The problem is, as usual, that we’re trying to define a point on a (branching) continuum such that everything on one side is a ‘bird’, and everything on the other side is not a ‘bird’. What counts as a ‘bird’ depends on where the point is placed, i.e. the definition.
But there’s nowhere on the continuum that you can place that point that leads to Archaeopteryx not being a transitional between the two end points (modern birds and either archeosaurs or dinosaurs). Just like there’s definition that you can set for ‘green’ that leads to this webpage’s background not being transitional between black and white.
Oh look, a new low. I can’t wait to see how you justify the existence of a clade defined solely by the presence of feathers. Even if you could, you wouldn’t be coming an inch closer to refuting the fact that birds evolved from archosaur ancestors (whether dinosaurs or, per Feduccia, more basal archosaurs).
Animals that fly, including bats, is the Biblical definition. Attempting to use possession of a single trait while ignoring every other trait which indicates phylogeny will not work.
Any character can be used to define a clade as long as that character only arises once. Of course there’s the difficulty of defining “feather”, so he’s only traded one ambiguity for another. Still, whatever reasonable definition you choose, there’s probably a clade you can get for it. And given the vagaries of fossil preservation, it may not be easy to recognize.
Well, the thesis that these animal had feathers is contested by Feduccia and Martin. Below are two passages taken from a review of Feduccia book by Jack Pettigrew that I find interesting regarding this issue.
- I once caught a flight to Sydney to see the famous feathered dinosaurs on display at the Australian Museum, which I discovered were not unequivocally feathered at all!;
- Another major point concerns one’s definition of a bird, a key issue in the first book. Feduccia has always maintained that birds are defined by their feathers, those unmistakeable and beautiful specialisations of the integument, with unique structures like rachis and barb, that bear no obvious relation to the collagenous filaments on the inside of the integument in a variety of Mesozoic vertebrates that have also been called “feathers”. This was the unconvincing “fuzz” that I saw on my trip to see “feathered dinosaurs” at the Australian Museum’s display of Liaoning fossils. Fuzz of this kind has also been described in completely unrelated pterosaurs and ornithiscian dinosaurs. Martin and Feduccia both have an uncomplicated viewpoint that fossils with feathers are birds (perhaps flightless ones, as dealt with below).
I am not arguing against the idea that birds may have evolved from basal archosaurs. My take is that birds, whatever their ancestors might have been, appeared abruptly with their feathers plainly formed and that this wonderful innovation cannot be explained by any type of neodarwinian gradualism.
And yet you bring quotes that indicate the diametrically opposite, that organisms with more primitive versions that are feather-like are in the fossil record, some of which are closely related to birds.
Once again we can ask this question you keep ignoring: why are there even fossils with such traits at all if evolution did not occur?
You haven’t even read Feduccia’s book(s), have you?
You should understand that most of those unconvincing dinosaurs with fuzz have been redefined as birds by Feduccia after later specimens have been found with true feathers. For example, Veliciraptor, which Feduccia once swore could not possibly be related to birds, all the characters shared with Archaeopteryx convergent, etc., is now a flightless bird, perhaps occasioned by the discovery of Microraptor. Collagen fibers transformed into feathers instantly! And no, “fuzz of this kind” in pterosaurs and ornithischians is rather different, though it may indeed by homologous. Note also that calling anything with feathers a bird does nothing to affect the relationships among species, and of course an animal can be a bird and a dinosaur at the same time: groups within groups.
So you’re arguing against Feduccia and the other BANDits. More quote-mining.
I doubt that. I did not just say “a single trait”, but qualified “a single trait while ignoring every other trait”. Otherwise, why would Feduccia argue birds to have descended from disosaurs at all? Of course, body plan, dentation, bone morphology and ancillary evidence all matter.
Probably not - although he keeps talking about what he knows of Feduccia’s writings, he hasn’t cited a single thing actually written by Feduccia, only reviews and opinion pieces written by others.
An interesting read – though I found the conversion to pdf (including chopping up illustrations to fit ‘pages’) somewhat distracting. Here’s the original:
Completely off-topic (although this thread is already so far off-topic that I don’t suppose it makes a difference), but as the review mentioned Greg Paul as the source of the ‘flightless birds’ hypothesis, I tracked down his Wikipedia article, and discovered that he had some interesting things to say about the Problem of Evil. I’m not sure that I agree with his viewpoint, but it does seem to add an additional wrinkle to this already complicated issue.
A second addendum: the review mentions that Feduccia attempts to use Dollo’s law of irreversibility to argue against a relationship between maniraptorans and non-maniraptoran theropods. It would seem that this law would also mean that secondarily-flightless birds should be distinguishable from pre-flight feathered dinosaurs. (Others were probably already aware of this – but it helps me to place my earlier naive intuitions within the framework of paleontological thought.)
