Article

A geometric morphometric analysis of hominin upper first molar shape.

Centro Nacional de Investigación sobre Evolución Humana (CENIEH), Avda. de la Paz, 28, 09006 Burgos, Spain.
Journal of Human Evolution (Impact Factor: 3.87). 10/2007; 53(3):272-85. DOI: 10.1016/j.jhevol.2007.02.002
Source: PubMed

ABSTRACT Recent studies have revealed interesting differences in upper first molar morphology across the hominin fossil record, particularly significant between H. sapiens and H. neanderthalensis. Usually these analyses have been performed by means of classic morphometric methods, including the measurement of relative cusp areas or the angles defined between cusps. Although these studies have provided valuable information for the morphological characterization of some hominin species, we believe that the analysis of this particular tooth could be more conclusive for taxonomic assignment. In this study, we have applied geometric morphometric methods to explore the morphological variability of the upper first molar (M(1)) across the human fossil record. Our emphasis focuses on the study of the phenetic relationships among the European middle Pleistocene populations (designated as H. heidelbergensis) with H. neanderthalensis and H. sapiens, but the inclusion of Australopithecus and early Homo specimens has helped us to assess the polarity of the observed traits. H. neanderthalensis presents a unique morphology characterized by a relatively distal displacement of the lingual cusps and protrusion in the external outline of a large and bulging hypocone. This morphology can be found in a less pronounced degree in the European early and middle Pleistocene populations, and reaches its maximum expression with the H. neanderthalensis lineage. In contrast, modern humans retain the primitive morphology with a square occlusal polygon associated with a round external outline.

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    08/2012, Degree: Masters of Science in Geosciences, Supervisor: Steven Wallace
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    08/2012, Degree: Masters of Science in Geosciences, concentrating in Paleontology, East Tennessee State University, Supervisor: Steven Wallace
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    [Show abstract] [Hide abstract]
    ABSTRACT: Guy Wilson Cave (GWC) in Sullivan County, Tennessee holds many late Pleistocene mammal fossils. Based on visual morphology, several partial mandibles with lower carnassial from GWC appeared to be musteloids. Geometric morphometrics has been successfully used to identify fragmentary fossils, so a landmark based, 2 dimensional technique was applied to identify the GWC musteloids using the lower carnassial. Digital images of several GWC fossils and of extant reference musteloids were combined using morphometric programs tpsDIG1, tpsUtil, and tpsSuper. Statistical data analysis was performed in PASW Statistics. Results successfully separated Mephitis mephitis (striped skunk) from M. macroura (hooded skunk) and Martes americana (American marten) from M. pennanti (fisher). Sex-based and geographical patterns were also found in the data. Sex separated all three species via the lower carnassial. Geographic divisions were found for Mephitis mephitis, Martes americana and M. pennanti populations that hint at interestingly unique biogeographical histories for each taxon.
    08/2012, Degree: Masters of Science in Geosciences, concentrating in Paleontology, East Tennessee State University, Supervisor: Steven Wallace

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