A small crocodile-like reptile that lived 125 million years ago is giving scientists an unusually detailed glimpse of what its skin looked like. Thanks to ultraviolet light, researchers have identified preserved skin, traces of soft tissues and even a possible color pattern on the tail of Montsecosuchus depereti, a species discovered in the Spanish Pyrenees.
The fossil, known for more than a century, has now revealed features that had remained hidden inside the rock. The specimen comes from the famous Pedrera de Meià fossil site in Catalonia, northeastern Spain. The animal died in a lake environment and was buried in fine sediments that later became limestone. Those conditions helped preserve much more than bones, something that is exceptionally rare in the fossil record.
Published in theZoological Journal of the Linnean Society, the study focuses on a fossil measuring about 50 centimeters (20 inches) long and housed at the Museum of Natural Sciences of Barcelona. Researchers from the Institut Català de Paleontologia Miquel Crusafont led the investigation.
A Fossil That Still Had Secrets To Reveal
Although Montsecosuchus depereti has been known since the early 20th century, scientists recently realized that the specimen contained details that had gone unnoticed. The breakthrough came when researchers examined it under ultraviolet light.
The research team explains that UV light makes fossilized tissues stand out from the surrounding rock, allowing structures invisible under normal lighting to become visible. What appeared was a surprisingly rich record of soft tissues, including preserved skin scales.
“UV light allows us to see details that would otherwise remain completely hidden in the rock,” said lead author Oscar Castillo-Visa.
The study revealed that the scales varied considerably in shape and size depending on where they were located on the body. Researchers also found no evidence of the tall tail fin seen in modern crocodiles, suggesting differences in body structure between ancient and living species.
Skin Structures Hint At Early Sensory Adaptations
The preserved skin offered more than a look at the animal’s outer covering. Researchers also identified structures that may represent sensory organs embedded within some of the scales.
These possible sensory organs were mainly found on the neck, limbs and along the sides of the body and tail. In living crocodiles, similar structures help detect touch, water movements, temperature changes and chemical signals.
The authors note that the fact these features appear only in smaller, peripheral scales may be significant. In their view, such sensory organs could initially have been restricted to specific areas of the body before becoming more widespread in later crocodilian relatives.
Ultraviolet imaging also revealed cartilaginous structures in the chest region. The findings indicate that Montsecosuchus already possessed an efficient respiratory system sharing some features with those of modern crocodiles.
“These traits indicate that, despite being a primitive animal, it was already very well adapted to a semiaquatic lifestyle,” Castillo-Visa said.
A Striped Tail Preserved Across Millions Of Years
The most eye-catching discovery came from the tail. Under ultraviolet light, researchers observed alternating light and dark bands running across several scales in the caudal region.
As reported in the study, these markings are interpreted as traces of the animal’s original coloration. The researchers said that the pattern may have acted as disruptive camouflage, helping break up the outline of the body in its environment.
If confirmed, the finding would make Montsecosuchus depereti the oldest crocodylomorph known to preserve evidence of coloration. Researchers remain cautious about determining the exact colors.
“At the moment we cannot say for sure what color the crocodile’s tail was, but it would be expected that it was not so different from current species, which also show different coloration patterns,” said co-author Albert G. Sellés.
The fossil comes from Pedrera de Meià, a site considered a Konservat-Lagerstätte, meaning it preserves delicate features that are usually lost over time. Data from the research team show that more than 8,000 fossils have been recovered there so far, including fish, amphibians, reptiles, plants, insects and crustaceans. For Montsecosuchus, that exceptional preservation has finally revealed details that remained hidden for more than 100 years.
