Trematochampsa, TAQUETI BUFFETAUT, 1974

Meunier, Louise M V & Larsson, Hans C E, 2018, Trematochampsa taqueti as a nomen dubium and the crocodyliform diversity of the Upper Cretaceous In Beceten Formation of Niger, Zoological Journal of the Linnean Society 182 (3), pp. 659-680 : 662-680

TREMATOCHAMPSA TAQUETI BUFFETAUT, 1974

( FIG. 2A–H)

Holotype: Ibc 231, isolated right lacrimal ( Fig. 2C–H)

Reducing Trematochampsa taqueti to a nomen dubium: The type of T. taqueti is an isolated right lacrimal, Ibc 231 ( Fig. 2C–H). We propose the taxon T. taqueti be reduced to a nomen dubium based on the following description and discussion of this specimen that can find no morphologies to diagnose this taxon from other known crocodyliforms. Furthermore, because the type is a single isolated element, neither associated nor confidently combined with any other material in the In Becetin crocodyliform collection, nothing from this collection can be assigned to T. taqueti as a lectotype.

The lacrimal Ibc 231 was described by Buffetaut in 1974 and 1976. The original diagnostic morphologies of T. taqueti that were present on the holotype are only the presence of a large antorbital fenestra on the lacrimal and maxilla and, by inference, a relatively small to medium body size ( 1–3 m) of the animal. The fenestra is relatively small, but the fossa is large. Both these morphologies are present in many small- to mediumsized Crocodyliformes and do not constitute unique diagnostic morphologies for T. taqueti .

Anteriorly, Ibc 231 has a large antorbital fossa that expands well beyond a small antorbital fenestra that is defined by a small circular edge on the anterodorsal margin of the lacrimal. Although the entire fenestra is not preserved because it would have been bounded also by the maxilla, the acute circumference of the bor- der on the lacrimal suggests the fenestra was small. The fossa expands ventrally to the maxilla contact and dorsally to a broken edge. The ventral edge of the fossa is marked by a low but distinct near horizontal ridge that may have been the external limit to the maxillary contact. Below this ridge, the lacrimal is relatively smooth and lightly textured, possibly to contact a thin superficial overlap from the maxilla. A similar ventral antorbital fenestra morphology is present in Uberabasuchus terrificus and Montealtosuchus arrudacamposi . This morphology suggests the antorbital fossa extended ventrally onto the maxilla. The remain- der of the external surface of the lacrimal is heavily ornamented anteroventrally with pitting and sulci extending onto the orbital margin. The posterior margin of the antorbital fenestra is sharply edged with the fossa placed deep from the lacrimal superficial surface, creating a sharp bony roof on the posterior margin of the fossa. This type of deeply inset antorbital fossa and ornamented orbital margin of the lacrimal is only otherwise present in U. terrificus and Mo. arrudacamposi .

The posteroventral corner of the lacrimal has a large, complex, ovate suture that contacted the jugal. The robust jugal contact posteroventrally and slender maxilla contact anteroventrally is shared with many Crocodyliformes, such as Araripesuchus (all species), Sebecia and Neosuchia . However, many notosuchians, including Malawisuchus and derived notosuchians (following Pol et al., 2014), lack a lacrimal–jugal contact implying no relationship to these taxa. The jugal and maxilla contact at the lacrimal of T. taqueti compares closest to Araripesuchus wegeneri , U. terrificus and Mo. arrudacamposi , with a robust butt lacrimal–jugal contact and a thin lacrimal–maxilla overlapping contact with the antorbital fossa extending onto the maxilla.

Dorsolaterally, the lacrimal is deeply ornamented and forms a sharp posterior edge to the antorbital fossa. The fossa is smooth and the lacrimal portion of the fossa bounds the posteroventral corner of a small antorbital fenestra. The lateral surface of the lacrimal is relatively straight in posterior aspect. The robust prefrontal suture occupies much of the posterodorsal and posterodorsomedial surfaces of the lacrimal. Medially, a low, horizontal crest extends anteriorly from the base of the prefrontal contact and another smaller crest parallels this crest anterodorsally. A large lacrimal duct pierces the dorsal orbital margin and appears to have been bordered dorsally by the prefrontal. Two smaller foramina lie medial to the lacrimal duct.

Many of these morphologies are present in U. terrificus , Mo. arrudacamposi , An. minor and Ar. wegeneri , but not in other Araripesuchus species. Specifically, the topology of bones surrounding the antorbital fenestra is shared with these taxa. Differences with Uberabasuchus include the vertically oriented lacrimal edge to the antorbital fossa, as opposed to the curving, posteroventral margin in Ibc 231. Additionally, the orbital margin on the lacrimal of Uberabasuchus is linear with an angular dorsal margin, whereas the orbital margin in Ibc 231 is gently concave. Differences with Anatosuchus include the lack of ornamentation and relatively narrow proportions in this taxon’s lacrimal bar. There are few differences with Ar. wegeneri , but one notable difference is the lack of a sharp-edged and roofing posteroventral margin of the antorbital fenestra. However, the posterior sharp and roofed edge of the antorbital fossa, ornamentation and orbital margin is nearly identical to Mo. arrudacamposi . In fact, close examination of both finds no diagnostic features to separate the two. All morphologies described above for Ibc 231 are also present in the lacrimal of Mo. arrudacamposi . Therefore, in light of these more recent crocodyliform discoveries, we find no autapomorphies for Ibc 231.

DESCRIPTION OF IN BECETEN FORMATION CROCODYLIFORMS

Lacrimal Ibc 229 ( Fig. 3): Five other lacrimals are part of the In Beceten collection. All are more fragmentary than Ibc 231 and only Ibc 229 presents some unique morphologies to defend it as different from Ibc 231. Ibc 229 is a small left lacrimal with a large antorbital fossa. The bone is broken anteriorly and the presence of an antorbital fenestra cannot be determined. The posterior portion of the fossa curves laterally to a smooth posterolateral surface of the lacrimal, with neither the sharp antorbital fossa edge nor heavy ornamentation present in Ibc 231. The orbital margin of Ibc 229 is more acutely angled and the lacrimal body in posterior aspect more slender than that of Ibc 231. Additionally, the lacrimal foramen is completely enclosed within the lacrimal, the dorsolateral corner of the lacrimal extends laterally and supported a palpebral articulation and the prefrontal contact extends from the dorsomedial surface as an anteriorly arcuate suture. The dorsal thickening of the lacrimal is approximately twice that of the remainder of the lacrimal body in posterior aspect. Ventrally, the jugal suture is relatively thin in posterior aspect and no wider than the maxilla suture. Medially, a single distinct crest extends anteriorly from the prefrontal suture to divide a dorsal and ventral medial pair of fossa. The lack of external ornamentation, presence of a jugal contact, antorbital fossa and dorsolateral support for a palpebral of this lacrimal compares well to An. minor .

Right premaxilla Ibc 425 ( Fig. 4A, F): Buffetaut (1974a, 1976) referred two fragmentary premaxillae to T. taqueti , but only described one right premaxilla, Ibc 425. He described it having between four and five alveoli, the penultimate being the biggest and a socket for a dentary tooth. We identify only three alveoli, with the second preserved as the largest. The total number is unknown, but all three alveoli are relatively large and divergent orientation from each other. The posterior portion of the premaxilla is missing, excluding any possibility of describing the likely posteriormost alveolus. A deep socket for a dentary tooth is present between the first and second preserved alveoli, indicating the premaxillary teeth covered the dentary teeth. Anterodorsally, a small portion of the narial passage is preserved. A broken secondary palate is present, just dorsal of a line of three large neurovascular foramina. The position of the secondary palate suggests a dorsoventrally snouted premaxilla with near vertical lingual alveolar surfaces, also a feature of sebecids, notosuchians, araripesuchids and so on. The external ornamentation is composed of deep pits. The large teeth, divergent alveoli of these large teeth, convex alveolar margin and tall lingual alveolar margins are reminiscent of sebecids. Many baurusuchids and peirosaurids also have enlarged premaxillary teeth, but these are oriented along a relatively horizontal alveolar margin. The external nares are oriented anterodorsally, and Buffetaut (1976) noted this additional similarity with Sebecus icaeorhinus . However, more recently described crocodyliforms, such as notosuchians including baurusuchians, and peirosaurids, share this morphology.

Left premaxilla Ibc 1483 ( Fig. 4B, C, G, H): A second premaxilla was also found labelled as T. taqueti and may be the second premaxilla attributed to T. taqueti Buffetaut (1974a , 1976). Indeed, some morphologies are shared between both premaxillae: externally ornamented with deep pits, three preserved alveoli with the second preserved as the largest, a fossa between the first and second preserved alveoli and convex alveolar margin. The line of foramina near the lingual margin of the alveoli are much more reduced and positioned nearer to the alveoli than in Ibc 425. Additionally, the lingual surface of the alveoli is shorter with a secondary palate nearer the alveolar openings. The posterior portion is well preserved and indicates a relatively small posterior alveolus that opens posteroventrally towards a large premaxilla–maxilla notch. The back of the alveolar rim of this alveolus is excavated dorsally onto the fossa. This morphology is present only in Sebecia ( sensu Larsson & Sues, 2007), Baurusuchus salgadoensis , Baurusuchus pachechoi and Goniopholis . The anterior portion is missing and may have housed one or two more alveoli. The palatal ramus curves anterodorsally, nearly congruent with the convex curvature of the alveolar margin. This morphology suggests the premaxillary portion of the secondary palate was anteroposteriorly convex, a morphology not present in other crocodyliforms, and possibly an autapomorphy for this taxon. A slight anterodorsal curvature is present on the palatal ramus in H. rebouli in this region. The anterior extent of the palatal ramus indicates the presence of a relatively large incisive foramen that approached the anterior alveolar margin. Buffetaut (1976) acknowledged similarities between T. taqueti and goniopholidids known at that time but suggested T. taqueti was unrelated and more phylogenetically basal. The dorsoventrally tall orientation of this premaxilla and posterodorsally excavated posterior alveolus suggests some sebecian affinity, perhaps near Peirosauridae . Overall, this premaxilla has a remarkable resemblance to the peirosaurid premaxilla, such as H. rebouli and Mo. arrudacamposi .

Maxilla Ibc 410 ( Fig. 4D, I): Buffetaut attributed nine maxillae to T. taqueti and described Ibc 410, a fragmentary anterior portion of a left maxilla. The maxilla is gently convex laterally, indicating a relatively brevirostrine snout. A suture is present for the premaxilla. It sloped dorsally and then posteriorly from a shallow premaxilla–maxilla notch. The entire external surface is ornamented, including near the alveolar margin. Five alveoli are preserved, and the m3 alveolus is approximately twice as large as the others. The external margin if the maxilla bulges gently around this large alveolus. The alveolar margin is ventrally convex and implies at least one festoon was present. A second may have been, but there is not enough preserved from the other fragments to be sure. Ventrally, a large palatal neurovascular foramen is present at the premaxilla–maxilla suture ( Buffetaut, 1976). This large foramen, with a complete external sculpturing, and brevirostrine shape, suggests affinities with Sebecia. The degree of sculpturing is most similar to peirosaurids, especially those of Hamadasuchus and Montealtosuchus , but its fragmentary state precludes a more definitive assignment.

Maxilla Ibc 400 ( Fig. 4E, J): Buffetaut (1974a) mentioned a fragmentary maxilla from a much larger crocodyliform than T. taqueti . Ibc 400 preserves shallow external ornamentation and three complete alveoli and the limits of two more on the anterior and posterior limits of the fragment. One replacement tooth is preserved. It is robust and conical with shallow, apicodistal striations and unserrated carinae. A broken surface for the palatal rami is preserved near the height of the tooth row. A portion of the nasal suture is preserved and faces dorsomedially. The degree of lateral convexity of the maxilla implies the taxon had a relatively tubular snout. The size, ornamentation, snout shape and tooth morphology are similar to those of Sarcosuchus imperator and suggest the presence of a large longirostrine taxon in the In Beceten Formation.

Prefrontals ( Buffetaut, 1976: pl. 2, fig. 4a, b): Four prefrontals were referred to T. taqueti with Ibc 658 illustrated by Buffetaut (1974a, 1976). The anterior part is broken, as well as the dorsomedial orbital edge. All the other prefrontals look similar. All are too fragmentary to ally them with any particular clade of Crocodyliformes. Minor differences between these prefrontals, such as slightly differing development of the processus pilaris, are as likely to be intraspecific as interspecific variations. The external, orbital margin has an elongate depression that probably received an anterior palpebral. The suture with the lacrimal is relatively vertical and has no indication of a lacrimal foramen. Therefore, this prefrontal may belong to the same taxon as lacrimal Ibc 229, but the two elements did not confidently fit together to be from the same individual. The general morphology of these prefrontals is similar to those of many crocodyliforms, including Ar. wegeneri and Sebecia (particularly Peirosauridae ).

Frontals Ibc 3 and Ibc 35 ( Buffetaut, 1976: pl. 2, figs 5a, b, 6a – c): About 40 frontals were referred to T. taqueti and two were illustrated, Ibc 3 and Ibc 35. The morphology of the frontals is generalized and was originally allied with Eusuchia ( Buffetaut, 1974a, 1976). Both are heavily sculpted on their external surfaces. Ibc 3 is more complete and preserves strongly concave orbital margins, in dorsal view. The orbital rims are also curved dorsally from the frontal body. No sagittal crests are present, and Ibc 3 preserves the anterior portions of the supratemporal fossa.

Frontal Ibc 9 ( Fig. 5E–H, E′ –H′): This frontal, although missing the anterior and posterolateral corners, differs from Ibc 3 in that the orbital margins are smooth and are not raised dorsally. A notch is scalloped at the posterior edge of the orbital margin to probably receive a posterior palpebral. The posterior portion of the frontal is flat and gradually becomes slightly depressed anteriorly, making it slightly concave towards the orbits. The interorbital margins are not as distinct as in Ibc 3 or in Ibc 14 in that those of Ibc 9 are not raised, the shallow sculpting does not vary across the frontal, and the orbital margins are less embayed. The postorbital articulated along a relatively vertical suture. Posteriorly, Ibc 9 has smooth margins for the supratemporal fenestra and no fossa extended anterodorsally onto the frontals. The ornamentation is formed of deep pits. Posteriorly, the dorsal portion of the frontal–parietal suture is transverse and triangular. The ventral portion of this suture is smaller, in posterior view, and stepped slightly anteriorly.

Frontal Ibc 14 ( Fig. 5A–D, A′ –D′): The general shape of this frontal is similar to the others. The orbital margins are not raised, and the transverse width between them is relatively small. The insertion surface for a posterior palpebral is straight. The postorbital suture is more complex than the other frontals. It presents a medially inset dorsal surface to receive a medial projection from the postorbital. Postorbital Ibc 240 has this morphology and fits perfectly with Ibc 14 ( Fig. 5I, I ′), suggesting they are from the same individual. A small portion of the posterior portion of the orbital margin is broken from the frontal, creating a small gap on the orbital edge when the postorbital is articulated. Like Ibc 9, the supratemporal fossa does not extend onto Ibc 14 and the anterior margin of the fenestra is quite restricted on the posterior surface of Ibc 14. When articulated with Ibc 240, the postorbital creates the anterolateral and much of the anterior margin of the supratemporal fenestra. An anteromedial prong from the postorbital is missing, but its suture is clearly present on the frontal. The postorbital Ibc 240 is similar to the one referred to T. taqueti , but the frontal Ibc 14 is not. These articulating bones present one more argument for the chimeric nature of the originally interpreted T. taqueti . All the frontals are about the same size and, thus, preclude these differences as ontogenetic variation of a single taxon. Posteriorly, the frontal–parietal suture is relatively linear, dorsally, but anteriorly inset ventrally, creating a complex suture visible in ventral view.

The absence of a sagittal a crest on these frontals is shared with some Araripesuchus species ( Ar. patagonicus ), many peirosaurids, including Montealtosuchus , and most Neosuchia . However, the frontals do not present enough morphologies to be linked to a specific family or genus. The connection between Ibc 9 and postorbital Ibc 240 does preclude these specimens from belonging to a pholidosaur or dyrosaur because the characteristic anterolateral postorbital prong is these taxa is absent.

Right postorbital Ibc 234 and 240 ( Buffetaut, 1976: pl. 2, f ig. 7; Fig. 5J–L, J′ –L′): Ibc 234 was illustrated by Buffetaut (1976), and we figure a comparable specimen. This postorbital morphotype is relatively cuboid, although a portion of the posterior ramus of Ibc 240 is broken. The entire dorsal surface is ornamented except for a small region along the orbit that probably received a small palpebral element. The postorbital bar swells dorsolaterally to conform with a short anterolateral process that extends beyond the skull table and projects laterally. An anterolateral process is relatively

to each view. Connexion between the frontal Ibc 9 and the postorbital Ibc 240 in (I) dorsal view. I ′, outline drawing. Right postorbital Ibc 240 in (J) dorsal, (K) lateral and (L) medial views. J ′, K ′, L ′, outline drawings corresponding to each view. Right postorbital Ibc 2038 in (M) dorsal, (N) lateral and (O) medial views. M ′, N ′, O ′, outline drawings corresponding to each view. Abbreviations: apap, articular surface for palpebral; cc, crista cranii; fo, foramen; j.s, suture for jugal; po.s, suture for postorbital; p.s, parietal suture; q.s, suture for quadrate. Scales are 1 cm.

common in crocodyliforms. There are two non-homologous conditions: one is depressed from the skull table to support a palpebral, as in Arariepesuchus; the other is an anteroventrally arched process to partially enclose the orbit, as in dyrosaurs. The lateral expansion of the postorbital bar forms a thick edge between the orbit and auditory region. The posterior surface of the postorbital bar is embayed to receive that anterior limit of the meatal chamber. Although similar anterior extensions of the meatal chamber onto the postorbital are present in many crocodyliforms, the robustness of the postorbital bar and near transverse orientation of the deep meatal chamber’s anterior surface is unique ( Montefeltro, Andrade & Larsson, 2016). By transverse, we mean, the anterior border of the meatal chamber does not slope anteriorly, as in Mariliasuchus and Araripesuchus , nor anterolaterally, as in Rukwasuchus , but rather is oriented nearly transversely. Likewise, although many crocodyliforms have a thin lateral ridge connecting the postorbital bar to an anterolateral prong, this ridge is inset from the skull table edge and does not form a distinct transverse border between the orbit and auditory region. The jugal contacts the ventrolateral surface of the postorbital bar and a foramen is present at the posterodorsal portion of the postorbital pillar. The tight fitting articulation between frontal Ibc 14 and postorbital Ibc 240 indicate they are from the same taxon and likely the same individual. However, neither presents morphologies to ally them with any particular crocodyliform.

Right postorbital Ibc 2038 ( Fig. 5M–O, M′ –O′): The right postorbital Ibc 2038 has deep hemispherical ornamentations on its dorsal surface whereas the other surfaces are smooth. This postorbital has a deep anterodorsal semilunate notch for a palpebral element that extends neither to the medial nor lateral edges of the orbital margin. The junction between the articular facet and the skull table presents some ornamentation. In dorsal view, the postorbital is slightly curved towards the frontal, making the supratemporal fenestra and lateral skull table laterally convex. Laterally, there is a deep pit. Like Ibc 234 and 240, the postorbital bar is subtriangular in cross-section with the medial surface being flat and extending slightly more ventrally than the lateral surface. The lateral surface supports a raised edge that extends along the height of the postorbital’s contribution to the postorbital bar to an anterolateral extension at the skull table. The posterior surface of the bar is embayed to house the anterior limit of the meatal chamber. The anterodorsolateral edge of the postorbital forms a well-developed prong that is at the level of the skull table and did not support a palpebral. The process in Ibc 2038 is larger than other In Beceten specimens and projects anterolaterally rather than laterally. In posterior view, a relatively large foramen is situated at the junction of the postorbital bar and skull table, hidden under the skull table. Medially, sutures with the quadrate and the laterosphenoid are present. Posteromedially, the postorbital presents a socket for the quadrate, whereas the laterosphenoid suture is situated posteromedially. No suture with the quadratojugal was observed, suggesting a limited quadratojugal contribution to the infratemporal fenestra. Although some morphologies, such as the robust lateral edge on the postorbital bar, are shared between the two In Beceten postorbital morphotypes, Ibc 2038 is slightly larger, more gracile, has thinner skull table processes with larger ornamentation pits and a larger and anterolaterally projecting orbital prong. Although these differences may be ontogenetic or intraspecific variations, we present them here as potential taxonomic differences.

Right jugal Ibc 140 ( Fig. 6A–D): Thirty fragmentary jugals were referred to T. taqueti and Ibc 140 was illustrated ( Buffetaut, 1974a, 1976). Ibc 140 is relatively robust with variable sculpting and pitting on its external surface. The relatively short anterior ramus has a nearly vertical anterior margin. Although part of this edge is eroded, the extensive medial sutural contact with the maxilla along the entire anterior portion suggests not much of the ramus is missing, creating a quadrate-shaped ramus, somewhat similar to that of Montealtosuchus . Although baurusuchians, such as Pissarrachampsa , also have a squared anterior jugal ramus, they lack the distinct external sculpturing ( Montefeltro, Larsson & Langer, 2011). The anteroventral edge of this ramus expands ventrally to accommodate a large cuboid, medial suture with the maxilla. The ectopterygoid suture is also expansive and is further supported by a ventral extension from the jugal. This ventral extension is unique among crocodyliforms. The joined sutural contacts with the maxilla and ectopterygoid indicate these two bones contacted each other on the palate. Three large foramina pierce the medial surface of the anterior ramus. All probably extend to a large foramen situated on the posteroventrolateral surface of the postorbital bar. The orbital margin is dorsolaterally ornamented with transverse grooves. The jugal’s contribution to the postorbital bar is slightly inset medially from the orbital margin and contacted the ventrolateral surface of the postorbital’s postorbital bar. The anteroventral border of the infratemporal fenestra is squared. The posterior ramus is approximately half the height of the anterior ramus and lunate-shaped in cross-section with a distinct medial concavity. The dorsal edge of the posterior ramus is relatively sharp edged. The large, blunt border of the anterior ramus is reminiscent to that of Montealtosuchus . The ventral extension of the ectopterygoid suture is somewhat similar to many notosuchians, including Mariliasuchus , Caipirasuchus and baurusuchians, although in these taxa, the ectopterygoid suture is placed further anteriorly, approximately half way along a long anterior ramus ( Zaher et al., 2006; Montefeltro et al., 2011; Pol et al., 2014).

Right jugal Ibc 131 ( Fig. 6E–H): This jugal represents a second jugal morphology that is more similar to neosuchian crocodyliforms. The external ornamentation is composed of defined, subcircular pits. Although slightly abraded, this jugal lacks the distinctive ventral prongs at the maxillary and ectopterygoid sutures. The anterior ramus is broken, but its ventral margin indicates it would have been longer than Ibc 140. Nothing can be determined about the shape of the anterior margin. The base of the postorbital pillar is more robust in Ibc 131 and extends gradually into the infratemporal fenestra and lacks the squared margin present in Ibc 140. The maxillary suture is triangular, and the ectopterygoid suture is arcuate, tapering anteriorly. Both sutures are separated from each other indicating the maxilla and ectopterygoid did not contact each other. Five foramina are present on the medial surface of the anterior ramus, diminishing in size anteriorly and probably extend to a relatively small posterior exit on the posteroventrolateral surface of the base of the postorbital bar.

Quadratojugal Ibc 91 ( Fig. 7A, B): The quadratojugal and quadrate (Ibc 120) referred to T. taqueti were not present with the rest of the type collection. All observations are based on the illustrations and descriptions from Buffetaut (1974a, 1976). Quadratojugal Ibc 91 was well described by Buffetaut and is notable in that it preserves a well-defined accessory condyle on its posterolateral end. This morphology indicates this quadratojugal extended to the end and capped the quadrate condyles laterally. This accessory condyle has since been used to diagnose Sebecia ( Larsson & Sues, 2007).

Quadrate Ibc 108 ( Fig. 7C–I): Two distinct morphotypes of quadrates assigned to T. taqueti can be identified. Ibc 108 was not mentioned by Buffetaut but differs from Ibc 120 in many respects. In posterodorsal view, the length of the quadrate body between the condyle and the suture with the squamosal. This length in Ibc 120 is about 3.5 cm, compared to a condylar width of 2.8 cm, whereas the length in Ibc 108 has a lower ratio of only 1.2 cm to a condyle width of 1.4 cm. The foramen aërium exits in both at approximately the same position (about a distance of half the condylar width from the distal end of the quadrate). The dorsal crest is more pronounced in Ibc 120 than in Ibc 108, with its posterior extension forming a subtriangular crest over the two hemicondyles. A large quadratojugal suture is present in dorsal, lateral and ventral views in Ibc 108 that is notched distally to create a concave region on the lateral quadrate hemicondyle. This morphology indicates the quadratojugal extended onto the lateral hemicondyle within a robust suture. Ibc 120 lacks this sutural morphology, particularly the distolateral concavity at the lateral hemicondyle, and does not show a presence of a quadratojugal overlapping the lateral hemicondyle. We tentatively associate the quadratojugal morphotype of Ibc 91 with the quadrate morphotype of Ibc 108.

In anteroventral view, Ibc 120 has moderately formed A and B crests (defined by Iordansky, 1973), whereas Ibc 108 has only a moderate A crest and no obvious B crest. Medially, Ibc 120 has a convex surface at and proximal to the medial hemicondyle whereas Ibc 108 has a distinct ventromedially oriented crest extending from the medial hemicondyle to the ventral otoccipital contact beneath the cranioquadrate passage.

Quadrate Ibc 120 ( Fig. 8A–C): Quadrate Ibc 120, however, could not articulate with quadratojugal Ibc 91. Its quadratojugal suture ends far anterior of the condyles. This quadrate is relatively elongate and straight with a long cranioquadrate canal bounded by relatively equal-sized quadrate-otoccipital sutures.

Quadrate Ibc 118 ( Fig. 8D–F): Another interesting quadrate was also placed along with the T. taqueti collection and was identified as an unknown taxon by Buffetaut (1974a). It is much larger than the other quadrates, with a condylar width of 5.7 cm. It is robust, with the dorsal otoccipital suture ending only 4.6 cm from the distal end. The foramen aërium is very large, and the cranioquadrate passage is nearly half the transverse height of the quadrate body. Dorsally, a distinct crest extends from the lateral edge of the medial hemicondyle to the dorsal otoccipital suture. The crest and its distal expansion create a subtriangular distal cross-section similar to the quadrates of Sebecia, Araripesuchus and many notosuchians.

Quadrate Ibc 119 ( Fig. 8G–I): Ibc 119 was originally referred to Libycosuchus sp. by Buffetaut (1974a, 1976). However, the Libycosuchus material used by Buffetaut was later referred to Hamadasuchus by Larsson & Sues (2007). Ibc 119 shares neither the single-crested B crest nor the distal articulation with the quadratojugal for an accessory condyle as in the material Buffetaut assigned to Libycosuchus . When compared to the holotype skull of Libycosuchus (BSPG 1912 VIII 574a, b), the medial hemicondyle of Libycosuchus tapers ventrally as an elongate process, quite different from the rounded, plesiomorphic hemicondyles of Ibc 119.

It compares well to Ar. wegeneri , although Ibc 119 is about three times larger. Similarities with Ar. wegeneri include the short, ventrally curved quadrate body, large dorsomedial crest from endocondyle, distally placed foramen aërium, bipartite B crest, shallow distal articular lappet for the quadratojugal distally, otoccipital and squamosal sutures that approach the condyles, and a greatly reduced cranioquadrate canal. Ibc 119 does not share the single-crested B crest nor distal articulation with the quadratojugal for an accessory condyle as in the material Buffetaut assigned to Libycosuchus sp. from Morocco, that Larsson & Sues (2007) lateral referred to Hamadasuchus .

Dentary Ibc 360 ( Fig. 9A–C): The most complete dentary is a fragment of a right dentary. The material was not found at the MNHN, and the description is based on the drawings provided by Buffetaut (1976). The mandibular symphysis is short and extends to the level of half of the fifth alveolus. Buffetaut noted the end of the symphysis at the level of the fourth alveolus and not the fifth ( Buffetaut, 1976). The splenial seems to have contacted the dentary at the level of the symphysis. However, without the original bone, the characters of the articular scar of the splenial are unknown. The short mandibular symphysis is somewhat similar to Goniopholis sp. indet. ( Salisbury, 2002: text-fig. 8) or Rugosuchus nonganensis , even though Wu, Cheng & Russell (2001) pointed out that the anterior end of the dentary was worn out. The dentary preserves nine alveoli, the biggest being the fourth. The general shape of the tooth line is relatively straight, as opposed to the festooned maxilla. The symphysis shows that the angle between the two dentaries would have been around 60°. Buffetaut (1976) mentioned the presence of a shallow socket for a maxilla tooth between the seventh and eighth alveoli. As the material could not be examined by the authors, the presence of the shallow pocket cannot be confirmed with certainty. Ibc 360 differs from the dentaries with shorter symphyses of Libycosuchus and An. minor or the elongate symphyses and procumbent teeth of advanced notosuchians and Araripesuchus .

Articular Ibc 160 ( Fig. 9D–F): Twelve fragmentary articulars were assigned to T. taqueti ( Buffetaut, 1974a) . The concave glenoid is relatively narrow, especially in comparison to the retroarticular process. The base of the retroarticular process is situated below the glenoid and directed posterodorsally. No distal portions are preserved, but the medial suture with the surangular indicated the surangular covered at least half the length of the retroarticular process.

Surangular Ibc 170 ( Fig. 9G–I): 29 fragmentary surangulars were assigned to T. taqueti . This bone participates to the lateral third of the mandibular cotyle ( Buffetaut, 1976). The presence of a mandibular fenestra is unknown, as all the surangulars are missing their anterior portions. Posterior to the glenoid, the surangular forms the lateral base of the retroarticular ramus that is more or less at the same level as the glenoid itself. This condition is different of what is observed in Araripesuchus , An. minor or derived notosuchians where the ramus is abruptly ventrally oriented. The surangular of Araripesuchus gomesii is also narrower and the glenoid is extremely restricted. This character is unknown for Ar. patagonicus and Ar. wegeneri . In Sebecus , the posterior surface is dorsoposteriorly oriented and could correspond to what is observed here. However, the surangular of Sebecus shows a strong lateral ridge. Dorsally, lateral depressions are situated near and behind the cotyle. This is observed neither in Libycosuchus nor other notosuchians. The surangular also has a broad contribution to the posterior margin of the articular cotyle and to the cotyle. The retroarticular ramus has a dorsolateral ridge, which would have formed the lateral limit of the insertion of the depressor mandibulae. A muscle scar lateral to the cotyle marks the insertion for the adductor mandibular externus superficialis.

Dentition ( Fig. 10A–C): Hundreds of teeth were recovered at In Beceten ranging from nearly complete to fragmentary. As Buffetaut (1976) mentioned, it is extremely difficult to identify crocodyliforms on the base of isolated teeth. Four tooth morphotypes are present. The largest is in place within maxilla Ibc 400 and has the robust, conical morphology of many neosuchians ( Fig. 4E, J). The other three tooth morphotypes have thin proximal and distal carinae and range from caniniform to slightly transversely compressed triangular teeth to low, rounded teeth with circular crosssections. The carinae on the latter two morphotypes have low serrations. This range of tooth morphologies is often present within individuals but is reminiscent of the tooth disparity in Ar. wegeneri and H. rebouli . No tooth was found embedded in the tooth bearing elements referred to T. taqueti , precluding a positive link between these teeth and even the formerly assigned material of T. taqueti .

Vertebrae (Ibc 701: Fig. 11A; Ibc 1078: Fig. 11B; Ibc 1080: Fig. 11C; Ibc 1180: Fig. 11D; Ibc 1123: Fig. 11E): Over 100 crocodyliform vertebrae were collected from the In Beceten Formation and all the small- to mediumsized specimens were assigned to T. taqueti with caution. Six were described and figured by Buffetaut (1976); however, the figured Ibc 702 and Ibc 1432 were not located in the T. taqueti collections. All centra are amphicoelous to slightly amphiplatyan. The posterior cervical Ibc 775 is quadrate with well-developed parapophyses and a large, but broken, hypapophysis. The hypapophysis is anteriorly placed and the portion preserved indicates it would have angled forward. This condition compares well to the posterior cervical hypapophyses of Se. icaeorhinus and extant crocodilians. Posterior cervical hypapophyses of Baurusuchus , Simosuchus , Araripesuchus tsangatsangana and Notosuchus terrestris all have low to absent hypapophyses. The neural arch is missing, but the centrum preserved a complete neurocentral suture, indicating an immature state for this specimen. The anterior dorsal Ibc 702 has a wellformed, anteriorly positioned hypapophysis and no trace of a parapophysis, indicating it was probably the fourth dorsal. The large hypapophysis is comparable to those of extant Crocodylia and Se. icaeorhinus , but not other co-evolved taxa. We tentatively assign Ibc 1078 and Ibc 702 to the same morphotype based on their shared hypertrophied hypapophyses.

Ibc 1078 was identified by Buffetaut (1976) as a posterior dorsal with articular facets for a sacral rib. This condition is unknown for crocodyliforms. However, other more recently discovered taxa do have expanded anterolateral centra of this form that are created by dorsolaterally positioned parapophyses on their anterior dorsals. The morphology of Ibc 1078 most closely resembles the anterior dorsals of Ar. tsangatsangana and moderately resembles those of Ma. insignis . This expanded anterolateral central face and absence of a hypapophysis in Ibc 1078 indicate this taxon is different from that represented by Ibc 1078 and Ibc 702.

The anterior caudal Ibc 1080 has a well-preserved neural arch with the transverse process located on the neurocentral suture. A large pair of posteroventral chevron facets is present. The neural spine is stout and oriented slightly posteriorly. The relatively short central length, posterior chevron facets and broad neural spine indicate this caudal is within the first five caudals. No features specific to any clade of crocodyliforms could be identified. Ibc 1180 and Ibc 1123 are caudal vertebrae from near the tail midlength and posterior third, respectively. They both have the characteristic paired ventral ridges that extend between the anterior and posterior chevron facets of crocodyliforms. In both, the transverse processes are positioned in the posterior half of the neural arch.

Humerus (Ibc 894: Fig. 12A, B; Ibc 1171: Fig. 12C, D): Both preserved fragmentary humera are small. The proximal head of the humerus Ibc 894 is relatively rounded but missing its proximolateral portion. The proximal articular surface is relatively simple, like that of Ar. tsangatsangana , lacking the posteroventral projection of Se. icaeorhinus and N. terrestris . Posteriorly, the fossa for the insertion of the scapulohumeralis caudalis is broad. The deltapectoral crest is located on the extreme lateral margin, as in Ar. tsangatsangana and most other crocodyliforms except N. terrestris and Se. icaeorhinus . The preserved overall shape of the humeral head, in posterior view, is similar to N. terrestris and Ar. tsangatsangana . The distal head (Ibc 1171) does not flare laterally as it does in Se. icaeorhinus but has relatively small distal condyles, as in Ar. tsangatsangana . The lateral and medial supracondylar crests are also poorly developed.

Ulna (Ibc 1164: Fig. 12E, F; Ibc 1312: Fig. 12G, H): The preserved proximal Ibc 1164 and distal Ibc 1312 portions are from relatively small and gracile ulnae. Although we are not convinced Ibc 1164 is a proximal ulna, we provisionally follow Buffetaut’s (1976) interpretation. The proximal surface of the ulna is triangular in outline but with poorly developed anterolateral and olecranon processes. The posterolateral surface is flat. The olecranon is reduced to a slight bulge, similar to other small bodied, gracile taxa such as Ar. tsangatsangana . The proximal anterolateral process, or ulnar humeral articular surface, is rounded and not offset from the ulnar body, unlike other described Crocodyliformes. Additionally, the ulnar radio humeralarticular surface is also weekly developed and the proximal contact surface for the radius is slightly convex, rather than the general concave condition of other Crocodyliformes. The distal end of the ulna is complex and triradiate, with the presence of an anterolateral bulge, anterior oblique process and a posterior oblique process. The distal posterolateral margin, in distal view, is relatively straight, like Se. icaeorhinus , lacking the distinct lateral apex in N. terrestris or the broad curve in Simosuchus clarki .

Femur (Ibc 625: Fig. 13A–D; Ibc 627: Fig. 13E; Ibc 1419: Fig. 13F, G): Ibc 625 and Ibc 627 are proximal left femora and appear to be from the same taxon. Ibc 625 preserves a complete right femoral head. Although the femur is relatively large, it shares many features with Ar. tsangatsangana but not Se. icaeorhinus , Si. clarki ( Sertich & Groenke, 2010) , nor Ma. insignis . The medial proximal crest is nearly absent like that of Ar. tsangatsangana and not expanded like that of Se. icaeorhinus . Not enough of the femoral shaft is preserved to determine whether the femoral head twists anteriorly and the shaft sigmoid. The femoral head is robust and anteromedially bent. A discrete proximal condylar fold extends anteroventrolaterally from the femoral head, similar to that of Ar. tsangatsangana . The fourth trochanter is well developed and complete in Ibc 627. A prominent flange for either the pubioischiofemoralis internus 1 (PIFI 1) or caudofemoralis longus (CFL) muscle insertion is present just anterior to the fourth trochanter. A large depression for the insertion of the caudofemoralis longus [ M. coccygeofemoralis sensu Brochu & Buckley (1999) and Pol (2005)] ( Turner, 2006) is present lateral to the fourth trochanter. This anterior process is more developed in Ibc 627 than in Se. icaeorhinus , N. terrestris and Ma. insignis . This anatomy is similar to Ar. tsangatsangana . Turner (2006) pointed out the complexity of this insertion zone and that the flange may be an attachment surface for two muscles: the CFL and the PIFI 1. Distally, the femur Ibc 1419 is about half the size of the other two femora and preserves poorly developed distal condyles, although this may be partly and artefact of erosion. The fibular condyle is more distally positioned, as in most crocodyliforms.

Tibia (Ibc 749: Fig. 13H; Ibc 1166: Fig. 13I): Ibc 749 and Ibc 1166 are proximal and distal portions of left tibiae, respectively. They indicate a relatively slender tibia. A well-developed fibular facet is present, as in Ar. tsangatsangana and Se. icaeorhinus . Distally, the articular surface for the calcaneum extends posteroproximally and the proportions and orientations of the calcaneal and astragular condyles are most similar to Ar. tsangatsangana and lack the extreme distomedial extension of the astragular facet of Se. icaeorhinus nor the robust morphology of Si. clarki and Ma. insignis . The lateral and medial profiles of the calcaneal and astragular condyles, respectively, are relatively cuboid with vertical surfaces, although they are slightly abraded.

SUMMARY AND CONCLUSIONS

DIVERSITY OF IN BECETEN CROCODYLIFORMES

Crocodyliform diversity of the In Beceten Formation was originally composed of T. taqueti , Libycosuchus sp. and a large indeterminate longirostrine taxon. The large quantity of material attributed to T. taqueti has aided its prominent inclusion in Crocodyliformes taxonomy and systematics. For decades, T. taqueti and Trematochampsidae have played important roles in Crocodyliformes systematics. Even recently, some authors have continued to use T. taqueti as a valid phylogenetic operational taxonomic unit. Sertich and O’Connor stated that their ‘[d]etailed investigation… of the In Becetin collection…validated their original referral…to a single species’, which was based on ‘[c]onsistency in patterns of complementary element suturing, ornamentation, size, and abundance’ ( Sertich & O’Connor, 2014: 588). A critical evaluation of the material, although, supports the presence of at least three taxa within this collection. Figure 14 presents a summary phylogeny of crocodyliforms discussed above and supporting taxa to present where each element morphotype may have taxonomic affiliations. The type material of ‘ T. taqueti ’ is a single lacrimal Ibc 231 and no other specimen could be positively associated with this lacrimal morphotype. This lacrimal does have a remarkable set of morphologies but are indistinguishable from the lacrimal of Mo. arrudacamposi .

One other lacrimal morphotype is present in the In Beceten collection referred to T. taqueti . Ibc 229 shares some morphologies with the taxa listed for the type lacrimal, and additionally Uruguaysuchus aznarezi . However, Ibc 229 lacks the orbital and antorbital fossa morphology of Montealtosuchus and Ibc 231. Two premaxilla morphotypes are preserved, and both share morphologies with Sebecus and Hamadasuchus , yet are distinct from each other. Two maxilla morphotypes are present. One is similar to that of Sarcosuchus and the other to sebecians. Two frontal morphotypes are present, and they both share morphologies with neosuchians and Ibc 14 also shares morphologies with Ar. wegeneri . Two postorbital morphotypes are present. One articulates with a frontal morphotype. Both have a meatal chamber fossa on their postorbital bars but otherwise differ in skull table dimensions and size and direction of an anterodorsal process.

Two jugal morphotypes are also present. One of them could not be assigned to any taxon but is similar to many basal neosuchians, whereas the other is similar to Baurusuchus and derived notosuchians. Only one quadratojugal morphotype was present and it shares the accessory mandibular condyle of Sebecia and is associated with one of the four identified quadrate morphotypes. The three other quadrate morphotypes share morphologies with both Araripesuchus and sebecians yet each have unique morphologies to readily distinguish them. The dentary morphotype shares morphologies with the goniopholidids.

Postcranial material can also be divided into multiple morphotypes. Two distinct vertebral morphotypes are identified. One shares the hypertrophied hypapophyses of Sebecus and neosuchians. The other shares the anterodorsolaterally expanded central faces of Araripesuchus tsangtsangana . The humerus, ulna, femur and tibia fragments compare well to Ar. tsangatsangana .

Trematochampsa taqueti was erected based on a large collection of unassociated crocodyliform bones. Although this taxon has featured in many discussions of crocodyliform systematics, we find no evidence to combine the entire collection into a single taxon. The type Ibc 231 right lacrimal lacks autapomorphies and is indeterminate from that of Mo. arrudacamposi . None of the many morphotypes we identified in the material articulates with this Ibc 231 and, therefore, none of the other material can be assigned to T. taqueti with confidence. Nearly every well-represented bone element could be divided into two or more morphotypes, each with morphological differences that are not generally considered within known ranges of intraspecific variation. Moreover, the quadrates assigned to T. taqueti represent at least three different morphotypes.

Based on the lack of diagnostic characters for the holotype of T. taqueti and absence of diagnostic morphologies for more inclusive taxa, we consider T. taqueti a nomen dubium. We also recommend abandoning the use of Trematochampsidae . Peirosauridae has generally had overlapping taxonomic content and would remain as an operational taxon.

Crocodyliform diversity of the In Beceten Formation was previously based on three taxa: T. taqueti , Libycosuchus sp. and a large indeterminate longirostrine. Because of the extensive similarities with Ar. wegeneri , this quadrate compares favourably with Araripesuchus rather than with Libycosuchus . The maxilla fragment, teeth and quadrate of the large longirostrine appear to be tethysuchian, with morphologies comparable to Sarcosuchus . The material formerly assigned to T. taqueti maps to multiple phylogenetic positions in crocodyliforms. Some material is allied with basal and advanced notosuchians, one jugal morphotype shares some similarities with Baurusuchia, many element morphotypes are similar to Araripesuchus and others to sebecians or other neosuchians. The jugal Ibc 140 and postorbital Ibc 2038 are not similar to any known crocodyliform, although they have some morphologies comparable to advanced notosuchians and Baurusuchia. In total, the material formerly referred to T. taqueti represents at least three different small- to medium-sized crocodyliform taxa.

The high crocodyliform diversity of the In Beceten Formation is not unexpected. Other north African Late Cretaceous formations, such as the Gadoufaoua Formation of Niger and Kem Kem Beds of Morocco, have equally high local crocodyliform diversities with taxa from many clades within Notosuchia and Neosuchia . Further exploration of the In Beceten Formation is warranted to discover its previously cryptic biodiversity.

ACKNOWLEDGEMENTS

The specimens studied here were loaned by R. Allain and C. Sagne. They also provided full access to the original type and the rest of the material. We also thank K. Seymour (ROM), D. Evans (ROM), M. Norell (AMNH), C. Mehling (AMNH) and P. Sereno (UChicago) for access to their collections. Discussion and comparative images are greatly acknowledged from F. Montefeltro, who also supplied the image used in Figure 2I, K. Improvements to the manuscript were made from suggestions provided by three anonymous reviewers. Funding was supplied by a Class of 66 award to L.M.V.M. and an NSERC Discovery Grant and Canada Research Chair to H.C.E.L.

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