As an Amazon Associate I earn from qualifying purchases.
Fossils from the Chinle Formation of Petrified Forest National Park in Arizona, the United States, expose that Sonselasuchus cedrusa types of shuvosaurid that lived about 215 million years back (Triassic duration), most likely started life strolling on 4 legs before moving to a bipedal position as it grew.
An artist’s restoration of Sonselasuchus cedrus in its environment in what is now Petrified Forest National Park, 215 million years earlier. Image credit: Gabriel Ugueto.
Sonselasuchus cedrus was a kind of Shuvosauridae, a little group of pseudosuchian archosaurs identified by a body strategy noticeably convergent with that of ornithomimid theropod dinosaurs.
The animal had to do with 63.5 cm (25 inches) high, had a toothless beak, a big eye socket and hollow bones.
“Although comparable to the ornithomimid dinosaurs these functions would have developed individually, and this resemblance was most likely due to the reality that croc-line and bird-line archosaurs progressed in the exact same communities and assembled upon comparable environmental functions,” stated Elliott Armour Smith, a scientist at the University of Washington.
“Also, regardless of the truth that functions like bipedalism, a toothless beak, hollow bones and a big orbit are particular of ornithomimid theropod dinosaurs, shuvosaurids like Sonselasuchus program that these functions progressed on the croc-line too.”
Sonselasuchus cedrus is represented by over 950 fossil specimens from a minimum of 36 people.
“By examining the percentages of the limb skeletons of various animals, we identified its bipedal position might have been the outcome of a differential development pattern,” Armour Smith stated.
“We believe that Sonselasuchus cedrus had more proportional forelimbs and hindlimbs as young, and their hindlimb grew longer and more robust through their adult years.”
“Essentially, we believe these animals started their lives on 4 legs … they then began strolling on 2 legs as they matured. This is especially strange.”
Sonselasuchus cedrus would have resided in the forest, and its particular name cedrus represents the cedar tree, an evergreen conifer comparable to those of Late Triassic forests.
“Since beginning fieldwork at Petrified Forest in 2014, we have actually gathered over 3,000 fossils from the Sonselasuchus bonebed, and it does not appear to reveal any indications of abating,” stated University of Washington’s Professor Christian Sidor.
“In addition to Sonselasuchusthe bonebed has actually yielded fossils of fish, amphibians, in addition to dinosaurs and other reptiles.”
The discovery is explained in a paper in the Journal of Vertebrate Paleontology
_____
Elliott Armour Smith & & Christian A. Sidor. 2026. Osteology and relationships of a brand-new shuvosaurid (Pseudosuchia, Poposauroidea) from the Upper Triassic Chinle Formation of Petrified Forest National Park, Arizona, U.S.A. Journal of Vertebrate Paleontologyreleased online march 8, 2026; doi: 10.1080/ 02724634.2025.2604859
Learn more
As an Amazon Associate I earn from qualifying purchases.
