Most dinosaur specimens are just fossilized bones, but a handful too Fossilized soft tissueA new look at a duck-billed dinosaur specimen called the Dakota suggests that these dinosaur “mummys” are more common than previously thought.
Petrified Dakota leather holds Wound and bite marks They were likely made by scavengers after the animal died, according to a study published Wednesday in the peer-reviewed journal PLOS One. That suggests that Edmontosaurus—a multi-ton herbivorous eater that died about 70 million years ago, before its fossilized remains were found in southwestern North Dakota in 1999—had been exposed to air long enough to become dry before being buried by sediments and subsequently petrified. .
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Previously, paleontologists believed that dinosaur mummies were usually formed when animals were buried with mud and sand. or other debris Within hours of death. It’s possible that this rapid burial scenario was less frequent than the researchers believe led to the fossilization of the Dakota, said study co-author Clint Boyd, chief paleontologist at the North Dakota Geological Survey, who is interested in the specimen.
Thus, there may be more specimens like the Dakota just waiting to be found.
“We remove them from the magical special cases category,” said Dr. Boyd of finding dinosaurs with fossilized skin and other soft tissues.
Since the first mummified dinosaurs were found in In the late 19th century, fewer than 20 nearly complete dinosaur mummies were discovered and described, according to Stephanie Drummer, a paleontologist at the University of Tennessee Knoxville and the study’s lead author.
For the study, Dr. Drumheller and her colleagues studied the skin of the Dakota and used a computerized tomography (CT) scan to look inside the specimen stored in Bismarck, ND, as part of the state’s fossil collection.
The dinosaur’s head, left arm and tail were missing. But the skin on his right arm bore bite marks, most likely caused by a crocodile-like predator, according to Dr. Drumheller. Its tail bore wounds, she said, that could have been caused by another bipedal predator, possibly a small Tyrannosaurus Rex.
Scans indicated that the Dakota’s skin dried out over months, if not longer, after the dinosaurs’ muscles and internal organs had eroded. The researchers said the waste collection helped rid the body of fluids and microbes that normally contribute to decomposition. Then the skin retracts, resting tightly on the underlying bone.
Mindy Householder, one of the authors of the new study, holds the right hand of a mummified Edmontosaurus at the Johnsrud Paleontology Laboratory in Bismarck, ND, in 2019.
picture:
Clint Boyd
Scientists called the previously undescribed embalming process “dry, then shrink.” A similar phenomenon can be seen when modern-day predators scavenge animal carcasses, Dr. Drummer said, adding: “The punctured line is that there are multiple pathways that can make you a mummy.”
Victoria Arbor, curator of paleontology at the Royal British Columbia Museum in Victoria, Canada, who was not involved in the study, said the researchers’ conclusions made sense.
“They suggest you don’t necessarily need really special circumstances” like a speedy burial, she said. “What you might need are predators, getting into the body cavity, and basically, like emptying them of all the viscosity.”
Dr. Arbor said the new research suggests that paleontologists need to be extra careful when examining dinosaur fossils. “If we don’t expect mummified specimens in an environment, we don’t look for them, and they may be missed over time,” she said.
Write to Aylin Woodward at [email protected]
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