Dolichocebus gaimanensis Is Not a Stem Platyrrhine

The lower molars of the early Miocene New World monkey Dolichocebus gaimanensis from Patagonia, considered by some to be a stem platyrrhine, are for all intents and purposes indistinguishable from the same teeth preserved in the type specimen of the middle Miocene Laventiana annectens from Colombia. Canine morphology further indicates that Dolichocebus is a cebine, closely related to living Saimiri. The phenetic and phyletic continuity of these extinct species, here classified as congeners, means they are the first fossil platyrrhines that link South America's southern and northern Miocene monkey faunas, possibly as vicariant communities or with ancestral-descendant species that evolved by phyletic evolution. These findings further refute the hypothesis that early Miocene platyrrhines are (1) monophyletic and (2) outside the so-called crown platyrrhine radiation. The connection between these species is additional evidence supporting the hypothesis that the pattern of platyrrhine evolution is notably distinct for the predominance of low-level taxonomic clades (genera, tribes, subfamilies) of prolonged ecophylogenetic stability, which is the essence of the Long-Lineage Hypothesis.