Type
Text
Type
Dissertation
Advisor
Demes, Brigitte | Jungers, William L. | Boyer, Doug | Lemelin, Pierre.
Date
2015-12-01
Keywords
Claws, Distal Phalanx, Grooming Claws, Nails, Primate Evolution, Primate Origins | Physical anthropology
Department
Department of Anthropology.
Language
en_US
Source
This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree.
Identifier
http://hdl.handle.net/11401/76955
Publisher
The Graduate School, Stony Brook University: Stony Brook, NY.
Format
application/pdf
Abstract
Human manual dexterity is strongly enhanced by the presence of flattened nails associated with well-developed apical pads. However, the presence of nails is not unique to humans; it is one of the few traits that unite all living primates. Further, the form of the keratinous structure (nail, claw, etc.) on the ends of primate digits is often considered to be a diagnostic trait of major primate clades; strepsirrhines (lemurs, lorises, and galagos) possess a grooming claw (a specialized nail or claw used to scratch and clean the fur around the head and neck) on each second pedal digit; tarsiers possess one on each second and third pedal digit; and most anthropoids (monkeys, apes, and humans) lack one. However, relatively little is known about the, origin, diversity, and homologies of primate nails and grooming claws. This dissertation has two major objectives. The first is to determine the distribution, polarities, and homologies of grooming claws in extant and fossil primates and assess their significance for phylogenetic interpretations. The second is to elucidate patterns in distal phalanx morphology among arboreal mammals in order to better understand the circumstances surrounding the origin of primate nails. Data were collected from a sample of preserved digit tips (n=55) and distal phalanges from extant (n=1106) and fossil species (n=53). These were studied using a variety of methods including traditional and virtual dissection, high resolution imaging techniques, principal components analysis, discriminant function analysis, and ancestral state reconstructions. Major findings can be summarized as follows. Grooming claws are demonstrated to be present in omomyiform primates, and three lineages of platyrrhine monkeys (Aotus, Callicebus, and Pithecia). The likely ancestral condition of the second pedal digit of primates is to bear a grooming claw, and those of strepsirrhines and tarsiers are likely homologous. The presence of primate-like nails in a non-primate mammal that is small bodied (~9g) and inhabits a terminal branch niche (honey possums) is confirmed, and a relationship between primate-like morphology of the distal phalanx and small body size is shown. It is likely that small body size in early primates facilitated the origin of nails. | 209 pages
Recommended Citation
Maiolino, Stephanie A., "Comparative Morphology of Primate Distal Phalanges: Implications for Early Primate Evolution and the Origins of the Primate Nail" (2015). Stony Brook Theses and Dissertations Collection, 2006-2020 (closed to submissions). 2823.
https://commons.library.stonybrook.edu/stony-brook-theses-and-dissertations-collection/2823