Araripesuchus wegeneri Buffetaut & Taquet 1979

Araripesuchus wegeneri Buffetaut & Taquet, 1979 Figs. 14–26 Tables 6–8 Buffetaut and Taquet (1979, fig. 1) Ortega et al. (2000, fig. 9) Turner (2006, figs. 5–7) Holotype. MNHN GDF700; snout composed of articulated upper and lower jaws and preserved to mid-orbit on the right side with several teeth preserving their crowns. Type locality. Gadoufaoua, Agadez District, Niger Republic (more precise locality unknown) (Fig. 1A, C). Horizon. Elrhaz Formation, Tegama Series; Lower Cretaceous (Aptian-Albian), ca. 110 Mya (Taquet 1976). Referred material. MNN GAD 19, nearly complete cranium lacking only portions of the left lacrimal and prefrontal, the palpebrals, and some of the teeth (Figs. 14–17, 19); MNN GAD 20, partial skeleton on block preserving the left side of the skull exposing the dentition in medial view and an articulated tail with dermal armor (Figs. 20, 21, 25A); MNN GAD 21, partial skeleton on block preserving the ventral portion of the skull, an articulated partial forelimb, and an articulated tail with dermal armor (Fig. 24, 25B); MNN GAD 22, partial skeleton on block preserving the ventral portion of the skull, an articulated right manus and pes, a right calcaneum, and an articulated tail with dermal armor (Fig. 26); MNN GAD 23, isolated snout on block composed of articulated upper and lower jaws and preserved to mid-orbit on the right side; MNN GAD 24, isolated left maxilla on block preserving the dentition; MNN GAD 25, partial skeleton preserving the posterior ends of the lower jaws and most of the postcranial skeleton except the tail; MNN GAD 26, edentulous right dentary from a juvenile (Fig. 18). An exceptional series of specimens are preserved in close proximity on a single block of sandstone (MNN GAD 20–24) (Fig. 23). Th ree individuals are fairly complete, partially articulated skeletons with their axial columns aligned side-by-side pointing in the same direction (MNN GAD 20–22). One of the three (MNN GAD 20) is slightly small- er than the other two. Also present are portions of at least two additional individuals, one represented by an articulated snout (MNN GAD 23) and the other by an isolated maxilla (MNN GAD 24). A minimum of five individuals thus are represented on the block. The close proximity and alignment of the three best preserved skeletons and the presence of additional individuals on a small block is unusual. Portions of the three best preserved skeletons (MNN GAD 20–22) and the isolated snout (MNN GAD 23) have been lost to postmortem surface erosion and would have been more complete. Some postmortem disarticulation is evident in all three of the most complete specimens (MNN GAD 20–22), although there is no obvious preferred direction or orientation to displaced elements. Th e strong curvature of the distal tail in three skeletons, in addition, is diffi cult to attribute to postmortem water transport, as the curvature in one of the skeletons opposes the curvature in the other two. Revised diagnosis. Small-bodied metasuchian (<1.0 m) characterized by an anterior premaxillary foramen anterior to the first premaxillary tooth; infratemporal bar of jugal with marginal fossa; supratemporal fossa with marked anteromedial corner; scalloped posterior margin of skull table with median process; reduction of the premaxillary palate to parasagittal shelves; median elliptical incisive foramen; dentary with prominent labial alveolar margin that obscures all alveoli in lateral view; caniniform (d4) to the largest crowns in the postcaniniform series (d13) with relatively low, mesiodistally broad (crown width 60–80% of crown height), denticulate crowns; and largest postcaniniform crowns with lingually deflected mesial carina and associated trough. Discussion. The referred cranium (MNN GAD19; Figs. 14–17, 19) removes any doubt about the assignment of the African species to Araripesuchus; the shape of the cranium and many of its structural details are close or identical with the type species Araripesuchus gomesii (Price 1959). Figure |4. Skull of the crocodyliform Araripesuchus wegeneri. Cranium (MNN GAD19). A Lateral view (reversed). B Dorsal view. C Ventral view. Scale bar equals 5 cm. Secondly, there is no doubt that cranium MNN GAD19 is correctly referred to A. wegeneri, because there are many features it shares only with the holotype, a partial snout (MNHN GDF700; Buffetaut and Taquet 1979). It is approximately 90% of the size of the holotype, based on measurements of the snout. Both have five premaxillary teeth. Th e jugal in both specimens expands in depth toward its anterior end and has a shallow sculpted fossa under the orbit. Other shared features found thus far only in the holotype and MNN GAD19 include a premaxillary sinus, small posterior spine on the maxilla that projects into the antorbital fenestra, flat strap-shaped border between the Figure |5. Skull of the crocodyliform Araripesuchus wegeneri. Drawings matching the cranium (MNN GAD19) in Fig. 14. A Lateral view (reversed). B Dorsal view. C Ventral view. Parallel lines indicate broken bone surface; dashed line indicates missing bone or tooth crown; grey tone indicates matrix. Scale bar equals 5 cm. Abbreviations: am3, 14, alveolus for maxillary tooth 3, 14; antfe, antorbital fenestra; antfo, antorbital fossa; apap, articular surface for palpebral; apm1, alveolus for premaxillary tooth 1; apmf, anterior premaxillary foramen; aqj, articular surface for the quadratojugal; be, buccal emargination; bo, basioccipital; bs, basisphenoid; bt, basal tubera; ch, choana; cqp, cranioquadrate passage; ec, ectopterygoid; Ef, Eustachian foramen; en, external naris; f, frontal; fl, flange; fo, foramen; gef, groove for ear flap; j, jugal; l, lacrimal; lf, lacrimal foramen; ls, laterosphenoid; m, maxilla; m1, 3, 7, maxillary tooth 1, 3, 7; n, nasal; nfo, narial fossa; oc, occipital condyle; ot, otoccipital; p, parietal; pf, prefrontal; pl, palatine; pm, premaxilla; pm3, 5, premaxillary tooth 3, 5; pmmf, premaxilla-maxilla foramen; po, postorbital; popr, paroccipital process; pos, preotic siphonium; pt, pterygoid; q, quadrate; qj, quadratojugal; se, septum; sq, squamosal; so, supraoccipital; sof, suborbital fenestra. choana and suborbital fenestra, and a V-shaped anterior margin of the choanae (Figs. 14, 15, 17). Finally, the fifth maxillary crown is preserved in both skulls and corresponds in detail regarding orientation, shape, and surface detail; the subcircular crown is angled posteroventrally, has a low short primary ridge near the crown apex laterally, has finely denticulate carinae, and has fine striations on the crown surface, some of which extend from the denticles. Dorsal skull roof. The following abbreviate description is based primarily on the well preserved cranium MNN GAD19 (Figs. 14–17, 19, 22; Table 7) and a nearly complete dentition in skull MNN GAD20, which was hemisected by erosion (Figs. 20, 21). The premaxilla exhibits many features important for determining phylogenetic position, the monophyly of Araripesuchus, and the distinction of A. wegeneri. Most of the external surface of the bone is smooth, except for the tip of the posterodorsal ramus (Figs. 14A, B, 15A, B, 16A). At the anterior tip of the premaxilla, an anterior premaxillary foramen is present and passes posterodorsally into the nasal passage (Fig. 16A). On the lateral aspect of the premaxilla, the posterior boundary of the narial fossa is indicated by an arcuate depression, posterior to which are located two large neurovascular foramina (posterior premaxillary foramina) and one smaller accessory foramen. One large foramen with a similar anteroventral groove has been described or shown in A. gomesii (Price 1959) (also AMNH 24450), A. patagonicus (Ortega et al. 2000) and A. tsangatsangana (Turner 2006). Posterior to these foramina is located the larger premaxillamaxilla foramen, which opens between these bones and extends ventrally to the alveolar margin as a narrow slit (Fig. 16A). In cross-section the body of the premaxilla posterior to the external nares is hollow (Fig. 17A), a highly unusual feature that is at least partially responsible for the inflated appearance of the premaxilla (Fig. 16A). Th is space, a premaxillary sinus, is also visible on the holotype, the cavity filled with matrix and exposed by erosion (MNHN GDF700). In the scan of A. wegeneri and in an acid-prepared skull of A. gomesii (AMNH 24450; Hecht 1991), the canal of the premaxilla-maxilla foramen appears to have an anterior diverticulum that may pneumatize the premaxilla. The scan also shows that the pair of large lateral foramina on the body of the premaxilla anterior to the premaxilla-maxilla foramen also communicate with the premaxillary sinus. The external surface of the maxilla is textured, except for a smooth surface along the arched, ventral alveolar margin dorsal to the postcaniniform teeth (Figs. 14A, 15A, 16A). Th e root of the caniniform tooth fills the swelling at the anterior end of the maxilla. Th e maxilla extends posteriorly to form the anterior margin of the antorbital fenestra and fossa. Above the fossa, a narrow prong of the maxilla contacts the prefrontal, separating the nasal and lacrimal. Th is is a sutural configuration present in A. tsangatsangana but absent in A. gomesii and A. patagonicus (Turner 2006), where the nasal contacts the lacrimal separating the maxilla and prefrontal. The nasal is textured mo

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