Christine Nguyen
Animal Life
MWF 10:00
Dr. Clark
May 5, 1998

                           Science. "How Reptiles Took Wing"
                                 Article by Bernice Wuethrich
                                Summary by Christine Nguyen

The earliest known flying vertebrate is Coelurosauravus jaekeli, which
is a 250-million-year-old animal that glides on a unique set of wings,
unlike any others known in living or extinct animals.  Paleontologists
are baffled as to how this reptile is able to fly; even though, its wing
support does not draw on the normal skeleton.  In fact, Robert Carroll
of McGill University in Montreal was the first paleontologist to
identify Coelurosauravus jaekeli as a flying reptile, back in 1978.
Since this reptile is now extinct, paleontologists must rely upon
existing and newly found fossils to interpret the reptile's capability
to fly.
Before 1990, paleontologists believed Coelurosauravus jaekeli's wing
rods were extensions of its ribs, thereby suggesting that the animal had
hinged, two-part ribs, like the wing struts of the modern gliding
lizard, "Draco."   However, Hans-Dieter Sues of the Royal Ontario Museum
in Toronto and Eberhard Frey of the State Museum of Natural History in
Karlsruhe, Germany questioned the existing explanation as to how this
reptile took flight.  Further examination of the reptile's anatomy led
them to reason that such a reconstruction required Coelurosauravus
jaekeli to have a rib and a vertebra for each of its 24 to 28 wing rods,
creating an animal with an implausibly long, flat trunk, stretched into
a kind of "reptilian pancake" (Wuethrich 1419).
Recent fossils found by private collectors were given to Hans-Dieter
Sues who then discovered the wing rods had nothing to do with the ribs.
In fact, Coelurosauravus's wings were supported by new bones that
directly formed in the skin, rather than by modifications of existing
bones.  This finding is pertinent to the way we think of evolution since
evolution involves taking an existing structure and making some new
function of it.  The Coelurosauravus jaekeli has taken the capacity to
produce bone and elaborated it to benefit its flight needs.  Kevin
Padian, a paleontologist and pterosaur expert at the University of
California states, "It may now prove interesting [after the new
discover] to take another look at later flying vertebrates that evolved
independently."  Therefore, the new understanding of Coelurosauravus
jaekeli has encouraged new insights into the mechanics and evolution of
flight in other animals.

Reference:
Wuethrich, Bernice. (1997, March 7).  How Reptiles Took Wing.  Science,
vol. 275 pp. 1419.
 
 
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