There’s more than one way to mummify a dinosaur, study finds

We rarely have time to write about all the cool science stories that come our way. Posting a special 12 Days of Christmas series. Not as rare as scientists believed.

Under certain conditions, dinosaur fossils may contain very well-preserved skin. But the authors of his October paper, published in the journal PLoS ONE, suggested that these dinosaur “mummies” may be more common than previously believed. Cleaning in the form of bite marks.

In this case, the term “mummies” refers to fossils with well-preserved skin and sometimes other soft tissues. As we have previously reported, most fossils are bones, shells, teeth, and other forms of ‘hard’ tissue, but rare fossils have preserved soft tissues such as skin, muscles, organs, and even eyeballs. may also be discovered. This can tell scientists much about the biology, ecology and evolutionary aspects of ancient organisms that skeletons alone cannot tell.

For example, last year, researchers used a combination of advanced imaging techniques to create a highly detailed 3D model of a 365-million-year-old Jurassic ammonite fossil, revealing never-before-seen internal muscles. did. Another team of British researchers conducted experiments looking at the decomposition of sea bass carcasses to learn how (and why) visceral soft tissues are selectively preserved in the fossil record. .

In the case of dinosaur mummies, debate continues over what appears to be a central contradiction. Dinosaur mummies discovered so far show signs of two distinct mummification processes. One is rapid burial, in which the corpse is rapidly covered, which greatly slows further decomposition and protects the remains from decay. Another common route is drying. This requires that the bodies remain exposed to the landscape for a period of time before burial.

The specimen in question is a partial skeleton of EdmontosaurusA duck-billed hadrosaurus found in the Hell Creek Formation of southwestern North Dakota and now part of the North Dakota Fossil Collection. This mummified dinosaur, called “Dakota,” showed evidence of both rapid burial and desiccation. Fossils have been studied using a variety of tools and techniques since 2008. The authors of the PLoS ONE paper also performed CT scans of the mummies, along with an analysis of the grain size of the surrounding sediments where the fossils were found. did.

There was evidence of multiple cuts and puncture wounds on the forelimbs and tail, and arcuate holes and abrasions on the bones of the arms, hands, and skin that closely resembled the shape of crocodile teeth. The tail also had a longer, V-shaped cut, likely created by larger carnivorous predators such as juveniles. T.Tyrannosaurus Rex.

The authors conclude that there are likely multiple pathways to dinosaur mummification, resolving the debate in a way that “does not require the convergence of surprisingly improbable events.” In short, dinosaur fossils could be mummified more frequently than previously thought.

In the case of Dakota, the shrunken appearance of the skin over the underlying bones is also found in other dinosaur mummies and is well documented in modern forensic research. We believe it was ‘mummified’ through a process called ‘contraction’. This involves imperfect scavenging, in which scavengers and decomposers target internal tissues to empty animal carcasses, leaving behind skin and bones. According to Forbes’ David Bressan, this is likely what happened to Dakota.

After the animal died, his body was probably eaten by a pack of crocodiles, the belly carcass opened, flies and beetles settled in, and the bones and skin cleaned from rotting flesh. exposed the interior of the dermis tissue, after which the outer layer slowly dried. Finally, perhaps by a sudden flash flood, the mummified remains were buried under the mud, and the circulating fluid deposited minerals, displacing remaining soft tissue and preserving the rock mold.

“Not only did Dakota teach us that durable soft tissues such as skin can be preserved in partially decaying cadavers, but these soft tissues also provide unique information about other animals that have interacted with cadavers after death. We can also provide a source,” said co-author Clint Boyd, a paleontologist at the North Dakota Geological Survey.

DOI: PLoS ONE, 2022. 10.1371/journal.pone.0275240 (About DOI).