, at the same time as the first Gassendiceras of the G. cf. essaouirae [START_REF] Bert | Origin of the Tethyan Hemihoplitidae tested with cladistics (Ancyloceratina, Ammonoidea, Early Cretaceous): an immigration event?[END_REF] group that migrate to the northwestern Tethyan margin from Moroccan representatives (see [START_REF] Bert | Origin of the Tethyan Hemihoplitidae tested with cladistics (Ancyloceratina, Ammonoidea, Early Cretaceous): an immigration event?[END_REF][START_REF] Company | Barremian ammonite faunas from the western High Atlas, Morocco -biostratigraphy and palaeobiogeography[END_REF]. There is no argument to indicate a link between Gassendiceras and Lenicostites gen. nov., which have a very different morphology, and above all a very different ontogeny (see the discussion of the genus Lenicostites gen. nov.). In this context, it is not possible to include the genus Lenicostites gen. nov. into the family Hemihoplitidae, which would make this family polyphyletic; family Lenicostitidae fam. nov. is thus proposed. Pending new data, this family is currently classified into the Ancyloceratoidea superfamily, a position reinforced by the presence of a widely perforated umbilicus (Vermeulen, 1996, pl. 3, fig. 5).

Genus Lenicostites gen. nov.

Denomination. From latin lenis, which means smooth (here smooth ribs).

Type-species. Lenicostites rusticus [START_REF] Vermeulen | Le Barrémien de Saint-Martin, Escragnolles[END_REF] vandenheckei Subzone in association with Toxancyloceras ebboi [START_REF] Delanoy | Toxancyloceras gen. nov. (Ammonoidea, Ancyloceratina) un nouveau genre du Barrémien supérieur[END_REF](see Bert et al., 2018, fig. 5 for the stratigraphical occurrence of this species) and Gassendiceras cf.

essaouirae;

(2) in the upper part (non-terminal) of the G. alpinum Subzone associated with numerous Barremitidae [the 'bed with little Barremites' of [START_REF] Cotillon | Le Crétacé inférieur de l'arc subalpin de Castellane entre l'Asse et le Varstratigraphie et sédimentologie[END_REF][START_REF] Vermeulen | Le Barrémien de Saint-Martin, Escragnolles[END_REF]and Bert, 2009; these Barremitidae have a morphology close to Nikolovites charrieri (d' [START_REF] Orbigny | Paléontologie française -Terrains crétacés -Tome 1[END_REF]]. And (3) in the Camereiceras limentinus Horizon.

Note that L. rusticus gen. nov. was used by Vermeulen (1998aVermeulen ( , 1998b) ) to define an ammonite horizon in the upper part of the Toxancyloceras vandenheckei Zone. Although this horizon was no longer used later (see [START_REF] Vermeulen | Etude stratigraphique et paléontologique de la famille des Pulchelliidae (Ammonoidea, Ammonitina, Endemocerataceae)[END_REF], the discovery of L. rusticus gen. nov. in a very wide range renders its use impossible in high resolution biostratigraphy.

Diagnosis. Medium sized genus (up to D=140 mm) with slightly overlapping planispiral whorls. Umbilicus wide and shallow, perforated in the innermost whorls. Subcircular whorl section, quite thick, which tends to heighten with growth. Convex flanks, periventral margin very rounded that gradually passes to the rounded venter. Abrupt peri-umbilical wall.

Ornamentation consisting of ribs most often simple, undifferentiated, thick, radial to slightly retroverse, sometimes a little sinuous but without forming an inflection on the venter. Thinner intercalary ribs, which do not always reach the base of the flanks; they are only present on the robust morphology of the species. In the inner whorls, the ribs are uniformly wide from the base to the top of the flanks and on the ventral area, while on the outermost whorls they widen from the upper quarter of the flanks and on the venter. Reinforcements of the ribs are visible at the base and at the top of the flanks; they are inconspicuous without ever forming a tubercle and they are more developed in the periventral zone of the body chamber.

Discussion. By their morphological and ornamental characteristics, the representatives of Lenicostites gen. nov. have been reported in the subfamily Hemihoplitinae (Hemihoplitidae) in the literature (=Hemihoplites rusticus, in [START_REF] Vermeulen | Le Barrémien de Saint-Martin, Escragnolles[END_REF][START_REF] Klein | Lower Cretaceous Ammonites III. Bochianitoidea, Protancyloceratoidea, Ancyloceratoidea, Ptychoceratoidea. Fossilium Catalogus I : Animalia[END_REF].

Morphologically, this genus undeniably recalls H. feraudianus (d [START_REF] Orbigny | Paléontologie française -Terrains crétacés -Tome 1[END_REF], which is the least tuberculate species of Hemihoplites (compare Fig. 2, 3 with Fig. 4). However, in Lenicostites gen. nov., the whorl section is rounded, whereas in H. feraudianus the flanks are systematically flatter with a well-defined ventral area. On terms of ornamentation, bifurcations are very common at the base of the flanks in H. feraudianus, whereas they are almost absent in L. rusticus gen. nov. The intercalated ribs are likewise very much rarer in Lenicostites gen. nov. But above all, in the latter, the ribs are radial with a slightly retroverted tendency, whereas in H. feraudianus the tendency is for the projection towards the front of the shell. Finally, in the inner and middle whorls of H. feraudianus, the ribs bear true small punctiform tubercles at the base and at the top of the flanks, contrary to L. rusticus gen. nov.

(see below the chapter description and ontogenesis of L. rusticus gen. nov.). Note that the first representatives of L. rusticus gen. nov. and the first H. feraudianus are separated by more than three ammonite subzones (Fig. 1).

All the other species belonging to the different genera of Hemihoplitinae (Hemihoplites, Camereiceras, Pachyhemihoplites) and Peirescinae (Spinocrioceras [START_REF] Kemper | Die Unterkreide im Untergund der Gehrdener Berge und in der Deister-Mulde[END_REF], Peirescites Bert et al., 2006) systematically have a differentiated ornamentation with trituberculate main ribs, which is never the case for Lenicostites gen. nov. However in this context, Lenicostites gen. nov. recalls the adult morphology (stage with smooth ribs, only present on body chamber) of the Pachyhemihoplites and Camereiceras microconchs [see for example the microconch morphology janus [START_REF] Thieuloy | Matheronites limentinus n. sp. (Ammonoidea) espèce-type d'un horizon-repère Barrémien supérieur du Vercors méridional (massif subalpin français)[END_REF] of Pachyhemihoplites gherti [START_REF] Sarkar | Révision des ammonites déroulées du Crétacé inférieur du Sud-Est de la France[END_REF], Camereciceras marchandi, or C. limentinus Thieuloy, 1979 -Fig. 5B-C]. In all cases, the ribs tendency is to retroversion in Lenicostites gen. nov., and in contrast to the forward projection in Hemihoplitinae.

Compared with Lenicostites gen. nov., the Gassendiceratinae Gassendiceras and Pseudoshasticrioceras Delanoy, 1998 are large sized heteromorphs with widely-differentiated ribs. Generally, one does not recognize in Lenicostites gen. nov. the ontogenetic stages, or their derivatives, common in all Hemihoplitidae (the Heberti, Barremense, etc., stages; see Bert et al., 2006[START_REF] Bert | Problems in the identity of "Crioceras" barremense Kilian, 1895, (Ancyloceratida, Late Barremian), and their proposed resolution[END_REF]Bert et al., and 2013)). Conversely to Lenicostites gen. nov., trituberculate ribs (prolonged by spines) are strongly present in the Gassendicaratinae.

Apart from Hemihoplitidae, some robust Martelites Conte, 1989 have a morphology close to Lenicostites gen. nov. In addition to a much more recent age (Martelites sarasini Subzone), the genus Martelites [START_REF] Conte | Fossiles du plateau d'Albion[END_REF](Heteroceratidae Spath, 1922) shows young helical whorls, which is never the case in Lenicostites gen. nov., and a relationship between these two genera is therefore totally excluded.

Patagonian ammonites classified as Hemihoplites (H. ploszkiewiczi Riccardi and Aguirre-Urreta, 1989, H. varicostatus Riccardi and Aguirre-Urreta, 1989 and H. feraudianus Aguirre-Urreta, 2002 non d'Orbigny, 1841 -here Homeomorphites gen. nov., see below chapter 5.8) by [START_REF] Riccardi | Hemihopltitid ammonoids from the Lower Cretaceous of Southern Patagonia[END_REF] and [START_REF] Aguirre-Urreta | Hemihoplitid Ammonoids from the Austral Basin of Argentina and Chile[END_REF], are morphologically close to Lenicostites rusticus gen. nov. because of the lack of tubercles and their general appearance (coiling). However, their ornamentation is different because of the numerous bifurcations of the ribs, their flexuous appearance from the inner whorls of the shell, the higher presence of intercalary ribs, and what looks like to rare reinforced ribs, low constrictions, or even 'zigzag' stages on the ventral area (perisphinctoid characters). The whorl section in Homeomorphites gen. nov. is also different with more angulous peri-umbilical and peri-ventral margins. The adult size is larger in the upper Barremian species Homeomorphites aguirreurretae gen. nov. et sp. nov., which have a different ontogenetic development with the presence of a smooth adult stage, absent in Lenicostites rusticus gen. nov. Finally, in the oldest species of this group, Homeomorphites ploszkiewiczi gen. nov., the ornamentation is much denser than in L. rusticus gen. nov.

Lenicostites rusticus [START_REF] Vermeulen | Le Barrémien de Saint-Martin, Escragnolles[END_REF] gen. nov.

Figs. 2, 3

v 1996 Hemihoplites rusticus sp. nov.; Vermeulen: p. 67-68;pl. 3, figs. 2-5. v 1998aHemihoplites rusticus Vermeulen, 1996;Vermeulen: pl. 4, figs. 7-8. Holotype. Specimen No. 4141351 of the J. Vermeulen's collection (see Vermeulen, 1996, pl. 3, fig. 2345, refigured here in Fig. 2A).

Type locality. The Saint-Martin ravine, near Escragnolles (crop-section VM -Alpes-Maritimes, southeastern France).

Type horizon. Bed VM/20 of the type section, which also delivers many small Barremites.

The bed 19 delivered Toxancyloceras vandenheckei [START_REF] Astier | Catalogue descriptif des Ancyloceras appartenant à l'étage Néocomien d'Escragnolles et des Basses-Alpes[END_REF] and T. bailense [START_REF] Vermeulen | Le Barrémien de Saint-Martin, Escragnolles[END_REF]. In the same area, an equivalent bed also delivered Gassendiceras multicostatum [START_REF] Sarkar | Révision des ammonites déroulées du Crétacé inférieur du Sud-Est de la France[END_REF]G. alpinum (d'Orbigny, 1850) (Bert et al., 2013[START_REF] Bert | Size reduction and ornamental oscillation within a Barremian lineage of giant heteromorphic ammonites (Early Cretaceous, northwestern Tethyan margin)[END_REF].

These faunas indicate the lower half of the T. vandenheckei Zone (T. vandenheckei Subzone and G. alpinum Horizon at the base of the G. alpinum Subzone). The bed 21a delivered some Gassendiceras quelquejeui Bert et al. 2006 (unpublished data) of the top of the G. alpinum Subzone. Thus, the bed 20 is constrained in the non-terminal upper part of the G. alpinum Subzone. This bed corresponds to the level 108 of the Majastre crop-section described by [START_REF] Bert | Description de Artareites landii nov. (Ammonoidea) du Barrémien supérieur de Majastre (Sud-Est de la France) et discussion sur les Helicancylidae Hyatt[END_REF].

Geographic occurrence. The same as the genus.

Stratigraphic occurrence. The same as the genus. 2D). In addition, the holotype (No. 4141351 of the J. Vermeulen's collection) was also examined; it is here refigured (Fig. 2A).

Material studied (N=8).

Measurements. Only one specimen is complete enough to be measured (mm). It is compared with the holotype (see [START_REF] Vermeulen | Le Barrémien de Saint-Martin, Escragnolles[END_REF]. D is the maximum measured diameter, Dph is the diameter of the phragmocone, H, W and U are respectively the height and width of the whorl and the diameter of the umbilicus. 2B) is a two-part fragmented half-whorl of an adult body chamber at a maximal extrapolated diameter of D=120 mm. The shell is plan-spiraled with slightly covering whorls. The whorl section is in all cases rounded and changes during growth, which makes it possible to distinguish two ontogenetic stages:

-(1) The inner and middle whorls, up to a diameter of about D=80 mm. At this point, the whorl section is thick, sub-circular with very convex flanks. The umbilical wall is very abrupt and connects to the flanks by an angular margin, blunted towards the end of the stage.

On the other hand, the periventral margin is very rounded and the flanks progressively move towards the rounded venter. The ornamentation consists of ribs, mostly simple, with the presence of thinner intercalated ribs on robust morphology (No. RNNGHP.SBC.06050-TAI/99.TAI153, Fig. 3, and RNNGHP.DBT.04171-MAN.BB34 -Fig. 2C), while they are almost absent otherwise. The ribs are thick, almost uniformly but slightly wide on the flanks, with a relatively radial to slightly retroverted pattern, without forming any inflection on the ventral area, where they are a little wider. However, they present inconspicuous enlargements at the base and the top of the flanks, but which cannot be described as bulges or never form a tubercle. There are no constrictions. At the end of this stage, the ornamentation becomes barely sinuous on the flanks and the ribs widen strongly from their upper third.

-(2) The outer whorl, known from the diameter of D=100 mm, corresponds to the end of the phragmocone and the body chamber. On this part of the shell, the whorl section is modified by increasing the height of the flanks (reduction of the value W/H), to become subquadratic rounded. The periventral margin remains very rounded and progressive while the flanks flatten. The ribs are enlarged from the upper third of the flanks and on the ventral area while they are weakened on the rest of the shell. The intercalated ribs are very rare from the mid-flank, even in the robust form, and do not seem to connect to the main ribs. Any evidence of reinforcement on the ribs has disappeared, with the exception of an increasingly pronounced shoulder during growth on the periventral margin (better visible on the robust morphology).

The number of specimens is too low to quantify validly the intraspecific variation under a stastistical approach. However, the variation observed between robust and gracile morphologies seems here to concern only the strength of the ornamentation and the presence of intercalated ribs. Considering the general laws of intraspecific variation in ammonites (see Bert, 2013Bert, , 2014)), this isolated character is not taken here to be the result of a species differentiation.

The suture lines could not be studied.

Discussion. The same as the genus.

Critical review of the taxa classified as Hemihoplitinae

In the literature, many occurrences of Hemihoplitinae have been reported all over the world in a large stratigraphic range (Fig. 6 -Valanginian to Aptian, see references in [START_REF] Klein | Lower Cretaceous Ammonites III. Bochianitoidea, Protancyloceratoidea, Ancyloceratoidea, Ptychoceratoidea. Fossilium Catalogus I : Animalia[END_REF], some of them being contradictory with the evolutionary history of the group. Thus, a critical review is essential to understand the geographic and stratigraphic distribution of the group, which appears in all probability in the late Tethyan Barremian [START_REF] Bert | Origin of the Tethyan Hemihoplitidae tested with cladistics (Ancyloceratina, Ammonoidea, Early Cretaceous): an immigration event?[END_REF].

The 'Hemihoplitinae' of Eastern Europe (Bulgaria) and Central Asia (Caucasus and

Turkmenistan)

Matheronites khwamliensis [START_REF] Rouchadzé | Les ammonites aptiennes de la Géorgie occidentale[END_REF] is reported from the locality of Lakhépa (Georgia) together with upper Barremian faunas. It is highly probable that this taxon belongs to the genus Hemihoplites (of which Matheronites Renngarten, 1926 is a junior synonym, see [START_REF] Klein | Lower Cretaceous Ammonites III. Bochianitoidea, Protancyloceratoidea, Ancyloceratoidea, Ptychoceratoidea. Fossilium Catalogus I : Animalia[END_REF] that seems to confirm the depiction of [START_REF] Kotetishvili | Stratigraphy and fauna of the colchiditic and adjacent horizons of Western Georgia[END_REF] and the stratigraphic distributions given by Kotetishvili et al. (2005, p. 417). In this case, its morphology with two peri-umbilical and periventral tubercles brings it closer to H.

feraudianus with which the synonymy is proposed here.

Matheronites ukensis Dimitrova, 1967 from the upper Barremian of Bulgaria was classified in the genus Camereiceras by Delanoy (1990a), followed by [START_REF] Klein | Lower Cretaceous Ammonites III. Bochianitoidea, Protancyloceratoidea, Ancyloceratoidea, Ptychoceratoidea. Fossilium Catalogus I : Animalia[END_REF]. In our view, this taxon, based on an incomplete type-specimen without the preserved inner whorls, is to be attached to the genus Martelites (Heteroceratidae), of which it represents a robust morphotype. This view is supported by the shape of the ribs and the high presence of bifurcations at the top of the flanks at the pre-adult stage, but also by the change of ornamentation at the adult stage with the acquisition of a majority of simple ribs progressively more spaced (compare Delanoy, 1997, pl. 51, fig. 1).

The type specimen of Acanthoceras ridzewskyi Karakasch, 1897 is quite small and morphologically resembles the Heberti stage known in most Hemihoplitidae (see Bert et al., 2013), with ribs all identical bearing ventro-lateral and lateral tubercles. [START_REF] Bogdanova | Substantiation of the Barremian/Aptian boundary[END_REF], and was considered to be a probable Hemihoplitidae (see Klein et al., 2007, p. 215-216). The lack of umbilical tubercles and the top Barremian stratigraphical assignation lead us to exclude A. ridzewskyi from Hemihoplitidae. In our opinion, the only comparable other taxon known in the uppermost Barremian with such morphology in the innermost whorls is Pseudocrioceras Spath, 1924a (both taxa are assumed to be contemporaneous by Kakabadze and Kotetishvili, 1995, p. 108). Description or figuration of innermost whorls of Pseudocrioceras are quite rare in the literature: the coiling could be crioconic or with contigous whorls, the lateral tubercles are high on the flanks and the umbilical tubercles could be very attenuated or absent (Kakabadze and Thieuloy, 1991, p. 90), just as in A. ridzewskyi. More exploration of this hypothesis is prevented by the very small size of the type specimen of A. ridzewskyi; thus, we tentatively propose this taxon in open nomenclature in the vicinity of the genus Pseudocrioceras (=P. ? ridzewskyi).

Matheronites brevicostatus [START_REF] Bogdanova | New Barremian ammonites from western Turkmenia[END_REF] was assigned to the genus Hemihoplites by Riccardi and Aguirre-Urreta (1989, p. 451), followed by Klein et al. (2007, p. 214). Despite of comparable suture line of ELUI type (compare Bogdanova, 1971, fig. 2 andWiedmann, 1966, fig. 35), its stratigraphic assignation to the Turkmeniceras turkmenicum Zone (uppermost Barremian -Bogdanova and Prozorovski, 1999) and its morphology with innermost rounded whorls, ornamentation with very flexuous ribs (especially in inner whorls) bearing a single row of marginal tubercles, intercalatory ribs present since the innermost whorls and most often only present on the venter (there are no intercalatory ribs in the trituberculate Hemihoplitidae's Heberti stage), discard M. brevicostatus from the Hemihoplitidae.

Matheronites turkmenicus [START_REF] Luppov | Ammonites from barremian deposits of eastern Karabugaz area (northwestern Turkmenia). Leningr. obshch[END_REF], figured only once by Luppov (1936, p. 122, pl. 1, fig. 1-3), was likened as well to Hemihoplites feraudianus by Riccardi and Aguirre-Urreta (1989, p. 451, 456), and later accepted in the genus Hemihoplites by Bogdanova and Prozorovsky (1999, p. 50) and Klein et al. (2007, p. 217). Its morphology seems very close to M. brevicostatus, and for the same reason we discard M. turkmenicus from the Hemihoplitidae. Pending more data about these two taxa, we left them in open nomenclature.

The boreal 'Hemihoplitinae'

Ancyloceras brevispina Von [START_REF] Koenen | Die Ammonitiden des norddeutschen Neocom (Valanginien, Hauterivien, Barrêmien und Aptien)[END_REF]Ancyloceras trispinosum (Von Koenen, 1902 non [START_REF] Kakabadze | Ancyloceratids of the south of the USSR and their stratigraphic significance[END_REF] where assigned to the genus Hemihoplites by [START_REF] Kakabadze | Ancyloceratids of the south of the USSR and their stratigraphic significance[END_REF], followed with doubt by [START_REF] Klein | Lower Cretaceous Ammonites III. Bochianitoidea, Protancyloceratoidea, Ancyloceratoidea, Ptychoceratoidea. Fossilium Catalogus I : Animalia[END_REF]. In our view, these taxa are close to the Parancyloceras of the P. aegoceras (Von [START_REF] Koenen | Die Ammonitiden des norddeutschen Neocom (Valanginien, Hauterivien, Barrêmien und Aptien)[END_REF] and P. bidentatum (Von [START_REF] Koenen | Die Ammonitiden des norddeutschen Neocom (Valanginien, Hauterivien, Barrêmien und Aptien)[END_REF] group from the P. bidentatum Zone (Boreal uppermost Barremian) because of their very particular morphology (paucituberculate in P. brevispina and with weaker tubercles in P.

trispinosum). Consequently, they are assigned here to the boreal genus Parancyloceras (Paracrioceratidae [START_REF] Bert | Origin of the Tethyan Hemihoplitidae tested with cladistics (Ancyloceratina, Ammonoidea, Early Cretaceous): an immigration event?[END_REF].

The case of the Patagonian 'Hemihoplites'

The morphology of the Argentinian 'Hemihoplites' (here Homeomorphites gen. nov., see , 2002), while a certain endemism for the Austral Basin was usually assumed (see for example [START_REF] Leanza | Ammoniten des Valangin und Hauterive (Unterkreide) von Neuquén und Mendoza, Argentinien[END_REF]. However, Delanoy had proposed (1990b) an origin of the Tethyan Hemihoplites feraudianus from older tuberculate European forms, but without further details. More recently, an origin of Hemihoplites among Camereiceras has been considered with an older rooting among Gassendiceras [START_REF] Vermeulen | Etude stratigraphique et paléontologique de la famille des Pulchelliidae (Ammonoidea, Ammonitina, Endemocerataceae)[END_REF]Bert et al., 2006;Bert, 2012a). Finally, [START_REF] Bert | Origin of the Tethyan Hemihoplitidae tested with cladistics (Ancyloceratina, Ammonoidea, Early Cretaceous): an immigration event?[END_REF] proposed an origin of the Hemihoplitidae (Gassendiceratinae), supported by a cladistic analysis, among the boreal Paracrioceratidae considering a migration via the Moroccan platform where intermediates are present (G.

essaouirae [START_REF] Bert | Origin of the Tethyan Hemihoplitidae tested with cladistics (Ancyloceratina, Ammonoidea, Early Cretaceous): an immigration event?[END_REF] (1989). Following Kakabaze and Hoedemaeker (2004), it is clear today that these forms are not Hemihoplitidae.

Their very different coiling (involute) with a high and compressed section, as well as their particular ornamentation with mid-flanks bifurcations, an almost smooth siphonal band and inflated ribs on the venter, also distances them from Homeomorphites gen. nov. These specimens can rather be compared with the genus Hatchericeras, and especially with H.

argentinense [START_REF] Stanton | The marine Cretaceous invertebrate[END_REF](compare Riccardi, 1988, pl. 10, fig. 1-2 and Leanza, 1970, pl. 39), which have very thin ribbing, similar to the specimens from Zululand; the suture line shows also a great resemblance (compare [START_REF] Stanton | The marine Cretaceous invertebrate[END_REF], pl. 9 with Klinger and Kennedy, 1992, fig. 37).

Due to its very particular morphology with a very narrow umbilicus, Hemihoplites? mexicanus, Imlay 1940, from upper Valanginian (Fig. 6 -upper member of the Taraises Formation, see Barragán and González-Arreola, 2009 and references), superficially recalls the faunas of south Africa figured by [START_REF] Klinger | Cretaceous faunas from Zululand and Natal, South Africa. Barremian representatives of the ammonite family Ancyloceratidae Gill, 1871[END_REF] [START_REF] Anderson | Lower Cretaceous deposits in California and Oregon[END_REF]]. A unique specimen of Hemihoplites sp. has been reported in Antarctica by [START_REF] Thomson | Ammonite faunas of the Lower Cretaceous of south-eastern Alexander Island[END_REF].

Hemihoplites (Matheronites) ridzewskii sachicaensis

It was collected in screes in a Keystone Cliff crop section, which stratigraphic attribution is uncertain, perhaps Aptian due to the presence of Antarcticoceras in the same formation (Thomson 1974, p. 39), or even upper Barremian following the opinion of [START_REF] Mourgues | Paléontologie stratigraphique (ammonites) et évolution tectono-sédimentaire du Bassin d'arrière arc de Chañarcillo (Berriasien -Albien, Nord du Chili[END_REF] based on the distribution of the Sanmartinoceras [START_REF] Bonarelli | Observaciones Geológicas en las inmediaciones del Lago San Martín (Territorio de Santa Cruz)[END_REF] but the idea of this possible affiliation was already present during the introduction of the taxon (Mourgues, 2007, pp. 240-241, 246). 'H.' perezi nomen nudum, with its lower Aptian assignation (Fig. 6) and very particular ornamentation with two closely spaced rows of periventral tubercles (Mourgues, 2007, p.75)

The Indonesian 'Hemihoplites'

In the description of lower Cretaceous ammonites from Western New Guinea (Irian Jaya, Indonesia), [START_REF] Skwarko | Early Barremian (Early Cretaceous) Mollusca from Western Irian Jaya, Indonesia[END_REF] introduced the species H. taminabuanensis, attributed to the genus Hemihoplites, from a high energy level (presence of glauconite and detrital quartz in the deposit) attemptedly assigned to the Barremian (p. 28). Indeed, Hemihoplites taminabuanensis Skwarko and Thieuloy, 1989 (and also H. sp.) shows very strong morphological affinities with the genus Hemihoplites, and especially with H.

feraudianus. However, the presence of very thin secondary riblets in the indonesian specimens, sometimes joining the primary ribs at midflanks to make a fibula pattern (see Skwarko and Thieuloy, 1989, pl. 4, fig. 3), is not an hemihoplitid character. Thus, pending more complete specimens and data about their age, the indonesian 'Hemihoplites' are left in open nomenclature.

The Indian genus Pascoeites Spath, 1933

Pascoeites [START_REF] Spath | Revision of the Jurassic Cephalopoda fauna of Kachh (Cutch). Part VI[END_REF](see Spath, 1933, p. 827, pl. CXXVI, fig. 5, 7, 12), of which the stratigraphic position was long unclear, was included with doubt in Hemihoplitidae by Wright (in [START_REF] Arkell | Mesozoic Ammonoidea[END_REF]. This position has since been followed by the authors, but without further clarification [START_REF] Klein | Lower Cretaceous Ammonites III. Bochianitoidea, Protancyloceratoidea, Ancyloceratoidea, Ptychoceratoidea. Fossilium Catalogus I : Animalia[END_REF] Formation is between the Golapille sandstones below and the Tirupati (Tripetty) sandstones above [START_REF] Pandey | Stratigraphy of Indian petroliferous basins[END_REF]. The Barremian/Aptian boundary known in Kachchh (between Sivaganga Formation, Ghuneri Member and Dalmiapuram Formation, Ukra Member) can be extended to the Cauvery Basin between the Golapille Formation and the Raghavapuram Formation, which implies that the overlying Raghavapuram Formation would be Aptian (S. Jain, pers. comm.). And thus, the genus Pascoeites is not Barremian but Aptian (Fig. 6) unrelated to the Hemihoplitidae; it is left in open nomenclature awaiting more data.

Analysis of the critical review

The 'hemihoplitid-like' morphology is characterized by a platiconic evolute shell with moderately overlapping whorls, and subrectangular whorl section (higher than thick) with a moderately rapid whorl growth. Such shell morphology takes place in the middle of the 3D pyramidal representation of the W-D-S morphospace, based on the classical Raup parameters [START_REF] Raup | Geometrical analysis of shell coiling: general problems[END_REF][START_REF] Raup | Geometric analysis of shell coiling: coiling in ammonoids[END_REF][START_REF] Tendler | Evolutionary tradeoffs, Pareto optimality and the morphology of ammonite shells[END_REF], fig. 7B). The ornamentation is at first well marked with straight or slightly sinuous ribs, often bifurcated; later the shell becomes smooth (Fig. 4A). This simplified morphology appears to be rather widespread, especially in view of the long list of taxa that have been assimilated to Hemihoplitidae in the literature, but which actually belong to other groups. This morphology is iterative at Valanginian, Hauterivian, Barremian and Aptian, and several taxa without any phyletic linkage, including outside Western Tethys, can develop it by convergence (homeomorphy).

Beside the cases of homeomorphy mentioned above (chapters 5.1-5.6), one could also mention the example of some Martelites of the latemost Barremian (compare [START_REF] Baudouin | Les faunes d'ammonites de la sous-zone à Sarasini (Barrémien supérieur) dans les Baronnies (Drôme, France)[END_REF], pl. 14, fig. 1 and Delanoy, 1992, pl. 37, fig. 1, with Delanoy, 1994, pl. 6, fig. 5). The resemblance is even more striking with the early Hauterivian genus Theodorites from Crimea (here assigned to the Neocomitidae, Endemoceratinae) by its general appearance and its ornamentation close to H. feraudianus (compare Baraboshkin and Mikhailova, 2006, fig. 2b and c, with Delanoy, 1990b, fig. 4 and 2 respectively), and its ventral area very similar to that of Camereiceras limentinus (compare Baraboshkin andMikhailova, 2006, fig. 2a, with Bert et al., 2010, fig. 2b).

All these convergent taxa that could be attributed to Hemihoplitinae for morphological reasons by the authors must now be excluded from this family, which leads to drastically review the palaeogeographical distribution of this group. Until proven otherwise, there is no Hemihoplitinae outside the northern and western margins of the Tethyan Realm (including its Caucasian margin to the east, and the Essaouira Basin in Morocco at the limit of the Proto Atlantic Ocean to the west).

Systematic implications

As seen above in the critical review (chapter 5.7), some taxa excluded from the

Hemihoplitidae have now to be reassigned; they are the Homeomorphitinae subfam. nov. gen. [START_REF] Salfeld | Kiel-und Furchenbildung auf der Schalenaussenseite der Ammonoideen in ihrer Bedeutung für die Systematik und Festlegung von Biozonen[END_REF]and Endemoceratinae Schindewolf, 1966(Neocomitidae Salfeld, 1921).

Compared to the Endemoceratinae Lyticoceras [START_REF] Hyatt | Cephalopoda[END_REF]Endemoceras Thiermann, 1964, the suture line is simpler with a trifid narrow and very weakly assymetrical lateral lobe L, whereas it is broad and strongly asymmetric in Endemoceratinae. The section is wider and the ornamentation is usually coarser without periventral tuberculation.

The Homeomorphitinae subfam. nov. are morphologically close to the genus Hatchericeras, which was usually classified in the Neocomitinae or even with doubts in the Endemoceratinae (see [START_REF] Klein | Lower Cretaceous Ammonites I. Perisphinctaceae 1. Himalayitidae, Olcostephanidae, Holcodiscidae, Neocomitidae, Oosterellidae. Fossilium Catalogus I : Animalia[END_REF]. However, the involute coiling with a relatively hight section and narrow umbilicus, clearly distances Hatchericeras from the Homeomorphitinae subfam. nov.

The Neocomitinae are really diversified in shell morphology (large to medium size, involute to evolute or uncoiled morphology) and ornamentation (thin ribs to strong trituberculated ribs / all identical ribs to differentiated ribs), which makes them hard to effectively and simply compare or differentiate from other comparable groups. However, compared to Neocomitinae (in general), the Homeomorphitinae subfam. nov. show much less rib diversity with no real tubercles or ribs differentiated. Large gerontic Neocomitinae could show change in ornamentention, to very strong ribs, which is not the case in Homeomorphitinae subfam. nov.

On the other hand, in the same way as with Hemihoplitinae and for identical reasons, the resemblance of Homeomorphites gen. nov. with Theodorites Baraboshkin and Michailova, 2006 is the result of a morphological convergence. This latter was classified in the Crioceratitinae Gill, 1871 by [START_REF] Baraboshkin | Theodorites -a new early Haterivian heteromorph ammonite genus from the Crimean Mountains[END_REF], between the genera Crioceratites Léveillé, 1837 (Crioceratitidae Gill, 1871, Ancyloceratoidea) and Lyticoceras Hyatt, 1900 (Endemoceratinae), for which [START_REF] Baraboshkin | Theodorites -a new early Haterivian heteromorph ammonite genus from the Crimean Mountains[END_REF] et al., 2013). Moreover, constrictions, reinforced ribs and 'zigzag' stages (asymmetry of the ornamentation on the ventral area), although rare in Homeomorphites gen. nov., are totally absent from all Hemihoplitidae. The ribs are spaced just before the smooth part of the body chamber, which is never the case in Hemihoplites (Fig. 4). Finally, the sutura formula is of 'neocomitid' type, while it is of 'ancyloceratid' type in Hemihoplitidae.

Homeomorphites gen. nov. is more evolute, with a much lower height whorl and a thicker whorl section than Hatchericeras. Adult size seems also larger for Hatchericeras.

Ornamentation, on the other hand, is quite comparable in flexuosity and orientation of the ribs, but with a higher primary bifurcation point, an earlier smooth stage, and a smoother ventral area in Hatchericeras. The suture line is quite different: it is simple, with a relatively narrow and very weakly asymmetric lateral lobe L in Homeomorphites gen. nov., while it is complex, with a broad, strongly asymmetric lateral lobe L in Hatchericeras.

Compared with Theodorites, the ribs are a bit more flexuous in Homeomorphites gen. nov.

and are not as attenuated on the ventral area. Theodorites also has periventral tubercles and peri-umbilical bulges, completely absent in Homeomorphites gen. nov.

The stratigraphic succession of species of the genus Homeomorphites gen. nov. is: Stratigraphic and geographical occurrence. The Shasticrioceratidae fam. nov. have a circum

Homeomorphites ploszkiewiczi (Favrella
Pacific repartition from Arctic Canada to California (western USA) and to Chile and Japan (Fig. 7). The family is also known in the Austral Basin in Antarctica. Shasticrioceras occurs in lower Barremian (Chile) and lower and upper Barremian-lowermost Aptian (California).

Antarcticoceras occurs in upper Barremian and lower Aptian (see Mourgues, 2007, p. 162 -Fig. 6).

Discussion. The genus Shasticrioceras was originally classified in Hemihoplitidae [START_REF] Anderson | Lower Cretaceous deposits in California and Oregon[END_REF][START_REF] Murphy | Paleontology and stratigraphy of the Lower Chickabally mudstone (Barremian-Aptian) in the Ono Quadrangle, Northern California[END_REF] and more recently in the 'catch-all' family Megacrioceratidae [START_REF] Vermeulen | Nouvelle classification à fondement phylogénétique des ammonites hétéromorphes du Crétacé inférieur[END_REF](see Klein et al., 2007), but its phyletic relationships have never been very

clearly established to support these propositions [note that in our point of view, the Megacrioceratidae are a probable synonym of the family Hamulinidae Gill, 1871 because of the very close relationships between Megacrioceras doublieri [START_REF] Jaubert | Description d'une espèce nouvelle d'Ancyloceras de l'étage néocomien de Castellane (Basses-Alpes)[END_REF] and the genus Hamulina d [START_REF] Orbigny | Prodrome de Paléontologie stratigraphique universelle des animaux mollusques et rayonnés[END_REF]. The genus Shasticrioceras has long been known in the lower and upper North American Barremian [START_REF] Murphy | Paleontology and stratigraphy of the Lower Chickabally mudstone (Barremian-Aptian) in the Ono Quadrangle, Northern California[END_REF] and Japan [START_REF] Matsukawa | The ammonites Crioceratites (Paracrioceras) and Shasticrioceras from the Barremian of southwest Japan[END_REF]. [START_REF] Mourgues | Paléontologie stratigraphique (ammonites) et évolution tectono-sédimentaire du Bassin d'arrière arc de Chañarcillo (Berriasien -Albien, Nord du Chili[END_REF] reported it more recently in Chile.

Antarcticoceras was originally left in open nomenclature by [START_REF] Thomson | Ammonite faunas of the Lower Cretaceous of south-eastern Alexander Island[END_REF], then was placed with doubt in the Ancyloceratidae by [START_REF] Klein | Lower Cretaceous Ammonites III. Bochianitoidea, Protancyloceratoidea, Ancyloceratoidea, Ptychoceratoidea. Fossilium Catalogus I : Animalia[END_REF]. This genus was assumed Aptian by [START_REF] Thomson | Ammonite faunas of the Lower Cretaceous of south-eastern Alexander Island[END_REF], but would rather be upper Barremian according to [START_REF] Mourgues | Paléontologie stratigraphique (ammonites) et évolution tectono-sédimentaire du Bassin d'arrière arc de Chañarcillo (Berriasien -Albien, Nord du Chili[END_REF].

In the constrained geographic context of the Chañarcillo Basin (Chile), besides the fact that the coiling and the shape of the ribs between Shasticrioceras and Antarcticoceras are very close with a very particular morphology of the ventral area whose flat ribs are framed by a peri-ventral punctiform tubercle, a phyletic link between both these two genera can be established with the simple acquisition, very early in ontogeny, of an additional tubercle at the top of the flanks very close to the perivental tubercle. This hypothesis is also supported by the representation by Murphy (1975, fig. 25) of a Shasticrioceras roddai [START_REF] Murphy | Paleontology and stratigraphy of the Lower Chickabally mudstone (Barremian-Aptian) in the Ono Quadrangle, Northern California[END_REF] showing a large (adult?) specimen with lateral and periventral tubercles very close together on the topflanks. In Japan, [START_REF] Matsukawa | The ammonites Crioceratites (Paracrioceras) and Shasticrioceras from the Barremian of southwest Japan[END_REF] also reported the lower Barremian Shasticrioceras intermedium [START_REF] Matsukawa | The ammonites Crioceratites (Paracrioceras) and Shasticrioceras from the Barremian of southwest Japan[END_REF] with 2-3 tubercles on the main ribs at adult stage. Finally, the attribution by [START_REF] Mourgues | Paléontologie stratigraphique (ammonites) et évolution tectono-sédimentaire du Bassin d'arrière arc de Chañarcillo (Berriasien -Albien, Nord du Chili[END_REF] (1) of the upper Barremian (Antarcticoceras domeycanum Zone) species A. domeycanum [START_REF] Bayle | Mémoire sur les fossiles secondaires recueillis dans le Chili par Ignace Domeyko, et sur les terrains auxquels ils appartiennent[END_REF] to the genus Antarcticoceras (previously ? Parancyloceras Spath, 1924a[START_REF] Klein | Lower Cretaceous Ammonites III. Bochianitoidea, Protancyloceratoidea, Ancyloceratoidea, Ptychoceratoidea. Fossilium Catalogus I : Animalia[END_REF], and (2) the description of A. perezi [START_REF] Mourgues | Paléontologie stratigraphique (ammonites) et évolution tectono-sédimentaire du Bassin d'arrière arc de Chañarcillo (Berriasien -Albien, Nord du Chili[END_REF] nomen nudum (later assigned to the genus Hemihoplites) at the base of the lower Aptian ('Hemihoplites' perezi Zone) with tubercles very close together in the periventral and topflank areas, typical of the Antarcticoceras, makes possible to fill the stratigraphic and morphological hiatus with the genus Shasticrioceras and to classify them together within the same family: the Shasticrioceratidae fam. nov.

6. Discussion about the phyletic position of Lenicostites gen. nov.

Lenicostites gen. nov. has a morphology close to Hemihoplitinae, however it departs from it by ontogeny and a number of characters (see above chapter 4). Is this morphological proximity a reflection of a phyletic link, or does it only reflect homeomorphy just as the above examples? Several hypotheses have to be considered.

Hypothesis (1): Lenicostites gen. nov. as an ancestor of the Hemihoplitinae or an offshoot of Gassendiceras

In the hypothesis where Lenicostites gen. nov. were the ancestor of the Hemihoplitinae, given their stratigraphic appearance, they would derive directly from the first Gassendiceras cf.

essaouirae present on the northwestern Tethyan margin, to make the link next with

Camereiceras breistrofferi, which is the oldest known Camereiceras at the top of the Gassendiceras alpinum Subzone. On the other hand, if Lenicostites gen. nov. were an offshoot of the Tethyan Gassendiceratinae, they would have at least a common ancestor: the only possible candidate is the top-early Barremian Moroccan G. essaouirae. These hypotheses come up against a number of objections concerning (1) ontogenesis and ornamentation, (2) adult size, (3) coiling, (4) evolutionary rhythms, and (5) stratigraphic coherence:

-(1) The Hemihoplitidae share a common ontogenetic trajectory and the Hemihoplitinae follow the constant trend initiated by their ancestor Gassendiceratinae. This trajectory is respected in Hemihoplitidae also in case of major evolutive changes such as the reversion of the heterochrony trend that lead to the appearance of Pseudoshasticrioceras, and later with the appearance of the helical coiling in Imerites Rouchadzé, 1933 (Fig. 1;[START_REF] Bert | Description de Artareites landii nov. (Ammonoidea) du Barrémien supérieur de Majastre (Sud-Est de la France) et discussion sur les Helicancylidae Hyatt[END_REF]Bert, 2014, p. 155-157). In these examples, the Barremense and Camereiceras stages are still present or little modified for mechanical reason (i.e. the presence of the helical coiling). Thus, in the case of Gassendiceras (the ancestors) and Camereiceras (the descendents), both genera have in common the Heberti stage in their innermost whorls, followed by the Barremense and Camereiceras stages (Fig. 5 -see Bert et al., 2006 for the extensive description of these stages). This trend and the associated trituberculate ontogenetic stages are totally absent in the supposed intermediates Lenicostites gen. nov. (Fig. 2-3), which does not fit with the hypothesis of a phyletic link between these genera. Moreover, if we consider the loss and complete subsequent recovery of these ontogenetic stages as a possibility, it would mean accepting an exact characters reversibility through time, which is in total contradiction with the Dollo's rule of the irreversibility of evolution.

-(2) It has been shown (Bert et al., 2013) that the Gassendiceras species reach a large size, around or above 350 mm in diameter. It is the same with the macroconchs of Camereiceras (D=325 mm for C. limentinus in Delanoy, 1990a, pl. 6), including the older species of this genus (D=300 mm for C. breistrofferi in Bert, 2014a, fig. 20a). However, this is not the case for Lenicostites gen. nov., which is much smaller with a body chamber that starts at around 110 mm in diameter with the ornamental stage change. In mollusks, the size seems more subject to the stabilizing effect of the natural selection than the ornamental characters [START_REF] Mayr | Animal species and evolution[END_REF], thus in a phyletic relationship hypothesis, it is rather unlikely that Lenicostites gen. nov. would break this stability otherwise than being a progenetic micromorph. In such an hypothesis, or if Lenicostites gen. nov. were an offshoot of Gasendiceras, they would share at least the early Heberti ontogenetic stage with octagonal section and trituberculate ribs known in innermost whorls of every Hemihoplitidae (or a modified version of it), or the strongly tuberculate Barremense stage that immediately succeed it. This is clearly not the case.

-( 3) With regard to coiling, the different species of the genus Gassendiceras systematically have heteromorphic shells, which is also the case for the older Camereiceras (whorls are crioconic non-joined in macroconchs, and tripartite or crioconic in microconchssee [START_REF] Bert | Considérations nouvelles sur quelques représentants barrémiens de Pulchelliidae Douville, 1890 et des Hemihoplitidae Spath, 1924 (Ammonoidea)[END_REF]Bert et al., 2006;Bert, 2012aBert, , 2014a)). To be more precise, the evolutionary trend from Gassendiceras to Camereiceras is towards the progressive loss of heteromorphy, fully achieved in C. limentinus. On the contrary, at the same time, in Lenicostites gen. nov. the shell is constantly plan-spiral with systematically contiguous whorls, wich discards it from the Gassendiceras/Camereiceras coiling trend.

-(4) The evolution of Lenicostites gen. nov. appears to be essentially in stasis, with no particular morphological differentiation visible between the oldest and most recent known forms, despite the stratigraphic departure of almost two ammonite subzones. In the assumption that Lenicostites gen. nov. would be intermediate between Gassendiceras and Camereiceras, or an offshoot of Gassendiceras, this sudden and transient stasis would be very difficult to explain in comparison with the hight speed of evolutionary changes known in Hemihoplitidae (both the ancestral Gassendiceratinae and the derived Hemihoplitinae), whose succession of species allows to establish successions of biostratigraphic horizons (Fig. 1 -see [START_REF] Bert | Nouveaux biohorizons et propositions pour le découpage biozonal ammonitique du Barrémien supérieur du Sud-Est de la France[END_REF]Bert and Bersac, 2013;Bert, 2014).

-(5) The succession Lenicostites gen. nov. / Camereiceras could be stratigraphically coherent (L. rusticus gen. nov. is still present together with C. limentinus and could, for example, give C. breistrofferi by cladogenesis), but the stratigraphic data available on the northwestern margin of the Tethys show that Lenicostites gen. nov. appear at the same time as their supposed ancestor, Gassendiceras. This observation remains problematic in the context of the hypothesis of an ancestor-descendant relationship. That said, a possible common ancestor for Gassendiceras and Lenicostites gen. nov., or the hypothesis of Lenicostites gen.

nov. as an offshoot of Gassendiceras, are not discarded only stratigraphically, but they are mostly ontogenetically (see above point 1): the common ontogenetic development of Hemihoplitidae (Heberti, Barremense, etc. stages) is not only present in the Tethyan late Barremian Gassendiceras, but also in their Moroccan ancestors (Gassendiceras essaouirae) at the top-early Barremian (see Bert and Bersac, 2013), long before the appearance of Lenicostites gen. nov.

In summary, to consider the hypothesis of Lenicostites gen. nov. as an ancestor of the Hemihoplitinae would lead to imagine a period of evolutionary stasis separated from two phases of rapid evolutionary changes by two major breaks. The first rupture could only be the result of a very sudden progeny, with abrupt regression of the size and major reconfiguration of the shell, which would lead to the loss of heteromorphy between the Tethyan G. cf.

essaouirae, or Moroccan G. essaouirae, and L. rusticus gen. nov. Cases of progenesis, sometimes involving extensive restructuring of the organism, have been described (Dommergues et al., 1986, p. 345-348;[START_REF] Landman | The complex nature of progenetic species -examples of Mesozoic ammonites[END_REF]Bert, 2004, p. 121-122). On the other hand, they do not explain the total loss of the ontogenetic stages (especially those known in the innermost whorls of every Hemihoplitidae) and the second break between L. rusticus gen. nov. and C. breistrofferi, with a complete reverse restructuring and the sudden reappearance of the ancestral ontogenetic stages (Heberti and Barremense stages). This inverse and exact restructuring would be a violation of Dollo's rule of the irreversibility of evolution [START_REF] Dollo | Les lois de l'évolution[END_REF][START_REF] Gould | Dollo on Dollo's Law: irreversibility and the status of evolutionary laws[END_REF], which goes beyond the simple repeatability or the iterative evolution of certain characters (see for example Bert et al., 2018, p. 182); as such it would be highly unlikely. All the arguments developped above are likely to rule out Lenicostites gen. nov. from the Hemihoplitidae.

Hypothesis (2): Lenicostites gen. nov. as an 'hemihoplitid-like' homeomorph

As stated above (chapters 4, 6.1), it is now clear that Lenicostites gen. nov. is not linked with the Hemihoplitidae: on the one hand, this genus is not at the origin of the Camereiceras, which succeed directly to the Gassendiceras in the upper part of the G. alpinum Subzone by the reduction of the Barremense stage in the inner whorls and by the centripetal development of the Camereiceras stage (Bert et al., 2006(Bert et al., , 2013;;Bert and Bersac, 2013). And on the other hand, Lenicostites gen. nov. is not derived from the Gassendiceras, of which it is not an offshoot.

As Lenicostites gen. nov. is independent of Hemihoplitidae, it represents a pure case of homeomorphy. In the same way, there is no reason to think that Lenicostites gen. nov. may be related, other than by the same phenomenon of homeomorphy, to Homeomorphitinae subfam.

nov. or to other groups detailed above (chapter 5), especially because of the important geographical, stratigraphic and phyletic hiatuses, and apomorphies specific to these groups. In the current state of knowledge, Lenicostites gen. nov. could be considered as a cryptogenic taxon. It could possibly have a migratory origin (?) given its simultaneous appearance in the south-east of France with Gassendiceras under favorable climatic and paleogeographic conditions [START_REF] Bert | Origin of the Tethyan Hemihoplitidae tested with cladistics (Ancyloceratina, Ammonoidea, Early Cretaceous): an immigration event?[END_REF].

Reasons for this particular widespread homeomorphism could be linked to the simplified generalist 'hemihoplitid-like' morphology, making it easily reproducible. Considering the Pareto optimality theory applied to ammonites [START_REF] Tendler | Evolutionary tradeoffs, Pareto optimality and the morphology of ammonite shells[END_REF], the 3D morphospace occupation of ammonoid shell, based on the Raup's parameters, occurs in a square pyramid with 5 vertices. Each of these extreme point of the Pareto space corresponds to archetype morphology optimized with respect to a single task (constraint). [START_REF] Tendler | Evolutionary tradeoffs, Pareto optimality and the morphology of ammonite shells[END_REF] have inferred these constraints as hydrodynamic efficiency, shell economy, rapid growth and size (including compactness). As said above (chapter 5.7), the 'hemihoplitid-like' shell morphology takes place in the middle of the pyramid. Such a position fits generalist morphologies, in the zone of maximum equilibrium between the different constraints that govern the construction of ammonite shells, namely a Pareto-optimal solution. It is therefore expected that the morphologies at the equilibrium of the constraints (knowing that this optimum can vary depending on the environment) are the easiest to reproduce and therefore the most often imitated (convergence). As this, such occupation position in the W-D-S morphospace is mainly explained by convergence over Pareto-optimal solutions, rather than only phylogenetic relationships (Tendler et al., 2015, p. 11).

Homeomorphy as a result of convergence, parallelism or iterative evolution?

It is well known that ammonites are a remarkable model for the study of phenotypic evolution, even if only their shell is accessible. This shell secreted by accretion performs the development of structures and morphologies sufficiently diversified to allow the paleontologists not only to recognize the different taxa and evolutionary patterns, but also to try to understand their processes. However, due to its nature and construction, the shell of ammonites necessarily develops sooner or later homeomorphies between different taxa that may or may not belong to different lineages and/or at very different times. Examples of homeomorphy in ammonites are numerous and have been the source of many discussions (see for example [START_REF] Kennedy | Aspects of ammonite biology, biogeography, and biostatigraphy[END_REF], p. 41-42, Monnet et al., 2015, p. 97 and Walton and Korn, 2017 with references). The consequences of this phenomenon and their perception by the researchers (with all the risks of producing polyphyletic taxa), had already been noted by Kilian in 1910: they can have major implications on phylogenetics, systematics and on the understanding of the evolutionary fact. In this respect, the case of Lenicostites gen. nov. is demonstrative of a peculiar ammonite, since it presents a part of the diagnostic characters of Hemihoplitinae but with a discordant stratigraphic distribution, which, without a more indepth study, could have led to some wrong conclusions with respect to the evolution and classification of the whole group (e.g. [START_REF] Vermeulen | Le Barrémien de Saint-Martin, Escragnolles[END_REF][START_REF] Vermeulen | Boundaries, ammonite fauna and main subdivisions of the stratotype of the Barremian[END_REF].

In a very Darwinian framework, it is expected that the external constraints of abiotic (environmental factors) and biotic (intra-or interspecific competition) factors constrained adaptation of the morphology of the ammonites shell (adaptive selection). It is generally accepted that homeomorphy between two forms could be the result of a morphofunctional adaptation linked to a similar way of life and thus to the occupation of the same ecological niche. The influence of these extrinsic constraints has often been overestimated with respect to internal constraints (construction, development and of course also genetic, but this aspect inaccessible in ammonites can only be deduced), whereas the evolution of organisms is an equilibrium between various mutually interacting processes (see [START_REF] Monnet | Chapter 5. Evolutionary Patterns of Ammonoids: Phenotypic Trends, Convergence, and Parallel Evolution[END_REF].

Understanding these constraints, and the relationships among them, is necessary to understand the causes of homeomorphy, which can be expressed according to different evolutionary phenomena, either convergence or parallelism (not mutually exclusive). The case of iteration is a little different, and although it is usually considered as a form of convergence, it can sometimes be a mixture of both and in this case be very constrained by intrinsic factors (see below the example of the Gregoryceras Spath, 1924a).

Convergence and parallel evolution are a main source of homoplasy, and following [START_REF] Serb | Charting Evolution's Trajectory : Using Molluscan Eye Diversity to Understand Parallel and Convergent Evolution[END_REF] they are distinct concepts (Fig. 8). Convergence appears to be the independent evolution of similar structural or functional components in two or more unrelated lineages. The homeomorphs given by evolutionary convergence do not share a common ancestor and they have evolved convergently to the same morphology, mainly because of adaptation to similar conditions (Fig. 8A -external constraints, see above).

In parallel evolution (Fig. 8B-C), two (or more) lineages have similar ancestral phenotype and the descendants have evolved in trajectories towards similar morphology. Parallel evolution assumes that the same common developmental processes are independently involved between the lineages (intrinsic factor), and thus is more frequent in closely related organisms. Parallel evolution would also be subject to natural selection, but obviously when the genome is still close between the lineages, they will be more likely to evolve identically in the same environment (Tintant, 1963, p. 474-475).

Iterative evolution uses the notion of repeatability of the phenotypic traits (Fig. 8D-E). This repeatability is usually argued by an adaptive response to changes in environmental cycles [START_REF] Milankovitch | Canon of Insolation and the Ice-Age Problem[END_REF], and thus would be totally dependent on external constraints (selection pressure - [START_REF] Bayer | Iterative evolution of Middle Jurassic ammonite Faunas[END_REF]. Examples show that ammonite lineages that have evolved iteratively are from generalist pools, rather distributed in pelagic environments, which have drifted to more specialized forms in platform edge environments (see the example of Physodoceras [START_REF] Hyatt | Cephalopoda[END_REF]in Hantzpergue, 1987, p. 520). The counter-example of the Gregoryceras, which have evolved from the Peltoceratoides Spath, 1925, shows that iterative evolution can also be expressed as a result of an evolutionary crisis (punctuated event of proteromorphosis type in the sense of [START_REF] Guex | Reinitialization of evolutionary clocks during sublethal environmental stress in some invertebrates[END_REF], which leads to the reappearance of ancestral characters (here the duplicated ventral tubercles, specific to Peltoceratoides, at the end of the lineage in Gregoryceras - [START_REF] Bonnot | Les Aspidoceratidae d'Europe occidentale au Callovien supérieur et à l'Oxfordien inférieur[END_REF][START_REF] Bert | Révision, étude systématique et évolution du genre Gregoryceras Spath, 1924 (Ammonoidea, Oxfordien)[END_REF]Bert, , 2014)). In this case, the morphological iteration is linked to a common genetic inheritance (internal constraint) and everything happens as if the punctuated event would reset the evolutionary trend and revive it on the same bases, which finally lead to homeomorphy by evolutionary parallelism shifted in time.

It does not seem possible to invoke a phenomenon of parallel evolution between Lenicostites gen. nov. and Hemihoplites, nor an evolutionary iteration like the Physodoceras or the Gregoryceras examples. On the one hand, there is no phyletic proximity between Lenicostites gen. nov. and the Hemihoplitinae (see the arguments developed above in chapters 4, 6.1), and on the other hand the general common morphology between these groups is rather generalist in a Pareto-optimal solution and does not require to invoke great ecological adaptations towards a constrained specialization. Finally, the most appropriate model in this case is that of homeomorphy given by evolutionary convergence, which also supposes that the external constraints are the strongest to reproduce this type of generalist 'hemihoplitid-like' simplified morphology.

The principle of Gause applied to Lenicostites gen. nov.: a matter of competitive replacement in favor of Hemihoplitinae

The principle of competition for the struggle for existence is at the root of the Darwinian theory, where 'the extinction of ancient forms is the almost inevitable consequence of the production of new forms' [START_REF] Darwin | L'origine des espèces : Au moyen de la sélection naturelle ou la préservation des races favorisées dans la lutte pour la vie[END_REF](Darwin, , reprint of 2008, p. 410), p. 410). Competition is an extremely complex phenomenon subtended by the interaction of two different processes: exploitation (the use of a resource in necessarily limited quantity) and interference (the interaction between the organisms affecting their reproduction or their survival). Interspecific competition has been studied in laboratory on various groups (e.g. paramecium for [START_REF] Gause | Vérifications expérimentales de la théorie mathématique de la lutte pour la vie[END_REF], beetles for Park, 1962) and experimental results have shown that in a given stable environment, two species that use the same type of limited resource cannot coexist for a very long time, which tends systematically to extinction of the least 'fit' species because of the competitively superior species [START_REF] Benton | Testing the roles of competition and expansion in Tetrapod evolution[END_REF][START_REF] Stanley | Predation defeats competition on the seafloor[END_REF]. There are many examples of the Gause principle of competitive replacement that have allowed it to be generalized [START_REF] Maynard-Smith | The genetics of stasis and punctuation[END_REF][START_REF] Rosenzweig | Species diversity in space and time[END_REF][START_REF] Simpson | The major features of evolution[END_REF][START_REF] Stanley | Macroevolution: pattern and process[END_REF][START_REF] Stebbins | Adaptative shifts and evolutionary novelty : a compositionist approach[END_REF], but the concept of aptitude is not always very clear. Park's experimental work (1962) has

shown that the result of competition between two species depends both on intrinsic factors but also on the environment, which may be more or less favorable to one or the other species. It turns out that the surviving species is not systematically the most favored at the beginning, nor the most representative in number of individuals, even if it is the most expected and the most frequent case. This could be explained by the fact that, in a natural environment [START_REF] Case | Interspecific competition, environmental gradients, gene flow, and the coevolution of species borders[END_REF], competition between two species reduces the both population densities, which decreases local adaptation (local adaptation concerns all changes in the frequency of genes, and the resulting phenotype, in response to selective pressures associated with the local environment). Despite the fact that this leaves room for a certain amount of chance, the strength of interspecific competition also depends on phenotypic similarity and plasticity:

greater phenotypic variability seems to induce a reduction in the negative effect of interspecific competition for the concerned taxon (Burgess et al., 2013, with references;[START_REF] Morten | Fluctuation in the body size of marine invertebreates througt the Plienbachian-Toarcian extinction event[END_REF].

In paleontology, these competitive interactions are still poorly studied, especially in ammonites, and most often after mass extinction events [START_REF] Benton | Testing the roles of competition and expansion in Tetrapod evolution[END_REF][START_REF] Morten | Fluctuation in the body size of marine invertebreates througt the Plienbachian-Toarcian extinction event[END_REF][START_REF] Hautmann | Competition in slow motion: the unusual case of benthic marine communities in the wake of the end-Permian mass extinction[END_REF]. However, according to some authors [START_REF] Benton | Testing the roles of competition and expansion in Tetrapod evolution[END_REF][START_REF] Stanley | Effects of competition on rates of evolution, with special reference to bivalve mollusks and mammals[END_REF][START_REF] Stanley | Predation defeats competition on the seafloor[END_REF], the role of competition has generally been exaggerated by paleontologists, and it would only play a minor role in most ecological communities because of the regulating action of predation, which would exert a pressure such as to desaturate the ecological niches.

Although sessile communities, such as bivalve mollusks, are more susceptible to the effects of predation than to competition, the same is not true for vagile forms such as mammals, trilobites, or ammonites, which are subject to a high rate of evolution [START_REF] Stanley | Effects of competition on rates of evolution, with special reference to bivalve mollusks and mammals[END_REF], and for which competition is likely to play an important role in terms of evolutionary divergence (the 'centrifugal force of evolution' of [START_REF] Mayr | Animal species and evolution[END_REF]. Thus, the rate of evolution is as high as competitive interactions between species is intense. As this, every successful adaptation of one species is done at the expense of the other species living in the same ecological niche. In other words, as stated in the Red Queen theory, the permanent evolution of a species is necessary to answer the fitness of the other species with which it co-evolve to avoid extinction [START_REF] Van Valen | A new evolutionary law[END_REF]: in the Darwinian frame, only the fittest species would survive in such a run.

By the foregoing, and based on the principle of morphology linked to functional needs in ammonites (e.g. [START_REF] Westermann | Ammonoid life and habitat[END_REF]Lukeneder, 2015) and on the constraints highlighted by the Pareto-optimal theory [START_REF] Tendler | Evolutionary tradeoffs, Pareto optimality and the morphology of ammonite shells[END_REF], it is reasonable to think that the morphology of Lenicostites gen. nov. suggests that it occupied an ecological niche very similar to

Hemihoplites feraudianus and adults microconchs of Hemihoplitinae with smooth ribbed body chamber (Camereiceras marchandi and C. limentinus -see Fig. 5B,C). Lenicostites gen. nov. was not contemporaneous with H. feraudianus, but it was with C. marchandi and limentinus, which was a favorable condition for the establishment of interspecific competition. As seen above, Camereiceras has characteristics generally associated with better competitiveness compared to Lenicostites gen. nov.: (1) the adult size of Camereiceras is larger, which presumably conferred it certain advantages in terms of defense against predation (Tendler et al., 2015, p. 6), increased food competition, increased success in mating and reproduction, increased individual longevity, and better energy use (see also Monnet et al., 2015, p. 116, with references); (2) Hemihoplitinae are much more dynamic with a higher evolutionary rate (rapid succession of species), while Lenicostites gen. nov. seems to be in a period of evolutionary stasis; (3) in terms of representativeness, Camereiceras is much more abundant than Lenicostites gen. nov. in the deposits, which suggests that its reproductive rate was higher (higher fitness); (4) preliminary studies (work in progress) show that

Camereiceras has an extraordinarily wide intraspecific variability (combination of both heterochronies and multipolar variations in the sense of Bert, 2014a, b), between forms highly tuberculate in the inner whorls and forms much more slender. In any case, this variability is much higher than that of Lenicostites gen. nov., where it concerns the robustness of ornamentation only (see description). This high difference in variability between the two groups could explain that Camereiceras has better supported competition with Lenicostites gen. nov. by a lesser impact of its negative effects. Of course, with only partial paleontological data (external ammonites shell) there is no guarantee that this example is evidenced or random, but here we interpret the disappearance of Lenicostites gen. nov., very soon after they meet the re-coiled Hemihoplitinae (Camereiceras marchandi and C. limentinus -Fig. 5), by the effect of interspecific competition: in this hypothesis, Lenicostites gen. nov. is a victim of the Gause Principle as it lost the Red Queen race.

Conclusions

The evolution, biostratigraphy and systematics of the ammonite family Hemihoplitidae is nowadays well known. Concerning the subfamily Hemihoplitinae, the genus Camereiceras is derived from the genus Gassendiceras (Gassendiceratinae) in the top Gassendiceras alpinum Subzone [START_REF] Bert | Origin of the Tethyan Hemihoplitidae tested with cladistics (Ancyloceratina, Ammonoidea, Early Cretaceous): an immigration event?[END_REF]. The older Camereiceras retain some characters from their ancestor (ornamentation pattern, general heteromorphic morphology and, above all, their ontogenetic stages), and their microconchs have an adult simplified morphology with smooth identical ribs. Later (in the Camereiceras limentinus Subzone), Camereiceras gives rise to Hemihoplites, of which the evolution shows a progressive reduction of the tubercles to give finally the simplified morphology known in H. feraudianus with weak tubercles. All this evolution is actually restrained to the north-west Tethyan margin (Fig. 7) at the early late Barremian only (T. vandenheckei and G. sartousiana zones -Fig. 1). In this context, the genus Lenicostites gen. nov. that suddenly appears in the middle T. vandenhekei Subzone with its simplified morphology very close to Hemihoplites feraudianus (compare Fig. 2-3 with Fig. 4) is unexpected because of its older age of three ammonites subzones, contemporary of the genera Gassendiceras and Camereiceras (in several occurrences according to new data collected in southeastern France -this work). Despite its large stratigraphic range, Lenicostites gen. nov. appears to be monospecific (L. rusticus gen. nov.) and in evolutionary stasis, unlike the Hemihoplitinae that show a high evolutionary rate. It is undeniable that Lenicostitidae fam. nov. are morphologically very close to Hemihoplitinae, however, the stratigraphic, ontogenetic, evolutionary and systematic analyses show that there is no connection between these families and that the resemblance is purely a case of homeomorphy, as they occupies the same solution in the morphological space of the Pareto optimality theory applied to ammonites [START_REF] Tendler | Evolutionary tradeoffs, Pareto optimality and the morphology of ammonite shells[END_REF]: the 'hemihoplitid-like' morphology.

In the light of the Lenicostites gen. nov., it is possible to re-examine the numerous occurrences of Hemihoplitinae reported in the literature in localities sometimes very distant from each other and from the Tethyan domain or even from the upper Barremian, which are sometimes contradictory with the evolutionary history of the group. The critical review of these reports allows a drastic revision and clarification of the systematic and paleogeographic distribution of Hemihoplitinae as a whole: until proven otherwise, there is no Hemihoplitinae outside the north and west margins of the Tethyan Realm (including its Caucasian margin in the east, and the Essaouira Basin in Morocco at the limit of the Proto Atlantic Ocean in the west). Actually, the 'hemihoplitid-like' morphology is iterative at the Valanginian, Hauterivian, Barremian and Aptian in several taxa without any phyletic links, which develop it by homeomorphy.

For example, it is now certain that the genus 'Hemihoplites' reported in Patagonia (Argentina These examples, which are independent from the Hemihoplitidae, show that the shared 'hemihoplitid-like' morphology is widespread, generalist and thus easily reproducible under the Pareto optimality theory (Pareto-optimal solution in the zone of maximum equilibrium between the different constraints that govern the construction of ammonite shells).

Homeomorphy is common in ammonites, and in the case of Lenicostites gen. nov. it is due to convergence (Fig. 8A) rather than parallelism (Fig. 8B-C) or iterative evolution (Fig. 8D-E).

Such homeomorphy could be the result of a morphofunctional adaptation related to similar living conditions (external constraints). The appearance of Camereiceras with a nonheteromorphic shell (Fig. 5B-C) established favorable conditions for interspecific competition. Camereiceras has characteristics generally associated with better competitiveness compared to Lenicostites gen. nov.: larger adult size [START_REF] Tendler | Evolutionary tradeoffs, Pareto optimality and the morphology of ammonite shells[END_REF], better evolutionary dynamics, probably higher reproductive rate and greater intraspecific variability (see Monnet et al., 2015, p. 116, with references,). Thus, the disappearance of Lenicostites gen. nov., very soon after they meet the re-coiled Hemihoplitinae (Camereiceras marchandi and C. limentinus), could be interpreted as the effect of interspecific competition, to go so far as a complete competitive replacement: in this hypothesis, Lenicostites gen. nov.

is a victim of the Gause Principle as it lost the Red Queen race (the permanent evolution of species being necessary to answer the fitness of the other species with which it co-evolve to avoid extinction - [START_REF] Van Valen | A new evolutionary law[END_REF]. Data from literature (see text), map modified after [START_REF] Barron | Paleogeography, 180 million years ago to the present[END_REF]. given by evolution of independent processes (a and b) towards similar morphology (circles) in two or more unrelated lineages (here 1-2 and 3-4), mainly because of adaptation to similar conditions (external constraints). This is the case for example with the Lenicostites gen. nov.

Figure captions

and Hemihoplitinae; B and C, homeomorphy by parallel evolution is given when the descendants of the same ancestral phenotype (species 1, square) have evolved in trajectories towards a similar morphology (circle). Here, the same common developemental processes was involved independently (a -intrinsic factor). See for example the parallel evolution of two Devonian ammonoid families (Auguritidae [START_REF] Bogoslovski | Eyfelskie ammonoidei Urale i voprosy klassifikatsii agoniatitov[END_REF]Pinacitidae Hyatt, 1900) in [START_REF] Monnet | Chapter 5. Evolutionary Patterns of Ammonoids: Phenotypic Trends, Convergence, and Parallel Evolution[END_REF]; D, iterative evolution can be given by adaptive convergence, which gives the repeatability of the phenotypic traits (extrinsic factor). In that case (see the example of Physodoceras in [START_REF] Hantzpergue | Les ammonites kimmeridgiennes du haut-fond d'europe occidentale : (perisphinctidae, aulacostephanidae et aspidoceratidae) : biochronologie, systématique, évolution, paléobiogéographie[END_REF], ammonite lineages 2 and 3 have evolved iteratively in platform edge environment (whatever the processes involved, a or b) from the generalist pelagic pool 1; E, iterative evolution can be also given by evolutionary crisis (punctuated event of proteromorphosis type -intrinsic factor), which leads to the reappearance of ancestral phenotype (circle), whatever the processes involved, a or b. This special case of parallel evolution shifted in time is known, for example, in Gregoryceras, which finally repeated the morphology known in its ancestor Peltoceratoides (see [START_REF] Bonnot | Les Aspidoceratidae d'Europe occidentale au Callovien supérieur et à l'Oxfordien inférieur[END_REF][START_REF] Bert | Révision, étude systématique et évolution du genre Gregoryceras Spath, 1924 (Ammonoidea, Oxfordien)[END_REF]Bert, , 2014)).

  Stratigraphic occurrence. Lenicostites gen. nov. is currently known to be present in several occurrences in the lower upper Barremian (Fig1):(1) in the middle part of the T.

  Fig.3-and RNNGHP.SBC.06050-TAI/99.TAI155 -Fig.2D). In addition, the holotype (No.

  However, and contrariwise to what is known in Hemihoplitidae, the umbilical tubercles are lacking here and the lateral tubercles are high on the flanks. When introduced, A. ridzewskyi Karakasch, 1897 was quoted with aptian faunas such as Hoplites deshayesi d'Orbigny, 1841, Acanthoceras martini d'Orbigny, 1841, Acanthoceras cornuelianum d'Orbigny, 1841, Aspidoceras royerianum d'Orbigny, 1841 and Costidiscus recticostatus d'Orbigny, 1841 in the sandy glauconitic marlstones near the village of Detich (Caucasus). More recently A. ridzewskyi was most precisely assigned to the Turkmeniceras turkmenicum Zone in the uppermost Barremian

  Kakabadze and Hoedemaeker, 2004 was introduced on the basis of a single Colombian specimen of very small size. This specimen has a morphology very close to the type specimen of Pseudocrioceras? ridzewskii, and for the same reasons (see above chapter 5.1) we propose the same assignation in open nomenclature in the vicinity of the genus Pseudocrioceras.

  Stratigraphic and geographical occurrence. The genus Homeomorphites gen. nov. is currently only known in the Austral Basin (Fig.7), eastern border of the southern Patagonian Cordillera (Argentina and Chile), in levels spanning lower Hauterivian (Favrella americana Zone) to upperBarremian (Fig. 6 -between the Hatchericeras patagonense and Colchidites-Sanmartinoceras zones -see[START_REF] Riccardi | The Cretaceous system of southern South America[END_REF][START_REF] Riccardi | Hemihopltitid ammonoids from the Lower Cretaceous of Southern Patagonia[END_REF][START_REF] Aguirre-Urreta | Hemihoplitid Ammonoids from the Austral Basin of Argentina and Chile[END_REF]. Diagnosis. Dimorphic genus with evolute shell and subquadratic to sub-oval whorl section, sometimes more compressed in large macronconchs [M]. Flanks and ventral area usually convex, more or less rounded [M] or flattish [m]. Ornamentation with flexuous ribs, simple or bifurcated near the umbilical margin (inner whorls) or just above the mid-part of the flanks.Intercalary ribs sometimes present. Size of the shell (from medium to large) and ribbing density (from dense to spaced) are different according to the species. On large macroconchs, the ribs disappear progressively in becoming less marked and more spaced and irregular, and the body chamber is smooth. Constrictions and reinforced ribs are scarce. Sometimes 'zigzag' ribs can occur on the ventral area. Suture formula of ELU 2 U 3 I type, with more or less asymmetric trifid L.Discussion. Homeomorphites gen. nov. shows dimorphism and a general morphology and shell size very close to the Hemihoplitinae, especially to Hemihoplites feraudianus (d[START_REF] Orbigny | Paléontologie française -Terrains crétacés -Tome 1[END_REF]. Despite of this,Kakabaze and Hoedemaeker (2004) had previously refused to assign the Patagonian species to the genus Hemihoplites (pp. 82-83) asLehmann et al. (2015, p. 238) did more recently . Actually, Homeomorphites gen. nov. never shows the tubercles systematically present in the Hemihoplitinae, nor their ontogenetic stages (see Bert

-

  [START_REF] Riccardi | Hemihopltitid ammonoids from the Lower Cretaceous of Southern Patagonia[END_REF][START_REF] Aguirre-Urreta | Hemihoplitid Ammonoids from the Austral Basin of Argentina and Chile[END_REF] actually corresponds to a genus of ammonite endemic to the Austral Basin, identified here under Homeomorphites gen. nov., which evolves locally from the early Hauterivian to the late Barremian by allometric hypermorphosis (heterochrony).In the same way, it is possible to propose a direct phyletic link from Shasticrioceras to Antarcticoceras based on data from Chañarcillo Basin (Chile -[START_REF] Mourgues | Paléontologie stratigraphique (ammonites) et évolution tectono-sédimentaire du Bassin d'arrière arc de Chañarcillo (Berriasien -Albien, Nord du Chili[END_REF]. This evolution is done by the simple acquisition of an additional tubercle at the top of the flanks very early during ontogeny. The attribution of the species A. domeycanum (late Barremian) to the genus Antarcticoceras and the description of A. perezi nomen nudum at the base of the early Aptian make possible to fill the stratigraphic and morphological hiatus between the both two genera and to classify them together within the same family: the Shasticrioceratidae fam. nov.

Figure 1 :

 1 Figure 1: Biostratigraphic chart of the upper Barremian (see references in the text), with the

Figure 2 :

 2 Figure 2: Lenicostites rusticus gen. nov. from the upper Barremian (Lower Cretaceous) of

Figure 3 :

 3 Figure 3: Nearly complete robust adult of Lenicostites rusticus[START_REF] Vermeulen | Le Barrémien de Saint-Martin, Escragnolles[END_REF] gen. nov.

Figure 4 :

 4 Figure 4: Hemihoplites feraudianus from the upper Barremian (Lower Cretaceous) of

Figure 5 :

 5 Figure 5: Camereiceras from the upper Barremian (Lower Cretaceous) of southeastern

Figure 6 :

 6 Figure 6: Correlation of the biostratigraphic charts between the north-west Tethys, the

Figure 7 :

 7 Figure 7: Paleogeographic map of the Barremian age showing the distribution of: the north-

Figure 8 :

 8 Figure 8: The different patterns of homeomorphy in ammonites; numbers 1 to 4 are different

  Geographic occurrence. Lenicostites gen. nov. is known in southeastern France, both in basinal and platform area.

gen. nov. Specific content. Lenicostites gen. nov. is currently monospecific.

Table 1 .

 1 Measurments of the two most complete specimens.

	N° specimens	D	Dph	H	W	U	H/D	W/D	U/D	W/H
	RNNGHP.SBC.06050-	140.00	118	53.72	47.76	56.48	0.38	0.34	0.40	0.89
	TAI/99.TAI153 Fig. 3	107.40		37.40	43.20	40.10	0.35	0.40	0.37	1.16
	4141351 (holotype -	52.40	?	19.00	18.90	19.60	0.36	0.36	0.37	1.00
	Fig. 2A)
	Description and ontogenesis. The collected specimens are few, but they give a good
	representation of the species. Specimen No. RNNGHP.SBC.06050-TAI/99.TAI153 (Fig. 3) is
	interpreted as robust morphology; it is the most complete, probably an adult, with a quarter

  In 1992, Klinger and Kennedy depicted two lower upper Barremian specimens from Zululand, which they compared to Hemihoplites varicostatus and H. ploszkiewiczi (here Homeomorphites gen. nov., see below chapter 5.8) because of their morphological similarity to the Argentinean faunas published by Riccardi and Aguirre-Urreta

	5.4. The other Austral, American and south African 'Hemihoplites'

. New data collected in southeastern France (work in progress) assert that the direct ancestor of H. feraudianus is the trituberculate species H. astarte (previousely reported as H. casanovai in

Bert et al., 2008, p. 3)

, present in the immediately older levels in the Barremian stratotype area (H. astarte Horizon). This species is derived from Camereiceras limentinus via H. cornagoae.

All these elements do not support the migratory hypothesis of H. feraudianus from populations of the Austral Basin, formulated by Aguirre-Urreta (2002), and the Homeomorphitinae subfam. nov. are here classified into the Neocomitidae (Perisphinctoidea -see below chapter 5.8. the discussions related to Homeomorphitinae subfam. nov. and Homeomorphites gen. nov.).

  Onthe other hand, the variation in rib spacing visible on the last whorl, and the importance of the interrib spaces in relation to the width of the ribs, is not a character known in Hemihoplites. This is the same with Hemihoplites sp. A reported byMyczynski (1977, pl. 6, fig. 5) in the Polier Formation of Cuba (El Herete, Sierra del Rosario), which bears 3-4 constrictions per whorl in the inner whorls, and a change in ornamentation in the last whorl with denser and prorsiradiate ribs bifurcated close to the ventral margin. Its uppermost Hauterivian attribution is assumed by the presence of Pseudothurmannia sp. in the same layer (not figured), while some Barremian specimens attributed to Karsteniceras sp. are also reported. Pending new data, these Mexican and Cuban specimens are left in open nomenclature.

	In his PhD thesis, Cantú Chapa (1963) reported the presence of Hemihoplites cf. feraudianus
	(pl. 3, fig. 6) in the eastern Mexico (Mexico-Tuxpan Road, km 216.7). Its very partial

under Hemihoplites sp. cf. ploszkiewiczi and H. sp. cf. varicostatus (here Hatchericeras argentinense). Pending more data, H.? mexicanus is left in open nomenclature.

preservation does not make it possible to form an opinion, but its Barremian attribution seems proved by the presence in the same site of Holcodiscus aff. perezianus (d

[START_REF] Orbigny | Prodrome de Paléontologie stratigraphique universelle des animaux mollusques et rayonnés[END_REF]

.

Hemihoplites? popenoi

[START_REF] Murphy | Paleontology and stratigraphy of the Lower Chickabally mudstone (Barremian-Aptian) in the Ono Quadrangle, Northern California[END_REF]

, from the Shasticrioceras patricki Zone, is a Shasticrioceras

[START_REF] Anderson | Lower Cretaceous deposits in California and Oregon[END_REF]

(here Shasticrioceratidae nov. fam., see below chapter 5.8) related species, unrelated to Hemihoplitidae. The S. patricki Zone has also delivered Kotetishvilia cf. compressissima (d

[START_REF] Orbigny | Paléontologie française -Terrains crétacés -Tome 1[END_REF]

, index species for the middle lower Barremian (Fig.

6

). It is not shocking to bring H.? popenoi close to the genus Shasticrioceras, which contains some taxa with a thick or very thick whorl section [e.g. Shasticrioceras inflatum

Anderson, 1938, Shasticrioceras wintunius

  species. Its thin ribs, closely spaced and projected towards the front of the shell from the periventral area are not characters of Hemihoplites; thus, pending more data this specimen is left in open nomenclature.

'Hemihoplites' perezi

Mourgues, 2007 (nomen nudum)

was first attributed to the genus Antarcticoceras (sensu

[START_REF] Mourgues | Paléontologie stratigraphique (ammonites) et évolution tectono-sédimentaire du Bassin d'arrière arc de Chañarcillo (Berriasien -Albien, Nord du Chili[END_REF]

as the last representative of a possible evolutionary lineage ['Crioceratites' ttofurus Mourgues, 2007 nomen nudum → Antarcticoceras domeykanum → 'Antarcticoceras' perezi nomen nudum]. In a second time, this species was assigned to the genus Hemihoplites without any explanation by Aguirre-Urreta et al. (2007a),

  , clearly does not belong to Hemihoplitidae. On the other hand, its belonging to the genus Antarcticoceras (here Shasticrioceratidae fam. nov.,The fragmentary and certainly teratological specimen of Crioceratites (Hemihoplites) n. sp. ex aff. C. (H.) soulieri[START_REF] Matheron | Recherches paléontologiques dans le midi de la France[END_REF], figured by[START_REF] Jeletzky | XI Biochronology : Standard of Phanerozoic Time; Cretaceous macrofaunas[END_REF] from the Barremian of British Columbia (Canada, North Pacific Realm), is morphologically closer to the genus

	Colombiceras Spath, 1923 than to Hemihoplitidae. This specimen is left in open
	nomenclature pending new data.
	see below chapter 5.8) is credible and deserves to be considered. It should be noted that the
	taxa introduced by Mourgues in his unpublished PhD (2007) are all nomen nudum for this
	reason. The publication announced by Aguirre-Urreta et al. (2007a, p. 158) to regulate this
	taxonomic situation is, to our knowledge, still unpublished to date: it now appears to be
	highly desirable.

  , particularly because of the uncertain age of the specimens studied bySpath (P. budavadensis Spath, 1933 and P. crassus Spath , 1933), which come from white shales with plants (Raghavpuram Shales Formation) from the Eastern peninsular India (Budavada village, Nellore District, in the Cauvery Basin). The age attributed by Spath ('probable Barremian') is essentially based on the presence of very badly preserved and crushed fossils and attributed by him to Holcodisciidae[Holcodiscus cf. perezianus, H. cf. caillaudianus (d'Orbigny, 1850), Gymnoplites simplex[START_REF] Spath | Revision of the Jurassic Cephalopoda fauna of Kachh (Cutch). Part VI[END_REF], and Hoplites cf. borowae Uhlig, 1883, H. cf. beskidensis Uhlig, 1883, H. codazzianus[START_REF] Karsten | Géologie de l'ancienne Colombie bolivarienne[END_REF] and Lytoceras sp. cf. vogdtiKarakasch, 1907. Traditionally, the Raghavapuram Shales

  nov. (with Homeomorphites aguirreurretae gen. nov. et sp. nov. [=Hemihoplites feraudianus in Aguirre-Urreta, 2002]) and the Shasticrioceratidae fam. nov. (with the lineage made by Shasticrioceras and Antarcticoceras).The Homeomorphitinae subfam. nov. do not have the ontogenic stages common to all the Hemihoplitidae (seeBert et al., 2013). More, several characters conjointly present, even sometimes episodic, in Homeomorphites gen. nov. (absence of tubercle or bulging of ribs; spacing of ribs before smooth stage; episodic presence of reinforced ribs and what looks like constrictions in some specimens; 'zigzag' stage; sutural formula with more than one umbilical lobe U of ELU 2 U 3 I type -clearly visible inRiccardi and Aguirre-Urreta, 1989, text-fig. 4a, 6) definitely discard the Homeomorphitinae subfam. nov. from the Hemihoplitidae, and more widely from the Ancyloceratoidea. Actually, these features remember 'perisphinctid' assemblage of characters. Of course, each of these characters taken separately is not exclusive of Perisphinctoidea Steinmann, 1890, but there combination allow to consider the Homeomorphitinae subfam. nov. as the ultimate representatives of the Perisphinctoidea, in the vicinity of the subfamilies Neocomitinae

	Superfamily: Perisphinctoidea Steinmann, 1890
	Familly: Neocomitidae Salfeld, 1921
	Subfamily: Homeomorphitinae subfam. nov.
	Type genus. Homeomorphites gen. nov.

Generic content. In the current state of knowledge, this subfamilly is monotypic.

Stratigraphic and geographical occurrence. The Homeomorphitinae subfam. nov. are restricted to southern hemisphere, especially the Austral Basin (South Patagonia, Argentina and Chile -Fig.

7

). Homeomorphites gen. nov. spans from lower Hauterivian to upper Barremian (see

[START_REF] Riccardi | Hemihopltitid ammonoids from the Lower Cretaceous of Southern Patagonia[END_REF][START_REF] Aguirre-Urreta | Hemihoplitid Ammonoids from the Austral Basin of Argentina and Chile[END_REF]

.

Discussion. The succession of species previously assigned to the genus Hemihoplites by Riccardi and Aguirre-Urreta (1989) and Aguirre-Urreta (2002), here Homeomorphites gen. nov., represents a coherent phyletic lineage both in terms of shared morphology and also stratigraphically as the species show a relatively continuous succession.

  assumed a phyletic link. Such phyletic link could question the Lyticoceras as Endemoceratinae, which are deemed to be linked with the Neocomitidae (Perisphinctoidea).

	Genus Homeomorphites gen. nov.
	Denomination. Because of the phenomenon of homeomorphy, which led to confusion with
	the genus Hemihoplites.
	Type species. Homeomorphites aguirreurretae gen. nov. et sp. nov. (=Hemihoplites
	feraudianus in Aguirre-Urreta, 2002).

Specific content. Homeomorphites aguirreurretae gen. nov. et sp. nov., Ho. ploszkiewiczi

[START_REF] Riccardi | Hemihopltitid ammonoids from the Lower Cretaceous of Southern Patagonia[END_REF]

and Ho. varicostatus

[START_REF] Riccardi | Hemihopltitid ammonoids from the Lower Cretaceous of Southern Patagonia[END_REF]

).

  americana Assemblage Zone in the upper lower Hauterivian according to Aguirre-Urreta et al., 2007b) → Ho. varicostatus (F. wilckensi and Hatchericeras patagonense assemblages zones in the upper Hauterivian and lower Barremian) → Ho. aguirreurretae gen. nov. et sp. nov. (non basal upper Barremian). The Colchidites-Sanmartinoceras zones (Fig. 6 -see Aguirre-Urreta, 2002). Homeomorphites aguirreurretae gen. nov. et sp. nov. is larger in size than Ho. varicostatus gen. nov. and Ho. ploszkiewiczi gen. nov. The ribbing density is also different as Ho. Hatchericeras patagonense Stanton, 1901 has a higher whorl section and a more closed umbilicus than Homeomorphites aguirreurretae gen. nov. et sp. nov. Ornamentation, on the other hand, is quite comparable in flexuosity and orientation of the ribs, but with an earlier smooth stage (80-100 mm versus 200 mm in diameter) and a smoother ventral area in Hatchericeras patagonense. The suture line is simpler and quite different with a narrower and more trifid symmetrical lobe L in Homeomorphites aguirreurretae gen. nov. et sp. nov.Compared with Hatchericeras argentinenseStanton,1901, Ho. aguirreurretae gen. nov. et sp. nov. has a more evolute coiling, a lower whorl height and a different ornamentation: the ribs are stronger, spaced and not attenuated on the ventral area.

	Diagnosis. Dimorphic species, macroconch [M] of large size (D=210 mm) and microconch
	evolutionary trend of this group has been described by Aguirre-Urreta (2002), who noted an [m] reaching D=70-80 mm. Evolute shell with section compressed for [M] or subrectangular
	increasing body size and coarser ribbing (ribs increasingly spaced in time). To this, one can for [m]. Umbilical shoulder and flanks rounded [M] or flattish [m]. Ventral area slightly
	add the acquisition of a new ontogenetic stage at the end of growth (smooth stage) by convex. Ornamentation with strong ribs, usually flexuous; they cross the venter without any
	allometric hypermorphosis (heterochrony in the sense of McKinney, 1988). The general weakening. Ribs are simple or bifurcated from the umbilical margin (inner whorls) or just
	morphology of the shell remains remarkably stable during this evolution, and the modification below the midflank. On the macroconch, the ribs disappear progressively in becoming less
	of the ornamentation could be related to the selective drift of the variability of the populations
	towards more and more robust forms (Aguirre-Urreta, 2002, p 496).
	Type locality. The Río Ghio locality, in the eastern border of the southern Patagonian
	Cordillera (Argentina).
	Type Level. The Río Belgrano Formation.
	aguirreurretae gen. nov. et sp. nov. shows more spaced and coarser ribs than the two other
	species of the genus.

Homeomorphites aguirreurretae

gen. nov. et sp. nov. 2002

Hemihoplites feraudianus (d

[START_REF] Orbigny | Paléontologie française -Terrains crétacés -Tome 1[END_REF]

; Aguirre-Urreta: text-fig.

4a

, pl. 1-2.

Denomination. This species is dedicated to Pr. María B. Aguirre-Urreta (University of Buenos Aires, Argentina), who discovered and described the specimens ascribed to this new species

(2002)

.

Holotype. The type specimen designated is the macroconch

No. CPBA 19156 (in Aguirre- Urreta, 2002, pl. 1)

. It is housed in the Cátedra de Paleontología de Buenos Aires, Ciudad Universitaria, Pabellón 2, 1428 Buenos Aires, Argentina.

Stratigraphic and geographical occurrence. The geographical distribution is the same as for the genus (Fig.

7

). Stratigraphically, Ho. aguirreurretae gen. nov. et sp. nov. is recorded in levels of the upper Barremian, just between the Hatchericeras patagonense and the marked and more spaced and irregular; the end of the phragmocone and the body chamber are smooth. Constrictions and reinforced ribs are scarce. Suture with L slightly deeper than E, moderately wide and asymmetrically trifid.

Discussion. Morphologically, Homeomorphites aguirreurretae gen. nov. et sp. nov. shows dimorphism and a general morphology and size of the shell very close to Hemihoplites feraudianus (d

[START_REF] Orbigny | Paléontologie française -Terrains crétacés -Tome 1[END_REF]

. Despite of this, the former lacks the tubercles systematically known in the latter. Moreover, the constrictions and reinforced ribs, albeit rare, are not an hemihoplitid character. Finally, the ribs are spaced just before the smooth part of the body chamber, which is never the case in Hemihoplites feraudianus. These differences are also discriminating against all other species of Hemihoplitinae, with a distinct ontogenic trend [i.e.

H. astarte, H. cornagoae, Camereiceras limentinus, C. marchandi, C. breistrofferi, and the representatives of the genus Pachyhemihoplites].

Compared with Theodorites theodori

Baraboshkin and Michailova, 2006

and Th. drushitsi

Baraboshkin and Michailova, 2006

, the ribs are a little more flexuous in Homeomorphites aguirreurretae gen. nov. et sp. nov. and are not as attenuated on the venter. Both species of Theodorites also have periventral tubercles and peri-umbilical bulges, completely absent in Homeomorphites aguirreurretae gen. nov. et sp. nov.

Family: Shasticrioceratidae fam. nov.

Type genus. Shasticrioceras

[START_REF] Anderson | Lower Cretaceous deposits in California and Oregon[END_REF]. Generic content. Shasticrioceras Anderson, 1938 (and its synonym Backraceras Mourgues, 2007 nomen nudum)

and Antarcticoceras

[START_REF] Thomson | Ammonite faunas of the Lower Cretaceous of south-eastern Alexander Island[END_REF]

Acknowledgments

This work was supported by the Geological National Nature Reserve of Haute-Provence (RNNGHP), managed by the Departmental Council of the Alpes de Haute-Provence (France), and by the Laboratory of the G.P.A. (Research group in ammonites paleobiology and biostratigraphy). We warmly acknowledge Sreepat Jain for his help with the Barremian/Aptian of India, and Abelardo Cantú Chapa for his help for Mexican ammonites. Miguel Company and Rafel Matamales-Andreu gave us valuable advices; we greatly appreciated their helpful discussions and constructive comments that hightly improved our work. Finally, we aknowledge both the two referees, Yves Dutour and Josep Moreno-Bedmar for their very constructive remarks. Declarations of interest: none.