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Oldest evidence for grooming claws in euprimates.

Publication ,  Journal Article
Boyer, DM; Maiolino, SA; Holroyd, PA; Morse, PE; Bloch, JI
Published in: Journal of human evolution
September 2018

Euprimates are unusual among mammals in having fingers and toes with flat nails. While it seems clear that the ancestral stock from which euprimates evolved had claw-bearing digits, the available fossil record has not yet contributed a detailed understanding of the transition from claws to nails. This study helps clarify the evolutionary history of the second pedal digit with fossils representing the distal phalanx of digit two (dpII), and has broader implications for other digits. Among extant primates, the keratinized structure on the pedal dpII widely varies in form. Extant strepsirrhines and tarsiers have narrow, distally tapering, dorsally inclined nails (termed a 'grooming claws' for their use in autogrooming), while extant anthropoids have more typical nails that are wider and lack distal tapering or dorsal inclination. At least two fossil primate species thought to be stem members of the Strepsirrhini appear to have had grooming claws, yet reconstructions of the ancestral euprimate condition based on direct evidence from the fossil record are ambiguous due to inadequate fossil evidence for the earliest haplorhines. Seven recently discovered, isolated distal phalanges from four early Eocene localities in Wyoming (USA) closely resemble those of the pedal dpII in extant prosimians. On the basis of faunal associations, size, and morphology, these specimens are recognized as the grooming phalanges of five genera of haplorhine primates, including one of the oldest known euprimates (∼56 Ma), Teilhardina brandti. Both the phylogenetic distribution and antiquity of primate grooming phalanges now strongly suggest that ancestral euprimates had grooming claws, that these structures were modified from a primitive claw rather than a flat nail, and that the evolutionary loss of 'grooming claws' represents an apomorphy for crown anthropoids.

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Published In

Journal of human evolution

DOI

EISSN

1095-8606

ISSN

0047-2484

Publication Date

September 2018

Volume

122

Start / End Page

1 / 22

Related Subject Headings

  • Wyoming
  • Primates
  • Hoof and Claw
  • Fossils
  • Finger Phalanges
  • Biological Evolution
  • Anthropology
  • Animals
  • 4301 Archaeology
  • 3104 Evolutionary biology
 

Citation

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ICMJE
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Boyer, D. M., Maiolino, S. A., Holroyd, P. A., Morse, P. E., & Bloch, J. I. (2018). Oldest evidence for grooming claws in euprimates. Journal of Human Evolution, 122, 1–22. https://doi.org/10.1016/j.jhevol.2018.03.010
Boyer, Doug M., Stephanie A. Maiolino, Patricia A. Holroyd, Paul E. Morse, and Jonathan I. Bloch. “Oldest evidence for grooming claws in euprimates.Journal of Human Evolution 122 (September 2018): 1–22. https://doi.org/10.1016/j.jhevol.2018.03.010.
Boyer DM, Maiolino SA, Holroyd PA, Morse PE, Bloch JI. Oldest evidence for grooming claws in euprimates. Journal of human evolution. 2018 Sep;122:1–22.
Boyer, Doug M., et al. “Oldest evidence for grooming claws in euprimates.Journal of Human Evolution, vol. 122, Sept. 2018, pp. 1–22. Epmc, doi:10.1016/j.jhevol.2018.03.010.
Boyer DM, Maiolino SA, Holroyd PA, Morse PE, Bloch JI. Oldest evidence for grooming claws in euprimates. Journal of human evolution. 2018 Sep;122:1–22.
Journal cover image

Published In

Journal of human evolution

DOI

EISSN

1095-8606

ISSN

0047-2484

Publication Date

September 2018

Volume

122

Start / End Page

1 / 22

Related Subject Headings

  • Wyoming
  • Primates
  • Hoof and Claw
  • Fossils
  • Finger Phalanges
  • Biological Evolution
  • Anthropology
  • Animals
  • 4301 Archaeology
  • 3104 Evolutionary biology