Cebupithecia

Cebupithecia is an extinct genus of New World monkeys from the Middle Miocene (Laventan in the South American land mammal ages; 13.8 to 11.8 Ma). Its remains have been found at the Konzentrat-Lagerstätte of La Venta in the Honda Group of Colombia. The type species is "C. sarmientoi".
Description.
Fossils of "Cebupithecia" were discovered in the "Monkey Beds" of the Honda Group, that has been dated to the Laventan, about 13.5 Ma. "Cebupithecia" had a dental formula of 2:1:3:3 on the lower jaw. The incisors of this species were procumbant, suggesting a close relation to "Pithecia". and the canines had a stout appearance. The molars were flat with cusps having little contours. "Cebupithecia" had an estimated average body mass of around . "Cebupithecia" had a relatively longer talar neck and a higher, more squared-shaped talar body. In these features, "Cebupithecia" is more like cebines or aotins than pitheciines, but its overall pattern is unlike any living platyrrhine group or any of the known fossils.
Movement.
"Cebupithecia" also exhibits a relatively large medial protuberance which is smoothed, another resemblance to aotins. The significance of these characters is difficult to interpret. "Cebupithecia" may be the most primitive known pitheciine, retaining shared primitive resemblances with aotins and cebines. Alternatively, its unusual morphology could reflect a unique, derived (for pitheciines) locomotor pattern. The talar features which distinguish "Cebupithecia" from other pitheciines indicate that leaping was relatively more frequent, as is also indicated by other postcranial features. The locomotor behavior of "Cebupithecia" has been reconstructed as frequent quadrupedalism and leaping, or more relying on vertical clinging and leaping rather than quadrupedal locomotion, much like members of the extant genus "Pithecia", to which the genus is related.
Later research suggests that "Cebupithecia" may have employed its tail differently than most nonprehensile-tailed platyrrhines living today, behaviors that
possibly involved tail-bracing or twisting during hindlimb (pedal grasping) suspensory behaviors. Such behaviors may serve as a preadaptive model for the full-fledged evolution of below-branch tail suspension and prehensility seen in other New World primates.
Evolution.
The evolutionary split between Pitheciidae, of which "Cebupithecia", and "Callicebus", including "Miocallicebus", also found in the Honda Group, has been placed at 15.2 million years ago.
Habitat.
The Honda Group, and more precisely the "Monkey Beds", are the richest site for fossil primates in South America. It has been argued that the monkeys of the Honda Group were living in habitat that was in contact with the Amazon and Orinoco Basins, and that La Venta itself was probably seasonally dry forest. From the same level as where "Cebupithecia" has been found, also fossils of "Aotus dindensis", "Micodon", "Mohanamico", "Saimiri annectens", "Saimiri fieldsi" and "Stirtonia tatacoensis" have been uncovered.