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Re: If Dinosaurs Could Fly
>>I think you're missing the point. Not all feathers serve an
>>function. In modern birds insulatory feathers are down feathers, not
>>flight/contour feathers. Down feathers are highly derived feathers.
>This is not to say, though, that contour feathers can have no
>function. More to the point, it says nothing about the insulating
>properties of "protofeathers", if that is what the structures on
>Sinosauropteryx really are. And it avoids other possible uses of body
>feathers such as display.
The only true insulatory feathers are the degenerate ( lacking
derived barblets) of ratites and flightless birds. Down is not an
effective insulator in wet conditions. One of the main causes of infant
mortality in juvenile birds is when the down feathers get wet and they
die of hypothermia. Pretty maladaptive.
>>feathers from which down feathers are derived functioned in flight,
>There is simply no hard evidence of which I am aware to support this
>statement. Frankly, we do not know whether contour and down feathers
>well as bristles, filoplumes and other feather types) evolved from
>feathers, or all of these evolved from an ancestral type (which might
>been the Sinosauropteryx-type protofeather).
Down feathers and filoplumes can be traced to contour feathers
quite easily. And as stated above down as insulation is maladaptive.
>There is a logical evolutionary progression
>>from scales (in ectothemic avian ancestors) to flight/contour feathers
>>ectothermic early birds) and finally to downy feathers (in later,
>I know of no evidence on the appearance of down; for all we know
>Archeopteryx could have been buried in the stuff, but it just didn't
There may be a speculative evolutionary progression, but when
>it comes to the facts we come up pretty short. In fact I do not thik
>progression you propose is "logical" at all - it seems supremely
>evolutionarily and/or developmentally speaking, to assume that a highly
>specialized integumentary structure would develop to a considerable
>of refinement on one part of the body and then (and only then) be
>for a different function on other parts of the body. If Currie is
>about his interpretation of Protoarchaeopteryx, the evidence is that
>than one type of featherlike structure could be present simultaneously
>even a creature well down on the bird family tree (whether or not its
>features correspond to those on Archaeopteryx's true ancestor, whatever
I agree here. There must be in essence a " pre-contour/flight
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