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Article: Geometric morphometric analyses of worn cheek teeth help identify extant and extinct gophers (Rodentia, Geomyidae)

Palaeontology - Volume 60 Part 2 - Cover
Publication: Palaeontology
Volume: 60
Part: 2
Publication Date: March 2017
Page(s): 281 307
Author(s): Jonathan J. M. Calede, and Jennifer W. Glusman
Addition Information

How to Cite

CALEDE, J.J.M., GLUSMAN, J.W. 2017. Geometric morphometric analyses of worn cheek teeth help identify extant and extinct gophers (Rodentia, Geomyidae). Palaeontology, 60, 2, 281-307. DOI: 10.1111/pala.12285

Author Information

  • Jonathan J. M. Calede - Department of Biology University of Washington Seattle WA USA (Email: caledj@uw.edu; jjmc001@bucknell.edu)
  • Jonathan J. M. Calede - Burke Museum of Natural History and Culture Seattle WA USA
  • Jennifer W. Glusman - Department of Biology University of Washington Seattle WA USA (Email: wade1047@uw.edu)

Publication History

  • Issue published online: 22 February 2017
  • Manuscript Accepted: 19 January 2017
  • Manuscript Received: 25 August 2016

Funded By

Paleontological Society Caster Award
Geological Society of America
Northwest Scientific Association student grant
Evolving Earth Foundation student research grant
University of California Museum of Paleontology Welles Fund
University of Washington Department of Biology Sargent Award

Online Version Hosted By

Wiley Online Library
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Abstract

Studies of the biostratigraphy and palaeoecology of fossil vertebrate assemblages require large samples of accurately identified specimens. Such analyses can be hampered by the inability to assign isolated and worn remains to specific taxa. Entoptychine gophers are a diverse group of burrowing rodents found in Oligo‐Miocene deposits of the western United States. In both entoptychines and their extant relatives the geomyines, diagnostic characters of the occlusal surface of the teeth are modified with wear, making difficult the identification of many isolated fossil teeth. We use geometric morphometrics to test the hypothesis that tooth shape informs taxonomic affinities and expected levels of morphological variation across gopher taxa. We also incorporate data from microcomputer tomography to investigate changes in occlusal surface shape through wear within individuals. Our analyses demonstrate the usefulness of our approach in identifying extant geomyines to the genus, subgenus and species levels, and fossil entoptychines to the genus and, in some cases, the species level. Our results cast doubt on the validity of some species within Entoptychus and suggest future revisions to entoptychine taxonomy. The amounts of morphological divergence observed among fossil and extant genera are similar. Fossil species do not differ greatly from extant ones in that regard either. Further work evaluating the morphological variation within and across entoptychine species, including unworn teeth and osteological material, will allow revised analyses of the biostratigraphy and palaeoecology of important Oligo‐Miocene mammalian assemblages of the western United States and help to infer the phylogenetic relationships and evolution of gophers.

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