Plateosaur - Classification and Type Material

Classification and Type Material

Plateosaurus was the first "prosauropod" to be described, and gives its name to the family Plateosauridae Marsh, 1895 as type genus. Initially, when the genus was poorly known, it was only included in Sauria, being some kind of reptile, but not in any more narrowly defined taxon. In 1845, von Meyer created the group Pachypodes (a defunct junior synonym of Dinosauria) to include Plateosaurus, Iguanodon, Megalosaurus and Hylaeosaurus. Plateosauridae was proposed by Othniel Charles Marsh in 1895 within Theropoda. Later it was moved to "Prosauropoda" by von Huene, a placement that was accepted by most authors. Before the advent of cladistics in paleontology during the 1980s, with its emphasis on monophyletic groups (clades), Plateosauridae was defined loosely, as large, broad-footed, broad-handed forms with relatively heavy skulls, unlike the smaller "anchisaurids" and sauropod-like "melanorosaurids". Reevaluation of "prosauropods" in light of the new methods of analysis led to the reduction of Plateosauridae. For many years the clade only included Plateosaurus and various junior synonyms, but later two more genera were considered to belong to it: Sellosaurus and possibly Unaysaurus. Of these, Sellosaurus is probably another junior synonym of Plateosaurus.

The type series of Plateosaurus engelhardti included "roughly 45 bone fragments", of which nearly half are lost. The remaining material is kept in the Institute for Palaeontology of the University of Erlangen-Nuremberg, Germany. From these bones, German palaeontologist Markus Moser in 2003 selected a partial sacrum (series of fused hip vertebrae) as a lectotype. The type locality is not known for certain, but Moser attempted to infer it from previous publications and the colour and preservation of the bones. He concluded that the material probably stems from the "Buchenbühl", roughly 2 kilometres (1.2 mi) south of Heroldsberg.

The type specimen of Plateosaurus gracilis, an incomplete postcranium, is kept at the Staatliches Museum für Naturkunde Stuttgart, Germany. The type locality is Heslach, a suburb of Stuttgart, Germany.