Scientists claim to have shed some light on how different species of dinosaurs co-existed in harsh prehistoric ecosystems.
Large, long-necked plant-eating dinosaurs such as Diplodocus and Brachiosaurus dominated the land between 210 million and 65 million years ago and would have required vast amounts of food.
These sauropods were the largest land animals of all time, with the biggest weighing 80 tonnes - more than 11 elephants.
Researchers from the University of Bristol and the Natural History Museum in London believe that multiple sauropod species survived in the same habitats because of their different diets.
The Late Jurassic Morrison Formation - a distinctive sequence of sedimentary rock in the western United States - contained more than ten species of sauropod, whereas the highly diverse faunas seen in modern Africa only support one gigantic species, the elephant.
Experts studied a digital reconstruction of the skulls, jaws and neck muscles of the sauropods Camarasaurus and Diplodocus to investigate how they fed.
David Button, a PhD student at Bristol's School of Earth Sciences, said: "Our results show that although neither could chew, the skulls of both dinosaurs were sophisticated cropping tools.
"Camarasaurus had a robust skull and strong bite, which would have allowed it to feed on tough leaves and branches.
"Meanwhile, the weaker bite and more delicate skull of Diplodocus would have restricted it to softer foods like ferns.
"However, Diplodocus could also have used its strong neck muscles to help it detach plant material through movements of the head. This indicates differences in diet between the two dinosaurs, which would have allowed them to co-exist."
The researchers also used a series of biomechanical measurements from other sauropod species to calculate the functional disparity in their skulls and jaws. They found that other Morrison Formation sauropods were also highly varied in feeding adaptations, which suggests they had different diets.
Professor Emily Rayfield of the University of Bristol, co-author of the report, said: "In modern animal communities differences in diet such as this - termed dietary niche partitioning - allow multiple similar species to co-exist by reducing competition for food.
"Although dietary niche partitioning has been suspected between Morrison Formation sauropods based on their structural features and patterns of tooth-wear, this is the first study to provide strong, numerical, biomechanical evidence for its presence in this fossil community."
Co-author Professor Paul Barrett of the Natural History Museum said: "Our study provides insight not only into the ecology of dinosaurs but more generally into the mechanisms supporting species-richness in other animal communities, both from the fossil record and in the present day."
