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The skin of a 67-million-year-old dinosaur has revealed bite marks and cuts from an ancient crocodile, and the way its flesh was torn could explain why it was mummified.
Skin breaks down much more easily than bone, so finding fossilized dinosaur skin is very rare.
New research on a 7-meter-long Edmontosaurus, a type of herbivorous hadrosaur, found near the town of Marmarth, North Dakota, in 1999, has shed light on the factors that allowed the skin to survive through the eons. .
Fossils of the "grandfather of crocodiles" give clues about how these animals came to land
"The bite marks were really unexpected. Soft tissues were thought not to be preserved if they were damaged before they were buried, so carnivore damage was what got us thinking about how these fossils formed," Stephanie said. Drumheller-Horton, a paleontologist in the Department of Earth and Planetary Sciences at the University of Tennessee and co-author of the new study.
The mummified dinosaur skin retained the bite marks of carnivores, probably ancient crocodiles.
Credit: North Dakota Geological Survey
Paleontologists used to think that a dinosaur, or any prehistoric creature, had to be buried extremely quickly in order for the soft tissues to be preserved, but that was not the case with this poor hadrosaur.
Researchers believe the bite marks on the hadrosaur's arm came from an ancient crocodilian relative, but they're not sure what kind of animal clawed or bit off its tail, though it was likely larger.
It is unclear whether the injuries to his arm and tail killed him or were inflicted by scavengers after his death.
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However, it was the dinosaur's misfortune that allowed its skin to survive, Drumheller-Horton explained.
"To put it in the least unpleasant way possible, piercing the skin allowed gases and liquids associated with decomposition to escape. This allowed the hollow skin to dry out. Naturally mummified skin like this can last for weeks to months." , even in fairly humid environments, and the longer it lasts, the more likely it is to be buried and fossilize," he explained.
The bluish color of the fossilized skin is not thought to reflect the color of the dinosaur while it was alive.
However, a high iron content in the rocks during the fossilization process may have affected it.
Although their color is often depicted as greenish-gray, it is largely unknown what color most dinosaurs were.
Studies of fossilized dinosaur feathers have revealed that some were surprisingly colorful.
Artistic impression of how the death of the dinosaur could have been.
Credit: North Dakota Geological Survey
Hadrosaur skin, however, has provided much information about the size and patterns of scales throughout the dinosaur's body, as well as the amount of muscle mass as a function of skin expansion in that area.
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"Skin breaks down much more easily than bone, so different, less-observed processes are needed to preserve skin long enough to be buried and fossilized," said research co-author Clint Boyd, a senior paleontologist at the Geological Survey. from North Dakota.
Boyd surmises that fewer than 20 true dinosaur "mummies" exist, with complete or nearly complete sets of soft-tissue remains.
"To put it into context, I have found thousands of fossils in my career, but only one of them had preserved skin impressions (an imprint of the skin, not the preserved skin itself) and I have never found one myself that had preserved skin. Boyd said via email.
The research was published Wednesday in the academic journal PLOS One.
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