Variation in the sacrum of phytosaurs: New evidence from a partial skeleton of Machaeroprosopus mccauleyi.

Phytosaurs are a group of Upper Triassic semi-aquatic archosauriform reptiles. Their variable skull morphology forms the foundation of our understanding of their relationships and paleoecology, while only a few studies have focused on demonstrating the existence of postcranial variation. The numbers of vertebrae in the sacrum are thought to vary from two, the plesiomorphic condition for archosauriforms, to three, with the addition of a sacralized dorsal (i.

Over 13,000 elements from a single bonebed help elucidate disarticulation and transport of an Edmontosaurus thanatocoenosis.

Over twenty years of work on the Hanson Ranch (HR) Bonebed in the Lance Formation of eastern Wyoming has yielded over 13,000 individual elements primarily of the hadrosaurid dinosaur Edmontosaurus annectens. The fossil bones are found normally-graded within a fine-grained (claystone to siltstone) bed that varies from one to two meters in thickness. Almost all specimens exhibit exquisite preservation (i.