Vancleavea

Vancleavea is a genus of extinct, armoured, non-archosaurian archosauriforms from the Late Triassic of western North America. The type and only known species is V. campi, named by Robert Long & Phillip A Murry in 1995. At that time, the genus was only known from fragmentary bones including osteoderms and vertebrae. However, since then many more fossils have been found, including a pair of nearly complete skeletons discovered in 2002. These finds have shown that members of the genus were bizarre semiaquatic reptiles. Vancleavea individuals had short snouts with large, fang-like teeth, and long bodies with small limbs. They were completely covered with bony plates known as osteoderms, which came in several different varieties distributed around the body. Phylogenetic analyses by professional paleontologists have shown that Vancleavea was an archosauriform, part of the lineage of reptiles that would lead to archosaurs such as dinosaurs and crocodilians. Vancleavea lacks certain traits which are present in most other archosauriforms, most notably the antorbital, mandibular and supratemporal fenestrae, which are weight-saving holes in the skulls of other taxa. However, other features clearly support its archosauriform identity, including a lack of intercentra, the presence of osteoderms, an ossified laterosphenoid, and several adaptations of the femur and ankle bones. In 2016, a new genus of archosauriform, Litorosuchus, was described. This genus resembled both Vancleavea and more typical archosauriforms in different respects, allowing Litorosuchus to act as a transitional fossil linking Vancleavea to less aberrant archosauriforms.

== History == left|thumb|Vancleavea fossils have been found throughout New Mexico and [[Arizona, but the most complete specimens hail from the Coelophysis Quarry at Ghost Ranch.]] Vancleavea was first discovered in 1962 from the Petrified Forest Member of the Petrified Forest National Park and initially described by Long and Murry in 1995. At that time the only described specimen was the holotype, PEFO 2427. The genus is named after Phillip Van Cleave, who discovered the first known remains of the genus. Since then, a number of remains have been found. A 2009 reevaluation of the genus by Nesbitt et al. formally described two additional specimens, GR 138 and 139. GR 138 is particularly notable due to being a nearly complete and articulated skeleton preserving a variety of osteoderms in the positions they would have been in during life. It was discovered at the Coelophysis Quarry in north-central New Mexico (Ghost Ranch), US, and was prepared at the Ruth Hall Museum of Paleontology in Abiquiú, New Mexico before its formal description. Vancleavea is a fairly common occurrence in most levels of the Chinle Formation, however, due to the poorly preserved remains, it is difficult to compare specimens across stratigraphic levels.