Globidentosuchus brachyrostris Scheyer, Aguilera, Delfino, Fortier, Carlini, Sánchez, Carrillo-Briceño, Quiroz and Sánchez-Villagra, 2013

Scheyer, TM & Delfino, M, 2016, The late Miocene caimanine fauna (Crocodylia: Alligatoroidea) of the Urumaco Formation, Venezuela, Palaeontologia Electronica 176 (4), pp. 1-57 : 11

Globidentosuchus brachyrostris Scheyer, Aguilera, Delfino, Fortier, Carlini, Sánchez, Carrillo-Briceño, Quiroz and Sánchez-Villagra, 2013

The material accessioned as AMU-CURS-067 ( Figures 8 , 9 ) from the Playa Larga locality, Middle Member of Urumaco Fm. includes: 1) a left mandibular ramus (35.6 cm preserved length) lacking part of the anterior symphyseal tip and posteriorly part of the surangular and angular, including the retroarticular process; 2) a fragment of the right mandibular ramus which lacks most of the anterior symphyseal area and everything posterior to the anterior edge of the external mandibular fenestra; 3) a fragment of the right maxilla with 7.5 alveoli, three of which carry tooth remains; 4) a fragment of a right premaxilla preserving 3.5 alveoli; and 5) an indeterminate cranial bone. In addition, four vertebrae and six other bone fragments were found associated with the above-mentioned cranial and mandibular bones.

The left mandibular ramus has the 14 posterior-most alveoli preserved, with the last eight still carrying teeth or broken-off tooth stumps. Given the shape of the preserved teeth and sizes of the alveoli, eight large crushing teeth were present in the living animal, similar to the condition in the holotype ( Scheyer et al., 2013). This specimen also shows the outlines of the external mandibular fenestra and the foramen intermandibularis caudalis, and a surangular-angular suture which extends more or less horizontally towards the posterior margin of the ramus (this suture is angled upwards in the holotype material of Caiman brevirostris , see Fortier et al., 2014). Both mandibular rami have the splenial participating anteriorly in the mandibular symphysis as in other specimens of Globidentosuchus brachyrostris and the sutural contacts of most of the bones in the posterior portion of the mandible are traceable ( Figure 9 ). The right portion of the mandible also carries a pathological circular bony excrescence lateral to the first and second crushing tooth. The premaxillary and the maxillary fragments and the surangular-angular portion of the right mandibular ramus also have pitting patterns preserved on the external bone surface.

The right maxilla fragment preserves the anterior portion of the bone from alveolus 1 (only partially preserved) to alveolus 8. The fourth alveolus has the largest diameter, followed by the adjacent alveoli anteriorly and posteriorly. Alveoli 6 to 8 are slightly labiolingually compressed, while alveoli 2 to 5 are filled with broken-off teeth remains. Dorsally the maxilla fragment is slightly domed, showing some irregularly spaced foramina. The borders of the premaxilla and the opposite maxilla are not preserved. The premaxillary fragment, on the other hand, is interpreted as including alveoli 2 to 4, with the fourth being the largest and the remaining two being of equal size. Anteromedially to alveolus 2, the first large occlusion pit is preserved. Dorsally the fragment is similarly domed and the surface carries numerous foramina. The borders of the external naris and the incisive foramen are not preserved.

Figures

FIGURE 8. Photographs of Globidentosuchus brachyrostris (AMU-CURS-067). 1-3, left ramus of lower jaw in lateral (1), medial (2), and dorsal (3) view. 4-6, anterior, portion of right ramus in lateral (4), medial (5), and dorsal (6) view. 7, 8, fragment of a (right?) maxilla in ventral (7) and lateral (8) view. 9, 10, Fragment of a (left?) premaxilla in ventral (9) and dorsal (10) view. 11, indeterminate cranial fragment found associated with the other skeletal element and therefore referred to the same specimen.

FIGURE 9. Photographs and interpretative drawings of Globidentosuchus brachyrostris lower jaw (AMU-CURS- 067). 1, 2, assembled right and left ramus in dorsal view showing posterior crushing dentition and the splenials participating in symphysis. 3, 4, posterior part of left ramus in lateral view. 5, 6, posterior part of left ramus in medial view. Note that fragment of articular is still partially present, articulating with the angular ventrally. Abbreviations: a, angular; ar, articular; co, coronoid; d, dentary; fic, foramen intermandibularis caudalis; fme; external mandibular fenestra; path, area of pathology; sa, surangular; sed, sediment; sp, splenial.