ribs, in front view protruding upwards in a V-shape, their inner sides creating a smooth, flat, top surface of the front tail vertebrae. The end of each caudal rib was furnished with a forward projecting hook-shaped expansion that connected to the caudal rib of the preceding vertebra. Forelimbs The forelimbs were proportionally shorter than in any other large carnivorous dinosaurs, including T.rex. The forearm was only a quarter the size of the upper arm. There were no carpalia in the hand, so that the metacarpals articulated directly with the forearm. The hand showed four basic digits, though apparently only the middle two of these ended in finger bones, while the fourth consisted of a single splint-like metacarpal that may have represented an external 'spur'. The fingers themselves were fused and immobile, and may have lacked claws. Carnotaurus differed from all other abelisaurids in having proportionally shorter and more robust forelimbs, and in having the fourth, splint-like metacarpal as the longest bone in the hand. A 2009 study suggests that the arms were vestigial in abelisaurids, because nerve fibers responsible for stimulus transmission were reduced to an extent seen in today's emus and kiwis, which also have vestigial forelimbs. Skin Carnotaurus was the first theropod dinosaur discovered with a significant number of fossil skin impressions. These impressions, found beneath the skeleton's right side, come from different body parts, including the lower jaw, the front of the neck, the shoulder girdle, and the rib cage. The largest patch of skin corresponds to the anterior part of the tail. Originally, the right side of the skull also was covered with large patches of skin—this was not recognized when the skull was prepared, and these patches were accidentally destroyed. However, the surface texture of several skull bones allows for inferences on their probable covering. A hummocky surface with grooves, pits, and small openings is found on the sides and front of the snout and indicates a scaly covering, possibly with flat scales as in today's crocodilians. The top of the snout was sculptured with numerous small holes and spikes – this texture can probably be correlated with a cornified pad (horny covering). Such a pad also occurred in Majungasaurus but was absent in Abelisaurus and Rugops. A row of large scales did probably surround the eye, as indicated by a hummocky surface with longitudinal grooves on the lacrimal and postorbital bones. The skin was