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

FEATHERS AND POSTURE..



> modern bats have full color day vision and black and white night vision like 
> humans, 

Only megabats surely?

> Watch birds clean themselves.  They have to do some really wierd things with 
> their wings to reach around them to clean hard-to-reach parts, because the 
> wing just doesn't want to do anything other than a flight position or a rest 
> position

Betty leads into a interesting thread (for me anyways): how life style, and
resulting anatomy, influence the properties of integument. Here's some things
to think about; 1) feathers are not resistant to erosion and get worn down if
bashed about too much; 2) birds have evolved a specific posture to keep their
feathers 'drawn in' and away from entangling foliage and such; 3) all
_Archaeopteryx_ specimens with good feather impressions reveal them to have been
nice, un-eroded feathers.

(2) has led several ornithologist to assume, as they do, that feathers evolved
for 'birdiness', with _Archaeopteryx_ being the first to possess them, and, due
to the nature of its feathers, being the first animal to have evolved the
'drawn-in' posture [tosh]. (1) shows, I believe, that protobirds like
_Archaeopteryx_ were not thrashing their wings around as butterfly nets, nor
were they terrestrial cursors. Backed up nicely by Fedduccia's work on claw
curvature. _Archaeopteryx_ was arboreal... perhaps. Rayner and others have
published data advocating gliding in protobirds, I mostly agree (damn you to
hell GD! -;), though obviously there's room for disagreement ('..perhaps someone
ought to tell bats that they are from now on condemned to crawl..' - anonymous).

If _A_ was a glider, just how did it get airborne? If you see it as a forest
dweller (facies upstream of Solenhofen, as Jerry _used_ to tell us), no problem.
If, on the other hand, _A_ was a 'crude shorebird', patrolling the lagoonal
shallows and picking up lame squid, fish and (if you ask Steve White) baby
plesiosaurs (-;), it inhabited an environment devoid of trees. I don't believe
Solenhofen sea breezes were strong enough to get protobirds airborne (needs more
research though), and.. there were no sea-cliffs (BOR). BUT there were 'scrubby
conifer bushes' about 1 metre high. If, due to fragile feathers, _A_ couldn't
clamber about in these things, might it have been able to jump onto them? This
is a hypothesis I considered when learning of comparisons between _A_ femora
and those of extant leapers like tarsiers and tree frogs. Dromaeosaurs, and
other dinosaurs, with their opisthopubicity, had the muscles for a powerful
leap.. why not the same for _A_? Phil Currie sees at least part of basal bird
evolution as something to do with saltation (hopping), does anybody know if he
thinks likewise for _A_? 

If it ever got 'on top' of such a problem, _A_ would at least be able to leap
and glide, over the lagoon.. 

Feel free to slash at the wrists of any of this stuff.

"I'm a scientist first and a gentleman second"
"Me? Science? Requires a sort of.. logic.."

DARREN NAISH