Shielded Triassic Reptile is Newest of its Kind from Petrified Forest National Park

Scutarx deltatylus is a large reptile recently found in the park

Image by Jeffrey Martz (NPS)

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News Release Date: January 26, 2016

Contact: Bill Parker, (928) 524-6228 x262

Petrified Forest, AZ—Four skeletons collected by paleontologists at Petrified Forest National Park over the last decade reveal the presence of a new species of extinct reptile. The technical paper in which it is first described was recently published in the journal PeerJ, which is freely available online at

Scutarx deltatylus (SKOO-tarks del-tuh-TIE-lus) roamed what is now the American southwest between 217 and 220 million years ago during the Late Triassic Period. The remains of Scutarx are found in rocks of the Chinle Formation, which were deposited by a large river system during the Triassic.

The name Scutarx means “shield fortress” in Latin because one skeleton was found near a geographic feature at Petrified Forest called “the Sandcastle”. The species name ‘deltatylus’ means ‘triangle knob’ in Greek and describes a characteristic feature of the bony plates that covered the back of each animal in life. Scutarx belongs to an extinct group of reptiles called aetosaurs. Aetosaurs are distant relatives of crocodiles and alligators, but their leaf-shaped teeth suggest that they ate plants and insects. Seven species of aetosaurs are now known from the park, which demonstrates that these animals were common members of the Triassic fauna. Aetosaurs had a valuable role in the ecosystem as one of the only recognized groups of reptiles that ate plants during that time.

According to lead park paleontologist Dr. Bill Parker, “Scutarx is an important discovery because it shows how diverse and numerous Triassic reptiles were before the rise of the dinosaurs. Animals such as aetosaurs were dominant on the landscape, and it was not until their extinction at the end of the Triassic Period that the dinosaurs became the dominant terrestrial animals”.

This find also emphasizes the importance of National Parks as areas of significant scientific value where ongoing research contributes to the understanding of the evolution of life on Earth.

Last updated: January 29, 2016

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