First Pre-Reptile to Walk on Four Legs Discovered

Well, either this or at least it’s the oldest creature known to walk upright on all its fours limbs thus far documented by science, specialists explain in their report in the Journal of Vertebrate Paleontology.

A study that looked at the bones of a prereptile known as Bunostegos akokanensis, which lived about 260 million years ago, revealed that it may have stood upright on all fours. According to a news release, scientists previously thought that all Permian herbivores had a sprawling body type – where their limbs would extend from the sides of their body and slant downward from their elbows, similar to some modern lizards. The researchers found that the hip joint in the hind limbs and the bones that make up the forelimbs had features seen only in upright animals.

“Imagine a cow-sized, plant-consuming reptile with a knobby cranium and bony armour down its again”, stated research co-writer Linda Tsuji of the Royal Ontario Museum in Canada who found the fossils in Niger together with a staff of paleontologists in 2003 and 2006. “The more we learn about this creature, the more we will learn about what appears to be an isolated environment in the center of Pangea”, commented Dr. Nick Fraser, a vertebrate paleontologist from the National Museum of Scotland. “But what’s interesting and special about Bunostegos is the forelimb, in that its anatomy is sprawling-precluding and seemingly directed underneath its body – unlike anything else at the time”. The answers lie in the pre-reptiles’ shoulder joint, humerus, elbow and ulna. “All the four-legged land animals that lived at the time have been shown to be sprawlers, with the legs coming out of the side of the body”, she said.

“Sprawling” posture describes the way lizards’ legs come out of their bodies – horizontally in the upper part of the limb, and vertically from the joint down to the ground.

Instead, the researchers believe the disgusting creature stood like a cow, and was about the same size. Additionally, Bunostegos akokanensis’ elbow movements were limited.

Bunostegos is a 260-million-year-old pre-reptile that roamed the supercontinent Pangea munching on plants.

Finally, the forearm is longer than the humerus in Bunostegos, which is a common trait among non-sprawlers, Turner said.

The significance of such an early instance of the upright posture is that Bunostegos dates very far again on the evolutionary tree, pushing again the clock on when this posture exhibits up in evolution.

According to the lead author of the study, it would not be a surprise if scientists eventually find peers of Bunostegos with straight posture, since for the long walks after meals the upright posture might have been necessary for survival. “There are many complexities about the evolution of the posture and locomotion we are working to better understand every day”.