Exhibit Spotlight: Microraptor zhaoianus
The only thing that could make this more awesome is if it were riding a shark and wielding a machine gun. Picture by Fred Wierum, used under Creative Commons.
Let’s scope out an indoors exhibit this time. Our Microraptor sculpture has been removed for refurbishing, but its nominal display poses it preparing to leap from the tree next to its North American cousin, distant in both relationship and geography, Hagryphus. Prepare yourself for the tiny awesomeness of Microraptor!
Like its species name suggests, this little dinosaur lived in China, specifically in Xiasanjiazi, Chaoyang County, western Liaoning (Did you think Greco-Latin based names were hard to pronounce? Try Chinese!). Time-wise, this little critter made its home in the Early Cretaceous, which also makes it one of the earliest dromaeosaurs known.
Microraptor currently holds the title of the smallest known adult dinosaur, beating out its German cousin, Compsognathus. We’ve found smaller dinosaur skeletons, like the sauropodomorph Mussaurus, but they’re all hatchlings.
Though some scientists have named as many as three species—M. zhaoianus, M. gui, and M. hanqingi—others contend these represent different sexes and/or growth stages. Resolving the species in this genus will require a broad survey of the available specimens, and that may take some time: scientists estimate that nearly 300 Microraptor specimens currently grace the collections of museums and private collectors scattered throughout China.
Despite the large number of specimens available for study, identifying them proves difficult because of the Chinese black market habit of falsifying fossils. Many a Microraptor has provided parts to a Frankenstein-like staging of dramatic-looking fossil scenes created by Chinese farmers to “enhance” their value in the illegal fossil trade. Scientists have to take extra precautions with Chinese fossils as a result, because the fossil chop shops know their trade well. One particularly infamous example, dubbed “Archeoraptor,” deceived scientists at National Geographic in 1999. The “Archeoraptor” concoction included the remains of 2-5 different animals, including Microraptor itself. Despite all the confusion, enough verifiable specimens of Microraptor exist to give scientists an exceptionally clear view of some of its physical makeup and habits.
Perhaps its most famous feature, its four—count ‘em, FOUR!—wings, have inspired further controversy. Fossils clearly show they have some of the aerodynamic features in modern bird wings, but other aspects of its skeleton complicate attempts to study its possible aerial capabilities. Some have described it with the phrase, “dinosaurian flying squirrel,” referring to a model of flight that depicted its legs outstretched to nearly the same extent as its arms during flight. More recent studies have uncovered information that makes that model unfeasible. The more likely model, based on wind-tunnel tests of the aerodynamics of different flight poses, found that its hind wings might have acted more like downward-facing stabilizers (as shown in the illustration). Surprisingly, they also found that the fan of feathers on its tail also generated lift, making it a sort of FIVE-winged glider. And gliding seems the more likely sort of locomotion for the animal: not only did its hips closely resemble those of other dromaeosaurs (making a biplane-like sprawl impossible) its shoulders also seem to lack the mobility needed to complete a full-powered stroke. However, scientists disagree on how to reconstruct the animal’s shoulder and hip joints since many specimens are preserved in a flattened “road kill” condition; some studies do show that it had at least the muscle power for approximating bird-like flight.
Another controversial study may have developed a technique for determining the color scheme of animals with some exceptionally well-preserved fossils, like Microraptor. It looks at the pigment-bearing cells found in feathers and scales, called melanosomes. By measuring the size and shape of these cells, scientists have a shot at determining its color. Though the technique still needs some fine tuning, it has created a good theory of Microraptor’s color. It likely bore black feathers with just a hint of blue iridescence, like a raven/hummingbird hybrid. Such a scheme does make sense for a small creature in a dark forest that still needs to show off once in a while to socialize with its own kind (if it did indeed engage in social behavior).
Several fossils give us some interesting information about its diet, and explain a few of its more peculiar features. Unlike other dromeosaurs, its teeth only bear saw-like serrations on one side. Even weirder, a couple of its lower teeth point outwards, slightly beyond the margin of the top jaw. These adaptations along with fossilized gut contents demonstrate Microraptor’s generalist diet: like modern house cats, it ate fish on a regular basis, small mammals, lizards, and small birds (which, in at least one case, it swallowed whole). A species of lizard new to science, dubbed Indrasaurus, turned up inside of a Microraptor fossil—two for the price of one! Contrary to popular depictions of 'raptors swarming over larger animals, this little dromaeosaur preferred smaller prey. Who knows? Maybe it would even have made a decent pet, suitable for Photoshopping into all sorts of memes. In this and many other ways, Microraptor serves as a reminder that even the famously vicious 'raptor clan displayed a staggering amount of behavioral and ecological variety.
Alexander, D. E., Gong, E., Martin, L. D., Burnham, D. A., & Falk, A. R. (2010). Model tests of gliding with different hindwing configurations in the four-winged dromaeosaurid Microraptor gui. Proceedings of the National Academy of Sciences, 107(7), 2972-2976.
Dyke, G., De Kat, R., Palmer, C., Van Der Kindere, J., Naish, D., & Ganapathisubramani, B. (2013). Aerodynamic performance of the feathered dinosaur Microraptor and the evolution of feathered flight. Nature Communications, 4(1), 1-9.
Li, Q., Gao, K. Q., Meng, Q., Clarke, J. A., Shawkey, M. D., D’Alba, L., ... & Vinther, J. (2012). Reconstruction of Microraptor and the evolution of iridescent plumage. Science, 335(6073), 1215-1219.
O'Connor, J., Zhou, Z., & Xu, X. (2011). Additional specimen of Microraptor provides unique evidence of dinosaurs preying on birds. Proceedings of the National Academy of Sciences, 108(49), 19662-19665.