1Department of Anatomical Sciences, Stony Brook University, 2Interdepartmental Doctoral Program in Anthropological Sciences, Stony Brook University
Saturday Morning, Alexander's
A primate’s preference for terrestrial or arboreal substrates plays an important role in other aspects of its biology including its locomotor behaviors. Unfortunately, determining substrate preference in extinct taxa is difficult for obvious reasons. Morphometric indices have been developed based on the postcranial skeleton of living primates with known behaviors that distinguish terrestrial and arboreal species. These metrics have been used to reconstruct substrate preferences, and thus locomotor behaviors in fossil primates. Particularly discriminating regions of the fore- and hind limbs include the hand, elbow, shoulder and ankle. However, morphological indicators of behavior are products of their evolutionary history. Therefore, discerning skeletal indicators of substrate preferences that are related to adaptations to arboreal or terrestrial niches and less tightly correlated to phylogenetic history is essential for constructing useful models for understanding the evolution of fossil taxa. To define indices with the strongest functional signal, we collected morphometric data from readily fossilized postcranial elements including the proximal ulna, distal humerus, astragalus, calcaneus, and phalanges from a diverse sample of extant primates and non-primate mammals that contain terrestrial and arboreal forms (i.e., Carnivora, Rodentia, and Marsupialia). Using a supertree including branch lengths for all clades included in this analysis, we applied phylogenetic comparative methods to our measurements to explicitly calculate the phylogenetic signal reflected by each variable. Although some metrics were significantly influenced by phylogeny in some clades, others do prove to be reliable for identifying substrate preferences in living mammals, and therefore are useful in reconstructing behavior in fossil taxa.