New research sheds light on the feeding behaviours of prehistoric marine reptiles known as plesiosaurs, suggesting they regularly ventured to shore to vomit indigestible parts of their meals. This groundbreaking study, published by Cambridge University Press, challenges long-standing assumptions about these ancient creatures and their dietary habits.
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Plesiosaurs, with their long necks and large bodies, have often been depicted as monstrous sea predators. However, the latest findings indicate they exhibited unglamorous eating practices. According to the research, which involved the discovery of fossilised plesiosaur vomit in a river delta location, these marine reptiles likely consumed shellfish in deeper waters before making their way to coastal shallows to regurgitate the inedible remains.
Paleontologist Dirk Knaust, who led the study, identified fossilised vomit pellets discovered in the sands of a 160-million-year-old delta situated about 50 kilometres off the Norwegian coast. The analysis revealed numerous shell fragments, which indicates that the creatures consumed marine life that thrived in saltwater environments. Remarkably, the remains of these shellfish were found in an area where freshwater conditions would have rendered their survival impossible.
The research documents over 20 clumps of vomit, with sizes ranging from that of a walnut to a mango. Knaust theorises that plesiosaurs swam close to the shore to relax after hunting, a behaviour reminiscent of modern fur seals and marine crocodiles that often haul out on land. Unlike these contemporary creatures, however, plesiosaurs would have likely remained submerged due to their considerable weight and unique body shape.
Historically, it was assumed that plesiosaurs would dive down to the seabed to scoop up their meals using their downward-facing heads. Evidence suggests, however, that as plesiosaurs lacked strong teeth to crush shells, they regurgitated the hard materials that couldn’t be digested. A comparison is drawn to owls, which similarly expel bones and fur from their prey in the form of pellets.
As Knaust sought to determine the specific species responsible for the vomit, he had to dismiss other possibilities, including fish and sharks. The size of the vomit pellets and the mix of contents pointed distinctly towards the cryptoclidid plesiosaurs, which measured between four to eight metres in length and roamed the oceans from the Middle Jurassic to the Early Cretaceous period, approximately 174 to 100.5 million years ago.
The research underscores the resiliency and adaptability of plesiosaurs, who survived for an astonishing 140 million years amidst multiple mass extinction events. Their fossil remains have been discovered across the globe, indicating their wide distribution and varying habitats. Knaust posits that this regurgitation behaviour may have been a common practice along many ancient shorelines.
In conclusion, the latest discoveries surrounding plesiosaur behaviour provide a fascinating glimpse into the lives of these extinct marine reptiles. As Knaust states, “there’s so much more we can learn from picking through what extinct animals threw up after dinner.” This pioneering research is poised to reshape our understanding of the dietary habits of one of the ocean’s most iconic predators.
As the study continues to be discussed within the scientific community, it highlights the importance of paleontological research in revealing the intricacies of ancient life and the behaviours that sustained it.