Strong tail muscles are the reason why proto-dinosaur ancestors became bipedal and this bipedalism was inherited by dinosaurs over the course of millions of years, says a new study by scientists in Canada.
University of Alberta scientists have revealed through their study published in Journal of Theoretical Biology that dinosaurs didn’t just start walking on their two back feet overnight, but it was strong tails of their proto-dinosaur ancestors that played a huge role in enabling the dinosaurs stand on their two feet and move about. This is by far one of the most plausible explanations behind the bipedalism of dinosaurs.
There have been studies previously that have suggested that the need to catch prey was one of the reasons why dinosaurs became bipedal, but that’s not the case say Scott Persons, postdoctoral fellow and lead author on the paper, and Phil Currie, renowned paleontologist and Canada Research Chair.
According to the scientists dinosaurs inherited this trait from smaller proto-dinosaurs having big, leg-powering muscles and it was because of these muscles that the proto-dinosaurs garnered the strength and power required to stand up on their two back feet and move about.
With passing generations and time, proto-dinosaurs evolved to a point that not only they started walking completely on their two back feet, but also started running and that too for longer distances. Adaptations like hind limb elongation allowed ancient dinosaurs to run faster, while smaller forelimbs helped to reduce body weight and improve balance. Eventually, some proto-dinosaurs gave up quadrupedal walking altogether, the scientists note.
Another point that the two researchers mention is the theory wherein it was suggested that early proto-dinosaurs stood on two legs for the sole purpose of free their hands for use in catching prey. The team says that the explanation doesn’t hold up because there are quite a few examples of herbivore dinosaurs that were bipedal. Further, quite a few early carnivore dinosaurs also evolved small forearms and instead of using their hands to grapple their prey, the dinosaurs relied on seizing their meals using their powerful jaws.
The duo also offers an explanation as to why modern day mammals like horse and cheetah that can run faster aren’t bipedal. The researchers explain that modern day mammals do not have the big tail-based leg muscles that would enable them to stand up and move about on their two back feet. They add that fossil records indicate that proto-mammal ancestors lost their tail muscles over 252 million years ago and one of the reasons could be that these animals at the time were adapting to dig and to live in burrows. In order to dig, mammals had strong front limbs. Muscular back legs and tails likely made it more difficult to maneuver in the narrow confines of a burrow.