Dry, scaly skin can be one of the least enjoyable parts of winter. But broadly speaking, tough, watertight skins allowed the ancestors of modern reptiles, birds, and mammals to move inland, while their thin-skinned amphibian relatives were able to move inland. I was able to stay.
In published research Published Thursday in Current Biology, scientists announced the discovery of the oldest known fossilized piece of skin. The pebble fragment, about the size of a human fingernail, likely belongs to an ancient reptile and provides valuable insight into the evolution of skin.
This piece of skin is one of countless traces of prehistoric life preserved in the Richards Spur limestone cave system near an oil well in southwestern Oklahoma. When animals fell into caves 289 million years ago, conditions were ideal for preservation. Fine clay deposits quickly buried the carcasses, low oxygen levels in the groundwater slowed the process of decomposition, and hydrocarbons from petroleum penetrated the tissues, slowing the process of decomposition. Bacteria friendly. The tar penetrated the fossils and stained them.
In 2018, former forensic analyst Bill May shared some small fragments of Richards Spur that he could not identify with paleontologist Robert Rice of the University of Toronto Mississauga.
“We were very excited about what we saw under the microscope,” said study author Dr. Rice.
“The texture of the skin is unique and interesting. It stands out from other fossil materials. It’s clearly not bone,” said Ethan Mooney, a master’s student who collaborated on the paper with Dr. Rice. Told. If anything, the fossilized tissue bore a striking resemblance to the scaly skin of a crocodile.
Tee Maho, a PhD student and another author of the paper, used a diamond-tipped blade to separate tiny sections of skin into hair-thin layers. The outermost layer had a hardened structure made of keratin, a protein found in mammalian hair and nails. These hardened structures, or keratinization, are characteristic of the skin of amniotes, land-dwelling vertebrates, including reptiles, birds, and mammals. The ancestors of amniotes evolved to live and reproduce outside of water, unlike their amphibious relatives.
Tough, impermeable skin was an important evolutionary adaptation for amniotes to occupy land, Mooney said, “because to survive in a terrestrial environment, you don’t want to dry out.”
The fossilized skin was found alone, unattached to bone. However, Richards Spahr discovered numerous fossils of a small lizard-like reptile called Captorhinus aguti. Scientists have not found fossils of C. aguti with attached skin, but they have seen fossils with remnants of keratinization. Dr Rice said the skin suggested it came from the same animal.
Hans Suss, a paleontologist at the National Museum of Natural History who was not involved in the study, agreed that the paper was “really the oldest example of fossilized skin” and said he was “thrilled” by the paper. Ta.
“We’ve been doing skin impressions, but here we can actually see the detailed structure under a microscope, as if the skin had just been taken from a live animal.” said Dr. Sue. “And that’s a really important discovery.”