Ahvaytum
From Shoshone 'An va·tum' meaning 'long ago', referring to the ancient nature of the specimen.
Late Triassic stages
Ahvaytum is an extinct genus of probable basal sauropodomorph saurischian dinosaurs from the Late Triassic Popo Agie Formation of Wyoming, United States. The genus contains a single species, A. bahndooiveche, known from fragmentary hindlimb bones. Ahvaytum represents the oldest known named dinosaur of the ancient Laurasian landmass.
Diagnosis
- Fossa on medial surface of astragalus that is open distally (autapomorphic among dinosaurs)
- Tibial facet does not extend onto anteromedial corner of astragalus
- Shallow laterodistal notch of astragalus
- Posterolateral ridge between anterior ascending process and posterolateral process taller than posterolateral process
- Proportionally wider astragalus with width/length ratio of 0.53; relatively wide fibular facet occupying more than one-quarter of transverse width
Species
Ahvaytum bahndooiveche Lovelace et al., 2025
Type species
From Shoshone 'ban·döi·ve·che' meaning "water's young handsome man" (a regional reference to salamanders) combined with the Shoshone word for 'dinosaur'.
- Holotype
- UWGM 1975 , University of Wisconsin Geology Museum
- Material
- Isolated left astragalus.
- Horizon
- lower Popo Agie Formation, Carnian, Late Triassic , 237.0–227.3 million years ago
- Locality
- Garrett's Surprise, Wyoming, United States
References
- Lovelace, D. M.; Kufner, A. M.; Fitch, A. J.; Curry Rogers, K.; Schmitz, M.; Schwartz, D. M.; LeClair-Diaz, A.; St.Clair, L.; Mann, J.; Teran, R. (2025). Rethinking dinosaur origins: oldest known equatorial dinosaur-bearing assemblage (mid-late Carnian Popo Agie FM, Wyoming, USA). Zoological Journal of the Linnean Society 203(1): zlae153. Oxford University Press. doi:10.1093/zoolinnean/zlae153 lovelace2025a