First Fossil Evidence That Sauropods Were Herbivores Supports a Widespread Assumption About the Long-Necked Dinosaurs
A recent discovery of a dinosaur’s preserved gut contents offers the first direct proof that sauropods were plant-eaters
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Since the late 1800s, experts have thought that the long-necked dinosaurs known as sauropods were herbivores. Given the flat shape of their small teeth and the giant size of their bodies—which were not equipped to chase around prey and would have required them to eat often—researchers assumed sauropods browsed from trees and other greenery.
But now, paleontologists have the first direct evidence of the dinosaurs’ diets, thanks to a layer of plant that survived in a fossil’s gut for at least 94 million years.
The gut contents—called cololites—were found inside the remains of a 36-foot-long juvenile Diamantinasaurus matildae. The fossil was unearthed by Stephen Poropat, a paleontologist at Curtin University in Australia, and his colleagues at the Winton Formation in Queensland in 2017. Much of the dinosaur’s body was well-preserved, and a layer of fossilized skin was still intact. They nicknamed the remains Judy after Judy Elliott, the co-founder of the Australian Age of Dinosaurs Museum.
“It’s the smoking gun, or the steaming guts, as it were—the actual direct evidence in the belly of the beast,” says Poropat to Kate Golembiewski at the New York Times. “It’s never been found before for a sauropod dinosaur.”
An analysis of Judy’s skeleton identified the preserved plants and showed that the dinosaur ate from conifers, flowering plants and extinct seed ferns. The vegetation was also mostly unchewed, which suggests Judy’s gut microbes did most of the work of digesting meals. The findings were published in the journal Current Biology on Monday.
“The tricky part here was proving the plant material wasn’t just random debris, and here the authors make a strong case, especially with evidence of the plants being sealed inside mineralized skin,” explains Martin Qvarnström, a paleontologist at Uppsala University in Sweden who was not involved in the work, to Peter de Kruijff at the Australian Broadcasting Corporation. The researchers also didn’t find many plants elsewhere near the site, Poropat tells the New York Times, which further cemented the idea that the vegetation had fossilized inside the dinosaur.
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Being a juvenile, Judy likely had a diet different from an adult Diamantinasaurus. An adult of the genus would have measured close to 50 feet long, and it would have been able to reach higher tree branches than Judy could. The study thus reveals a “moment in time” for the dinosaur during which Judy had some characteristics of both adults and juveniles, says Cary Woodruff, a paleontologist at the Frost Museum of Science who was not involved in the work, to the Australian Broadcasting Corporation.
“Previous studies have shown that in some species, the young had pointed snouts, likely for selective feeding, and when they grew up, they had broad ‘muzzles’ for grazing,” Woodruff explains. “And in some, the young had teeth designed for both soft and coarse vegetation.”
“It’s always nice to find actual evidence of what extinct creatures, like gigantic dinosaurs, were eating,” says John Long, a paleontologist at Flinders University in Australia who was not involved in the study, to James Woodford at New Scientist. “If we only had skulls of panda bears, we would assume they ate what other bears ate—not just bamboo.”
Judy is now on display at the Australian Age of Dinosaurs Museum in Winton, Queensland, so if you find yourself in the area, you can take a look at the sauropod’s last meal for yourself.
