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The skin of a 67-million-year-old dinosaur has revealed the bites and stings of an ancient crocodile, which may explain how its flesh was ripped off and mummified.
Skin decays much more easily than bones, so it is very rare to find fossilized dinosaur skin.
New research on a 7-meter (23-foot) long Edmontosaurus, a type of plant-eating hadrosaur discovered in 1999 near the town of Marmarth, North Dakota, sheds light on what factors made skin survive for eons.
“The bite marks were really unexpected. “It was thought that soft tissues wouldn’t be preserved if they were damaged before burial, so it’s carnivore damage that got us thinking about how these fossils form,” said Stephanie Drumheller-Horton, a paleontologist in the University of Tennessee’s Department of Earth and Planetary Sciences who co-authored the new study. .
Paleontologists used to think that a dinosaur, or any prehistoric creature, had to be buried very quickly to preserve its soft tissues, but this was not the case with this poor hadrosaur.
Researchers believe the bite marks on the hadrosaur’s arm came from an ancient relative of the crocodile, but they’re not sure what kind of animal clawed or bit the tail – although it was likely larger. It is not clear if the injuries to his arm and tail killed him or if he was caused by the shoes after his death.
However, it was the dinosaur’s misfortune that allowed its skin to be preserved, Drumheller-Horton explained.
“To try to put it in the most disgusting way possible: puncturing the skin allowed the gases and liquids associated with later decomposition to escape. This left the skin behind to dry. Mummified skin can naturally last for weeks or months even in relatively humid environments, and the longer it lasts, the more likely it is to undergo burial and fossilization,” he said.
The bluish color of the fossilized skin does not seem to reflect what the dinosaur would have been like when it was alive. However, the high iron content in the rocks may have contributed to the fossilization process.
Although often depicted as greenish gray, what color most dinosaurs were is largely unknown. Studies of fossilized dinosaur feathers have revealed that some were surprisingly colorful.
The skin of the hadrosaur, however, has provided a lot of information about the size and patterns of scales across the dinosaur’s body, as well as the amount of muscle mass, given the extent of the skin in that area.
“Skin decomposes much more easily than bones, so different and less common processes must have occurred to preserve skin long enough to be buried and fossilized,” said study author Clint Boyd, a senior paleontologist with the North Dakota Geological Survey.
He said there were perhaps fewer than 20 true dinosaur “mummies,” complete or nearly complete sets of soft-tissue remains.
“I’ve found thousands of fossils to put in context in my career, but only one of these preserved skin impressions (an impression of skin, not the actual preserved skin itself) and I’ve never found one that had skin preserved,” Boyd said via email.
The study was published in the journal PLOS One on Wednesday.