Montsecosuchus depereti fossil shows soft tissues under UV light

UV Light Exposes Hidden Soft Tissues in Montsecosuchus depereti

Paleontologists Oscar Castillo-Visa and Jesús Serrano identified the soft tissue structures while building a database of fossils from the Montsec mountain range. When illuminated with ultraviolet rays, the fossilized tissues fluoresced differently from the surrounding limestone matrix, revealing details that remained hidden under normal lighting conditions since the specimen was unearthed more than a century ago. According to Oscar Castillo-Visa, the lead author of the research, UV light allows scientists to observe features that would otherwise stay completely concealed within the rock.

Early Skin Morphology and Sensory Organ Distribution

The analysis provides the first detailed description of the skin of Montsecosuchus depereti, documenting epidermal scales that varied significantly in shape and size across the roughly 50-centimeter-long body. The specimen lacks the vertically flattened caudal fin seen in modern crocodiles. Instead, researchers identified possible sensory organs located within specific scales around the neck, limbs, and the lateral margins of the trunk and tail. In living crocodilians, these localized structures function as receptors for touch, water pressure variations, thermal shifts, and chemical stimuli. Their restriction to the outer edges of the body in the fossil suggests such sensory systems may have evolved in localized areas before spreading more broadly across later lineages.

Respiratory Anatomy and Semi-Aquatic Adaptations

Ultraviolet imaging also exposed cartilaginous structures within the thorax of the fossil. These anatomical features indicate that the ancient species possessed an efficient respiratory system sharing key similarities with modern crocodiles. The combination of thoracic cartilage and localized sensory scales demonstrates that despite being an early, primitive animal, the species was already well adapted to a semi-aquatic lifestyle in the karstic lake environment of the Catalan Pre-Pyrenees, as noted by lead author Castillo-Visa.

Possible Ancient Coloration and Camouflage Patterns

The most striking observation involves alternating light and dark bands visible across some of the tail scales under UV light. Researchers interpret these transverse markings as the animal’s original color pattern, which could have functioned as camouflage to break up the silhouette of the reptile. While co-author Albert G. Sellés emphasizes that the exact hues cannot be confirmed from the fossil, a verified pattern would make Montsecosuchus the oldest known crocodylomorph with preserved evidence of coloration.

Frequently Asked Questions

When and where was the Montsecosuchus depereti fossil discovered?

The 50-centimeter-long specimen was unearthed more than a century ago at the Pedrera de Meià site in Catalonia, Spain, and is currently housed at the Museum of Natural Sciences of Barcelona.

What technology revealed the hidden soft tissues?

Researchers Oscar Castillo-Visa and Jesús Serrano used ultraviolet (UV) light, which caused the fossilized epidermal scales, cartilage, and tissue remnants to stand out against the surrounding limestone.

Does the fossil preserve the actual colors of the ancient crocodile?

The UV light revealed transverse light and dark bands on the tail scales interpreted as a color pattern for camouflage, but researchers cannot determine the exact original colors.