Fossilized Vomit Reveals Jurassic Plesiosaur Feeding Habits
Ancient regurgitation offers clues to marine reptiles' diet and resting behavior.
1Unexpected fossil discovery
Paleontologist Dirk Knaust analyzed fossilized vomit clumps found in North Sea rock cores near Norway's Troll oil field. The specimens contained shells, worm tubes, and sea lily fragments, indicating a large marine predator's diet. These regurgitalites, dating back to the Jurassic period, were preserved in river sediment and crustacean burrows. The discovery came during a carbon storage project where Equinor drilled seabed cores. Knaust has examined thousands of feet of such cores over three decades of research.
2Identifying the ancient predator
Initial CT scans suggested an ichthyosaur origin, but further analysis pointed to cryptoclidid plesiosaurs as the likely source. These long-necked marine reptiles grew 13-26 feet long and survived for over 140 million years. The size of the vomit pellets (some 4 inches across) ruled out fish or cephalopods as possible sources. Plesiosaurs' stomach contents found in Australia matched the Norwegian specimens, strengthening the identification. Their anatomy suggests they swallowed hard-shelled prey whole before regurgitating indigestible parts.
3Feeding behavior revealed
The fossilized vomit composition indicates plesiosaurs fed in deep marine waters before moving toward shore. Prey species requiring stable salinity levels suggest feeding occurred away from freshwater-influenced deltas. Plesiosaurs likely used their long necks to gather food from the seafloor, consuming shellfish and squid-like belemnites. Only soft parts were digested, with hard shells concentrated into gastric pellets. This matches modern marine predators' feeding patterns, though with unique prehistoric adaptations.
4Post-meal resting patterns
Knaust theorizes plesiosaurs may have sought sheltered coastal waters after feeding, similar to modern fur seals and marine crocodiles. Their body weight and shape would have kept them submerged during these rest periods. The discovery location suggests they carried meals toward shore before regurgitating. This behavior might explain why some pellets fossilized near river deltas rather than open ocean. The findings provide rare insight into daily rhythms of extinct marine reptiles.
5Scientific significance
This marks the first identified plesiosaur vomit fossil, offering direct evidence of their diet and digestion. The research methodology combined CT scanning, mineral analysis, and comparative anatomy with modern species. Findings were published in Geological Magazine after rigorous peer review. Such discoveries help reconstruct ancient marine ecosystems and predator-prey relationships. They also demonstrate how industrial activities like oil drilling can unexpectedly advance paleontology.
6Preservation factors
Mucus played a crucial role in holding the regurgitated pellets together long enough for fossilization. Most would have broken apart in ocean currents, but some were protected in sediment or crustacean burrows. The specimens survived 150 million years due to ideal geological conditions beneath the North Sea. Their preservation quality allowed detailed analysis of both prey composition and predator biology. This case shows how rare taphonomic conditions can yield extraordinary scientific insights.
7Research challenges
Distinguishing fossilized vomit from feces required careful examination of undigested content and mineral composition. The team analyzed over 20 pellets, comparing them to known examples from other species. Lack of fish bones helped rule out certain predators like crocodiles that inhabited the same waters. The research bridges paleontology and ichnology (study of trace fossils). Such work often involves examining industrial core samples not originally collected for scientific purposes.
8Future research directions
Knaust believes this discovery opens new avenues for studying prehistoric predator behavior through trace fossils. Similar analysis could be applied to other marine reptile species across different geological periods. The findings may help identify previously misclassified fossils in museum collections. Ongoing industrial activities in the North Sea could yield more specimens. This approach demonstrates how paleontology can extract maximum information from unconventional fossil types.