Arizonasaurus
Middle Triassic archosaur with a distinctive back sail.
It is known for having a large back sail formed by elongated neural spines of its vertebrae.
- location
- Moenkopi Formation, northern Arizona
- classification
- Ctenosauriscid archosaur (pseudosuchian)
- type_species
- Arizonasaurus babbitti
- known_for
- Large back sail formed by elongated neural spines
Lore & Background
Arizonasaurus had a sail made of tall neural spines, similar to those of other basal archosaurs such as Ctenosauriscus, Bromsgroveia, and Hypselorhachis. It is described from two braincase specimens, which show some ancestral features plesiomorphic for crurotarsans.
Reader's Guide
Arizonasaurus is significant as a well-preserved Middle Triassic pseudosuchian archosaur that helps clarify the early evolution of archosaurs, including the divergence of birds and crocodiles. Its presence in the Moenkopi Formation suggests that this divergence occurred earlier than previously thought. The ctenosauriscids, including Arizonasaurus, show that Triassic faunas were more widespread across Europe, Asia, North America, and Africa. The pelvic girdle of Arizonasaurus links it with Ctenosauriscus, Lotosaurus, Bromsgroveia, and Hypselorhachis, and newly identified pseudosuchian features indicate that poposauroids and ctenosauriscids form a monophyletic group more derived than rauisuchians. The fauna of the Moenkopi Formation represents a transitional stage between older and younger faunas.
Did You Know?
- Arizonasaurus means 'Arizona reptile'.
- Arizonasaurus had a sail made of tall neural spines, similar to those of Ctenosauriscus, Bromsgroveia, and Hypselorhachis.
Frequently Asked Questions
What is Arizonasaurus?
Arizonasaurus is a Middle Triassic archosaur whose type species is Arizonasaurus babbitti. It belongs to the ctenosauriscid family within the broader pseudosuchian lineage.
What is Arizonasaurus most famous for?
Its standout feature is a tall dorsal sail constructed from greatly elongated neural spines running along the vertebral column. This sail is the single trait that most sets it apart from other archosaurs of its era.
Where were Arizonasaurus fossils found?
Remains of this animal come from the Moenkopi Formation in northern Arizona. That rock unit preserves a Middle Triassic landscape in what is now the southwestern United States.
How is Arizonasaurus classified among prehistoric animals?
It is placed in the ctenosauriscid group, a family of early pseudosuchian archosaurs. This links it to the ancestral line that later gave rise to crocodilians and their relatives.
What time period did Arizonasaurus live in?
It roamed the Earth during the Middle Triassic, roughly 240 million years ago. At that time it was one of the more distinctive land-dwelling archosaurs in its ecosystem.
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