Primate origins: Lessons from a neotropical marsupial

Abstract

The didelphid Caluromys shows evolutionary convergence towards prosimians in having a relatively large brain, large eyes, small litters, slow development, and agile locomotion. The selection pressures that favored the emergence of primate-like traits in Caluromys from a generalized didelphid ancestor may be analogous to the selection pressures favoring the initial divergence of primates from a primitive nonprimate ancestor, and thus Caluromys provides an independent test of the arboreal hypothesis Primates, pp. 97-122, 1972), and the angiosperm exploitation hypothesis (Sussman: American Journal of Primatologx in press) of primate origins. Quantitative data on freeranging C. derbianus in Costa Rica demonstrate that it is highly arboreal, uses visually directed predation to capture arthropod prey, and makes extensive use of terminal branch foraging, where it feeds on small angiosperm products. These observations are consistent with predictions from each model of primate origins, thus suggesting that the hypotheses are not mutually exclusive but are interdependent. The initial divergence of primates probably involved exploitation of the rich angiosperm products and associated insects found in fine terminal branches; visually directed predation may have evolved as an efficient method of insect capture in the terminal branch milieu.

Primate origins, human origins, and the end of higher taxa

“…Several recent accounts 64,102,114 suggest that the features that distinguish primates from other mammals today originated through a gradual accretion of small adaptive changes, producing a cascade of more and more concentrically arranged taxa with smaller and smaller clusters of less and less important synapomorphies (Fig. 5), just as we saw in the early mammals.…”

Effects of support diameter and compliance on common marmoset (Callithrix jacchus) gait kinematics

“…Because the fine-branch environment has often been cited as the fundamental niche of early primates (e.g. Cartmill, 1972;Rasmussen, 1990;Sussman et al, 2013), investigating the precise mechanical demands of moving on supports that are both narrow and compliant is critical to understanding primate locomotor adaptation and evolution.…”

Forelimb proportions and kinematics: how are small primates different from other small mammals?

“…Several authors have, therefore, emphasised the importance of studying the behaviour and ecology of small arboreal mammals in reconstructing the early evolution of primates and understanding the functional significance of special morphological adaptations (LeGros Clark, 1959;Cartmill, 1972;Martin, 1972;Cartmill, 1974;Jenkins, 1974;Rasmussen, 1990;Gebo, 2004;Sargis et al, 2007). Various locomotor studies have shown that small mammals display a high level of similarity in their locomotor kinematics and limb proportions independent of phylogeny and locomotor habitat (Jenkins, 1971;Fischer et al, 2002).…”