Abstract
WALKER1 has restated the long-held belief that both birds and crocodiles evolved from thecodont ancestors, but he added the novel suggestion that these two groups arose from a common thecodont ancestor and thus are much more closely related than has been previously realized. Inasmuch as the Thecodontia include the most primitive as well as the most ancient archosaurs known, it is highly probable that all subsequent archosaurs (including birds) were derived from members of this order. Although Walker may be correct, I do not think that the evidence cited indicates such a close relationship between birds and crocodiles as he proposes.
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OSTROM, J. The Ancestry of Birds. Nature 242, 136 (1973). https://doi.org/10.1038/242136a0
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DOI: https://doi.org/10.1038/242136a0
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