Small theropod and bird teeth from the late Cretaceous (late Campanian) Judith River Group, Alberta

Abstract

A collection of over 1,700 small theropod teeth from the Judith River Group (Campanian;˜79.5–74 Ma) allows our understanding of the diversity and variation of small theropods in this assemblage to be refined. In addition to the previously recognized taxa, a series of morphologically distinct groups are recognized that may represent distinct taxa in some cases. Teeth with the Paronychodon-like features of a flat surface with longitudinal ridges on one side are resolved into a few discrete morphotypes. Two of these are included in Paronychodon lacustris and two additional morphotypes are hypothesized to represent distinct taxa, here referred to as ?Dromaeosaurus morphotype A and Genus and species indet. A. The teeth of Paronychodon lacustris and ?Dromaeosaurus morphotype A share a distinctive wear pattern that suggests tooth functioning involved contact between the flat surfaces of opposing teeth. Two species of Richardoestesia, R. gilmorei and R. isosceles, are present in the assemblage. Additionally, bird teeth are identified in the assemblage and are described in this review.Bivariate plots were used to document the variation in the theropod teeth, especially in the features that distinguish between Richardoestesia gilmorei, R. isosceles, Saurornitholestes, and Dromaeosaurus. Considerable overlap is present in all plots, so although the teeth are morphologically distinct, they are not easily distinguished by quantitative means.

Palaeoenvironmental drivers of vertebrate community composition in the Belly River Group (Campanian) of Alberta, Canada, with implications for dinosaur biogeography

“…Vertebrate microfossil sites from the Belly River Group have provided a wealth of knowledge on vertebrate palaeoecology [12, 14, 15, 52, 55, 56]. Vertebrate microfossil sites, sensu [57], are useful in overcoming issues of low sample size that commonly hinder palaeontological investigations, as they are both abundant and each site can preserve large numbers of small teeth, bones, and scales of numerous taxa thought to represent much of the vertebrate community composition of a given area [12–16, 53, 55, 58].…”

Small Theropod Teeth from the Late Cretaceous of the San Juan Basin, Northwestern New Mexico and Their Implications for Understanding Latest Cretaceous Dinosaur Evolution

“…Most teeth referred to Troodontidae are bulbous near their base with a nearly circular basal cross section and a pronounced basal constriction [21], [38].…”

The Molí del Baró-1 site, a diverse fossil assemblage from the uppermost Maastrichtian of the southern Pyrenees (north-eastern Iberia)

“…because of the absence of diagnostic material. The relatively small size of the denticles suggests affinity to Richardoestesia (Currie et al, 1990;Sankey et al, 2002;Llorens, 2010). MCD5033 resembles the Richardoestesia specimen from the lower Maastrichtian of the L'Abeller locality in the Eastern Tremp Syncline (Prieto-M arquez et al, 2000).…”