Clues for Dinosaurs’ Diets Discovered within the Chemistry of Their Fossil Tooth | Jackson School of Geosciences

July 24, 2025

You are what you eat, it seems — even when your final meal was 150 million years in the past.

While the grub itself could also be lengthy gone, a file of dinosaurs’ favourite meals has been stowed away of their historical tooth enamel during the last eon. When researchers at The University of Texas at Austin took an in depth look, they found that some dinosaurs had been discerning eaters, with completely different species preferring completely different plant elements.

Tooth enamel accommodates calcium isotopes that replicate the vary of meals the dinosaurs ate; several types of crops have completely different chemical signatures, and discrete elements of bushes — from buds to bark — can even have distinctive signatures. According to the research’s lead writer Liam Norris, the outcomes assist clarify how so many behemoth creatures all lived collectively in the identical space on the identical time.

“The ecosystem that I studied has been a mystery for a long time because it has these giant herbivores all coexisting,” mentioned Norris, a latest doctoral graduate at UT’s Jackson School of Geosciences. “The idea is that they were all eating different things, and now we have found proof of that.”

The findings had been printed in Palaeogeography, Palaeoclimatology, Palaeoecology.

Norris inspected enamel from 4 dinosaur species and one crocodyliform, each herbivores and carnivores, that roamed the Western U.S. through the Late Jurassic. The plant-eaters are the long-necked Camarasaurus; the short-armed Camptosaurus; and the trunk-legged Diplodocus. The meat-eaters are the bipedal Allosaurus and the comparatively small, crocodile-like Eutretauranosuchus. The bones and enamel of those historical creatures had been all discovered within the Carnegie Quarry deposit in northeast Utah, which is believed to have shaped throughout an excessive drought in as little as six months to some thousand years.

“We were very lucky to be able to study fossils of dinosaurs that lived together and were all rapidly preserved in a single deposit,” mentioned Rowan Martindale, an affiliate professor on the Jackson School’s Department of Earth and Planetary Sciences. “The Jurassic tomb preserved a unique paleontological gem and these skeletons are beautifully displayed at Dinosaur National Monument.”

Norris, who now works on the Texas Science & Natural History Museum, studied enamel from 17 particular person animals throughout these 5 species. The specimens had been loaned by the Utah Field House of Natural History State Park Museum or accessed within the area at Dinosaur National Monument. He shaved off a dusting of their enamel, which he took again to the Jackson School for calcium isotope evaluation. Jackson School Professor John Lassiter and Radiogenic Isotope Laboratory Manager Aaron Satkoski, each co-authors on the paper, helped to research and interpret these information.

Previously, scientists believed that enormous herbivorous dinosaurs coexisted by munching on completely different ranges of the tree cover based on peak. However, Norris’s analysis reveals that plant peak wasn’t the one issue driving the differentiation of their diets — as an alternative, it was particular plant elements.

For instance, Norris discovered that the Camptosaurus was a somewhat discerning eater, preferring softer, extra nutritious plant elements resembling leaves and buds. The Camarasaurus ate largely conifers, with a desire for woody plant tissues. The Diplodocus ate extra of a blended food plan that included smooth ferns and horsetail crops decrease to the bottom, in addition to harder plant elements.

“This differentiation in diet makes sense with what we see from the morphology of these animals: the different height, the different snout shape. Then, we bring in this geochemical data, which is a very concrete piece of evidence to add to that pot,” Norris mentioned.

This analysis additionally supplies fascinating meals for thought to a concept about long-necked dinosaurs having versatile necks that could possibly be used to succeed in many areas of vegetation with out having to expend the vitality to maneuver the remainder of their physique. This analysis, which reveals that the dinosaurs ate from completely different ranges of the tree cover, furthers that line of considering.

The carnivores within the research — the Allosaurus and Eutretauranosuchus — had an overlap in calcium isotope values, which might imply that they ate a few of the identical issues. However, the outcomes additionally confirmed that the Eutretauranosuchus is extra more likely to have eaten fish, whereas the Allosaurus primarily ate herbivorous dinosaurs — presumably together with the three different dinosaur species talked about on this research.

For this historical ecosystem to have supported so many huge dinosaurs with such particular dietary proclivities helps to color an image of the vegetation and plant productiveness of the time.

“It’s really just more proof that this ecosystem was as spectacular as we thought it was,” Norris mentioned.

Henry Fricke of Colorado College additionally co-authored the research.