

An artist's impression of Bunostegos akokanensis. Image Credit: CC BY-SA 4.0 DiBgd

A prehistoric reptile the size of a cow may have been the first to ever stand upright on four limbs.

260 million years ago, during what is known as the Permian era, ground-dwelling reptiles tended to 'sprawl' on the ground like modern lizards and used their legs to haul themselves along.There was however one species that appeared to defy this behavior - a cow-sized reptile known as Bunostegos akokanensis which may have also been the first to evolve the ability to stand upright.Unlike that of its sprawling cousins, this four-legged beast possessed forelimb shoulder joints that faced downwards like those of later quadrupeds - enabling it to stand and walk on all four legs."The elements and features within the forelimb bones won’t allow a sprawling posture. That’s unique," said study co-author Morgan Turner of Brown University. "There are many complexities about the evolution of posture and locomotion we are working to better understand every day.""The anatomy of Bunostegos is unexpected, illuminating and tells us we still have much to learn."