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Dinosaur Monophyly and a New Class of Vertebrates

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Abstract

TRADITIONALLY dinosaurs are classified as two or three separate, independent groups of reptiles in the Subclass Archosauria. But evidence from bone histology, locomotor dynamics, and predator/prey ratios strongly suggest that dinosaurs were endotherms with high aerobic exercise metabolism, physiologically much more like birds and cursorial mammals than any living reptiles1–8. Recently Ostrom has argued forcefully that birds are direct descendants of dinosaurs and inherited high exercise metabolism from dinosaurs1,8. Here we present evidence that dinosaurs are a single, monophyletic group, and that the key advancements of endothermy and high exercise metabolism are justification for removing dinosaurs from the Reptilia and placing them with birds in a new class, the Dinosauria.

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Authors and Affiliations

  1. Department of Vertebrate Paleontology, Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts, 02138

    ROBERT T. BAKKER

  2. Department of Biology, University of Bridgeport, Bridgeport, Connecticut, 06602

    PETER M. GALTON

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  1. ROBERT T. BAKKER
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  2. PETER M. GALTON
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BAKKER, R., GALTON, P. Dinosaur Monophyly and a New Class of Vertebrates. Nature 248, 168–172 (1974). https://doi.org/10.1038/248168a0

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  • DOI: https://doi.org/10.1038/248168a0

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