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

Silence of the new paper

While it occasionally happens that the DML gets no mail for a day, I'm
not even getting bounced spam from the list.  I normally get 50-100 of
those a day.  I'm in the midst of an eerie quiet...  As a test, I'll
toss in something that I'm sure no one here will have anything to say

Palmer, C. and Dyke, G.J. (in press). "Biomechanics of the unique
pterosaur pteroid", _Proceedings of the Royal Society Series B,
Biological Sciences_, doi: 10.1098/rspb.2009.1899


Pterosaurs, flying reptiles from the Mesozoic, had wing membranes that
were supported by their arm bones and a super-elongate fourth finger.
Associated with the wing, pterosaurs also possessed a unique wrist
bone—the pteroid—that functioned to support the forward part of the
membrane in front of the leading edge, the propatagium. Pteroid shape
varies across pterosaurs and reconstructions of its orientation vary
(projecting anteriorly to the wing leading edge or medially, lying
alongside it) and imply differences in the way that pterosaurs
controlled their wings. Here we show, using biomechanical analysis and
considerations of aerodynamic efficiency of a representative
ornithocheirid pterosaur, that an anteriorly orientated pteroid is
highly unlikely. Unless these pterosaurs only flew steadily and had
very low body masses, their pteroids would have been likely to break
if orientated anteriorly; the degree of movement required for a
forward orientation would have introduced extreme membrane strains and
required impractical tensioning in the propatagium membrane. This
result can be generalized for other pterodactyloid pterosaurs because
the resultant geometry of an anteriorly orientated pteroid would have
reduced the aerodynamic performance of all wings and required the same
impractical properties in the propatagium membrane. We demonstrate
quantitatively that the more traditional reconstruction of a medially
orientated pteroid was much more stable both structurally and
aerodynamically, reflecting likely life position.

Mickey Rowe     (MickeyPRowe@gmail.com)