Читать книгу Hadrosaurs - David A. Eberth - Страница 43

Basal, or “hypsilophodontian-grade” ornithopods sensu lato (Norman et al., 2004; see also Butler et al., 2008), are generally small–medium sized (1–3 m long), bipedal cursors with simple leaf-shaped teeth in both upper and lower jaws; their dental morphology is similar in morphology to that described by Thulborn (1970) and is typical of all basal ornithischians. At the base of the tree, the outgroup is polarized (in this analysis, crudely) against what appear to be more derived taxa in the absence of a consideration of the substantially greater diversity of hypsilophodontian-grade ornithopods (see Butler et al., 2008).