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Petrified time capsule: In Thuringia, paleontologists have discovered the oldest scale imprints of a reptile. They come from a lizard-sized animal that rested in the mud, leaving imprints of its body and skin structure. The prints are the earliest evidence of epidermal dandruff – the cornified skin structures that are typical of modern reptiles. The prehistoric reptile has even left the imprint of its cloaca – this is also the oldest known to date.
Whether crocodile, snake or lizard: typical characteristics of most reptiles are their scales. These mostly angular horn plates are formed by the epidermis, the outer layer of the skin. This distinguishes them from the bone scales of the fish originating from deeper skin layers and first landgoers among the vertebrates. But when prehistoric reptiles first developed their typical skin flakes is unclear.
“Such soft tissue structures are extremely rare in the fossil report – and the further we go back in Earth’s history, the more extraordinary they become,” explains first author Lorenzo Marchetti of the Museum of Natural History Berlin. Among the earliest evidence of reptile scales to date are 286 to 289-million-year-old fossil skin pieces from the U.S., as well as the 290-million-year-old lying track of a dimetrodon, which was only discovered in Thuringia in 2025. Scale prints These prints show the scales on the hind leg of Cabarzichnus pulchrus. © Lorenzo Marchetti Scale prints of a Lizard-Sized Prehistoric Reptile
Now there is an even older find – also in Thuringia. In the so-called Goldlauter formation from the late Carbon Age 298 to 299 million years ago, Marchetti and his team have discovered the fossilized lying traces and footprints of a lizard-sized reptile. This Cabarzichnus pulchrus baptized animal left well-preserved imprints in the mud, which show its hull, triangular head, tail and lateral legs.
The crucial thing, however, is that even fine details of the skin structure of this reptile were preserved in the fossil sludge. On the trunk, the legs and the bottom of the tail, the imprints of square scales can be seen, which are close to each other in orderly rows. “They thus show a morphology and arrangement similar to the epidermal shoods of modern reptiles,” the paleontologists report. In their view, these prints must therefore come from real scales.
“The Epidermis scales of Cabarzichnus are thus the oldest definitive evidence of such skin structures in an early reptile,” say Marchetti and his colleagues.
The paleontologists discovered another special feature in the fossil prints from the tail base of the small prehistoric reptile. There was a narrow slit, surrounded by several differently shaped scales. “The modified scales around this opening are consistent with the scale forms around the cloaca opening of modern scale creepers,” the researchers report. This common outcome of the intestine and reproductive organs is typical for reptiles, birds and almost all other land vertebrates except the mammals.
Yet the fine structures of this opening are almost never preserved in fossils. The new find is also a real rarity. “It’s the earliest fossil evidence of a cloaca opening at amniotes,” Marchetti and his colleagues write. The next oldest fossil of a cloaca is around 170 million years younger and comes from a Cretaceous reptile. Across instead of longitudinal
The cloaca print of Cabarzichnus reveals that the opening in these early reptiles was aligned transversely to the body axis. Thus, the shape and orientation of their cloaca differs from today's crocodiles. It is more similar to the cloaca form of turtles, lizards and snakes, as the paleontologists explain. This gives new insights into the evolution of this body opening in early land vertebrates.
“Trace fossils are far more than just footprints,” emphasizes Marchetti. “They preserve details of the anatomy that would otherwise be completely lost and make a decisive contribution to better understanding the evolution of the early land vertebrates.”