Figure 5. Partial braincase and left quadrate ramus of KNM FLKNI, Crocodylus anthropophagus, in medial (A), dorsolateral (B), and posterior (C) view. Scale = 5 cm. doi:10.1371/journal.pone.0009333.g005 Extinct Horned Crocodile the retroarticular process. Most preserved specimens (e.g. NNHM- OLD-1001, Fig. 2O) indicate a posterior ramus of the angular that extends roughly as far posteriorly as the surangular on the retroarticular process, but NHM R5893 suggests a truncated angular that terminates anterior to the surangular. Such a condition is highly unusual for any crocodylian, and in light of the consistently non-truncated angulars in other specimens, the NHM specimen is best viewed as aberrant. The surangular (Fig. 6) bears a pair of anterior processes. The dorsalmost process extends anteriorly to the dentary toothrow, and the ventral process is anteroposteriorly shorter and dorsoventrally wider. Its contact with the dentary in lateral view is linear and intersects the external mandibular fenestra along its anterodorsal margin. The surangular forms the entire posterior margin of the fenestra (Fig. 6B); the holotype (Fig. 3O) suggests intersection of the surangular-angular suture at the posteriormost end of the mandibular fenestra, but this is because the slender process of the surangular that would extend to the ventral margin is broken off. The smooth dorsal surface extends laterally between the mandibular fenestra and glenoid fossa, forming a robust lateral shelf (Fig. 2S). It passes along the dorsolateral surface of the retroarticular process and extends all the way to the posterior tip. Dorsally, the surangular contributes to the lateral glenoid subfossa. The descending ramus of the articular is triangular in cross- section, tapering to a rounded apex ventrally (Fig. 6). Its anterior surface is concave, and it bears a thin lamina on its lateral margin that passes along the medial surface of the surangular. A small foramen passes between the articular and surangular immediately ventral to this lamina. The glenoid fossa is comprised of two dorsal subfossae, and a sharply bowed angular-surangular suture passes through the lateral subfossa. The dorsal surface of the retro- articular process is also divided into two fossae separated by a low, broad anteroposterior ridge. A small foramen aereum pierces the articular at the anteromedial edge of the retroarticular process. All associated teeth are conical and bear unserrated mesiodistal carinae. Associated postcranial material is consistent with homologues in living species of Crocodylus. The atlas intercentrum is a wedge- Figure 6. Mandibular remains referred to Crocodylus anthropophagus. KNM BKII OLD 1960: left postdentary bones and posterior end of dentary, medial (A) and lateral (B) view; KNM FLKNI, dentaries and portion of right splenial, dorsal view (C); NHM R.5893, left dentary and splenial, medial (D) and lateral (E) view. Scale = 5 cm. doi:10.1371/journal.pone.0009333.g006 PLoS ONE | www.plosone.org 7 February 2010 | Volume 5 | Issue 2 | e9333