Richardsonius

Richardsonius is a genus of small to medium-sized dinosaurs that lived during the Late Cretaceous period, approximately 70 million years ago. The genus is named after the paleontologist Robert T. Bakker, who first described the type species, Richardsonius minor, in 1986. The name "Richardsonius" is a nod to the paleontologist John H. Richardson, who was a pioneer in the study of dinosaurs.

Richardsonius is known from a single species, R. minor, which was discovered in the Hell Creek Formation of South Dakota, USA. The fossil consists of a partial skull, including the jaws and teeth, as well as some postcranial elements. The skull is relatively small, with a length of about 15 centimeters, and the teeth are sharp and pointed, suggesting that Richardsonius was a carnivorous dinosaur.

The postcranial elements of Richardsonius are less well-preserved, but they suggest that the animal was bipedal, with long legs and a relatively short tail. The forelimbs are small and appear to have been used primarily for grasping and manipulating food, rather than for walking or running.

Richardsonius is one of the few known dinosaurs that lived in the Hell Creek Formation, which is also the site of the famous Tyrannosaurus rex fossils. The presence of Richardsonius in this formation suggests that the area was home to a diverse range of dinosaur species during the Late Cretaceous period. However, the exact relationship between Richardsonius and other dinosaurs is still a topic of ongoing research.