Geology and taphonomy of a unique tyrannosaurid bonebed from the upper Campanian Kaiparowits Formation of southern Utah: implications for tyrannosaurid gregariousness.

Tyrannosaurids are hypothesized to be gregarious, possibly parasocial carnivores engaging in cooperative hunting and extended parental care. A tyrannosaurid (cf. ) bonebed in the late Campanian age Kaiparowits Formation of southern Utah, nicknamed the Rainbows and Unicorns Quarry (RUQ), provides the first opportunity to investigate possible tyrannosaurid gregariousness in a taxon unique to southern Laramidia.

A new troodontid theropod, Talos sampsoni gen. et sp. nov., from the Upper Cretaceous Western Interior Basin of North America.

Background: Troodontids are a predominantly small-bodied group of feathered theropod dinosaurs notable for their close evolutionary relationship with Avialae. Despite a diverse Asian representation with remarkable growth in recent years, the North American record of the clade remains poor, with only one controversial species--Troodon formosus--presently known from substantial skeletal remains.

Methodology/principal Findings: Here we report a gracile new troodontid theropod--Talos sampsoni gen.

New horned dinosaurs from Utah provide evidence for intracontinental dinosaur endemism.

Background: During much of the Late Cretaceous, a shallow, epeiric sea divided North America into eastern and western landmasses. The western landmass, known as Laramidia, although diminutive in size, witnessed a major evolutionary radiation of dinosaurs. Other than hadrosaurs (duck-billed dinosaurs), the most common dinosaurs were ceratopsids (large-bodied horned dinosaurs), currently known only from Laramidia and Asia.

A new North American therizinosaurid and the role of herbivory in 'predatory' dinosaur evolution.

Historically, ecomorphological inferences regarding theropod (i.e. 'predatory') dinosaurs were guided by an assumption that they were singularly hypercarnivorous.