Eoneophron infernalis Atkins-Weltman et al., 2024 (new genus and species)
(Tibiotarsus [fused shin and ankle bones] of Eoneophron infernalis, from Atkins-Weltman et al., 2024)
Meaning of name: Eoneophron = dawn [in Greek] Neophron [genus of the extant Egyptian vulture, sometimes called the "Pharaoh's chicken"]; infernalis = from Hell [in Latin]
Age: Late Cretaceous (Maastrichtian)
Where found: Hell Creek Formation, South Dakota, U.S.A.
How much is known: A partial right hindlimb.
Notes: Eoneophron was an oviraptorosaur, a group of bird-like theropods with short and often toothless skulls. The only other oviraptorosaur that had previously been named from the Hell Creek Formation was the much larger Anzu, which is estimated as having weighed between 200–350 kg. The type specimen of Eoneophron, on the other hand, is thought to have weighed around 78 kg. However, the microscopic structure of its bones indicates that it was close to fully grown when it died, suggesting that it is not a juvenile specimen of Anzu. Eoneophron is also unusual in that two of its ankle bones were fused to its tibia (shin bone); among oviraptorosaurs, this feature is otherwise known only in Avimimus from the Late Cretaceous of Central Asia.
Reference: Atkins-Weltman, K.L., D.J. Simon, H.N. Woodward, G.F. Funston, and E. Snively. 2024. A new oviraptorosaur (Dinosauria: Theropoda) from the end-Maastrichtian Hell Creek Formation of North America. PLoS ONE 19: e0294901. doi: 10.1371/journal.pone.0294901