New look at the origin of birds and crocodiles


DURING the period 1926–73 most ornithologists and vertebrate palaeontologists supported Heilmann's theory of avian origins. Heilmann1 argued that all dinosaurs and pterosaurs were too specialised to have been ancestral to birds. Instead he chose to derive birds directly from a primitive group of Triassic archosaurs, the Pseudosuchia. Heilmann's theory has recently been challenged by Walker2–4, who has suggested that birds evolved from an early crocodilian, and by Ostrom5–10, who argued that birds descended from theropod dinosaurs. We recently began a study of the otic region in archosaurs and birds, in search of advanced, homologous features which would give definitive support to one theory or the other. The results of this investigation, discussed below, strongly support a hypothesis of a common pseudosuchian origin for birds and crocodiles, independent of dinosaurs.

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WHETSTONE, K., MARTIN, L. New look at the origin of birds and crocodiles. Nature 279, 234–236 (1979).

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