Researchers Found Jurassic Marine Reptile Fossil Pellets
The discovery reveals how ancient plesiosaurs expelled indigestible prey remains to manage their dietary intake.
Updated on Oct. 8, 2026 in Geology
Geologists identified more than 20 fossilized regurgitated food masses from marine reptiles within North Sea rock cores. The study provides evidence that these animals traveled to coastal waters to purge waste during the Middle to Upper Jurassic period.
Why it matters
Understanding this behavior offers insight into the biological limitations of marine predators that lacked teeth designed for crushing hard skeletal material. The findings clarify the dietary management strategies of long-extinct marine ecosystems.
The fossilized masses contain concentrated remains of bivalves, shellfish, cephalopods, and tubular worms. Cryptoclidid plesiosaurs, which grew between four and eight metres long, relied on these pellets because their anatomy was unsuited for processing hard skeletal materials.
The players
Cryptoclidid plesiosaurs
A group of marine reptiles ranging from four to eight metres in length that thrived between the Middle Jurassic and Early Cretaceous.
The details
Plesiosaurs occupied a unique ecological niche, utilizing their long necks to sweep the seafloor for prey. Because their teeth were not evolved to crush hard shells, these organisms likely accumulated tough indigestible materials in their stomachs. Once full, these remains were compressed and regurgitated as compact pellets, a process that appears to have occurred in shallow coastal waters rather than open seas.
Timeline
The deposits were formed during the Middle to Upper Jurassic period.
Cryptoclidid plesiosaurs existed over a timespan of 140 million years.
The Tech Race
This discovery adds to a growing body of evidence regarding ancient marine behavior, following similar findings in coastal regions like Britain. It advances the comparative study of predator-prey dynamics across diverse Jurassic geological formations.
This study provides a clearer picture of how prehistoric marine ecosystems functioned through the recovery of physical samples from 50 kilometres off the coast of modern Norway. It expands the known record of fossilized behavior in the North Sea region.
The takeaway
These findings underscore how specialized feeding behaviors defined the success of large marine reptiles for millions of years. Paleontologists continue to analyze these offshore deposits to determine if similar pellet-expulsion sites exist in other Jurassic-era sediment layers.
Further reading
For more on how ancient environments are reconstructed, visit the Geology section.
