[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
re: Digiy - loss - 5 finger fliers - stiff tails
I was surprised when Dino George said
" Reduction of digit IV is explained by the formation of the avian wing. It's
not a climbing problem solution (nor is digit V reduction for that matter),
it's a flying problem solution. Alternative explanations are of course
possible, but I'm only interested in alternative explanations that improve a
wing, because that is what >actually happened<. An explanation of manual
digital reduction that ignores the evolutionary development of the wing falls
into the category of a miracle: the digits just happened to become reduced
for some reason or other, and wow, they miraculously became fit for flying
(along with all those other adaptations that appeared for reasons other than
Given arboreal lifestyle, feathers, small size, lightweight construction,
and enough time, avian flight follows almost automatically."
I felt that he had not demonstrated an arboreal lifestyle when he ignored
features which would make such a lifestyle difficult and elements that
suggest they evolved to support a vertical bipedal gait more useful on
ground. For his theory to work, I felt he needed to demonstrate that 4 and 5
finger ancestors had feathers and could fly as I felt features for a bipedal
gait and reduced digits were present long before the current evidence for
feathered flight. Hence he had not shown what "actually happened" but
something that may have happened if his BCF theory is correct
However, if protoavis or some other 5 fingered feathered flier existed,
his explanation would be reasonable to me if, the vertical pubis and
shortened fingers did not occur first. The questions now are: Do we know if
there were early 5 fingered feathered fliers?
If so, were their ancestors already bipedal.
In addition, the stiff tails appear to me to be a feature evolved from a
feathered rudder. It did not allow faster turning as I have seen mentioned
(when compared to a flexible tail of the same size). It also appears to be
related to reduced reliance on tail based muscles being used in providing
forward thrust, (also suggesting a flying ancestor would be possible).
Right or wrong, that is my current take on the digit loss subject.
Mark "glad I commented earlier" Shelly