MICRORAPTOR zhaoianus.

Acrylics and inks on cardboard.

Cover for Dinopress (Japan).

After the debacle and forgery of Archaeoraptor, something had to be done about it.MICRORAPTOR zhaoianus The scientific community had in their hands the remains of two animals glued together and none of them properly described. To add to the problem, there were dozens of dromaeosaur feathered tails awaiting description in China. At the 2000 Florida Symposium, Xu Xing and the Chinese researchers told me in person that they had the counterslab and the rest of the body of the mysterious tail attached to the "Archaeoraptor" specimen.

Fortunately, it has finally been described and published in Nature earlier this year. It has been claimed that this is probably the smallest dinosaur to date (size very similar to Archaeopteryx, 45 cm long including tail) and in a surprising controversial move, Xu et al have described it as an arboreal dinosaur. Dromaeosaur and troodontid stiffened tail mixed with perching feet. It may be that even discrete sickle claws and retractable toes were used as climbing devices.
Microraptor was probably flightless and had a mosaic of dinosaur and avian characters. The ulna is strongly bowed and the radius is less than 70% of ulnar width. The ulnofemoral ratio is comparable to dromaeosaurids, Protarchaeopteryx and some oviraptorosaurs, while it is much smaller than Archaeopteryx and other volant forms. The semilunate carpal has a larger contact with metacarpal II than metacarpal I, which differs from dromaeosaurids, but agrees with avians and more basal taxa.
Twenty-four or twenty-five caudal vertebrae are present. Transverse processes end before caudal eleven, but most caudals possess dromaeosaurid-like elongate prezygapophyses and chevrons.


MICRORAPTOR zhaoianus

Feathers are preserved around the ulna, manus, pelvis, femur and tibia. They have an outline similar to those of Yixian birds. Femoral impressions have an outline similar to feathers and are 25-30 mm long. Other impressions near the pelvis and tibia are shorter. Rachis-like impressions are preserved near the femur and manus.
Keratinous sheaths are preserved on the pedal unguals, making the claws half again as long as the unguals. Studies of arc measurements show Microraptor plots with climbers, while Archaeopteryx, Confuciusornis and Sinornis plot with perchers, Sinornithosaurus plots between perchers and runners, and Compsognathus and Caudipteryx plot with runners.
Microraptor is most closely related to Archaeopteryx,Rahonavis, Sinornithosaurus and Bambiraptor among eumaniraptorans.
In my reconstruction, I have incorporated the most recent fossil evidence regarding distribution of insulatory integument (dino-fuzz and feathers). Despite rather dubious "political" moves by Storrs Olson giving official precedence to the name "archaeoraptor" (a chimaera), I hope that Microraptor, the real thing, will keep its nomenclatural priority.
Yet another nail in the coffin of the "birds are not dinosaurs" outdated fan club... and more and better specimens are still to come!
Is this the specimen that defenders of the "Trees Down" origin of flight theory needed to convince us ?
Only time will tell, but we are anticipating more descriptions of arboreal dinosaurs in the future (there's at at least one even smaller and weirder than Microraptor, with an extremely elongated third finger, but unfortunately it still hasn't been properly described and published).
So keep watching this space!




With special thanks to Mickey Mortimer and Mark Norell.


Microraptor (Update 2003!).
The evidence was there from the beginning (only too fragmentary and faint in the fossil to be seen clearly).
Following the new discoveries of complete and fully feathered specimens, I have added the missing metatarsal flight (!) feathers that finally give us the true picture of Microraptor, a veritable 'four winged' wonder.
Reappraisal of the articulation pelvis-femur makes the 'spreading legs' (proposed right from the first version of this painting) more likely, helping this animal in a functional biplane flight from branch to branch.
The origin of flight might have been more complex than it seemed, although Microraptor most probably was an evolutionary side branch, not a direct ancestor of any modern bird. This one was one of many trees-down or tree-tree evolutionary exercises in flight. See the Chinese Revolution Part 3 for hypothetical usage of those feathers.

 

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