'Exquisitely Preserved' Dinosaur Skin Trace Discovered in South Korea

Tuesday, April 9, 2019

A small dinosaur—probably about the size of a blackbird—stalks a lakeshore. That animal left footprints in the mud that hardened and lasted for over 110 million years, until a team of scientists uncovered them in South Korea. (Artist’s interpretation by Zifeng Wang.)

Several footprints and exquisitely-preserved skin impressions made by a small theropod dinosaur approximately 120 million years ago (Aptian age of the Early Cretaceous Period) have been found in the Jinju City area in Korea.

Paleontologists are used to finding dinosaur bones and tracks. But remnants of soft tissue, like muscles or skin, are rare and often not well preserved. A very small percentage of tracks – much less than 1% – show skin traces.

Kyung-Soo Kim, PhD, of Chinju National University of Education recently found a set of very small tracks with perfect skin traces near Jinju City, Korea. CU Denver Professor Emeritus of Geology Martin Lockley, PhD, – with Kim, Jong Deock Lim of Korea and Lida Xing of Beijing – wrote a paper about the skin traces for the journal Scientific Reports. They described the skin as “exquisitely-preserved.”

Four-track Minisauripus trackway. Image credit: Kim et al, doi: 10.1038/s41598-019-38633-4.

First dinosaur tracks ever found with perfect skin impressions

“These are the first tracks ever found where perfect skin impressions cover the entire surface of every track,” Lockley said. The skin patterns of different groups of dinosaurs varied and, like fingerprints, were signatures of differences in anatomy.

The skin traces come from tracks of the smallest known theropod, the Minisauripus. The footprints are only an inch long, and the scientists were able to find perfectly preserved skin traces on them. This was the 10th discovery of a site with Minisauripus tracks and the first to show skin traces.

The tracks, found during large-scale excavations, were nearly lost. Kim, who is in charge of predevelopment paleontological survey and rescue, was able to stop the excavation when he spotted the first track on a broken slab. With the help of his team, he found four more tracks with perfect skin traces.

How to perfectly preserve dinosaur skin

“The tracks were made on a very thin layer of fine mud,” Lockley said, “rather like a coat of fresh paint only a millimeter thick.” When the blackbird-sized dinosaur stepped on this firm, sticky surface, the skin texture of the foot was reproduced perfectly, without slipping or sliding.

Evidence shows that, just before the tracks were made, there had been a rain shower leaving water-drop impressions. In one place, the dinosaur had stepped on a fresh rain drop mark, proving rain came first, and the dinosaur step came second. All this delicate evidence was preserved by being gently covered with more fine mud.

Minisauripus: natural impression (A) and cast (B) of track TL 2 showing area enlarged in frame F; note skin traces in hypex area between digits II and III; (C) natural cast of track TR1, showing area enlarged in frame E; note narrow, digit II intersecting raindrop impressions; (D) isolated track t; note skin traces in hypex area between digits II and III; E and F details of skin trace ornament in 2.0 x 2.0 mm areas of digits IV and II respectively from tracks TL2 and TR1; casts show in frames B-F are essentially replicas of the living foot. Image credit: Kim et al, doi: 10.1038/s41598-019-38633-4.

The ultimate secret of skin care

The texture of the dinosaur skin is the grade of a medium sandpaper, but with the tiny scale traces in perfect arrays, like a well-woven fabric. Each little scale trace is only a third- or a half-millimeter in diameter and very similar to rare examples of mummified skin seen on the feet of a couple of feathered birds from China. But the team noted that, although the skin texture is the same, the shape of the feet of the Chinese birds and the Korean dinosaur were quite different.

The paper reports the skin pattern as similar to examples from much larger, carnivorous theropod dinosaur tracks, in which scales are much larger but never preserved across the whole footprint.

The more distantly-related giant brontosaurs had scales that left traces 2-3 centimeters in diameter, the size of a quarter. So the delicate, perfectly-preserved Minisauripus skin texture is like a shrunken version of the skin of a much larger relative, with no shrinkage of the skin traces.

“This is the ultimate secret of skin care,” Lockley said.

Source: www.cudenvertoday.org