An assessment of the anseriform affinities of “Telmabates” howardae

Abstract

“Telmabates” howardae, identified from a tibiotarsus discovered in the early Eocene Las Flores Formation in Chubut Province, Argentina, was initially classified under the extinct family Presbyornithidae. However, this classification was later dismissed, and it was deemed incertae sedis. In this study, we suggest a new genus for “Telmabates” howardae and evaluate its relationships within Anseriformes. Its familial relationships remain unclear due to the location of the distal opening of the canalis extensorius, the shape of the sulcus m. fibularis (smooth and laterally bounded by a ridge, similar to that of Saintandrea or Dendrocygna), and the medial position of the condyles. However, unlike Anatidae and Romainvillidae, the condylus medialis is smaller and blunt, whereas in these taxa, it is large and narrow. This suggests that this species was more terrestrial and less adapted to swimming than Anatidae.