Studies reveal that some dinosaurs were picky eaters. A study of a 150-million-year-old dinosaur tooth challenges long-standing assumptions about their diet. For example, certain herbivorous dinosaurs preferred specific parts of a plant. Analysis of calcium isotopes in tooth enamel indicates that food habits depended less on the size of the dinosaurs, but more on the texture and nutritional value of their food.
“My big takeaway is that the herbivores had different diets, and it is likely that the parts of a plant that these animals eat [are] a more significant driver than height,” says Liam Norris, a paleontologist at the Texas Science & Natural History Museum in Austin. “So, if they are eating softer parts like leaves versus eating twigs or maybe bark, that looks like it is more significant.”
Norris and his colleagues compared the calcium isotope levels in dinosaur enamel with those of modern herbivores’ tooth enamel. The team inferred that the gigantic sauropod Camarasaurus mainly ate more woody plants and twigs from treetops, while the smaller, beaked Camptosaurus preferred softer plant parts like leaves and buds.
According to dinosaur expert Paul Barrett of the Natural History Museum in London, this study will be helpful in cases where the dinosaur diets are a bit ambiguous and the knowledge about their diets is fuzzy.
Norris and his team also estimated the calcium isotope levels in the teeth of carnivorous dinosaurs and compared them to those of two modern ones. The team’s observations suggest that the crocodile-like Eutretauranosuchus mainly ate fish, and the ferocious theropod Allosaurus dined mostly on the flesh of other dinosaurs; however, they didn’t eat the bones, unlike the later theropod Tyrannosaurus rex.
The researchers gathered some of their samples from Carnegie Quarry, a part of the Morrison Formation and a famous fossil site in Utah’s National Monument. Norris and colleagues sampled directly from the quarry wall, although some of the teeth were already removed for research. Carnegie Quarry is believed to be an oxbow lake or a riverbed where dinosaur bones piled up.
Although the deduction of diet from calcium isotope measurement is quite common, this is the first time the method has been used on a sample of such great age. This makes this experiment special and unique.
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