Noasaurus

Noasaurus ('Northwestern Argentina lizard') is a genus of ceratosaurian theropod dinosaur genus from the late Campanian-Maastrichtian (Late Cretaceous) of Argentina. The type and only species is N. leali. In the mid-seventies, a fragmentary small theropod skeleton was discovered by Jaime Eduardo Powell and José Fernando Bonaparte at the Estancia El Brete-site. In 1977, the discovery was reported in the scientific literature. The type species, Noasaurus leali, was named and described by Bonaparte and Powell in 1980. The generic name begins with a usual abbreviation of noroeste Argentina, 'northwest Argentina'. The specific name honours the owner of the site, Fidel Leal. The holotype, PVL 4061, was found in a layer of the Lecho Formation of Salta Province, Argentina, dating from the late Cretaceous period, more precisely the early Maastrichtian stage, about seventy million years ago. It consists of a partial skeleton with skull. It contains the maxilla, the quadrate bone, two neck vertebrae, two neck ribs, the centrum of a back vertebra, two hand claws, a finger phalanx and the second right metatarsal bone. One of the hand claws was initially identified as a second toe claw. In 2004, it was recognised as a hand claw, at which occasion the second hand claw was referred. In 1999, a neck vertebra found at the site, specimen MACM 622, was identified as oviraptorosaurian, a rare proof that the Oviraptorosauria had invaded the Gondwanan continents. In 2007 however, it was reidentified as a noasaurid vertebra, probably belonging to the Noasaurus holotype. Noasaurus was a small theropod. Its length has been estimated at 1.5 metres, its weight at fifteen kilogrammes. The maxilla bears at least eleven teeth. The teeth are recurved and have serrations at the front and rear edges. The neck is probably long as the neck vertebrae are very elongated. These vertebrae are also strongly vertically compressed with a low neural spine and bear long epipophyses, a typical abelisauroid trait. While originally reported to have a raptorial 'sickle claw' on the foot similar to the claws of the more advanced dromaeosaurids, subsequent studies showed that the claw actually came from the hand. The claw is exceptionally curved, has parallel base sides in top view, and possesses a deep triangular cavity at the base underside.