Primates and the Early Miocene mammalian arboreal guild of Patagonia

VIZCAÍNO S.F.; TOLEDO N.; BARGO, M.S.; MUÑOZ, N. A.

Austin

Congreso; The 87th Annual Meeting of the American Association of Physical Anthropologists; 2018

American Association of Physical Anthropologists

During the Early Miocene, a time interval that includes the initiation of the Mid-Miocene Climatic Optimum, platyrrhines lived at 51°S in Argentine Patagonia, well beyond their most southern modern distribution. Homunculus patagonicus, the best known taxon, is represented by crania, mandibles, teeth, and a several postcranial elements, allowing the reconstruction of its position within the mammalian arboreal guild. We employed a broad array of data and methods to analyze three main biological traits - body size, diet, and substrate use- for all the arboreal mammals of a geographically and temporally restricted paleofauna (dated at 17.5-17.4 Ma), which is among the late Early Miocene paleocommunities known from the coastal Atlantic localities of the Santa Cruz Formation. Homunculus patagonicus has been estimated as an approximately 2.7 kg, above-branch quadruped that fed on mixtures of fruits and leaves. It shared the herbivorous arboreal guild with some seven genera of sloths (leaf eaters, between 30-100 kg) and two of rodents (one a fruit and leaf eater of ~0.65 kg; and the other a leaf eater of ~10-15 kg); none of them similar in size to H. patagonicus. Body size must have constrained branch size use, reducing competition among herbivores. Daily activity patterns (i.e., diurnal vs. nocturnal habits) may have been additional factors influencing putative niche partition. However, although H. patagonicus has been proposed as probably diurnal, such patterns cannot yet be assessed for most taxa. The scansorial borhyaenid metathere Acrocyon sectorius (~11.5 kg) may have been its main predator.