Alcidedorbignya

Alcidedorbignya is an extinct pantodont mammal known from the Early Paleocene Santa Lucia Formation at Tiupampa near Mizque, Cochabamba, Bolivia.
Following a naming convention established by pioneering Argentine palaeontologist Florentino Ameghino, the genus name honours French naturalist Alcide d'Orbigny.

Description

Estimated 25 cm head-body length and 500 grams, this was a small squirrel sized animal, terrestrial with possible scansorial habits, and either herbivorous or omnivorous.
Alcidedorbignya is one of the oldest and most primitive of the pantodonts and the only pantodont genus known from South America. Not only have some scientists questioned the age of the type locality, instead advocating an Asian origin for the pantodonts, Alcidedorbignya's bare existence obscures the origins of the already enigmatic pantodonts. Taxonomic similarities indicate that there was a mammalian interchange between North and South America during the early Paleocene, and the North American pantodont Pantolambda is a potential descendant of Alcidedorbignya.
Alciddedorbignya is known from several specimens of upper and lower dentitions, including juveniles. P^3–4 have V-shaped ectolophs, indicating it was a primitive pantodont. Other molar characteristics makes it unique among pantodonts. On the molars, the paracone and metacone are separated and not connate as in Bemalambda and Harpyodus. As in these two genera, there is neither a mesostyle on M^1–2 nor a strongly V-shaped centocrista as in eupantodonts. It is still unclear which the primitive condition is in pantodont upper dentition, and the position of Alcidedorbignya near the base of the clade remain unresolved.