Ornithodiran archosaurs

Archosaurs are divided into two groups: Ornithodirans (birds and their extinct relatives) and Pseudosuchians (like crocodiles, alligators, and their extinct relatives).

small skeleton perched among larger skeletons
Skeleton of a pterosaur on display at the Rainbow Forest Museum



A single small, toothy lower jaw is all that informs us that these flying reptiles used to once live at Petrified Forest. Often confused with birds, pterosaurs are closely related to dinosaurs but are a part of their own distinct evolutionary lineage. Petrified Forest's representative was small, but later pterosaurs (150 million years younger than the ones from the park) could grow to be the size of a small airplane!

drawing of archosaur roughly size of great dane

NPS/Jeff Martz


Silesaurids are closely related to dinosaurs and existed alongside of them in the Late Triassic of what are now Arizona, New Mexico, and Poland. They generally had long necks and one species walked on all four of its limbs. Silesaurids are only known from a few fragmentary limb bones at Petrified Forest.

colorful drawing of dinosaur

NPS/Jeff Martz


Despite the Triassic being the "Dawn of the Dinosaurs," dinosaurs were outnumbered and outmatched by pseudosuchians during that period. The two dinosaurs from the park were small meat-eaters that probably just tried to stay out of the way of the huge phytosaurs and rauisuchids.

Coelophysis, an animal made famous by the large bone bed at Ghost Ranch, NM, is known from the park from the skeletons of a handful of individuals.

drawing of dinosaur in profile

NPS/Jeff Martz

Chindesaurus is represented by a partial skeleton and fragmentary fossils throughout the park.

The first Chindesaurus was discovered in Petrified Forest the 1980s and received a great deal of international media attention. Nicknamed "Gertie", the new species was billed at the time as the oldest dinosaur ever found on the planet.

fossil leg bone pieced back together
Leg bone of Chindesaurus


Last updated: May 3, 2016

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