Extinct Horned Crocodile Figure 2. Craniomandibular remains of NNHM-OLD-1001, holotype, Crocodylus anthropophagus. A, partial left nasal, dorsal view; B, right quadratojugal, lateral view; C, right jugal, lateral view; D, left jugal, lateral view; E, left jugal, medial view; F, right otic region and quadrate ramus, lateral view; G, left quadrate ramus, dorsal view; H, left quadrate ramus, ventral view; I, left quadrate ramus and paroccipital process, posteromedial view; J, braincase, posterior view; K, right pterygoid wing, ventral view; L, left pterygoid wing, ventral view; M, right ectopterygoid, ventral view; N, left ectopterygoid, ventral view; O, right postdentary bones, lateral view; P, left quadrate, dorsal view; Q, left surangular, medial view; R, fragment of dentary; S, left surangular, lateral view. Scale = 5 cm. doi:10.1371/journal.pone.0009333.g002 The lacrimal forms the anterior margin of the orbit. The outline is not completely preserved, but it extended further anteriorly than the prefrontal. An oval aperture on its posterior surface, within the orbital margin, indicates the posterior opening of the lacrimal duct. It connected with the jugal laterally. The partial left lacrimal associated with the holotype (Fig. 1J) preserves a series of thin anteroposteriorly-oriented crests on its dorsal surface – a mediolaterally robust crest extending from the lacrimal-prefrontal suture at the orbital margin and two thinner crests lateral to a shallow groove extending from the orbit. The medial crest and dorsal groove are generally present in most crocodyliforms (including most Crocodylus), but the lateral crests are not. They are not apparent on the other specimens preserving portions of the lacrimal (e.g. KNM FLKNI, Fig. 4F; NHM R5893, Fig. 4O), but this could be preservational – none of these preserves much of the lacrimal lateral to the dorsal groove. Nevertheless, pending better information on variation, these features are only provisionally considered diagnostic for the species. The prefrontal forms the anteromedial margin of the orbit and extends anteriorly to form an acute process between the nasal and lacrimal. Based on NHM R5893 (Fig. 4O), the anterior process extended approximately as far forward as the frontal. Its lateral margin, where it contacts the lacrimal, is concave. The descending processes forming the dorsal part of the prefrontal pillars are mediolaterally compressed structures, and the left descending process of KNM CROC K OLD 62 (Fig. 4D) bears a medial process that is constricted at its base and anteroposteriorly elongate medially. The dorsal surface of the frontal between the orbits is flat (Figs. 1K, 4C,F,O). Its anterior process is sharply demarcated from the main frontal body, and the broad anterior process itself terminates at an acute point approximately at the same level as the anterior margins of the prefrontal and the orbit. The frontopa- rietal suture is imperfectly preserved, but the posterior surface of the frontal is convex, and the suture did not pass within the supratemporal fenestra. Those portions of the prefrontal and frontal bordering the orbit are sharply upturned (Fig. 4D). On each side, they form a continuous robust lamina extending from the prefrontal-lacrimal contact to the frontal-postorbital suture. The medial crest on the lacrimal can be seen as a rostral continuation of this structure. The frontal-prefrontal suture changes orientation from mediolateral to anteroposterior at a right angle immediately medial to the lamina. Two prominent knobs extend dorsally from each lamina, one entirely on the prefrontal and another at the frontal-prefrontal contact. This is most apparent on the holotype (Fig. 1K). The postorbital includes a broadly crescentic dorsal corpus and columnar descending process comprising the dorsal and, ventrally, the medial portion of the postorbital bar. In at least one specimen (e.g. NNHM-OLD-1001, Fig. 1H), it expands dorsally as it approaches the squamosal posteriorly; but another isolated squamosal (Fig. 4N) expands abruptly behind its sutural surface PLoS ONE | www.plosone.org 4 February 2010 | Volume 5 | Issue 2 | e9333