Beautifully fossilized theropod skin impressions found in a trackway

[Logo7]

Five tiny tracks belonging to the theropod ichnogenus Minisauripus, commonly regarded to be the smallest dinosaur ever discovered, have been found in the Jinju Formation in South Korea. These tracks are about an inch long and were imprinted between 112 and 120 million years ago. However, all five of these tracks contain beautifully preserved skin impressions over the entire surface of the track. The scales seen in the tracks are each between one-third and one-half a millimeter in diameter and were displayed in perfect arrays. The scientists believe that the texture of this animal's skin would have been similar to the grade of a medium sandpaper. The skin patterns are similar to those of Cretaceous birds from China, but the shape of the footprints is distinctly nonavian in nature. In fact, the skin pattern bears a resemblance to fragmentary track skin impressions from larger theropod dinosaurs, suggesting that Minisauripus is a predatory dinosaur as well. It is believed that these footprints were made when the dinosaur stepped on a thin, millimeter thick layer of mud that was sufficiently firm and sticky to prevent it from sliding around and smudging the prints. It is also possible that the skin itself was loose and flexible, allowing it to spread when it contacted with the mud and preventing the skin traces from being smeared by the animal's shifting and sliding feet. After the footprints were left, they were preserved by another fine mud layer. The layer of mud the footprints were left in was so thin that even the imprint of raindrops that fell before the dinosaur arrived were left behind, with one of these imprints being stepped on by one of the footprints. The tracks also extend the record of Minisauripus in Korea, as these footprints are between 10 and 20 million years older than all previously known Korean Minisauripus tracks, which were excavated in the between 112 and 100 million year old Haman Formation. Here are the fossilized tracks and a reconstruction of the animal that made them as well as a link to the paper describing them.




Paper (open access!): https://www.nature.com/articles/s41598-019-38633-4#Sec7