Inconsistent Reasoning Governs Evolutionary Interpretations of Feathered Dinosaurs
Nature news is reporting another feathered dinosaur. The title of the Nature news article says, "Crested dinosaur pushes back dawn of feather." This dinosaur is from around 130 mya, but feathers are already known from the bird Archaeopteryx around 150 mya. So how does it push back the origin of feathers?
Their reasoning is that the feathers on this new species, dubbed Concavenator corcovatus, appear in a different lineage than the one that supposedly led to birds. Since "such structures [feathers] are unlikely to have evolved separately in both groups" they use evolutionary reasoning to infer that "the common ancestor of the two predatory dinosaur branches, 'could have been feathered'." This pushes the origin of feathers back to "Middle Jurassic (175 to 161 million years ago)." Again, their reasoning which "pushes back the dawn of feathers" is entirely evolutionary, not based upon actually finding feathers.
Keep in mind, however, that they didn't find actual feathers on this fossil. They only think they found quill knobs--attachment points for feathers. As the Nature newspiece says:
But it is the bumps on the dinosaur's arms that have caused a stir: the researchers think that they may have been part of structures that anchored quills to the creature's bones.
If all it takes to establish feathers are a few quill knobs, then why exclude a fossil called Protoavis, with many other birdlike features, from having feathers? Protoavis' discoverer Sankar Chatterjee wrote, "The presence of feathers is inferred indirectly from the development of quill knobs." (Chatterjee, The Rise of Birds. Johns Hopkins University Press, 1997)
So why do many scientists oppose Protoavis being a bird, or at least being related to birds? The reasoning against Protoavis being a bird, again, is governed by evolutionary considerations. As Michael Benton explains, it would wreak havoc with standard evolutionary story:
However, if Protoavis is a bird (Chatterjee, 1995), then the point of origin of the group moves back to the late Triassic, and that would distort many parts of the phylogeny, not only of birds, but also of Dinosauria in general.
(Michael J. Benton, 1998. "The quality of the fossil record of vertebrates." pp. 269-303, in Donovan, S. K. and Paul, C. R. C. (eds), The adequacy of the fossil record. Wiley, New York)
In other words, the problem with Protoavis is that it appears in the fossil record around the same time as the earliest dinosaurs. If it's a bird, then it seems highly unlikely that birds are descended from dinosaurs. In fact, in such a case it wouldn't be clear what birds are descended from. This scenario is obviously disfavored by many evolutionists.
Benton's admissions about Protoavis make it all the more striking that he's quoted in the Nature newspiece as follows:
the bumps on Concavenator's arms 'look exactly like insertions on rather massive flight feathers on bird wings', says Michael Benton, a palaeobiologist at the University of Bristol, UK.
So they accept quill knobs as being evidence of feathers when it fits with their evolutionary paradigm, but they reject such reasoning when it overturns their theories.
Concavenator's promoters are saying "We're going to have to conceive of more dinosaurs as being more like birds." But to establish Concavenator as a bird-like feathered dinosaur, they must accept inconsistent evolutionary reasoning, which, if applied consistently to fossils like Protoavis, could undermine the entire dino-to-bird theory