Araripesuchus

Araripesuchus sp. Fig. 31 Material. MNN GAD 27; isolated left dentary lacking teeth. 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). Discussion. With the notable exception of MNN GAD27, all of the cranial remains of Araripesuchus recovered from the Elrhaz Formation pertain to subadult or adult individuals with skull lengths between 10–15 cm. MNN GAD27, a left dentary lacking teeth with preserved crowns (Fig. 31), is approximately twice the length of the specimens described above for A. wegeneri and A. rattoides and would pertain to a skull approximately 25–30 cm long. In addition to its large size, the number of postcaniniform alveoli is greater than in other specimens. Probably at least three additional postcaniniform teeth are present. The largest teeth in the dentary of A. wegeneri are between alveoli 10 and 13. In this larger dentary, the postcaniniform alveoli increase in size markedly starting with alveolus 13, suggesting that the comparable range for the largest dentary teeth would be alveoli 13–16. Finally, the dorsal surface of dentary medial to the postcaniniform series (Fig. 31C) is flat, horizontal, and devoid of the accessory splenial articular scar observed in A. wegeneri (Fig. 18B) and A. rattoides (Fig. 27B). In medial view, for example, no part of the nonarticular symphyseal surface medial to the tooth row is exposed, in contrast to the other African species (Figs. 27B, 28C, 31B). The differences between this specimen and the others suggest the presence of a second, larger species of Araripesuchus in the Elrhaz Formation. A similar circumstance was recently proposed for fossil material recovered from the La Buitrera locality in the Candeleros Formation in Argentina (Pol and Apesteguia 2005). There, a second larger species similar in size to MNN GAD27 occurs as a contemporary of a more common smaller species of Araripesuchus (A. buitreraensis) with a skull length of under 15 cm. On the other hand, increased tooth number and better defined or developed features Figure 3|. Left dentary of the crocodyliform Araripesuchus sp. Cast (UCRC PVC7) of an isolated, edentulous left dentary (MNN GAD27). A Lateral view. B Medial view (reversed). C Dorsal view (reversed). Scale bar equals 1 cm. Abbreviations: ad3–5, 9, 13, 14, alveolus for dentary tooth 3–5, 9, 13, 14; asp, articular surface for the splenial; be, buccal emargination; dsym, dentary symphysis; fo, foramen; gr, groove; Mc, Meckel’s canal. may manifest themselves in particularly large individuals within a species. We are inclined to regard MNN GAD27 as a distinct species but await confirmation from more complete remains before establishing formal taxonomic recognition. Mahajangasuchidae fam. n. urn:lsid:zoobank.org:act: 6C28D343-821D-4CF6-B293-F12EDBB59B15 Diagnosis. Mid- to large-sized (̴ 4–6 m) metasuchians with fused nasals, lacrimalnasal contact absent, postorbital bearing an oval laterally facing fossa that may have served for articulation with the posterior palpebral, squamosal and parietal form a hornlike posterodorsal process, steeply arched ventral jugal margin with a ventrolateral fossa at apex, ectopterygoid vertical and flush at jugal contact rather than arching medially, jaw articulation below posterior tooth row, pterygoid choanal septum with anterior footplate for palatine, pterygoid choanal septum with ventral edge expanded to approximately 40% of septum length, and pterygoid choanal wall invaginated dorsal to posterior margin of palate, deep mandibular symphysis oriented at approximately 45° anterodorsally, dorsolateral ridge on surangular, and maxillary tooth row terminates anterior to orbit. Etymology. Named on the basis of Mahajangasuchus insignis (Buckley and Brochu 1999), the first described member of the clade. New fossil finds continue to expand basal metasuchian diversity, although interrelationships are poorly established. Establishing this stem-based taxon for Mahajangasuchus, Kaprosuchus and taxa closer to them than to several other metasuchians establishes a well known anchor among basal metasuchians, to which other taxa may eventually be assigned. Phylogenetic definition. The most inclusive clade containing Mahajangasuchus insignis Buckley and Brochu 1999 but not Notosuchus terrestris Woodward 1896, Simosuchus clarki Buckley et al. 2000, Araripesuchus gomesii Price 1959, Baurusuchus pachecoi Price 1945, Peirosaurus torminni Price 1955, Goniopholis crassidens Owen 1842, Pholidosaurus schaumbergensis Meyer 1841, Crocodylus niloticus (Laurenti 1768). Discussion. Kaprosuchus saharicus represents a distinctive new crocodyliform distinguished by numerous cranial autapomorphies. Derived characters shared with other crocodyliforms are limited, although a suite of features listed in the familial diagnosis above links K. saharicus to the unusual crocodyliform, Mahajangasuchus insignis, from the Upper Cretaceous of Madagascar (Buckley and Brochu 1999; Turner and Buckley 2008). Th ese are described in more detail below (see Phylogenetic relationships).

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