Bird-like characteristics of the jaws and teeth of troodontid theropods (Dinosauria, Saurischia)

ABSTRACT

The discovery of a new dentary of “Stenonychosaurus inequalis” with six germ teeth prompted a critical examination of all jaws and teeth attributed to Troodon, Stenonychosaurus, and Pectinodon. It is concluded that Troodon is the senior synonym of these genera, and that the name Troodontidae has priority over Saurornithoididae. Troodontid dentaries are unique amongst the Theropoda in that they lack interdental plates. Previous reports that Dromaeosaurus, Deinonychus, and Saurornitholestes do not have interdental plates are erroneous. Premaxillary, maxillary, anterior dentary and dentary teeth can be distinguished from each other. Each troodontid tooth has a constriction between the crown and root that is more comparable with birds and crocodiles than with other theropods.