Earliest Known Fossilized Reptile Skin Imprint Discovered

Scientists have identified the world's earliest known fossilized imprint of reptile skin. The impression, approximately 300 million years old, includes details of scales and a cloaca. This discovery provides new insights into the early development of reptiles and their skin structures.

Paleontologist Lorenzo Marchetti from the German Natural History Museum in Berlin stated that such soft-tissue structures are exceptionally rare in the fossil record, particularly from early Earth history.

Origin of the Ancient Imprint

The fossil originated from the sedimentary Goldlauter Formation in Germany's Thuringian Forest Basin. Analysis of the imprint indicates it was made by a reptile measuring approximately 9 centimeters (3.5 inches) in length.

Marchetti and his team named the trace fossil Cabarzichnus pulchrus, designating it as a newly described species of reptile resting trace. Its size and nearby footprints suggest that C. pulchrus was likely a bolosaurian, an early branch of the reptile lineage. It lived around 295 million years ago during the Asselian age of the early Permian, a period of rapid reptile diversification.

Unveiling Anatomical Details

The imprint displays clear belly scales, which are keratin-based structures functioning as armor. A notable feature at the base of the tail is a vent-like opening surrounded by modified scales, interpreted as a cloaca.

This discovery predates the previous record, a Psittacosaurus cloaca dated to approximately 120 million years ago. This establishes it as the earliest fossil record of a cloacal vent in amniotes and supports the view that the cloaca was present in early reptiles.

C. pulchrus' cloaca exhibits a different shape and orientation compared to those of Psittacosaurus, other dinosaurs, and crocodiles, instead resembling those of modern turtles, lizards, and snakes.

The fossil also preserves rows of polygonal epidermal scales across the trunk, limbs, head, and tail. These scales are composed of keratin, similar to those of contemporary reptiles, rather than older bony dermal armor.

The Value of Trace Fossils

Marchetti noted that trace fossils offer more than simple footprints; they preserve anatomical details that would otherwise be lost and are crucial for understanding the evolution of early terrestrial vertebrates.

The research was published in Current Biology.