The pros and cons of the paper have been well expressed by comments in the New York Times article of June 23, 2000, and in other media stories that had actually bothered to talk to non-members of the publishing team. I only offer a few comments at this time, but my summary is that the structures of Longisquama are not feathers.
First, what would happen if someone wrote an article that described hair on, say, a very early pterosaur? The reaction would be that this was fascinating, but not likely to have much to do with mammalian ancestry. There is a bucket of evidence that pterosaurs and mammals are not as closely related to one another as they are to other groups: any hair-like structure on pterosaurs would have been separately evolved. And that, roughly, is where we are with birds and Longisquama.
Second, this is not the first time that Longisquama has been interpreted biologically, though the Oregon State press release implies that the specimens had not been looked at for decades. Robert Bakker suggested that the structures set along its back were thermoregulatory; and both Susan Evans and the team of Haubold and Buffetaut interpreted them as parts of a gliding mechanism. Strangely, Jones et al. produced a drawing for their Oregon State press release, but not for the publication, that showed the structures of Longisquama laid out as a gliding airfoil. The press release said that Ruben and Jones had come up with the reconstruction, but that reconstruction looks to me uncannily like the reconstruction published years ago by Haubold and Buffetaut. Jones et al. even reference Haubold and Buffetaut in their paper (without mentioning the reconstruction by these authors, or commenting on the anatomical differences between their interpretations). "What's wrong with this picture?", in other words, and at all sorts of levels.
Third, Terry Jones, the lead author, was ready to say for a press release that Longisquama "looks like an ancestral bird even if you ignore the feathers. The teeth, pectoral structure, neck, and skull are just like those of birds." If this is true, it is astonishing that Jones et al. did not say so in their published paper, and document it thoroughly: it would have been truly compelling evidence for their argument. Instead, Jones et al. wrote, "the taxonomic status of Longisquama is poorly understood" (p. 2204). Apparently someone told the New York Times that Longisquama has a furcula, but again, this is not included in the paper, where it would have had great supportive value.
Fourth, the structures on Longisquama are arranged with a spacing of one per rib along the back. This is an astonishing coincidence if they are feathers, and certainly needs explanation. If the structures along the back of Longisquama are feathers, they are unlike any other feathers in living or extinct birds, in that they are few, tremendously long, inserted along the spine, and laid out sideways well beyond the ribcage.
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RC, June 28, 2000.