The fragmentary holotype specimen of Noasaurus, PVL 4061, was discovered in the 1970s by Jaime Eduardo Powell and José Fernando Bonaparte and comes from strata from the Lecho Formation.

In the mid-seventies, the fragmentary skeleton of a small theropod was discovered by Jaime Eduardo Powell and José Fernando Bonaparte at the El Brete fossil site in Salta Province, Argentina.

[3] The holotype of Noasaurus, PVL 4061, was found in a layer of the Lecho Formation dating from the late Cretaceous period, more precisely the early Maastrichtian stage, about seventy million years ago.

[4] 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.

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.

The alveolar margin of the maxilla was concave, and the dorsal (top) part of the maxillary fossa bore a diagonal ridge.

[1] Based on Noasaurus' elongated cervical vertebrae and comparisons with other noasaurids, its neck was long and sigmoidal, bearing an S-shaped curve.

The following cladogram is based on the phylogenetic analysis conducted by Rauhut and Carrano in 2016, showing the relationships of Elaphrosaurus among the noasaurids:[10]Abelisauridae Laevisuchus Deltadromeus Limusaurus

Noting that abelisaurids tend to have very short arms, he wondered whether the forelimbs of Noasaurus were of limited length also, forcing the animal to employ a kicking technique instead of grasping the back of a victim in order to disembowel it with the foot claws, a method he assumed the dromaeosaurids used.

[9] Instead, as proposed by Hendrickx et al. in 2024, it may have been utilised to snag fish from the water, making it instead convergent with the enlarged thumb claw of spinosaurids like Baryonyx.