Researchers from the University of Bristol and London's Natural History Museum now have an idea how dinosaurs managed to co-exist with each other, and the clue is in how they ate.
Large, long-necked, herbivorous dinosaurs called sauropods dominated the earth about 65 to 210 million years ago. There were different sauropods during that era and the biggest were the Brachiosaurus and Diplodocus. As the largest of land animals that ever lived, these dinosaurs weighed the equivalent of over 11 elephants or 80 tons. Because of their size, they would have required a lot of food to survive.
Still, there was no competition within sauropods. This struck researchers as odd because these massive creatures should have been competing with each other for resources.
To unravel the mystery, David Button and colleagues turned to a novel combo of approaches. They found out that while sauropods were massive in size, they had relatively small heads. Focusing on the jaws and skulls of saurpods, researchers used biomechanical means to see how these parts of the head functioned and how they could have affected ecology during the Jurassic era.
With the help of CT scans, sauropod skulls were reconstructed, including neck and jaw muscles from the Diplodocus and Camarasaurus. These species were chosen because they were common during the Late Jurassic Morrison Formation. These species have been known as well to co-exist.
A biomechanical model of the Camarasaurus skull was created using the Finite Element Analysis modeling technique. Once the skull was made, it was compared to an existing model of a Diplodocus skull to determine the eating habits of dinosaurs.
"Our results show that although neither could chew, the skulls of both dinosaurs were sophisticated cropping tools," explained Button, a Ph.D. student from the university and the museum.
The strong bite and robust skull of the Camarasaurus would have allowed it to eat tougher branches and leaves. The weaker bite and more fragile skull of the Diplodocus, on the other hand, would have restricted the dinosaur's diet to softer plants like ferns. Because the two dinosaurs have different diets, they were able to co-exist.
Co-author Emily Rayfield, professor at the University of Bristol, adds that dietary niche partitioning, as dietary differences in an animal community are called, allows species similar to each other to reduce competition and co-exist. While researchers suspected dietary niche partitioning was the reason from the very beginning, this was the first time that strong, biomechanical evidence was provided.
Published in the Proceedings of the Royal Society B, the research received funding support from the Natural Environment Research Council.
