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Tail vanes and tail feathers

>From Dave Peters

Dear Tracy,

If you like, please share the following short message with the dino list
and invite comment:

A recent reconstruction of Campylognathoides zitteli made me pause to
consider another possible use for the tail vanes on pterosaurs and the
tail feathers on the earliest birds. 

A tail vane is preserved on C. zitteli (Plieninger 1895) and the pattern
within the vane indicates a close affinity to the tail hairs sprouting
from Cosesaurus, Sordes and the anurognathids, only broader.

More to the point: The base of the pterosaur tail appears flexible
enough to elevate the attenuated tail vertically when on all fours or
standing bipedally. When doing this, the tail and folded wing tips are
all about the same height - more than twice as high as the elevated
head. Perhaps you will be able to imagine that slight movements at the
base of the tail and wing fingers produce large arcs of movements
overhead. Perhaps the tail, acting like an inverted pendulum or railroad
crossing arm, swung in some sort of rhythm with the swinging wing tips.

Is it a coincidence that C.zitteli has the largest vane and longest
wings relative to the torso of any basal pterosaur? Or was it selection?

Feathers tipping the attenuated tail of a dromie might have attracted
attention in the same fashion. And that goes double for Confusciusornis.

David Peters

Tracy L. Ford
P. O. Box 1171
Poway Ca  92074