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Re: Did Feathers Evolve for Dispaly? We Still Don't Know!



Some other things I was thinking...
How can we say this discovery indicates the original adaptive function
of protofeathers is display on the basis of Sinosauropteryx, when the
protofeathers are older (present in ornithischians and apparently, in
pterosaurs, if protofeathers and pycnofibres are homologous, which
seems likely as far as I know)?
Second, the presence of melanosomes seems good to reject
Lingham-Soliar's collagen hypothesis, but I am not sure it serves to
support the primarily-for-display hypothesis, because as far as I
know, melanosomes are common in the integument of non-avian
vertebrates. They may be present in the protofeathers just because
they were common in the integument.


2010/1/28 Augusto Haro <augustoharo@gmail.com>:
> Perhaps observing hairy pterosaurs may help us deciding... There seem
> to be a large number of pterosaurs with pycnofibres. Are the
> pycnofibres present only around the body profile in pterosaurs? And,
> are there pterosaurs, in different death positions (i.e., some
> dorsoventrally flattened, some others laterally flattened), preserving
> hair only around the boundaries of the fossil? This would suggest
> we do not have reason for supposing there is no hair outside of the
> rims of the fossil.
>
>
> 2010/1/28 Thomas R. Holtz, Jr. <tholtz@umd.edu>:
>> Tim Williams wrote (okay, quoted):
>>
>>> "Furthermore, we now know that the simplest feathers in dinosaurs such as
>>> _Sinosauropteryx_ were only present over limited parts of its body – for
>>> example, as a crest down the midline of the back and round the tail –
>>> and so they would have had only a limited function in thermoregulation."
>>
>> Actually, I am not at all convinced that these were present only over
>> limited parts of the body. The situation is such that we only get
>> preservation where sediment meets sediment, and thus only in halos around
>> the organism. Unfortunately we can't tell if these are the only fuzzy
>> parts, or simply the lucky fraction of the fuzzy parts that get preserved.
>>
>> --
>> Thomas R. Holtz, Jr.
>> Email: tholtz@umd.edu   Phone: 301-405-4084
>> Office: Centreville 1216
>> Senior Lecturer, Vertebrate Paleontology
>> Dept. of Geology, University of Maryland
>> http://www.geol.umd.edu/~tholtz/
>> Fax: 301-314-9661
>>
>> Faculty Director, Earth, Life & Time Program, College Park Scholars
>> http://www.geol.umd.edu/~jmerck/eltsite/
>> Faculty Director, Science & Global Change Program, College Park Scholars
>> http://www.geol.umd.edu/sgc
>> Fax: 301-314-9843
>>
>> Mailing Address:        Thomas R. Holtz, Jr.
>>                        Department of Geology
>>                        Building 237, Room 1117
>>                        University of Maryland
>>                        College Park, MD 20742 USA
>>
>>
>>
>