Poposauroidea

Poposauroidea Temporal range: Early-Late Triassic, Olenekian–Rhaetian PreЄ Є O S D C P T J K Pg N
Mounted skeleton of Sillosuchus longicervix in Japan
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Paracrocodylomorpha
Branch:	†Poposauroidea Nopsca, 1923
Subgroups
† Qianosuchus † Ctenosauriscidae † Poposauridae † Lotosauridae † Shuvosauridae

Poposauroidea is a clade of paracrocodylomorpha. It includes poposaurids, shuvosaurids, and ctenosauriscids, but excludes the large predatory quadrupedal rauisuchians such as rauisuchids and prestosuchids. Although it was first formally defined in 2007, the term has been used for many years. The group has been referred to as Poposauridae by some authors, although this name is often used more narrowly to refer to the family that includes Poposaurus and its close relatives.

Franz Nopcsa first used the term Poposauridae in 1923 to refer to poposauroids. At this time, the sole member of the group was Poposaurus, which was considered to be a theropod dinosaur. Over the following years, poposauroids were placed in various groups, including Saurischia, Theropoda, and Carnosauria. This classification existed up until the 1970s, when better remains indicated that Poposaurus was a crurotarsan rather than a dinosaur. Other genera such as Sillosuchus and Shuvosaurus were later erected. Like Poposaurus, Shuvosaurus was originally thought to be a theropod dinosaur.

Sankar Chatterjee reclassified poposauroids as theropod dinosaurs with his description of the new genus Postosuchus in 1985. Chaterjee even considered poposauroids to be the ancestors of tyrannosaurs. Postosuchus was widely considered to be a poposauroid for the next ten years and was included in many phylogenetic analyses of Triassic archosaurs. In 1995, Robert Long and Phillip A Murry showed that the original material of Postosuchus was a chimera (paleontology), or collection of bones from several different animals. According to Long and Murry, Chaterjee's Postosuchus material included bones of Poposaurus and Shuvosaurus, giving the impression that it was a poposauroid. Postosuchus has since been classified as a rauisuchid, and poposauroids are generally considered not to be theropod dinosaurs.