A team of researchers has uncovered plant remains in the abdomen of a sauropod, providing direct evidence of their herbivorous diet. This discovery, on a fossil dating back 94 to 101 million years, reveals a diversity of consumed plants and a key role of gut microbes in digestion.
Artist's impression of Diamantinasaurus matildae feeding.
Credit: Travis Tischler
Sauropods, these Mesozoic giants, dominated terrestrial ecosystems for millions of years. Their diet, long presumed to be herbivorous, had until now only been inferred from their anatomy. The discovery of fossilized gut contents changes everything.
Analysis of the recovered plants shows these dinosaurs didn't chew their food. They relied on fermentation by their gut microbiota for digestion. This bulk feeding strategy allowed them to thrive for 130 million years.
Among the identified plants were conifers and angiosperms, the latter being a surprise. Their presence suggests sauropods quickly adapted to new plants that appeared 100 million years ago. This dietary flexibility may explain their evolutionary success.
Young sauropods likely fed on low-growing plants, while adults could reach higher vegetation. This feeding strategy, combined with rapid growth, probably contributed to their gigantism and longevity.
Mackenzie Enchelmaier, collections manager, presents the fossilized gut contents.
Credit: Stephen Poropat How did sauropods digest their food without chewing?
Sauropods had a unique digestive system capable of processing large quantities of plant matter without requiring chewing. They relied on their gut microbiota, microorganisms that fermented plants to extract nutrients.
This digestion method is similar to that seen in some modern herbivores like cows, which also use fermentation to break down cellulose. However, the scale at which sauropods operated was unprecedented due to their gigantic size.
The absence of chewing meant sauropods could quickly ingest large quantities of food, maximizing their energy intake. This feeding efficiency was crucial for supporting their metabolism and rapid growth.
This discovery highlights the importance of microbes in the evolution of herbivorous dinosaurs. Without them, sauropods might never have reached such massive proportions.
Why is the discovery of angiosperms in sauropod diets significant?
Angiosperms, or flowering plants, appeared relatively late in Earth's history. Their presence in sauropod diets indicates these dinosaurs quickly adapted to new food sources.
This dietary flexibility likely played a key role in their evolutionary success. By incorporating angiosperms into their diet, sauropods could exploit an abundant and diverse food resource.
The coexistence of sauropods and angiosperms also suggests interaction between dinosaurs and their environment. Flowering plants may have benefited from seed dispersal by these giants.
This discovery opens new perspectives on the coevolution of dinosaurs and plants, showing how changes in flora influenced the feeding habits of prehistoric herbivores.