Evolution of thumbnails across Rodentia

The unguis (hoof, claw, or nail) of the first digit (D1, also known as the thumb or pollex) of the tetrapod hand exhibits numerous functional adaptations, but its macroevolutionary association with ecological diversity is unknown. Across Rodentia, we find that most extant genera and ancestral lineages bear D1 nails. Exceptions follow structure-function associations that arose independently multiple times, specifically, the gain of D1 claws with subterranean habits and the loss of D1 ungues with oral-only feeding behavior. We hypothesize that early acquisition of D1 nails and manually dexterous food handling was crucial for rodents to adaptively leverage cranial specializations for efficient gnawing and thereby exploit hard seeds and nuts, a niche that they dominated after the extinction of multituberculates. Our study recasts ideas about rodent evolution and uncovers a previously unrecognized contributor to their successful radiation.

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Publication Details

Journal
Science
Published
2025-09-04
DOI
https://doi.org/10.1126/science.ads7926
Citations
1
Primary Topic
Evolution and Paleontology Studies
Type
article
Field-Weighted Citation Impact
4.33

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article

Evolution of thumbnails across Rodentia

Anderson Feijó, Rafaela Velloso Missagia, Bruce D. Patterson, Paulina D. Jenkins et al.
1 citations
Science
Evolution and Paleontology Studies
4.33
article

Evolution of thumbnails across Rodentia

Anderson Feijó, Rafaela Velloso Missagia, Bruce D. Patterson, Paulina D. Jenkins, Gordon M. Shepherd, Maximilian L. Allen, Lauren Johnson
article en
1 citations

Abstract

The unguis (hoof, claw, or nail) of the first digit (D1, also known as the thumb or pollex) of the tetrapod hand exhibits numerous functional adaptations, but its macroevolutionary association with ecological diversity is unknown. Across Rodentia, we find that most extant genera and ancestral lineages bear D1 nails. Exceptions follow structure-function associations that arose independently multiple times, specifically, the gain of D1 claws with subterranean habits and the loss of D1 ungues with oral-only feeding behavior. We hypothesize that early acquisition of D1 nails and manually dexterous food handling was crucial for rodents to adaptively leverage cranial specializations for efficient gnawing and thereby exploit hard seeds and nuts, a niche that they dominated after the extinction of multituberculates. Our study recasts ideas about rodent evolution and uncovers a previously unrecognized contributor to their successful radiation.

ScienceVol. 389(6764)
Northwestern University (US), Natural History Museum (GB), University of Illinois Urbana-Champaign (US), Universidade de São Paulo (BR), Chinese Academy of Sciences (CN), Field Museum of Natural History (US), Institute of Zoology (CN)
American Museum of Natural History, Field Museum, National Natural Science Foundation of China, Conselho Nacional de Desenvolvimento Científico e Tecnológico, National Institutes of Health, National Museum of Natural History
Openalex Percentile: Top 7%
Evolution and Paleontology Studies
4.33
DOIOpen Access PDFOpenAlex
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