First skull ofAntillothrix bernensis, an extinct relict monkey from the Dominican Republic

Abstract

The nearly pristine remains of Antillothrix bernensis, a capuchin-sized (Cebus) extinct platyrrhine from the Dominican Republic, have been found submerged in an underwater cave. This represents the first specimen of an extinct Caribbean primate with diagnostic craniodental and skeletal parts in association, only the second example of a skull from the region, and one of the most complete specimens of a fossil platyrrhine cranium yet discovered. Cranially, it closely resembles living cebines but is more conservative. Dentally, it is less bunodont and more primitive than Cebus, with crowns resembling Saimiri (squirrel monkeys) and one of the oldest definitive cebines, the late Early Miocene Killikaike blakei from Argentina. The tricuspid second molar also resembles the enigmatic marmosets and tamarins, whose origins continue to present a major gap in knowledge of primate evolution. While the femur is oddly short and stout, the ulna, though more robust, compares well with Cebus. As a member of the cebid clade, Antillothrix demonstrates that insular Caribbean monkeys are not monophyletically related and may not be the product of a single colonizing event. Antillothrix bernensis is an intriguing mosaic whose primitive characters are consistent with an early origin, possibly antedating the assembly of the modern primate fauna in greater Amazonia during the La Venta horizon. While most Greater Antillean primate specimens are quite young geologically, this vanished radiation, known from Cuba (Paralouatta) and Jamaica (Xenothrix) as well as Hispaniola, appears to be composed of long-lived lineages like several other mainland clades.

Preliminary notes on a newly discovered skull of the extinct monkey Antillothrix from Hispaniola and the origin of the Greater Antillean monkeys

“…Rosenberger et al (2010) describe a femur and ulna of the same animal, and suggest that this species was a heavily built arborealist that may have engaged in arboreal climbing. However, an undescribed distal humerus from Trou Wòch Sa Wo, Haiti, associated with teeth referable to A. bernensis, resembles that of typical platyrrhine arboreal quadrupeds (personal observation, MacPhee et al, 2007; MacPhee, 2009).…”

“…The nuchal plane is oriented quite vertically, and the angle of basicranial flexion is distinctly airorhynch. Some of the features of the new skull (the robusticity of the zygomatic arch and the degree of cranial flexure) are unknown hithertodthe area is broken away in the recently described specimen MHD-01 1 (Rosenberger et al, 2010 report a narrow interorbital breadth and a small postglenoid process in MHD-01. These features may be accounted for by age differences.…”

“…Another specimen consisting of a skull reassembled from fragments, associated with postcranial bones of a young adult Antillothrix, was reported after submission of this manuscript (Rosenberger et al, 2010).…”

“…MacPhee and Woods (1982) agreed that CENDIA-1 is cebine, but elevated it to a new genus, Antillothrix. Some researchers continue to regard Antillothrix as a cebine (Saimiri plus Cebus) (Rosenberger, 2002;Rosenberger et al, 2010), while others combine Antillothrix, Paralouatta and Xenothrix into a clade that they consider to be a sistertaxon to Callicebus (MacPhee et al, 1995;Horovitz, 1999;MacPhee and Horovitz, 2004) (Fig. 3).…”

“…Definitive phylogenetic placement of Antillothrix awaits a revised phylogenetic analysis combining Paralouatta, Xenothrix, PN-09-01, and MHD-01 (Rosenberger et al, 2010). Such an analysis may provide insight into the manner and timing of the arrival of mammals into the Greater Antilles.…”