Pseudosuchian
| Pseudosuchia Temporal range: Early Triassic - Holocene, 250–0 Ma |
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|---|---|
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| Ornithosuchidae | |
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| Suchia | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Archosauria |
| Clade: |
Pseudosuchia Zittel, 1887 |
| Subgroups | |
| Synonyms | |
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Crocodylotarsi Benton & Clark, 1988 |
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Crocodylotarsi Benton & Clark, 1988
Pseudosuchia ("false crocodiles") is one of two major divisions of Archosauria and includes living crocodilians and all archosaurs more closely related to crocodilians than to birds (what are often called "crocodilian-line archosaurs"). The name was originally given to a group of superficially crocodile-like prehistoric reptiles from the Triassic period, but fell out of use in the late 20th century, especially after the name Crurotarsi was established in 1990 to label the clade (evolutionary grouping) of archosaurs encompassing most reptiles previously identified as pseudosuchians. By this time, Pseudosuchia had also been defined as a clade, but it was not widely embraced until 2011, when paleontologist Sterling Nesbitt proposed that Crurotarsi, as it was originally defined, must include not only crocodilian-line archosaurs, but all other archosaurs including birds, non-avian dinosaurs, and pterosaurs. The clade Pseudosuchia as originally defined could still be used to identify crocodilian-line archosaurs, and since many recent studies support Nesbitt's findings, Pseudosuchia is now commonly used.
The name Pseudosuchia was coined by Karl Alfred von Zittel in 1887-1890 to include three taxa (two aetosaurs and Dyoplax) that were superficially crocodilian-like, but were not actually crocodilian. Hence the name "false crocodiles".
In mid-20th century textbooks, like Alfred Sherwood Romer's Vertebrate Paleontology and Edwin H. Colbert's Evolution of the Vertebrates, Pseudosuchia constitutes one of the suborders of the now-abandoned order Thecodontia. Zittel's aetosaurs were placed in their own suborder, Aetosauria. Colbert considered small lightly built archosaurs, such as Ornithosuchus and Hesperosuchus —both of which were at the time reconstructed as theropod dinosaur-like bipeds — to be typical pseudosuchians. These small forms were assumed to be the ancestors of all later archosaurs. The name Pseudosuchia became a wastebasket taxon into which all thecodonts that did not fit in the other three suborders could be placed. Even Sharovipteryx and Longisquama, two enigmatic Triassic reptiles that bear little resemblance to archosaurs, have been regarded as pseudosuchians.
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