This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Plesiosaurs swam into river deltas to vomit up shells and other indigestible elements of their marine meals, suggests new research published by Cambridge University Press. The behavior resembles that of today's fur seals and marine crocodiles.
Previous research into plesiosaur anatomy and movement suggests the iconic long-necked marine reptile angled its head down to collect shellfish from the seafloor. The animal couldn't crush shells or other skeletal material with its teeth, it is thought, so its stomach compacted it to be vomited as pellets, as animals including owls do today. In a study published in Geological Magazine, paleontologist Dr.
Dirk Knaust offers new insights into the behavior of these successful sea monsters. Knaust identified the fossilized remains of plesiosaur vomit pellets in what would have been the shallow waters of river deltas, 50 kilometers (31 miles) off the Norwegian coast. The shellfish, which Knaust identified in the vomit, needed the kind of steady salt levels found in the open ocean to survive.
But Knaust discovered that the vomit was deposited in a river delta in which incoming freshwater would have continually changed the salt levels, making it impossible for these sensitive creatures to live there. So how did their remains get into the delta? Knaust's detailed analysis of more than 20 regurgitalites—clumps of fossilized vomit ranging in size from a walnut to a mango—led him to the conclusion that plesiosaurs must have eaten the shellfish from the seafloor in deeper water before swimming to shore to vomit up their hard, indigestible parts.
Knaust said, "There has been a lot of research into fossilized vomit over the last decade, but most of it has focused on vertebrates eating other vertebrates. This is the first time that plesiosaur vomit, and the shellfish in it, have been identified, and these creatures tell us a great deal." Over the last three decades, Knaust—a specialist in the fossil traces left by invertebrates—has analyzed several thousand meters of drill core samples taken from North Sea wells operated by his employer, the Norwegian energy company Equinor ASA. The vomit fossils he studied mainly come from the development of a subsea storage site for CO2 in the vicinity of the Troll gas and oil field.
"Plesiosaurs may have come close to shore to relax or sleep after hunting, and that's likely when they vomited," Knaust said. "We see fur seals and marine crocodiles doing something similar today, but while they go onto land, plesiosaurs probably remained submerged due to their weight and shape." While dangers lurked in the deep, dinosaurs—two-legged predators and long-necked herbivores—roamed the delta lands nearby. Knaust and his colleagues have identified parts of their footprints in some of the extracted cores.
Extract — continue reading at the source.
