Deinonychus antirrhopus (Ostrom, 1969)

Brownstein, Chase Doran, 2021, Dromaeosaurid crania demonstrate the progressive loss of facial pneumaticity in coelurosaurian dinosaurs, Zoological Journal of the Linnean Society 191 (1), pp. 87-112 : 96

Deinonychus antirrhopus

As in other theropod dinosaurs, the antorbital sinus would have overlain much of the exterior surface of the anterior half of the skull of Deinonychus antirrhopus , where it would have been bordered anteriorly by a crescentic ridge of bone developing out of the maxilla and posteriorly by the jugal and lacrimal in lateral view ( Fig. 4A; e.g . Witmer, 1997; Witmer & Ridgely, 2008; Tahara & Larsson, 2011; Gold et al., 2013). The crescentic ridge of bone on the maxilla of Deinonychus borders the antorbital fossa, which houses the promaxillary and maxillary fenestra in addition to the anterior half of the antorbital sinus. Thus, the shape of the antorbital fossa provides information on the shape of the antorbital sinus ( Fig. 4A ). In Deinonychus , this sinus was clearly ovoid anteriorly, closely bordering the nasal dorsally. The antorbital fossa extends forward before terminating approximately two-thirds into the posterior-anterior run of the maxilla, which clearly bordered more than half of the antorbital sinus dorsoventrally. The antorbital fossa is gently undercut dorsoposteriorly and ventrally, and is more strongly undercut anteriorly and anterodorsally. This morphological information suggests the antorbital sinus may have extended past the ventral border of the antorbital fossa slightly. The antorbital sinus would have also produced several diverticula within the antorbital fossa—the maxillary antrum and promaxillary sinus—that would have sat partially within the maxillary and promaxillary fenestra ( Witmer, 1997; Witmer & Ridgely, 2008; Tahara & Larsson, 2011; Gold et al., 2013).

Figures

Figure 4. Reconstruction of the antorbital sinus in coelurosaurs. The second sentence in the figure caption should read: Skulls of (A) Velociraptor, (B) Tsaagan, (C) Tyrannosaurus, (D) Deinonychus, (E) Saurornithoides, and (F) Khaan. Antorbital sinus in blue, with location of the maxillary fenestra in black and promaxillary fenestra in yellow. Photo of Deinonychus courtesy of the Division of Vertebrate Paleontology, Peabody Museum of Natural History.