In a groundbreaking discovery, researchers have identified the world's oldest known fragment of fossilized reptile skin, originating from an Oklahoma cave. This remarkable find, detailed in a study published today in Current Biology, dates back to the late Paleozoic Era, surpassing previous examples by over 20 million years.
The late Paleozoic Era witnessed the emergence of numerous species from water to land, marking a pivotal moment in evolution. Understanding how animal skin adapted to this transition has long been a challenge in paleontological research. However, this newfound reptilian skin fragment sheds light on the unchanged complexity of reptile scales since their initial evolution, according to Phil Bell, a paleontologist from the University of New England.
The fossilized skin fragment, remarkably well-preserved for nearly 300 million years, was discovered in the limestone caves of Richards Spur, Oklahoma. These caves, once filled with petroleum and tar from the Woodford Shale, provided an ideal environment for fossil preservation due to fine sediment deposits and low oxygen conditions.
Ethan Mooney, lead author of the study and a paleontology master's candidate at the University of Toronto, explains that the fossil belongs to Captorhinus aguti, an iguana-sized reptile crucial for survival on land. The reptile's scaly outer layer, composed of keratin similar to human hair and fingernails, is a testament to the adaptation necessary for terrestrial life.
What makes this discovery truly extraordinary is the inclusion of an inner dermis layer—rarely preserved in fossils—alongside the well-preserved tough epidermis. The 3D fossil showcases individual bands of folded scales separated by a flexible "hinge" region, allowing for growth and movement, a feature also observed in the skin of modern snakes and worm lizards.
Robert Reisz, a paleontologist at the University of Toronto and corresponding author, highlights the uniqueness of this find compared to mummified skin discovered elsewhere. At approximately 300 million years old, this fossilized skin sets a new record, providing unprecedented insights into the early evolution of reptilian skin.
While the researchers suspect the skin belonged to C. aguti, the absence of an associated skeleton leaves room for speculation. Nevertheless, the wrinkled, pebble-like texture resembling crocodile skin and the hinge region similar to structures in modern reptiles further emphasize the significance of this ancient discovery. Phil Bell expresses excitement, stating that confirming typical scaly skin in some of the earliest reptiles through the fossil record is truly groundbreaking.
More: https://www.science.org/content/article/fossilized-reptile-skin-oklahoma-cave-oldest-record
