[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: T.Rex Feather Skepticism

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