Glight of the Cryptophugoid I

A piece of Lanchester’s phugoid theory (above left), a schematic representation of phugoid oscillation (above center), and a forward-staggered balsa biplane glider (above right). A reconstruction of Microraptor from the American Museum of Natural History’s Liaoning Diorama (below).

PNAS has recently published Chatterjee and Templin’s biplane reconstruction of the famous tetrapteryx Microraptor. As mentioned briefly in the two-headed choristodere post, Microraptor was part of the ‘Archaeoraptor‘ fossil chimera along with the early avialan Yanornis. By a quirk of nomenclature it’s possible that the name Archaeoraptor has priority although the name is universally eschewed and many regard it as invalid.

In spite of the nude and dubious circumstances, ‘Archaeoraptor‘ is a rather appropriate signifier for the dinosaur half of the forgery, which appears to be a basal Deinonychosaurian (i.e. an early ‘raptor’). Of course, Microraptor certainly fits the diminutive dinosaur equally well and it appears that this is the name that will stick. Another synonym ‘Cryptovolans‘, forms half the inspiration for the incredibly weak pun in the title. As if that weren’t enough, the bird half of ‘Archaeoraptor‘ was briefly known as Archaeovolans before being sucked into synonymy with the bilingual chimera Yanornis.

At any rate, the true Microraptor is far more stunning than any Chinese farmer or ‘agenda-driven evilutionist‘ could have dreamed.

Figure from Xu et al. (2003)

A few things make microraptor particularly noteworthy. First of all, it’s not a bird, but a non-avian theropod. Feathered dinosaurs are relatively blasé at this point, but this is a dinosaur with wings (or something rather like them). And not just wings, but four wings one for each limb.

The next question becomes “what the hell was Microraptor doing with four wings?” Well, dragonfly-style tandem flight seems unlikely, it appears that Microraptor wasn’t really well constructed for powered flight (although it may have equally adept in the air as its distant cousin Archaeopteryx). In the paper from which I ganked the above figure, Xu et al. imagine Microraptor as a flying-squirrel-style glider using it’s fore and hindwings to create a large gliding plane around much of its body. The new PNAS paper has Microraptor as a split-level glider, holding the hindwings below the forewings to create two distinct gliding planes.

Chatterjee and Templin’s biplane idea has been kicking around for a while, but the new paper shows the results of some aerodynamic performance modelling for different configurations of the hindwing. While they can’t rule out the single-plane model, the calculations suggest that in this configuration Microraptor would have difficulty controlling the speed of its descent requiring a soft landing pad (either flexible branches or soft ground cover). In contrast the biplane model appears much more stable and the authors indicate that this was the more likely configuration.

While the thought of dinosaurs perfecting biplane gliding several hundred million years before the Wright brothers is certainly appealing, this isn’t what interests me the most about the new paper. What’s far more interesting is the suggestion that Microraptor may have used its biplane to achieve phugoid flight. But for more on that you’ll have to wait for the follow up post.

Picasso and Braque by Mark Tansey (1992)

Postscript: As usual I’ve been scooped by Matt at HMNH. Living the Scientific Life also has a very nice summary which appears in I & The Bird #41.