Archosaurs | |
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Crocodiles basking in the sun. Crocodiles can move quite fast on land by tucking their legs under their body: an archosaur feature. | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Reptilia |
Clade: | Eucrocopoda |
Clade: | Archosauria Cope, 1869 |
Subgroups | |
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Synonyms | |
Arctopoda Haeckel, 1895 |
Archosaurs are a large group of reptiles, including all crocodiles, birds, dinosaurs, and pterosaurs (flying reptiles). There are also a number of smaller extinct groups, mostly from the Triassic period.[1]
The Archosaurs are definitely a monophyletic clade, and do not include reptiles such as the Squamata (lizards and snakes) and the Sphenodontia (Sphenodon).[2]
They have these diagnostic features,[3] called synapomorphies in cladistics talk:
The archosaurs or their immediate ancestors survived the catastrophic Permian–Triassic extinction event. Benton comments: "The key tetrapods to benefit from the Permo-Triassic mass extinction was the Archosauromorpha".[4] Then, in the early and middle Triassic, there was rapid evolution into the types of aquatic and land tetrapods which dominated the rest of the Mesozoic era.
This is an even wider group, which includes diapsid Sauropsida which appeared in the middle Permian and Triassic periods. Their relationships are not well established at present.