| rdfs:comment
| - The hypothesis does not propose that birds in the proper sense evolved earlier than did other dinosaurs or other archosaurs: rather, it posits that small, bird-like, arboreal archosaurs were the direct ancestors of all the archosaurs that came later on (proper birds included). Olshevsky was aware of this fact, and apparently considered the alternative acronym GOODD, meaning George Olshevsky On Dinosaur Descendants. This was, of course, meant as opposite to the BADD (Birds Are Dinosaur Descendants): the term George uses for the 'conventional' or 'mainstream' view of avian origins outlined in the first two paragraphs above. 'BADD' is bad, according to BCF, as it imagines that small size, feathers and arboreal habits all evolved very late in archosaur evolution, and exclusively within manirap
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| abstract
| - The hypothesis does not propose that birds in the proper sense evolved earlier than did other dinosaurs or other archosaurs: rather, it posits that small, bird-like, arboreal archosaurs were the direct ancestors of all the archosaurs that came later on (proper birds included). Olshevsky was aware of this fact, and apparently considered the alternative acronym GOODD, meaning George Olshevsky On Dinosaur Descendants. This was, of course, meant as opposite to the BADD (Birds Are Dinosaur Descendants): the term George uses for the 'conventional' or 'mainstream' view of avian origins outlined in the first two paragraphs above. 'BADD' is bad, according to BCF, as it imagines that small size, feathers and arboreal habits all evolved very late in archosaur evolution, and exclusively within maniraptoran theropod dinosaurs. "BCF" accepts the close relationship between dinosaurs and birds, but argues that, merely given this relationship, it is just as likely that dinosaurs descended from birds as the other way around. It should be emphasized that the term "birds" in this case refers to a morphological state, not to Aves as they have been cladistically defined. Olshevsky does not claim that the branch leading to modern birds split off from other dinosaurs very early; in fact precisely the opposite: he thinks that Aves is but the most derived expression of a vast diversification of flying dinosaurs all through the Jurassic. BCF admits that most dinosaurs found are large and very derived in morphology compared to a hypothetical flying ancestor, and it also accepts the results of cladistic analysis connecting these large species into a cladogram, suggesting that the intermediate forms were also large. BCF could have avoided this problem by claiming that just a very basal form was volant and all subsequent forms large. Instead Olshevsky resorted to a far more radical position by emphasising the point that a cladogram doesn't logically imply the morphology of its intermediate steps. He claimed, basing himself partly on Cope's law, that there was a hidden stem lineage of small arboreal forms that during the Mesozoic was the real engine driving dinosaurian evolution, generating time and again larger ground-dwelling species. The smallness and arboreality of the forms was used to explain the fact that they rarely left a trace in the fossil record. Of course being small and arboreal doesn't imply the capacity to fly and Olshevsky allowed his hypothesis to diverge in three subhypotheses: the weakest was that the stem line consisted of small tree-living species; the stronger was that these could glide; the strongest that they possessed full powered flight.
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![[RDF Data]](/fct/images/sw-rdf-blue.png)