Ahvaytum bahndooiveche was named by Lovelace et al. (2025) [Ahvaytum bahndooiveche shares a combination of features present in sauropodomorph dinosaurs to the exclusion of theropods, herrerasaurs, and ornithischians, including: a flat, roller-shaped distal surface of the astragalus shared with sauropodomorphs but not herrerasaurs and neotheropods (Marsh et al. 2019); a tibial facet that does not extend on to the anteromedial corner of the astragalus shared with all sauropodomorphs in our study, the silesaurid Lewisuchus admixtus Romer, 1972, the theropods Lepidus praecisio and Eodromaeus murphi Martinez et al., 2011, and the herrerasaurs Tawa hallae Nesbitt et al., 2009 and Chindesaurus bryansmalli Long and Murry, 1995; a shallow laterodistal notch of the astragalus shared with non-massopodan sauropodomorphs, except Panphagia protos Martinez and Alcober, 2009 and Efraasia minor von Huene, 1875 (sensu Galton 1973) and the herrerasaur T. hallae; a rounded anterior and medial margin on the proximomedial surface of the astragalus shared with the theropod Eodromaeus murphi and sauropodomorphs, except Saturnalia tupiniquim Langer et al., 1999 and a referred specimen of Buriolestes schultzi Cabreira et al., 2016 (sensu Moro et al. 2024); a posterolateral ridge between the anterior ascending process and the posterolateral process that is always taller than the posterolateral process shared with the herrerasaurids Herrerasaurus ischgualastensis Reig, 1963 and Sanjuansaurus gordilloi Alcober and Martnez, 2010 and sauropodomorphs, except Unaysaurus tolentinoi Leal et al., 2004. Ahvaytum bahndooiveche is differentiated from all other sauropodomorphs with comparable material by the following autapomorphy: fossa on the medial surface of the astragalus that is open distally. Ahvaytum bahndooiveche is differentiated from Eoraptor lunensis Sereno et al., 1993, Mbiresaurus raathi Griffin et al., 2022, P. protos, S. tupiniquim, and a referred specimen of B. schultzi by a proportionally wider astragalus (max. anteroposterior length/max. transverse width: Ahvaytum0.53, Buriolestes0.71, Eoraptor0.63, Mbiresaurus0.64, Panphagia0.88, and Saturnalia0.73) and by a relatively wide fibular facet occupying more than a quarter of the transverse width of the astragalus. Further differentiated from Eoraptor lunensis by a posteromedial angle on the astragalus. Further differentiated from a referred specimen of B. schultzi (Moro et al., 2024) by a poorly proximally expanded posteromedial process (pyramidal process of some authors) and by a relatively tall posterolateral process (posterior ascending process of some authors). Further differentiated from both B. schultzi and M. raathi by a posterolateral process that is level with the posterior margin of the astragalus in proximal view.]. Its type specimen is UWGM 1975, a limb element (isolated left astragalus), and it is a 3D body fossil. Its type locality is Garrett's Surprise, which is in a Carnian terrestrial horizon in the Popo Agie Formation of Wyoming. It is the type species of Ahvaytum.