Plesiosaurs, the long-necked marine reptiles of the Jurassic, may have made deliberate trips to river deltas to regurgitate the indigestible parts of their meals, according to new research. The study, published by Cambridge University Press, suggests that these creatures swam into shallow, brackish waters to vomit up shells and other hard remnants that could not be processed by their digestive systems.
The behavior is strikingly similar to that of modern fur seals and marine crocodiles, which also come ashore or into shallow waters to rid themselves of undigested material. This parallel hints that such a strategy may have been an effective way to avoid carrying excess weight or to clear the stomach for the next hunt, though the exact reasons remain speculative.
Because the evidence comes from a single study, the conclusions are presented as a plausible interpretation rather than a settled fact. The researchers based their hypothesis on fossilized remains and the distribution of vomit-like deposits in ancient delta environments, but further work will be needed to confirm whether this was a widespread habit among plesiosaurs or an occasional behavior.