RE: Microraptor Had Iridescent Plumage

[Jaime Headden <qi_leong@hotmail.com>]

While I agree on the reconstruction of the pollex (first manual digit) with 
large feathers (potentially sticking forward), I question the qualification of 
these as an "alula," which is a derived structure for aerodynamic control. 
While it may be analogous and homologous, and may even be present in other 
paravians leading to ornithurines and what not where "real" alulae are 
prevalent, I argue that its function AS an alula is hampered and perhaps 
rendered poorly by the mobility of the digit:

The function of the digit in prehension (due to eversion of the basal joint of 
the digit during extension/flexion) seems to render this digit as an alula in 
poor light. Rather, I might presume that the digit is typically overlain by 
feathers which have been displaced or splayed due to the preservation medium 
(the same thing that renders feathers splayed out into irregular haloes in 
lagerstätte-preserved birds [and bird-like paravian maniraptoran coelurosaurian 
neotetanuran averostran theropodan dinosaurian archosaurian reptiles]), and 
that their position and/or arrangement doesn't do much to argue that the 
feathers were "alular." That's my off-the-cuff take.

Cheers,

  Jaime A. Headden
  The Bite Stuff (site v2)
  http://qilong.wordpress.com/

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)


"Ever since man first left his cave and met a stranger with a
different language and a new way of looking at things, the human race
has had a dream: to kill him, so we don't have to learn his language or
his new way of looking at things." --- Zapp Brannigan (Beast With a Billion 
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