Plesiosaurs were among the most successful marine reptiles in the planet’s history, even though – like their terrestrial equivalents, the dinosaurs – they failed to survive the great extinction 65 million years ago.
Everything we know about them, therefore, comes from their fossils: bones, teeth and, lately, even less “noble” remains. A study published in Geological Magazine in fact, it analyzes a very particular find found in Norway: plesiosaur vomit, which tells us a lot about its eating habits and more.
Prehistoric wads
The vomit analyzed in the study was most likely produced by such a specimen Cryptoclidus: these Jurassic plesiosaurs could reach eight meters in length, but despite their size and sea monster-like appearance they were not particularly frightening predators.
On the contrary, they fed mainly on shells and other small marine creatures, which they “picked up” from the seabed thanks to their long necks. They didn’t even have a particularly powerful bite: they couldn’t break the shells, and had to swallow them whole and digest them that way.
What they could not digest, the plesiosaurs vomited in the form of “pellets” compacted from the stomach: a form of waste very similar, for example, to the wads of today’s owls.
The Cambridge team that conducted the study found around twenty samples of this vomit off the coast of Norway, and was able to analyze it in detail, first of all confirming the plesiosaurs’ feeding method. What didn’t add up in the analysis was that the remains contained in the vomit all belonged to oceanic animals, while the place where it was found was, in Jurassic times, a river delta.
Napping and vomiting
This means that plesiosaurs had eaten, and then vomited, sea animals, but they had done so in a river. A peculiarity common to all the samples analyzed, which led the researchers to formulate a hypothesis: the plesiosaurs went hunting in the open sea, but returned to shore to complete digestion and expel all the material that they had not managed to assimilate.
It’s not such an absurd behavior: today sea lions and saltwater crocodiles also do it, with the only difference that the plesiosaurs stopped on shore without leaving the water. According to the authors of the study, it was also a way to rest after hunting: vomiting was just a consequence of digestion and relaxation.
Now the idea is to continue looking for plesiosaur vomit to discover even more about its habits. According to the study, such finds are much more abundant than we thought.
