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 million years old.
Nuciruptor resembles living pitheciins in having elongated, 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 diastemata separate its lower incisors from the
canines. 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. Neither 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. The monkeys of the Honda Group arguably were living in habitat that was in contact with the
Amazon and
Orinoco Basins, and that La Venta itself was probably seasonally dry forest. == See also ==