An Illustrated Guide to Dinosaur Feeding Biology by Nabavizadeh Ali;Weishampel David B.;

Author:Nabavizadeh, Ali;Weishampel, David B.;
Language: eng
Format: epub
Publisher: Johns Hopkins University Press
Published: 2023-06-15T00:00:00+00:00

Heterodontosauridae

For reference in understanding relationships and clade affiliation of early ornithischians discussed in this chapter, see the phylogeny (fig. 10.1) and taxon list (table 10.1) below.

According to phylogenetic analyses by Butler et al. (2008), Heterodontosauridae is among the earliest-diverging clades within Ornithischia. Heterodontosaurids ranged from the Early Jurassic to Early Cretaceous and had nearly worldwide distribution. The skulls of heterodontosaurids (e.g., Heterodontosaurus [fig. 10.2], Tianyulong, Echinodon, Pegomastax, Fruitadens, Abrictosaurus, and Manidens) are generally no larger than the palm of your hand and possess a deep occiput with a midline sagittal crest that extends from just behind the orbits to the caudal edge of the skull roof. Heterodontosaurids have a triangular snout with large orbits and antorbital fossae. A dorsally arched notch is present at the premaxillary-maxillary junction, where a caniniform (i.e., “canine-like”) fang from the corresponding region of the dentary rests inside at occlusion. Otherwise, the tooth-bearing regions of the maxilla and dentary sit parallel to one another at occlusion. Typically, the heterodontosaurid dentition consists of small premaxillary teeth, one caniniform tooth at the mesial end on the dentary resting just caudal to those premaxillary teeth at occlusion, and a row of precisely occluding “hypsodont” cheek teeth (adapted for constant wearing) with flat oblique occlusal surfaces (Norman et al., 2011; see below). Their temporal region (and supratemporal fenestra) was rostrocaudally broad and transversely narrow, and the postorbital adductor region and infratemporal fenestra are subrectangular and vertically oriented. The palate of heterodontosaurids is broad, with a moderately sized pterygoid flange.

Figure 10.1. Phylogeny of early Ornithischia, largely based on Butler et al. (2008) and Boyd (2015).

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