When Ancient Reptiles Went to the Bathroom
Long before modern whales ruled the oceans, the Jurassic seas were dominated by long‑necked plesiosaurs. These apex predators prowled the waters of what is now Western Europe, yet a new study from Cambridge University reveals that they also had a very human‑like problem: a stubborn, indigestible dinner that forced them to seek the shoreline to vomit.
Discovery of Fossilized Regurgitation
Paleontologist Dirk Knaust, working with core samples from a Norwegian CO₂‑storage project, identified more than twenty fossilised “regurgitalites” – compact, walnut‑sized clumps of ancient vomit. The specimens were recovered from what used to be a river mouth, roughly 50 km off the present‑day Norwegian coast. Their preservation was exceptional: a slimy coating and rapid burial by sediment protected the delicate structures from wave action.
What the Contents Reveal
Microscopic analysis showed a mixture of hard‑shelled organisms – bivalve fragments, belemnite rostra, sea‑leaves, and worm tubes – all items that plesiosaurs could not crush with their teeth. The animals apparently swallowed these prey whole, allowing their powerful stomachs to grind the material. The residual, unbreakable bits were then compacted into dense pellets and expelled, much like the “owl pellets” familiar to modern birdwatchers.
Modern Analogues
The behaviour mirrors that of today’s pinnipeds and saltwater crocodiles, which also retreat to shallow water or land to purge indigestible shells. However, unlike seals that haul out onto beaches, plesiosaurs likely remained submerged, using their massive bodies and buoyancy to stay near the coast while they regurgitated.
Implications for Jurassic Ecology
The presence of marine shells in a freshwater‑influenced deposit indicates that the reptiles travelled from the open ocean to the estuary specifically to rid themselves of the waste. This suggests a previously unknown pattern of coastal foraging followed by a brief “rest stop” for digestion. Moreover, the discovery expands the fossil record of non‑vertebrate diet traces, which has traditionally focused on predator‑prey bone assemblages.
Beyond the regurgitalites, Knaust also uncovered fossilised coprolites and even a fragment of an ichthyosaur skeleton, underscoring the rich tapestry of marine life that once inhabited the North Sea basin. The study marks the first time that plesiosaur vomit containing shell fragments has been positively identified, offering a rare glimpse into the daily struggles of these Jurassic giants.
Understanding how these ancient reptiles dealt with hard‑shelled meals not only enriches our picture of their biology but also helps reconstruct the nutrient cycles of prehistoric seas.
Source: https://scientias.nl/brakende-zeemonsters-plesiosauriers-zwommen-naar-de-kust-om-over-te-geven/
