Friday, April 20, 2007

Attention: flying lizards.

After talking to a bunch of 4th graders at Sewanee Elementary about dinosaurs and birds, I've become a little obsessed with one of my examples. Microcraptor gui is a small Dromaeosaur fossil from Liaoning province, China - a locality famous for little feathered early Cretaceous stuff, and a lot of other things. I bought some Liaoning fossils (illegally of course) at the Tucson Gem and Mineral Show. But my slab had only a fish and a bug. The Liaoning locality is a lot like the Solnhofen of Germany, another formation with famous feather impressions. Microraptor gui doesn't just have arm feathers, it has leg feathers too. It's pretty clear that we're dealing with a four-wing├Ęd beast.

One of the tougher parts about Paleontology as a science is the ease with which the imagination can run wild. Even famous Paleontologists can easily undermine good careers and reputations by going nuts with guessing games. I'm thinking of Bob Bakker. But I also think that imagination has its place in fossil storytelling if we don't treat it as gospel, especially if it's done with solid evolutionary principles in mind. There's nothing wrong with going overboard in awe of evolution's abundant strategic reserves. This fossil is fascinating because of the detail it shows, but that dangerous knowledge about its feathers only lets me guess and invent even more. The speculative aspect of Paleontology is at the heart of this project; this is science, so we say, but what hypotheses can we really disprove about this animal's former life? Well, a lot, in fact. You could prove, if you like, that the bones in the chest might not have been able to support flapping muscles, or that the arm sockets could only extend so far, or that the tail is too heavy to use for much but ballast. We call it adaptive functional morphology, and it can be pretty cool.

But that sort of thing only works to a point. If we consider what we know about extant species, and how even detailed observations of living organisms always leave more questions, it is easy to see how fossils are only the barest of telegrams from the former world. Imbellishment was the mode of research for a century in the discipline, and it still is for amateurs. There are far more armchair wiseacre layman Paleontologists than there are Chemists or Physicists and so on. To whit: I will speculate a bit about some of these drawings of our fossil's animated existence. I like the first one. The legs are tucked in under the body, and it looks like the guy has just leaped from a treetrunk. As just a gut reaction, the construal of a fixed gliding posture makes a lot more sense to me than the flapping screeching, leg-drag generating pose of the color photo.

It helps to see these protoavians as novel lizards rather than half-formed birds. The uber-Victorian notion of directional, progressive, incremental evolution concluding in familiar forms has dogged the Theory of Life for 200 years, and we've got to put it to an end. The real story here seems to be (when we consider the fossil evidence from the Natural Historian's prospective) that just as a flying squirrel today is not on its way to becoming a bat, our dinosaur friend is not on his way to becoming a sparrow. Microraptor gui was quite content being an efficient gliding arboreal predator. It was perfectly equipped to do whatever it was that kept it alive. If it wasn't, it wouldn't have existed at all. Its descendents, however, were free to be selected in any direction that worked.

We still have gliding frogs, flying snakes (seriously, in Malaysia), gliding geckos, flying fish, and flying squirrels. Why don't we still have feathered, toothy gliding tree-terrors in the woods? I don't know, and the standard Paleoanswers are tired. Powered vertebrate flight has evolved independently at least three separate times in the planet's history with pterodactyls, bats and birds. We don't seem to keep many of the gliding ancestors of real flyers around for long. But the spectacle of an Eastern Pipistrell gnabbing a fleeing moth, or an Osprey snatching a wriggly fish seems like a good enough consolation prize for now.

For science to remain an interesting and worthwile paradigm, we must rejoice in the fact that some things are very hard to know, and some ought to stay that way. Frustration with the unexplained is not sufficient motivation for real discovery, or honest inquiry. Good scientific answers can only come from passionate curiosity. We should avoid the aarogance of knowledge and cultivate reverance for the unknown. Let's not obsess over making all our guesses into scientific fact. We're not looking for some archive of universal anwers, we want a full life of worthwhile questions.


  1. The naturalist's journey has only begun and for all intents and purposes will go on forever; that it is possible to spend a lifetime in a Megellanic voyage around the trunk of a single tree; that as the exploration is pressed, it will engage more of the things close to the human heart and spirit. And if this much is true, it seems possible that the naturalists vision is only a specialized product of a BIOPHILIC instinct shared by all, that it can be elaborated to benefit more and more people. Humanity is exalted not because we are so far above other living creatures, but because knowing them well elevates the very concept of life." -E.O. Wilson, "Biophilia"

  2. Here's to well-formed, insightful, questions. Ginger and I drank to that late on Friday and then she told me she would be retiring to her boyfriend's place for the evening.