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Earliest evidence for efficient oral processing in a terrestrial herbivore

Abstract

Herbivores can increase their digestion rate by mechanically reducing particle size through oral trituration1. Groups of terrestrial vertebrates with the greatest capacity to reduce tough plant foods orally are also the most abundant and diverse, as exemplified by ornithopod dinosaurs during the Mesozoic and extant artiodactyl and perissodactyl mammals2. Thus, the effective oral processing of high-fibre plant material seems to represent an evolutionary innovation of both functional and macroevolutionary significance. However, evidence for oral processing is poorly documented in the fossil record, especially during the initial stages of terrestrial vertebrate diversification3,4. Here we report on the basal anomodont Suminia getmanovi, the only known Palaeozoic vertebrate in which unequivocal specializations in its cranium and teeth for high-fibre herbivory are well preserved. We propose that the capacity to comminute tough plant foods was critical to the diversification of anomodonts, the most diverse, widely dispersed and abundant group of Palaeozoic terrestrial vertebrates, and to the onset of modern terrestrial ecosystems.

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Figure 1: Skull of Suminia getmanovi, PIN 2212/62.
Figure 3: Reconstructed power stroke in Suminia.
Figure 4: Lingual surface of the right upper tooth row and buccal surface of the right lower tooth row of Suminia (PIN 2212/62) and photomicrograph image of U8 tooth.
Figure 2: Skull restoration of Suminia getmanovi.

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Acknowledgements

Specimens of Suminia were prepared and loaned to us by M. F. Ivachnenko and A. Khlupin. We thank H.-D. Sues, K. Smith, W. Hylander and J. Rensberger for comments on earlier versions, and D. Scott for assistance with the figures. Support for this research was provided by the National Geographic Society and Natural Sciences and Engineering Research Council of Canada.

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Rybczynski, N., Reisz, R. Earliest evidence for efficient oral processing in a terrestrial herbivore. Nature 411, 684–687 (2001). https://doi.org/10.1038/35079567

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