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Study Says Plesiosaurs Regurgitated Shell‑Filled Pellets in Shallow Waters

Researchers interpret more than 20 fossilized regurgitalites as evidence that these marine reptiles carried hard‑shelled prey into coastal shallows and expelled indigestible parts.

Overview

  • A peer‑reviewed paper by paleontologist Dirk Knaust, published in Geological Magazine and reported across outlets on Tuesday, presents more than 20 compact regurgitalites as the study’s central evidence.
  • Regurgitalites are fossilized vomit: the North Sea samples range from walnut to mango size and are dominated by broken bivalves, cephalopod remains and tubular‑worm tubes rather than bones.
  • The pellets were recovered from drill cores taken about 50 km off the Norwegian coast in sediments that once formed a Jurassic river delta, but the shelly species inside require saltier, open‑ocean conditions.
  • Knaust ruled out other local predators such as sharks, crocodiles and some ichthyosaurs based on pellet size and content and concluded cryptoclidid plesiosaurs best match the feeding profile, while noting the attribution is inferential.
  • The fossils likely fossilized because mucus compaction, rapid burial by river sediment, or protection in crustacean burrows preserved the pellets, and the finding offers a new way to study ancient marine diets and behavior as follow‑up work continues.