Dinosaur Skin impression in South Korea

Scales are a type of skin seen in reptiles and birds. Since scales are usually tough, they serve to protect the body. Occasionally, scales have been found in dinosaur fossils as well. In most cases, dinosaur scales are discovered as impressions in rock. These fossilized scales allow us to understand what dinosaur scales may have looked like.

 From South Korea, there are several cases of the dinosaur scale trace. In this article, I would like to discuss on those. 

 

Dinosaur skin impression. Source: https://commons.wikimedia.org/wiki/File:Dakota_skin_impression.jpg

 

1. Dinosaur skin impressions in fossilized footprints

(1) Minisauripus tracks from South Korea

 In 2019, a well-preserved impression of dinosaur scales was found in a fossilized footprint discovered in Jinju City. While previous finds of footprints with scale impressions had been reported, this was the first case where the scale pattern was completely preserved.

The footprint was found in the Jinju Formation, a geological layer approximately 123 million years old, located in Jinju Innovation City. It was uncovered during construction in Jeongchon-myeon, where numerous dinosaur footprints were discovered. Among them was the subject of this article—a Minisauripus footprint.

 First identified in China in 1995, Minisauripus footprints belong to a very small theropod dinosaur. These footprints have been considered the tracks of either a newly hatched dinosaur or a very small carnivorous species, though no definitive conclusion has been reached.

 The Minisauripus tracks found in the Jinju Formation were imprinted on sandstone and mudstone layers approximately 2 cm thick, with an impression depth of less than 1 cm. A counterpart of the rock with the footprint impression was also found on a 7 cm-thick rock layer. A total of 5 footprints were discovered—4 forming a walking sequence (left foot–right foot–left foot–right foot) and one separate from the others. The footprints measured an average of 2.38 cm in length and 1.93 cm in width. The separate footprint was even smaller, measuring 2.3 cm in length and 1.3 cm in width. The walking sequence stretched about 20.03 cm.

Minisauripus Tracks Found in Jinju Innovation City. A: Walking sequence. B : Counterpart rock with footprint impressions. C: Isolated footprint. Source: Kim et al. (2019).

 

Locality of Minisauripus in Jinju Formation. Source: Kim et al. (2019).

(2). The first fully preserved skin impression in a footprint

 As mentioned earlier, Minisauripus footprints were first reported in China in 1995. Since then, they have been found at eight sites in China and South Korea, including a discovery in Haman in 2008. However, what makes the Minisauripus footprints unique from the Jinju Formation is the presence of a well-preserved skin impression.

 The skin pattern consists of densely packed, tiny protrusions approximately 0.5 mm in size, completely covering the footprint. While skin impressions have been found in dinosaur footprints before, this was the first case where the pattern was preserved in its entirety. This makes the Jinju Minisauripus an exceptionally significant discovery.

 

Minisauripus with Preserved Skin Impressions. Source: Kim et al. (2019).

(3). The significance of the Minisauripus fossil discovery in Jinju Formation

 The Minisauripus footprints found in Jinju hold four key significances:

1. The Oldest Minisauripus Tracks Found in South Korea
   The footprints were imprinted approximately 123 million years ago, making them the oldest Minisauripus footprints discovered in South Korea. The previously known Minisauripus tracks from Haman Formation date back to around 105 million years ago, meaning the tracks from Jinju Formation extend the known range of these footprints further into the past.
2. Revealing the Skin Structure of Dinosaur Foot Soles
   With the complete preservation of skin impressions in the footprints, researchers gained valuable insights into the texture and structure of dinosaur foot soles.
3. Understanding Dinosaur Locomotion
   Analysis of the footprint’s skin impressions revealed how the dinosaur walked. The study concluded that the dinosaur's heel touched the ground first, followed by the sequential contact of the toes.
4. Confirming the Small Size of Minisauripus as a Theropod Dinosaur
   Since Minisauripus was first discovered, there has been debate about whether the footprints belonged to a tiny adult dinosaur or a juvenile. By analyzing the proportions of the footprints from the Jinju Formation, researchers concluded that the tracks likely belonged to a small-sized carnivorous dinosaur rather than a juvenile of a larger species.

 Besides the well-preserved Minisauripus footprint, several other discoveries of dinosaur skin fossils have been made in South Korea. The first case of dinosaur skin impressions in the country was found in the fossil site of the Gyeongnam Science Education Center in Jinju. Initially thought to be a trace fossil left by invertebrates (classified as Paleodictyon), it was later reinterpreted as a sauropod skin impression.

This article will now focus on another skin fossil reported in 2010 from the southern coast of South Korea. Specifically, this fossil is a skin impression, where the texture of the skin was imprinted rather than the actual skin itself being preserved. 

 

2. Dinosaur Skin Fossils Discovered in the Southern Coast of South Korea

The southern coast of South Korea has geological formations from the dinosaur era, including the Jindong and Haman formations. These formations, estimated to be 112–100 million years old, have yielded numerous dinosaur and bird footprints. One famous site is the Goseong Dinosaur Tracksite, where South Korea’s first dinosaur footprints were discovered.

In 2010, Professors Kim Jeong-Ryul (Korea National University of Education), Kim Kyung-Soo (Jinju National University of Education), and Seo Seung-Jo, along with Professor Martin Lockley (University of Colorado Denver), reported three dinosaur skin fossils from the southern coast. These fossils were found in Deokmyeong-ri (Goseong), Gain-ri (Namhae), and Samcheonpo (Sacheon).

Dinosaur skin fossils found in Deokmyeong-ri (A), Gain-ri (B), and Samcheonpo (C). Source: Kim et al. (2010).

• The Deokmyeong-ri skin fossil measured 18 cm in length and 13 cm in width, with tightly packed pentagonal and round scales ranging from 1–2.6 cm in diameter.
• The Gain-ri skin fossil was 17 cm by 12 cm, with irregular pentagonal, hexagonal, and heptagonal scales, measuring 2–2.5 cm in diameter.
• The Samcheonpo skin fossil was 21 cm by 13 cm, featuring irregular pentagonal and hexagonal scales with some rounded forms. The scales varied from 1.2–2.7 cm in diameter.

These skin fossils were concluded to be from sauropod dinosaurs due to their strong resemblance to previously known sauropod skin impressions.

Localities of the fossil sites. Source: Kim et al. (2010).

3. Additional Dinosaur Skin Fossils from Sacheon

 In the same year, two additional dinosaur skin fossils were reported from Sacheon. Researchers from Pukyong National University, Chonnam National University, and others described these discoveries:

• The first specimen resembled the tightly packed, hexagonal pattern found in hadrosaurid dinosaurs. The scales measured 1–1.2 mm in diameter and were found in what was believed to be a floodplain environment.
• The second specimen had polygonal to oval-shaped scales, ranging from 1.5–5 cm in diameter. It was found in a lake environment and was identified as resembling the skin impressions of large sauropods.

Dinosaur Skin Fossils from Sacheon. Source: Paik et al. (2010).

 

Locality of the dinosaur skin fossil from Sacheon. Source: Paik et al. (2010).

 South Korea’s southern coastal region is rich in dinosaur footprints, as it was once a water-rich environment where dinosaurs frequently gathered. Some of these dinosaurs left more than just footprints—they also left behind impressions of their skin, offering a rare glimpse into their appearance. It would be fascinating to witness these ancient creatures in their natural habitat.

 

Reference

 

Kim, J. Y., Kim, K. S., Lockley, M. G., & Seo, S. J. (2010). Dinosaur skin impressions from the Cretaceous of Korea: new insights into modes of preservation. Palaeogeography, Palaeoclimatology, Palaeoecology, 293(1-2), 167-174.

 

Kim, K. S., Lockley, M. G., Lim, J. D., & Xing, L. (2019). Exquisitely-preserved, high-definition skin traces in diminutive theropod tracks from the Cretaceous of Korea. Scientific reports, 9(1), 1-10.

 

Paik, I. S., Kim, H. J., & Huh, M. (2010). Impressions of dinosaur skin from the Cretaceous Haman Formation in Korea. Journal of Asian Earth Sciences, 39(4), 270-274.

 

Yang, S.Y., Yun, C.S., Kim, T.W., (2003). Pictorial Book of Korean Fossils. Academy Book Company, Seoul, Korea. 419 pp. (in Korean).