Re: T.Rex Feather Skepticism

[Tommy Tyrberg <tommy.tyrberg@norrkoping.mail.telia.com>]

Frank Bliss wrote:
>The cute tyrant looks like a good prey item for a hungry Upper Cretaceous 
mammal to me. >Interesting that almost all domesticated barnyard birds are 
fluffy and cute from the egg. I >wonder if artificial selection by man had 
anything to do with that or just an adaptation for >surviving for cold 
roosts. (Of course that theory goes out the window regarding turkeys!) 
Of >course lot of other birds are born naked and "ugly" but do pen feather 
up pretty quickly. Nothing >is more homely than a baby parrot in pin 
feathers. I agree that we anthropoids do tend to prefer >baby creatures as 
cute. Something about the mammalian survival benefit of cuteness ingrained 
into >our collective wishful thinking.

It seems clear that we are simply hardwired to consider small, chubby, 
seemingly helpless creatures as being cute. This reaction seems 
particularily strong if they have large frontally directed eyes (half-grown 
chicks of Tengmalm's Owl for example are *incredibly* cute).

Michael Habib wrote:
>Most domesticated barnyard birds are largely terrestrial, precocial forms 
(and generally >galliform birds, specifically). They are 'fluffy' because 
they must be capable of >thermoregulation soon after birth. The reason we 
tend to domesticate such birds is probably >several-fold, including:
>
>1) They have large, light-fiber based pectoralis major muscles (good for 
short, sprinting >flights), and we find this yummy.
>
>2) They live largely on the ground (which is related to point number 1), 
which makes them easier >to contain and raise.
>
>
>These traits happen to be somewhat correlated with precociality (though 
this is, in part, a >phylogenetic effect). Thus, these traits are 
correlated with fluffiness. Other than the >phylogenetic constraints, 
ground-living birds that are poor sustained fliers probably tend to 
be >precocial, because the offspring are under pressure to leave the nest 
early, and they presumably >utilize a food source available without flight 
(since the adults are poor sustained fliers).
>
>The exceptions to much of the above are domesticated waterfowl; in that 
they are strong sustained >fliers. However, they still feed on the surface 
(water, instead of terrestrial surfaces), and >they still nest on the 
ground in accessible regions (and they are considered to be sister taxa 
to >galliforms, in many analyses), so it is not surprising that they, too 
are precocial.

It is mostly a phylogenetic effect. All important domesticated birds are 
either Galliforms or Anseriforms which are primitively precocial (as is 
Paleognaths and indeed Neornithes). Also while galliforms and anseriforms 
are presumably primitively ground-nesting many ducks nest in treeholes and 
among the Galliformes the Cracidae are largely tree-nesting and tree-living 
(and the chicks are incidentally rather better at scrambling around in the 
trees than the adults).

T. Michael Casey wrote:
>Which brings up an interesting question: are any ground birds altricial?

Answer: Yes lots (e g larks, meadowlarks, buntings, harriers and even a few 
ground-living woodpeckers and tits). However these are all secondarily 
ground birds. Groups that are primitively ground-living all seem to be 
precocial. Precociality once lost seems to be very difficult to re-evolve 
(perhaps because it is more or less the opposite of neoteny).

Tommy Tyrberg