A study has revealed how dinosaurs’ stomachs worked

The study was published in the journal *Paleobiology*.

Soft tissues, including the stomach and intestines, are almost never preserved as fossils. Scientists therefore have to look for indirect evidence of how the digestive system worked.

One such indication is gastroliths – stones that some dinosaurs swallowed along with their food.

Details

The researchers compared dinosaur gastroliths with the stomach stones of modern birds and crocodiles and discovered a pattern: the more worn down the stones were, the more effectively they ground up food in the powerful muscular stomach.

• Some dinosaurs ‘ground’ their food in their stomachs

Analysis showed that many toothless theropods had well-rounded and smooth gastroliths.

This suggests that such dinosaurs probably ground plant matter directly in their stomachs using powerful muscles — much as chickens and other birds do today, using their muscular stomachs.

• Others managed without such a mechanism

The gastroliths of some large herbivorous dinosaurs, including giant sauropods and members of the group to which Triceratops belongs, looked quite different.

Their gastroliths have retained sharp edges, indicating minimal mechanical action within the stomach.

According to the authors, these animals may have relied on well-developed teeth and jaws, as well as on prolonged digestion of food in the gut through fermentation, much like modern large herbivores.

• Dinosaurs did not have a single, unified digestive system

The authors of the study believe that different lineages of dinosaurs independently developed their own strategies for processing food.

Some relied on a powerful muscular stomach and gastroliths, others on efficient chewing, and others still on prolonged intestinal fermentation. This suggests that the evolution of the dinosaur digestive system followed several different paths.

Why this is important

The research helps us understand not only the diet of these ancient animals, but also the characteristics of their lifestyle, metabolism and evolution.

In future, the scientists plan to combine data on gastroliths with an analysis of the structure of teeth and jaws in order to reconstruct the feeding habits of various groups of dinosaurs even more accurately.

Source

Study: Ryuji Takasaki et al. ‘Gastrolith shape as an indicator of digestive function and its implications for dinosaurian digestive strategies’.

Journal: *Paleobiology* (2026).