A sauropod dinosaur fossil has been found with preserved stomach contents for the first time, providing insights into what they ate and how

An artist’s impression of Diamantinasaurus matildae, a sauropod dinosaur that lived about 94 million years ago Travis Tischler

The fossilised gut contents of a sauropod dinosaur have been studied for the first time, revealing that the largest land animals that have ever lived were herbivores that barely chewed their food.

A fossil nicknamed Judy, from the species Diamantinasaurus matildae, was excavated near Winton in Queensland, Australia, in May 2017.

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Judy’s remains had been disturbed by scavengers shortly after death, sometime between 94 million and 101 million years ago, but large parts of the dinosaur’s body were intact, including mineralised sections of its skin. Most remarkably, its gut contents were preserved, containing an array of vegetation.

Until now, it was assumed from the skulls and jaws of sauropods that they were vegetarians, but palaeontologists had no direct evidence of what was in their diet.

“It’s hard not to view Judy with a sense of awe that you maybe don’t get with other sauropods,” says Stephen Poropat of Curtin University in Perth, Australia, part of the team that excavated and analysed the fossil.

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Measuring around 11 metres long, with a 4-metre neck and a 3.3-metre tail, Judy was probably not yet fully grown when she died. Her skin and gut contents will go on display at the Australian Age of Dinosaurs Museum in Winton on 9 June.

“You can really get a sense of Judy’s overall size and the shape of the whole animal, which is something that just hasn’t been possible with previous sauropod fossils in Australia because none of them are anywhere near as complete as Judy is,” says Poropat.

The dinosaur’s belly was “chock-full” of vegetation, he says. “The plants were all inside the skin and within the body cavity and we were confident we had the possible gut contents of this animal. We knew we possibly had a world-first.”

The fossilised gut contents of Judy, including leaves Stephen Poropat

Among this material, the team identified leaves and fruiting bodies from conifers including Araucaria and Austrosequoia wintonensis, as well as leaves from unidentified flowering plants. While the vegetation appeared sheared, it was unchewed and of such a wide range that the team members think Judy was an indiscriminate bulk feeder.

“There’s no mastication happening in the mouth at all,” says Poropat. “It’s just simple snip and swallow.”

With such a vast array of unchewed vegetation in Judy’s abdominal cavity, it is likely that sauropods would have emitted large amounts of methane, as elephants and rhinos do, he adds.

“It’s always nice to find actual evidence of what extinct creatures, like gigantic dinosaurs, were eating,” says John Long at Flinders University in Adelaide, Australia, who was not involved in the study. “If we only had skulls of panda bears, we would assume they ate what other bears ate – not just bamboo.”

“Up until now, we have only speculated that these giants ate plants. Now we know, not only did they eat plants but ate a variety of species from both the ground and from the branches of trees,” says Long.