Blue Collar Scientist

Microraptor fossil. The image is from Wikimedia Commons, where it is licensed under the Creative Commons Attribution ShareAlike 2.5 license. Unfortunately, no author name is provided.

I’ve just finished watching the latest Nova, which aired last night (all praise be to TIVO). The episode was about Microraptor.

The early part of the documentary set up some controversy by contrasting the ideas of Larry Martin with those of various AMNH paleontologists and staff, and their collaborators at other institutions. Martin proposes that the development of flight from ground-dwelling dinosaurs¹ doesn’t make much sense, without really giving any compelling reasons. He also says that this model is necessary for the evolution of birds from dinosaurs, and again, I don’t fully understand why he thinks that. As I’m fond of saying here, just because you say something doesn’t make it true. I’m unable to think of a reason that arboreal dinosaurs developing flight means that birds can’t have evolved from dinosaurs.

He did make a reproduction of Microraptor which featured splayed femurs. The documentary covered pretty convincingly why the reproduction was not plausible - even I could see that Martin’s pelvis was flatter than a pancake. The documentary covered the similarity of the splayed rear-limb model to lizard anatomy, but I don’t think I really understood why Martin believed - even if everything else he said was true, which I wasn’t convinced of - that Microraptor could not have secondarily splayed rear limbs.

Anyone?

The AMNH team certainly seemed to be doing the better science from what Nova presented. Not only was their model constructed with some pretty rigorous methods, they recruited a multidisciplinary team of experts in various fields and hiked out to a wind tunnel to test it. It made Martin’s approach look a bit parochial. The latter half of the documentary seemed to abandon any further coverage of Martin’s work.

The wind tunnel scene was pretty interesting. I’ve been part of similar groups of scientists trying out and testing new ideas, and what Nova showed is pretty much how scientists act - on the whole very competitive, but very collegial and with few exceptions willing to admit it when the data proves them wrong. As usual, Nova was well worth watching.

1. the “ground-up” model, as he puts it, which for some reason has me picturing dinosaurs flying into airplane propellers end ending up as ingredients in my hamburger [↩]

Intelligent Design Creationists have said for some time that bats pose a problem for evolutionary theory.

Things are even tougher for the evolutionist with the knowledge that the ‘oldest known’ complete fossils of bats … show indications of a fully-developed echolocation system.

Evolutionary theory predicts that in such cases, transitional forms did exist, and are possibly waiting to be discovered in the fossil record. And today, Carl Zimmer reports on his blog about a newly discovered bat fossil.

The ear bones in its head don’t have the distinctive shape found in living bats that echolocate, suggesting that it had to rely on sight and sound to catch prey–insects, judging from its teeth. Flight evolved first in bats … and echolocation only came later.

Oh. That must really suck to be an intelligent design creationist who thinks that bats popped out of nowhere with echolocation fully developed, then.

It turns out this bat fossil is the most primitive bat ever found, and it has several other transitional attributes:

1. Evolutionary theory predicts that early bats would have body proportions similar to that of the walking mammals from which bats evolved. This fossil has shorter arms, and longer legs, than modern bats. Prediction fulfilled!
2. Almost all modern bats have only a single claw. Evolutionary theory predicts that early bats should have a full compliment of claws, and that bats who lived in between these times should show a gradual loss of claws. Many bat fossils are single-clawed with vestigial claws on other fingers, thus fulfilling the prediction as far as was able. But this bat completes things - it has claws on all five fingers, just like evolution predicts.
3. Evolutionary theory predicts that as a lineage evolves flight, early fliers will be less strong, less powerful flyers than later ones. Some evolutionary biologists have also hypothesized that powered flight most likely evolved from early gliding. Most modern bats fly with a full-time power stroke, flapping their wings continually during flight. But this fossil’s wings suggest that it alternated between flapping and gliding. Prediction fulfilled!

This is just a summary - go read Carl’s story. It’s outstanding, and it has pictures.