Direct evidence of the diet of a large herbivorous dinosaur that lived in present-day Australia 100 million years ago has been found in its intestines. Until now, it was assumed that it was herbivorous based on its dental structure and anatomical features, but this is the first time its actual diet has been confirmed.
A research team from Curtin University in Australia announced on the 10th that they discovered plant fossils in the stomach contents of the sauropod dinosaur "Diamantinasaurus matildae," marking the first such find in the world. The research results were published in the international journal "Current Biology" that day.
Diamantinasaurus was a dinosaur that lived during the mid-Cretaceous period approximately 94 to 101 million years ago. Like other sauropod dinosaurs, including Brachiosaurus, it had a long neck, long tail, and giant body. Until now, experts have assumed that most sauropods were herbivorous based on their dental shape, jaw structure, and neck length, but there had been no direct confirmation of this.
The research team analyzed the skeleton of a Diamantinasaurus named "Judy," which was excavated from the Winton Formation in Queensland, Australia, in 2017. Although Judy's skeleton was found scattered due to being eaten by other animals at the time, undigested intestinal contents were fully preserved near the pelvis.
The fossils found in the dinosaur's stomach included leaves and seed pods from conifers, ferns, and flowering angiosperms. This suggests that Diamantinasaurus was more of a glutton that consumed whatever plants were readily available rather than selectively feeding on specific plants. It supports the hypothesis that sauropod dinosaurs were indeed herbivorous and consumed a variety of plants in large quantities.
Stephen Poropat, a researcher at Curtin University who led the study, noted, "The fact that the plants were found not chewed but cleanly cut indicates that this dinosaur swallowed food with little chewing." He explained that digestion likely relied mostly on gut microorganisms and fermentation.
In particular, traces of angiosperms were also found in the dinosaur's intestinal contents. Angiosperms began to spread in Australia about 100 million years ago, and the fact that dinosaurs consumed them indicates that their diet habits changed in line with evolution. It was previously thought that the diet of herbivorous dinosaurs consisted mainly of ferns and gymnosperms like cycads.
The research team speculated that dinosaurs consumed plants close to the ground during their juveniles and, as they grew, began to eat plants from higher up. The analyzed dinosaur was still not fully grown. Evidence was also found that younger dinosaurs primarily consumed tender shoots and seed pods of easier-to-digest plants.
However, researcher Poropat said, "While the stomach contents of Diamantinasaurus provide crucial clues to understanding the role of sauropod dinosaurs in their ecosystem and their evolutionary strategies, one dinosaur's last meal cannot represent the diet of all sauropods. Seasonal factors and health conditions may have influenced their diets as well."
References
Current Biology (2025), DOI: https://doi.org/10.1016/j.cub.2025.04.053