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Re: Archaeopteryx had black feathers
I'm not certain of the answer on that front, but I suspect the melanosomes
themselves are providing structural support, and the strength of that support
is related to cross-linking inside the capsule. However, there may also be
pigments outside the melanosomes that has more structural importance. I do
have a contact that would know the details, and I will see if he can clarify
for me sometime this week. I'll post a summary to the DML.
On Jan 24, 2012, at 3:23 PM, Jason Brougham wrote:
> Now how does that work when the melanin is restricted to the contents of
> melanosomes? In other words, how can it cross-link the keratin that makes up
> the feather structure if the melanin is only inside the capsule - like
> melanosome? perhaps there is also melanin outside the melanosomes?
> From: owner-DINOSAUR@usc.edu [owner-DINOSAUR@usc.edu] on behalf of Habib,
> Michael [MHabib@Chatham.edu]
> Sent: Tuesday, January 24, 2012 3:02 PM
> To: email@example.com
> Cc: firstname.lastname@example.org; "email@example.com"@listproc.usc.edu
> Subject: Re: Archaeopteryx had black feathers
> Many of the true pigments (as opposed to structural coloration), particularly
> melanin, provide improved chemical cross-linking within the integumentary
> structures they invest. As a result, pigment-carrying feathers, scales, and
> hair, particularly those that carry melanin, resist buckling, bending, and
> abrasion more effectively than the equivalent structures without pigments.
> Whether or not being more rigid and resistant to abrasion is an advantage, of
> course, depends on the circumstances and usage of the structure in question.
> Sometimes greater compliance is more advantageous than high rigidity.
> On Jan 24, 2012, at 1:57 PM, Erik Boehm wrote:
>> Wait a minute,Can someone explain to me what structural properties melanin
>> I thought it was a mere pigment, with no real structural properties as you
>> find in Keratin of Chitin.
>> So can someone explain to me what they mean by:"the extensive melanization
>> would have provided
>> structural advantages to the Archaeopteryx wing feather"?
>> --- On Tue, 1/24/12, Ben Creisler <firstname.lastname@example.org> wrote:
>> From: Ben Creisler <email@example.com>
>> Subject: Archaeopteryx had black feathers
>> To: firstname.lastname@example.org
>> Date: Tuesday, January 24, 2012, 9:57 AM
>> From: Ben Creisler
>> A new online article in Nature Communications:
>> Ryan M. Carney, Jakob Vinther, Matthew D. Shawkey, Liliana D'Alba &
>> Jörg Ackermann (2012)
>> New evidence on the colour and nature of the isolated Archaeopteryx feather.
>> Nature Communications 3 (637)
>> Archaeopteryx has been regarded as an icon of evolution ever since its
>> discovery from the Late Jurassic limestone deposits of Solnhofen,
>> Germany in 1861. Here we report the first evidence of colour from
>> Archaeopteryx based on fossilized colour-imparting melanosomes
>> discovered in this isolated feather specimen. Using a phylogenetically
>> diverse database of extant bird feathers, statistical analysis of
>> melanosome morphology predicts that the original colour of this
>> Archaeopteryx feather was black, with 95% probability. Furthermore,
>> reexamination of the feather's morphology leads us to interpret it as
>> an upper major primary covert, contrary to previous interpretations.
>> Additional findings reveal that the specimen is preserved as an
>> organosulphur residue, and that barbule microstructure identical to
>> that of modern bird feathers had evolved as early as the Jurassic. As
>> in extant birds, the extensive melanization would have provided
>> structural advantages to the Archaeopteryx wing feather during this
>> early evolutionary stage of dinosaur flight.
>> News stories:
> Michael Habib
> Assistant Professor of Biology
> Chatham University
> Woodland Road, Pittsburgh PA 15232
> Buhl Hall, Room 226A
> (443) 280-0181
Assistant Professor of Biology
Woodland Road, Pittsburgh PA 15232
Buhl Hall, Room 226A