Scientists have discovered an ancient relative of crocodiles that walked on two legs

The study was published in the Journal of Vertebrate Paleontology.

The new species was named Sonselasuchus cedrus. Its remains were found in the Petrified Forest National Park in Arizona (USA).

Details

Paleontologists studied hundreds of bones found at the excavation site. In total, the researchers found about 950 fossils related to this animal.

Scientists estimate that an adult Sonselasuchus was about the size of a poodle - about 60 centimetres tall.

Analyses of the skeleton revealed an unusual feature. In young individuals, the front and hind limbs were about the same length, so they travelled on four legs.

However, as they grew, the hind limbs became longer and stronger. As a result, adult animals could walk on two legs.

What it means

According to the researchers, the find helps to better understand the evolution of ancient reptiles.

Despite the similarities to some dinosaurs, this species belongs to the line of ancient relatives of crocodiles. This means that features such as:

• bipedal locomotion
• beak without teeth
• hollow bones

could have appeared independently in different groups of ancient animals.

Scientists believe this is an example of convergent evolution, where similar traits develop in different species living in similar environments.

Background

Sonselasuchus belonged to the Shuvosauridae, a group of ancient archosaurs that lived during the age of the dinosaurs about 225-201 million years ago.

At the excavation site, scientists found not only the bones of this animal, but also the remains of fish, amphibians, dinosaurs and other ancient reptiles.

Source

Osteology and relationships of a new shuvosaurid (Pseudosuchia, Poposauroidea) from the Upper Triassic Chinle Formation of Petrified Forest National Park, Arizona, U.S.A., Journal of Vertebrate Paleontology(2026).