Arizonasaurus
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Arizonasaurus Temporal range: Middle Triassic, 243 Ma |
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| Model, Museum am Lowentor, Stuttgard | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Paracrocodylomorpha |
| Branch: | †Poposauroidea |
| Family: | †Ctenosauriscidae |
| Genus: |
†Arizonasaurus Welles, 1947 |
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Arizonasaurus was a ctenosauriscid archosaur from the Middle Triassic (243 million years ago).Arizonasaurus is found in the Middle Triassic Moenkopi Formation of northern Arizona. A fairly complete skeleton was found in 2002 by Sterling Nesbitt. The taxon has a large sailback formed by elongate neural spines of the vertebrae. The type species, Arizonasaurus babbitti, was named by Samuel Paul Welles in 1947.
It had a sail made of tall neural spines, that was similar to those of other basal archosaurs like Ctenosauriscus, Lotosaurus, Bromsgroveia, and Hypselorhachis.
Arizonasaurus is described from two specimens of braincases. Some ancestral features of the braincase of Arizonasaurus are plesiomorphic for crurotarsans.
Below is a list of characteristics found by Nesbitt in 2005 that distinguish Arizonasaurus:
The type species, Arizonasaurus babbitti, was named by Samuel Paul Welles in 1947 on the basis of a few teeth and a maxilla, labelled as specimen UCMP 36232. A fairly complete skeleton was found in 2002 by Sterling Nesbitt.
Arizonasaurus was closely related to Ctenosauriscus, and together with a few other genera they make up Ctenosauriscidae. The ctenosauriscids were closely related to the poposaurids, as shown by a few shared derived characteristics. The pelvic girdle in Arizonasaurus unites this taxon with Ctenosauriscus, Lotosaurus, Bromsgroveia, and Hypselorhachus. Together, newly identified pseudosuchian features act as evidence that poposaurids, like Poposaurus, Sillosuchus, and Chatterjeea, and ctenosauriscids form a monophyletic group and are both derived rauisuchians.
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