A new Mongolian tyrannosauroid and the evolution of Eutyrannosauria.

Eutyrannosaurians were large predatory dinosaurs that dominated Asian and North American terrestrial faunas in latest Cretaceous times. These apex predators arose from smaller-bodied tyrannosauroids during the 'middle' Cretaceous that are poorly known owing to the paucity of fossil material. Here we report on a new tyrannosauroid, Khankhuuluu mongoliensis gen.

Ontogenetic Changes in Endocranial Anatomy in Gorgosaurus libratus (Theropoda: Tyrannosauridae) Provide Insight Into the Evolution of the Tyrannosauroid Endocranium.

Over the past two decades, increased accessibility to computed tomography (CT) scanners has greatly facilitated documentation of the endocranium in numerous extinct theropod taxa. However, most of these studies have focused on the morphology of mature individuals, thus changes or variation through ontogeny of the endocranium in theropods remains largely unknown. The current study sheds light on the endocranial anatomy of the eutyrannosaurian tyrannosauroid, Gorgosaurus libratus, in both an ontogenetic and evolutionary context.

Exceptionally preserved stomach contents of a young tyrannosaurid reveal an ontogenetic dietary shift in an iconic extinct predator.

Tyrannosaurids were large carnivorous dinosaurs that underwent major changes in skull robusticity and body proportions as they grew, suggesting that they occupied different ecological niches during their life span. Although adults commonly fed on dinosaurian megaherbivores, the diet of juvenile tyrannosaurids is largely unknown. Here, we describe a remarkable specimen of a juvenile that preserves the articulated hindlimbs of two yearling caenagnathid dinosaurs inside its abdominal cavity.

Reassessment of a juvenile Daspletosaurus from the Late Cretaceous of Alberta, Canada with implications for the identification of immature tyrannosaurids.

Daspletosaurus is a large tyrannosaurine found in upper Campanian deposits of Alberta and Montana. Although several large subadult and adult individuals of this taxon are known, only one juvenile individual, TMP 1994.143.