Noasaurus

During the latter half of the 20th century, a series of fossil-hunting expeditions were dispatched across to Argentina. In April 1975, an team of college students and paleontologists from the of San Miguel de Tucumán explored fossiliferous outcrops at El Brete, south of the El Brete Estancia, which is a fossiliferous (fossil-bearing) site that is from the middle section of the Lecho Formation. One of the hand claws was initially identified as a second toe claw. The tetrapod fossils of El Brete were first recorded by Boneparte et al. in 1977, including the theropod recovered which was described as belonging to a coelurosaur theropod. The type and only known species, Noasaurus leali, was named and briefly described by Bonaparte and Powell in 1980 alongside Saltasaurus. The generic name Noasaurus begins with a usual abbreviation of noroeste Argentina, "northwest Argentina". The specific name honours the discoverer of the site, Juan Carlos Leal. The unusual nature of Noasaurus' anatomy led Bonaparte to erect the family Noasauridae, a group originally thought to be closely related to the basal coelurosaurians Coelurus and Compsognathus. In 2007 however, it was reidentified as a noasaurid vertebra, probably belonging to the Noasaurus holotype. The decades following Noasaurus' description revealed that it was one of many noasaurid dinosaurs in the group Ceratosauria, with genera named from Madagascar, and many other countries. In 2024, a study by an international team of researchers led by Christophe Hendrickx described the holotype of Noasaurus in further detail and evaluated its paleobiology, paleoecology, classification, and anatomy. ==Description==

Noasaurus was a small theropod. Gregory S. Paul estimated its length at and its weight at . In 2024, Hendrickx et al. used the reconstructed size of the skull and the dimensions of the second metatarsal to provide length estimates of and , respectively. They abstained from providing a mass estimate due to the lack of the necessary limb elements, and the possibility that the Noasaurus holotype was a juvenile. A histological analysis could not be performed on the holotype, as it was prohibited, thus its age is currently unknown. Although a non-ungual phalanx is known (likely from the third digit), the overall manus anatomy of Noasaurus is uncertain, due to the strong modification of abelisauroid forelimbs in comparison to other theropods and the difficulty in ascertaining homology. When articulated, the ungual and digital phalanges are fairly immobile. The only known hind limb element is the second right metatarsal. The medial surface bears a low, elliptical bulge, likely serving as a muscle attachment point, and as the point of origin for the extensor muscles of the second digit. ==Classification==

Noasaurus is today considered to be a member of the Ceratosauria. Originally, it was seen as a member of the Coelurosauria. Bonaparte and Powell assigned it to a family of its own, the Noasauridae.In 2024, Hendrickx et al.. recovered Noasaurus in a polytomy with Laevisuchus, Masiakasaurus, Velocisaurus, and Vespersaurus, likely representing a radiation of small-bodied noasaurids that occurred during the Late Cretaceous. ==Paleobiology==

In 1980, it was thought that the presumed foot claw functioned as a sickle claw. == Palaeoenvironment ==

and Saltasaurus behind The stratigraphic composition of the Lecho Formation, from which the holotype of Noasaurus is known, suggests that its depositional environment was a coastal plain, pockmarked with ponds and lagoons, Outside of dinosaurs (both avian and non-avian), no animal fossils are known from the Lecho Formation. The only named non-avian dinosaur from the locality, outside of Noasaurus, was the titanosaur Saltasaurus, though teeth indicate the presence of a large abelisaurid. ==See also==