RE: Cretaceous feathers

[Tim Williams <twilliams_alpha@hotmail.com>]

Eike wrote:

> Slightly asymmetric vanes, slightly but noticeably
> arched shaft, robust, usually plentiful melanin. No
> Enantiornithes fossil with feather impressions found
> so far has these on its tail (they have fluff and
> sometimes streamers), nor do the longer-tailed birds
> (Archie's tail feathers are similar though, but less
> asymmetric and almost straight), nor fan-tailed
> non-avian theropods like _Caudipteryx_ (straight ?and
> pointed).


Yes - and given that these "neognath"-style rectrices are present in basal 
euronitheans (e.g., _Yanornis_), they appear to be primitive for modern birds.

However, I would hesitate in referring to _Caudipteryx_ or _Protarchaeopteryx_ 
as "fan-tailed", given that the term "rectricial fan" is usually reserved for 
when the rectrices attached to the pygostyle are capable of spreading out 
("fanned") in a radial manner (as in modern fling birds - see Gatesy & Dial 
Evolution 50: 2037-2048).  _Caudipteryx_ and _Protarchaeopteryx_ have no 
pygostyle, and the rectrices are essentially arranged as a "frond", as in 
_Archaeopteryx_, except they are attached only to the distal caudals.


> Next time you see a pigeon slowing to land, note the
> way the tail is used. It should become rather obvious
> then what I mean. (And for what little we know at
> present, this function requires the short pygostyle of
> modern birds and their immediate ancestors, not the
> long one of other theropods, and it wouldn't work with
> an Archie-type tail either).

Yes, exactly.


> Contrary to what the
> BAND/secondary-flightless people want everybody to
> believe, feather evolution was by no means a straight
> single progressive lineage.)

I couldn't agree more.



Cheers

Tim
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