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Re: Jehol in Nature




An exceptionally preserved Lower Cretaceous ecosystem
ZHONGHE ZHOU, PAUL M. BARRETT & JASON HILTON
http://www.nature.com/nlink/v421/n6925/abs/nature01420_fs.html

The article includes a mention of _Microraptor_:

"_Microraptor_, another Jehol theropod with true feathers, is the smallest known dromaeosaurid (trunk length approximately 50 mm). It exhibits several pedal characteristics that have been suggested as potentially consistent with a climbing/perching mode of life, whereas other features of the skeleton demonstrate that it was not a volant or secondarily flightless animal. The discovery of this possibly arboreal dromaeosaurid has contributed to the debate over the origin of flight, and has been cited as evidence for the now heterodox view that flight originated from the trees down (by gliding and jumping down from trees), rather than from the ground up (by running and leaping for prey)."

I would hesitate to characterize the trees-down model for the evolution of avian flight as "heterodox". The idea that small theropods, including the ancestors of birds, may have been arboreal was gaining momentum long before the discovery of _Microraptor_.

"However, detailed functional morphological studies on _Microraptor_ have not yet been attempted and are needed to test its proposed arboreal mode of life."

The original description of _M. zhaoianus_ included a comparison of its pedal proportions with other taxa for the purpose of functional anatomy. Further, the discovery of _M, gui_, with its four "wings", would appear to shift the burden of proof why this genus was *not* arboreal.

Also in the article...

"The presence of feathers in _Caudipteryx_ and _Protarchaeopteryx_ has been dismissed as a vestige of secondary flightlessness, and the identification of these structures as integumentary features has been questioned, but these interpretations have not been supported by other studies. Phylogenetic evidence demonstrates emphatically that these animals were primarily flightless non-avian theropods, not secondarily flightless basal birds,..."

No mention of the peculiar notion that feathered dromaeosaurids ("raptors") were flightless birds too, and not theropods at all (a la Czerkas, Feduccia, &c). I call this notion "Raptors Are Birds In Disguise" - or RABID for short.



Tim

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