built up of a mosaic of polygonal, non-overlapping scales measuring approximately in diameter. This mosaic was divided by thin, parallel grooves. Scalation was similar across different body parts with the exception of the head, which apparently showed a different, irregular pattern of scales. There is no evidence of feathers. Larger bump-like structures were distributed over the sides of the neck, back and tail in irregular rows. These bumps were in diameter and up to in height and often showed a low midline ridge. They were set apart from each other and became larger towards the animal's top. The bumps probably represent feature scales – clusters of condensed scutes – similar to those seen on the soft frill running along the body midline in hadrosaurid ("duck-billed") dinosaurs. These structures did not contain bone. Stephen Czerkas (1997) suggested that these structures may have protected the animal's sides while fighting members of the same species (conspecifics) and other theropods, arguing that similar structures can be found on the neck of the modern iguana where they provide limited protection in combat. More recent studies of the skin of Carnotaurus published in 2021 suggest that previous depictions of the scales on the body are inaccurate, and the larger feature scales were randomly distributed along the body, not distributed in discrete rows like in older artistic depictions and illustrations. There is also no sign of progressive size variation in feature scales along different areas along the body. The basement scales of Carnotaurus were by comparison highly variable, ranging in size from small and elongated, to large and polygonal, and from circular-to-lenticular in the thoracic, scapular, and tail regions, respectively. This scale differentiation may have been related to regulating body heat and shedding excess heat via thermoregulation due to its large body size and active lifestyle. Classification Carnotaurus is one of the best-understood genera of the Abelisauridae, a family of large theropods restricted to the ancient southern supercontinent Gondwana. Abelisaurids were the dominant predators in the Late Cretaceous of Gondwana, replacing the carcharodontosaurids and occupying the ecological niche filled by the tyrannosaurids in the northern continents. Several notable traits that evolved within this family, including shortening of the skull and arms as well as peculiarities in the cervical and caudal vertebrae, were more pronounced in Carnotaurus than in any other abelisaurid. Though relationships within the Abelisauridae are debated, Carnotaurus is consistently shown to be one of the