Fossil range: Middle Triassic
Arizonasaurus BW
Arizonasaurus babbitti
Scientific classification



(Unranked) :







Welles, 1947


Arizonasaurus (Arizona lizard) is an extinct genus of archosaurian reptile from the Mesozoic Era, specifically a ctenosauriscid archosaur from the Middle Triassic Period (240 million years ago). It was closely related to crocodiles, and is near the split between dinosaurs and crocodiles. 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 paleontologist Samuel Paul Welles in 1947.

Discovery and namingEdit

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.[2] A fairly complete skeleton was found in 2002 by Sterling Nesbitt.


The holotype of A. babbitti consists of a single bone of the left jaw, that differed through from other known archosaurs. In 2002, additional remains were unearthed in the formation; part of the spinal column, the skull, and the basin, were found. The remains were identified in 2003 through sterling J. Nesbitt as a partially preserved skeleton of a subadult individual of A. babbitti, due to the almost identical jaw bones.



The fossil findings of A. babbitti come from the upper Moenkopi Formation in Arizona, USA. The remains were confirmed to be Middle Triassic through the presence of the fossilized remains of Eocyclotosaurus, a temnospondyl that lived during the same time period.


Postosuchus BW

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