An innovative computer model of sauropod dinosaur feet reveals for the first time that a cushioned pad at the back of the heel was essential to the animals’ ability to carry their massive weight. For the sauropods to become the biggest creatures ever to walk the planet, they likely needed to evolve soft heel pads early in their development. These dinosaurs could weigh up to 50 tons and controlled global ecosystems for roughly 100 million years.
This week, the research was published in Science Advances. As the name implies, these reptiles roar and stomp when threatened. The massive size of certain sauropod species is one of the features that stand out the most; the ground would have trembled under the dinosaurs’ feet as they moved.
The name Brontosaurus, given to one of the earliest documented sauropods, was chosen because of the resemblance it bore to a thunder lizard. The sauropods weren’t always enormous despite their lengthy necks, tails, and pillar-like legs. A relative of the saurischian theropods, these dinosaurs likely wouldn’t have weighed greater than an ostrich and walked on two legs. They evolved about 230 million years ago.
However, beginning approximately 210 Ma, sauropod relatives began to grow in size, eventually nearing 1 ton in body mass. The greatest sauropods, which included Argentinosaurus, Patagotitan, and Australotitan, likely weighed more over 50 tons as adults. This is 10 times as much as the African elephant, which is the largest land mammal alive today. The feet of such massive creatures would have to be enormous. The Kimberley area of Western Australia is home to some enormous sauropod footprints, measuring more than 1.7 meters in length.
What, exactly, were the feet of sauropods look like, and how did they manage to hold their owners’ massive adult weight? The forefeet resemble those of elephants in that the bones are placed in a nearly vertical, semicircular column; however, the bones of the fingers, with the exception of the thumb, are much smaller. Sauropod “hand” prints are often spherical or “bean-shaped” in appearance.
Even while sauropods are often shown with a columnar body, their feet were really much different from those of elephants. The pliability of the bones of a sauropod’s toes suggests that it possessed long, dexterous toes. Their fossilized footprints demonstrate that they had the ability to expand their toes, changing the splay of their foot as they walked over varied terrain.
It has been widely believed that sauropods, like other dinosaurs, moved on their toes, with the ankle joint raised slightly off the ground. However, a big “heel” imprint may be seen in several sauropod footprints. The discovery of these pads has prompted many paleontologists to hypothesize that sauropods may have had a heel pad of some kind. But until now, the only real proof that sauropods had a heel pad was speculative based on their footprints.
