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First Flying Dinosaurs Had Biplane Structure
unchiujar writes to mention a BBC article about the design of the first flying dinosaurs. These possible early ancestors of avians apparently resembled biplanes in many ways, with legs hanging down in a fashion similar to WWI fighters. The researchers who made this discovery use this to argue the 'trees down' model of flight evolution, but the article points out this design may possibly be a failed evolutionary experiment. From the article: "Dr Chatterjee, from Texas Tech University in Lubbock, US, explained that two lines of evidence had led the team to this conclusion. Firstly, the researchers argue, dinosaurs and birds move their legs in a vertical plane, not sideways as the tandem flight pattern requires. Secondly, the feathers on Microraptor's hind legs are asymmetrical; one of the two vanes that extend either side of the shaft is narrower than the other. Aerodynamically, the narrow leading edge of these feathers should face forward in flight, against the direction of airflow. This would have given the flying reptiles lift. "
I know several vertebrate paleontologists, and every time I hear them talk about this guy, the general impression I get is that he's kind of a crank. He's not, to put it mildly, well-respected in the vert paleo community, and his views on this are about as widely held as the view that Wensleydale cheese is the root taxon for frogs.
From July:
Ancient Reptile Had Wings Like a Fighter Jet
The Humblest Mollusk on the Net
This creature doesn't fly, it glides. The forward motion comes from falling from the tree.
Finding other idiots on
Except it wasn't the first design for non-insect flying animals.
Pterosaurs preceeding flying dinosaurs by 75 million years. Pterosaurs were single winged and enormously successful.
Modern birds evolved from the first flying dinosaurs, not from Pterosaurs, although Pterosaurs and dinosaurs had a common ancestor.
There are 4 independant times flight evolved: Insects, pterosaurs, birds, and mammals. 4 different wing structures developed, and in the latter 3 cases, 3 different bone arrangments to support the wings.
If only we could fall into a woman's arms without falling into her hands
Without flaming your question. I assume what your really meant was "How did they evolve".
Assume for a moment that feather like structures were already in nature. (Think hair or quills like porcupine)
Now, if you lived in the trees, like squirrels, it might be advantages to stay in the trees and avoid predators that walk along the ground. So to find food, you either climbed down quickly, and run to the next tree -or- you jump from tree to tree.
If you had feathers you could probably jump further, meaning you can reach trees that your less endowed friends couldn't. Making them the more likely target for said predators. So you breed and they become food for predators. So the offspring will have traits that promote far flying or gliding.
Lets see, 200000000 years of dinosaurs. Lets estimate an average lifespan of 10 years, lets also estimate 2 years of age is old enough to breed and that they lay 4 eggs every year. That's, err, a lot of tries. You do the math.
TODO: create/find/steal funny sig.
why can't we identify a currently living transitionary animal to a currently existing "latest and greatest" evolved creature?
EVERY population is "transitionary." Evolution occurs in populations, not individuals. Successful genes propagate through populations and unsuccessful ones are weeded out. Over time that genetic drift combined with division into subpopulations produces sufficient variances that we then see them in the fossil record as distinct. Fossil remains are rare, so what we have is a sparse sampling of what has lived. However, there are cases where in layer after layer the shifts in a population can be seen. The reptile-to-mammal transition for example, has lots of fossil examples of the incremental variations of populations over an extended period.
But really-- read a book. This is not rocket science, and popular books on evolutionary details are not hard to read. Asking a question like "how come there are no transitions" merely shows how ignorant you truly are about the subject. The question itself is erroneous as it presumes ridiculous things like a reptile suddenly giving birth to a half-bird or something which has nothing to do with how evolution works. Trotting out dated creationist canards does not speak well for your education. If you wish to argue against evolution, find out what it is first before you start asking "how long have you been beating your wife"-type questions.