For over a century, sauropod dinosaurs such as Brontosaurus and Brachiosaurus have been predominantly classified as herbivores. Yet, the lack of concrete evidence to support this classification, particularly in the form of fossilized gut contents, has persisted until recently. A remarkable discovery made by a team of palaeontologists during a dinosaur dig in the outback of Queensland, Australia, has now changed that.
The specimen, affectionately named “Judy,” represents an incredibly well-preserved sauropod with fossilized remains of its last meal still found within its abdomen. In a groundbreaking new paper published in Current Biology, researchers reveal key insights from Judy’s remarkable condition, making her not only the most complete sauropod ever found in Australia but also the first to exhibit fossilized skin.
Sauropods, the colossal land-dwelling creatures that roamed the Earth during the Jurassic and Cretaceous periods, had a reign spanning roughly 130 million years. They joined a long list of species that went extinct during the mass extinction event at the end of the Cretaceous, about 66 million years ago. Since the unearthing of the first complete sauropod skeletons in the 1870s, the understanding that these giants were primarily plant-eaters has rarely been questioned.
The anatomical features of sauropods make their herbivorous diet believable. With teeth ill-suited for tearing flesh or crushing bone and a body structure that precluded any form of predatory behavior, it’s logical that they primarily consumed plants. Furthermore, to maintain their immense size, sauropods would have required a continuous and abundant supply of vegetation.
Despite having a uniform appearance characterized by sturdy bodies, long necks, and four sturdy legs, sauropods did exhibit variations that suggest a diverse feeding strategy. Different species displayed various snout shapes, tooth structures, neck lengths, and even differences in shoulder and hip heights. Such diversity would have shaped their feeding habits, allowing them to reach different types of vegetation.
The discovery of Judy, aided by the Australian Age of Dinosaurs Museum in Winton, underscores the increasing frequency of significant sauropod finds in the region. In 2017, this team, which included the author of the current study, unearthed Judy’s nearly 95-million-year-old remains. Upon examination, they discovered a remarkable feature: a considerable layer in Judy’s belly area, nearly two square meters in size, filled with fossilized plant remains.
Intriguingly, this plant-filled layer was only found in Judy’s abdomen and lay on the inside surface of the fossilized skin, leading researchers to hypothesize they had come across Judy’s last meal. This find marked a significant milestone as the first instance of discovered sauropod gut contents.
To clarify Judy’s classification, extensive analysis of her skeleton determined that she belonged to the species Diamantinasaurus matildae. Further investigation of the preserved gut contents took place at leading research facilities, including the Australian Synchrotron and CSIRO, utilizing methods such as X-ray and neutron scanning. These advanced techniques allowed scientists to visualize the plants preserved as voids within the rock without damaging the specimen.
Chemical composition analysis of the gut contents, skin, and surrounding material provided deeper insights into Judy’s diet. The findings indicated that the materials had solidified due to microbial activity in an acidic environment, potentially related to stomach acids, with minerals stemming from the breakdown of Judy’s tissues.
Judy’s gut contents confirmed long-held beliefs that sauropods primarily consumed plant material, and they also revealed their method of digestion. Unlike modern animals that extensively chew their food, it appears these dinosaurs consumed vegetation with minimal chewing, relying heavily on gut microbes for digestion. In particular, Judy’s last meals included conifer bracts, seed pods from extinct seed ferns, and leaves from angiosperms or flowering plants.
The presence of conifer bracts, a food source indicative of high-level feeding, supports earlier scientific assumptions regarding the feeding habits of Diamantinasaurus. However, the discovery of lower-growing flowering plants within her remains suggests that Judy was not at full size when she died, indicating a potential shift in dietary preferences during their growth. This presents an intriguing nuance in our understanding of sauropod feeding strategies, hinting at behavioral adaptations that may have developed with age.
Presently, Judy’s skeleton and gut contents are displayed at the Australian Age of Dinosaurs Museum, creating an impressive link between the distant past and the present. As palaeontologists continue to study such finds, they are reshaping our understanding of these iconic giants and their role in the prehistoric ecosystem.
In conclusion, Judy serves as both a fascinating specimen and a testament to the persistent curiosity of palaeontological research. While the idea of having one’s last meal displayed publicly may be unsettling, the contribution to science remains invaluable, enhancing our comprehension of these majestic creatures and their environmental interactions.
image source from：https://www.zmescience.com/science/news-science/judy-saurpod-dinosaur-diet/
