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| Ashaninkacebus simpsoni Marivaux, Negri, Antoine, Stutz, Condamine, Kerber, Pujos, Santos, Alvim, Hsiou, Bissaro, Adami-Rodrigues & Ribeiro, 2023 |
Abstract
Recent fossil discoveries in Western Amazonia revealed that two distinct anthropoid primate clades of African origin colonized South America near the Eocene/Oligocene transition (ca. 34 Ma). Here, we describe a diminutive fossil primate from Brazilian Amazonia and suggest that, surprisingly, a third clade of anthropoids was involved in the Paleogene colonization of South America by primates. This new taxon, Ashaninkacebus simpsoni gen. et sp. nov., has strong dental affinities with Asian African stem anthropoids: the Eosimiiformes. Morphology-based phylogenetic analyses of early Old World anthropoids and extinct and extant New World monkeys (platyrrhines) support relationships of both Ashaninkacebus and Amamria (late middle Eocene, North Africa) to the South Asian Eosimiidae. Afro-Arabia, then a mega island, played the role of a biogeographic stopover between South Asia and South America for anthropoid primates and hystricognathous rodents. The earliest primates from South America bear little adaptive resemblance to later Oligocene-early Miocene platyrrhine monkeys, and the scarcity of available paleontological data precludes elucidating firmly their affinities with or within Platyrrhini. Nonetheless, these data shed light on some of their life history traits, revealing a particularly small body size and a diet consisting primarily of insects and possibly fruit, which would have increased their chances of survival on a natural floating island during this extraordinary over-water trip to South America from Africa. Divergence-time estimates between Old and New World taxa indicate that the transatlantic dispersal(s) could source in the intense flooding events associated with the late middle Eocene climatic optimum (ca. 40.5 Ma) in Western Africa.
Keywords: Brazilian Amazonia; Platyrrhini; paleobiogeography; phylogeny; teeth.
Ashaninkacebus simpsoni gen. et sp. nov.
Significance:
Western Amazonia has recently revealed that two distinct anthropoid primate clades of African origin colonized South America near the Eocene/Oligocene transition (ca. 34 Ma). Here, we report a new fossil primate from Brazilian Amazonia pointing to a third clade involved in that colonization. Surprisingly, this taxon has strong affinities with eosimiid anthropoids of South Asian origin. These data highlight some of the life history traits (very-small-bodied size and insectivory/frugivory) that would have increased the chances of survival on a natural raft during this extraordinary transatlantic journey from Africa to South America. Estimated splits between New and Old World taxa indicate that the dispersal(s) coincides with the late middle Eocene climatic optimum (ca. 40.5 Ma), which generated intense flooding events.
Laurent Marivaux, Francisco R. Negri, Pierre-Olivier Antoine, Narla S Stutz, Fabien L. Condamine, Leonardo Kerber, François Pujos, Roberto Ventura Santos, André M. V. Alvim, Annie S. Hsiou, Marcos C. Bissaro Jr., Karen Adami-Rodrigues and Ana Maria Ribeiro. 2023. An eosimiid Primate of South Asian Affinities in the Paleogene of Western Amazonia and the Origin of New World Monkeys. Proc Natl Acad Sci USA. 120 (28) e2301338120. DOI: 10.1073/pnas.2301338120
