A 125-million-year-old crocodile fossil discovered in northeastern Spain has provided new insights into the animal’s skin, possible sensory organs, and respiratory system. The fossil, cataloged as MGB-512, is about 50 centimeters long and is housed at the Museum of Natural Sciences in Barcelona. It was first discovered over a century ago and received some scientific interest in the 1990s, but recent research has uncovered previously hidden details. Paleontologists Oscar Castillo and Jesús Serrano were compiling a database of fossils from the Montsec region when they examined the holotype of Montsecosuchus depereti under ultraviolet light. This technique revealed structures that had remained invisible in the rock, including the shape and distribution of soft tissues like epidermal scales. This is the first detailed look at the skin of this ancient crocodile, which is known to science since the early 1900s. The scales of Montsecosuchus depereti varied in size and shape across the body, and the animal lacked the prominent tail fin seen in modern crocodiles. Researchers also identified possible sensory structures in the skin, particularly around the neck, limbs, and along the trunk and tail. In living crocodiles, such structures can detect touch, water pressure, and even chemical signals. In Montsecosuchus, these structures appeared only in small scales on the edges of the body, suggesting that sensory organs may have evolved in specific areas before spreading across the skin in later crocodile relatives. The ultraviolet analysis also revealed cartilaginous structures in the chest, indicating that Montsecosuchus had a respiratory system similar to that of modern crocodiles. This suggests that efficient breathing mechanisms evolved early in crocodile history, despite the animal being considered relatively primitive. The fossil also shows alternating light and dark bands on the tail, which researchers believe could represent the animal’s original coloration. These patterns may have helped it blend into its environment, making it harder for predators or prey to spot. While the exact colors remain unknown, scientists speculate that they were not vastly different from those of modern crocodiles. The discovery highlights the significance of the Catalan fossil record in understanding the evolution of ancient vertebrates. La Pedrera de Meià, the site where the fossil was found, is classified as a Konservat-Lagerstätte—a rare type of fossil site where soft tissues are exceptionally well preserved. This site has yielded over 8,000 fossils, including spiders, insects, fish, amphibians, and early plants like Montsechia, the first known flowering plant. The Montsec de Meià Interpretation Center in Vilanova de Meià showcases more than 100 of these remarkable fossils, and the Orígens Geopark offers an online collection of the site’s most notable specimens. The fossil record from this area is also part of the "Dinosaurs of the Pyrenees" project, which aims to highlight the rich paleontological history of the Catalan Pyrenees.