The Poposauridae are a family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 of large (around 2.5 to 5 meters long) carnivorous

Carnivore

A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...

 archosaur

Archosaur

Archosaurs are a group of diapsid amniotes whose living representatives consist of modern birds and crocodilians. This group also includes all extinct non-avian dinosaurs, many extinct crocodilian relatives, and pterosaurs. Archosauria, the archosaur clade, is a crown group that includes the most...

s which lived alongside dinosaur

Dinosaur

Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...

s during the Late Triassic

Late Triassic

The Late Triassic is in the geologic timescale the third and final of three epochs of the Triassic period. The corresponding series is known as the Upper Triassic. In the past it was sometimes called the Keuper, after a German lithostratigraphic group that has a roughly corresponding age...

. They are known from fossil remains from North and South America. Originally believed to be theropod dinosaur

Dinosaur

Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...

s (they mirrored the theropods in a number of respects, such as features of the skull and bipedal locomotion), cladistic

Cladistics

Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...

 analysis has shown them to be of closer relation to crocodiles.

An early cladistic analysis of crocodylotarsan archosaur

Archosaur

Archosaurs are a group of diapsid amniotes whose living representatives consist of modern birds and crocodilians. This group also includes all extinct non-avian dinosaurs, many extinct crocodilian relatives, and pterosaurs. Archosauria, the archosaur clade, is a crown group that includes the most...

s included Poposaurus

Poposaurus

Poposaurus is a genus of reptile from the Late Triassic of the southwestern United States. It was a crurotarsan archosaur which lived in what is now Wyoming, Utah, Arizona and Texas. The type species, Poposaurus gracilis, was described by M. G. Mehl in 1915. The second species, P...

, Postosuchus

Postosuchus

Postosuchus, meaning "crocodile from Post ", was a basal archosaur that lived in what is now North America during the middle through to the late Triassic period...

, Teratosaurus

Teratosaurus

Teratosaurus was a genus of rauisuchian known from the Triassic Stubensandstein of Germany...

, and Bromsgroveia

Bromsgroveia

Bromsgroveia is an extinct genus of predatory archosaur from the Triassic of England. Ctenosauriscids were a group of rauisuchians that was related to the ancestors of modern crocodiles and alligators....

within Poposauridae. However, later studies found Teratosaurus

Teratosaurus

Teratosaurus was a genus of rauisuchian known from the Triassic Stubensandstein of Germany...

to be a rauisuchid

Rauisuchidae

Rauisuchidae is a group of large predatory Triassic archosaurs, and constitute advanced representatives of the larger group Rauisuchia. There is some disagreement over which genera should be included in the Prestosuchidae, which in Rauisuchidae, and which in the Poposauridae, and indeed whether...

. All recent phylogenetic analyses place Postosuchus

Postosuchus

Postosuchus, meaning "crocodile from Post ", was a basal archosaur that lived in what is now North America during the middle through to the late Triassic period...

either as a rauisuchid or a prestosuchid

Prestosuchidae

Prestosuchids were a group of Triassic carnivorous archosaurs. They were large active terrestrial apex predators, ranging from around in length. They succeeded the Erythrosuchidae as the largest archosaurs of their time...

.

Genera

Genus	Status	Age	Location	Description	Images
†Dolichobrachium Dolichobrachium Dolichobrachium is a dubious genus of extinct poposaurid crurotarsan. Fossils have been found from the Popo Agie Formation in Wyoming and are of Late Triassic age. It was one of the first rauisuchians to have been named....	Nomen dubium Nomen dubium In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application... .	Late Triassic Late Triassic The Late Triassic is in the geologic timescale the third and final of three epochs of the Triassic period. The corresponding series is known as the Upper Triassic. In the past it was sometimes called the Keuper, after a German lithostratigraphic group that has a roughly corresponding age...	North America North America North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
†Lythrosuchus	Junior synonym.			Junior synonym of Poposaurus
†Poposaurus Poposaurus Poposaurus is a genus of reptile from the Late Triassic of the southwestern United States. It was a crurotarsan archosaur which lived in what is now Wyoming, Utah, Arizona and Texas. The type species, Poposaurus gracilis, was described by M. G. Mehl in 1915. The second species, P...	Valid.	Late Triassic Late Triassic The Late Triassic is in the geologic timescale the third and final of three epochs of the Triassic period. The corresponding series is known as the Upper Triassic. In the past it was sometimes called the Keuper, after a German lithostratigraphic group that has a roughly corresponding age...	North America North America North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas... .

Further reading

• Galton, P. M.
  Peter Galton
  Peter M. Galton is a British vertebrate paleontologist working in America, who has to date written or co-written about a hundred papers in scientific journals or chapters in paleontology textbooks, especially on ornithischian and prosauropod dinosaurs.With Robert Bakker in a joint article...
  
  , 1985, The poposaurid thecodontian Teratosaurus suevicus von Meyer, plus referred specimens mostly based on prosauropod dinosaurs. Stuttgarter Beitrage zur Naturkunde, B 116: 1-29.

External links

• Palaeos
• Taxon Search
• Mikko's Phylogeny Archive
• Re: Postosuchus/Rauisuchus - Dinosaur Mailing List archives