Nuciruptor

Nuciruptor 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 "N. rubricae".
Etymology.
The name "Nuciruptor rubricae" is derived from the Latin "nuci" ("nut") and "ruptor" meaning "to break". "Rubricae" refers to the red beds where the fossils have been found.
Description.
A lower mandible fossil of "Nuciruptor" was discovered in the El Cardón redbeds of the Cerro Colorado Member of the Villavieja Formation, Honda Group, just below the San Francisco Sandstone which has been dated to the Laventan, about 12.8 ± 0.2 Ma. From the same locality, fossils of "Saimiri annectens" were recovered.
"Nuciruptor" resembles living pitheciins in having elongate, procumbent, and styliform lower incisors with very weak lingual heels. Moreover, as in living pitheciins, the incisors are set in a procumbently oriented mandibular symphysis, and its mandibular corpus deepens appreciably under the molars. At the same time, "Nuciruptor" does not possess several of the distinctive synapomorphies of extant pitheciins. "Nuciruptor" remains more primitive than living pitheciins in that no diastema separates its lower incisors from the canine. Its lower canines retain the primitive structure in not having a sharply deﬁned protocristid. P2 is not a robust or high-crowned tooth and does not have a metaconid. Nor are the other premolars molarised by the addition of large talonids. The estimated weight of "Nuciruptor" was . The genus shows similarity with another fossil primate from La Venta, "Cebupithecia".
As "Cebupithecia", "Nuciruptor" is thought to be an ancestral saki (Pitheciidae).
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.