Cow-sized 'pre-reptile' may have been first creature to stand upright on all fours

A cow-sized "pre-reptile" that lived 260 million years ago could have been the first creature to stand upright on all fours, scientists have revealed.

Fossil bones belonging to Bunostegos akokanensis show it did not "sprawl" like other animals alive during the Permian era and modern lizards.

Standing upright would have allowed it to save energy and make longer journeys between meals.

The bones of several of the animals were found in Niger, which was an arid region 260 million years ago.

Describing the creature, Dr Linda Tsuji, from the Royal Ontario Museum in Canada, who helped uncover the fossils, said: "Imagine a cow-sized, plant-eating reptile with a knobby skull and bony armour down its back."

The findings, published in the Journal of Vertebrate Paleontology, showed that the creature's forelimb shoulder joint was facing down, so that its humerus - the bone running to the elbow - would have been positioned vertically beneath.

Co-author Morgan Turner, from Brown University in the US, said: "The elements and features within the forelimb bones won't allow a sprawling posture. That's unique.

"The anatomy of Bunostegos is unexpected, illuminating and tells us we still have much to learn."