What did the biggest land animals to ever live actually eat for dinner? For decades, scientists have pieced together clues from fossilized teeth and jawbones, trying to guess the menu of colossal, long-necked dinosaurs called sauropods—think Brontosaurus and Diplodocus. But now, for the first time ever, paleontologists have uncovered the actual last meal of one of these giants, and it’s revealing a surprising twist in their ancient eating habits. This unprecedented discovery isn’t just filling a gap in our knowledge; it’s rewriting what we thought we knew about how these titans survived and thrived for millions of years.
Unearthing an Ancient Lunchbox
The incredible find happened in 2017 in Queensland, Australia. Researchers were carefully digging up “Judy,” a subadult Diamantinasaurus matildae, a type of sauropod that lived about 94 to 101 million years ago. Even as a subadult, Judy was enormous, stretching at least 36 feet long. As they worked around where her stomach would have been, they hit a surprisingly hard layer of rock, packed with ancient plant fragments. This wasn’t just any rock; it was a fossilized stomach, or “cololite,” containing direct evidence of her last meal.
To be absolutely sure this was genuine gut content, the team put their discovery through a rigorous scientific checklist of 13 criteria. Judy’s stomach contents met 11 of them, a strong confirmation that this was indeed the real deal, unlike other less certain findings from different dinosaurs. They then used high-tech scanning like CT scans (similar to medical X-rays) and even neutron tomography to create detailed 3D images of the plant fossils without disturbing them. Chemical tests also helped identify the types of plants and even minerals, like brushite, which indicated the acidic, oxygen-free conditions inside the dinosaur’s gut that helped preserve this unique record.
A Surprising Mix on the Menu
What was on Judy’s plate? The most common items were pieces of conifers, like tiny leaves from an ancient type of pine or fir tree. This was consistent with some theories about sauropod diets, which often assumed they were high browsers, munching on tall trees.
But here’s where it gets interesting: the gut contents also contained angiosperms, which are simply flowering plants. Millions of years ago, flowering plants were relatively new and often smaller, lower-growing. Finding them in a sauropod’s stomach proposes that Diamantinasaurus wasn’t just reaching for the highest branches; it was also bending down to eat these newer, smaller plants. The meal also included bits of ancient seed ferns.
This combination of tall conifers and low-growing flowering plants indicates that Diamantinasaurus was a “mixed-level browser.” This challenges older ideas about sauropod diets, which were often based on their teeth and jaw shapes. Previously, scientists thought a dinosaur like Diamantinasaurus, with its broad snout, mainly ate higher-level foliage. This discovery provides direct proof that its diet was far more varied than its anatomy alone would suggest.
The plant pieces themselves offered more clues. Many were small, some just half an inch, with larger leaves no thicker than a millimeter. There were no big branches, and many pieces looked frayed or crushed, but still identifiable. This evidence points to sauropods practicing “minimal oral processing”—they didn’t chew their food much, if at all. Instead, they likely swallowed massive amounts of plant matter quickly, relying on their huge digestive systems and the microbes within to break down the tough plant fibers. This “bulk feeding” approach, simply gulping down whatever was available, was clearly a highly successful strategy for these giants.
Why This Matters: The Key to Dino Success
This single, invaluable fossil provides an extraordinary window into the daily life of a sauropod. It confirms that these dinosaurs were indeed plant-eaters, solidifying a long-held belief. More significantly, it shows that Diamantinasaurus—and quite possibly other sauropods—were incredibly adaptable eaters. They weren’t picky, sticking to just one type of plant or feeding at a specific height. This flexibility would have been a huge advantage in a world where plant life was constantly evolving. As new groups like flowering plants emerged, a flexible diet would have allowed sauropods to adapt and exploit various food sources, making them more resilient to environmental changes.
The fact that this was a subadult Diamantinasaurus is also noteworthy. It’s thought that sauropods might have changed their diets as they grew. Younger, smaller dinosaurs would have eaten lower-growing plants, but as they got bigger, their feeding range would have expanded. This fossil seems to capture that transition, with a subadult already demonstrating a varied diet.
This discovery also sheds light on why sauropod stomach contents have been so rare. The fast digestion by gut microbes, combined with decay and the harsh process of fossilization, meant that stomach contents rarely survived. The exceptional preservation of this Diamantinasaurus, including its fossilized skin alongside its gut contents, suggests unique conditions immediately after its death allowed for this unprecedented fossilization. The ability to consume a wide range of plants, coupled with a bulk-feeding strategy that maximized nutrient intake without extensive chewing, proved to be a winning formula for sauropods, contributing to their remarkable success and dominance for over 130 million years.
Paper Summary
Methodology
The study analyzed fossilized gut contents from a subadult Diamantinasaurus matildae specimen (AODF 0888) found in the Winton Formation, Queensland, Australia (94-101 million years ago). The distinct, indurated layer containing plant fossils was confirmed as genuine gut content by meeting 11 of 13 established scientific criteria. Analysis involved advanced imaging techniques (CT scans, neutron tomography) and chemical analyses (XRD, TIMA, GC-MS, GCxGC-TOFMS) to identify plant types, mineral composition, and organic biomarkers.
Results
The gut contents revealed a diverse diet of conifers (Austrosequoia wintonensis, Araucaria), seed ferns (Carnoconites spp.), and angiosperms (flowering plants). This indicates the sauropod was an indiscriminate, bulk feeder engaging in “mixed-level Browse,” consuming plants from both higher and lower levels. Plant fragments were small, showed minimal chewing, and their preservation suggested an acidic, oxygen-deprived gut environment.
Limitations
This study is based on a single subadult sauropod specimen, providing only a snapshot of its last meal(s). Therefore, it is unknown if this represents a typical diet, the diet of a stressed animal, or how diet might have varied with age (juvenile vs. adult) or seasonality. Two of the 13 identification criteria (presence of gastroliths, prey animal bones) were not met, and one (palynomorphs) was unknowable.
Funding and Disclosures
The research received funding from the Australian Research Council, including an ARC Laureate Fellowship (FL210100103) and ARC Infrastructure Grants (LE190100053, LP0991658, LE130100145). Access to the Australian Synchrotron and the Dingo thermal-neutron imaging instrument was via merit-access grants.
Publication Information
The paper, titled “Fossilized gut contents elucidate the feeding habits of sauropod dinosaurs,” was authored by Stephen F. Poropat et al. It was published on June 9, 2025, in Current Biology, Volume 35, pages 2597-2613. The DOI is https://doi.org/10.1016/j.cub.2025.04.053.