Racing Dinosaurs with Spoilers 60
PhilHibbs writes "The BBC is reporting a new theory - dinosaurs flapped their proto-wings to generate downforce for added traction when running up-hill. Another one to add to the many theories of the evolution of flight."
Re:Insect flight (Score:4, Insightful)
Since evolution is still happening all around us, we can look at some of the "proto-wings" we see today and make some inferences.
We have squirrels that glide out of trees by stretching the skin between their legs.
We have snakes that do something similar.
We have flightless birds that still flap their wings when they run.
We have lizards that stretch membranes much like the flying squirrel. Some of them do it to glide, while others do it to control their temperature.
If feathers were only for flight, the flightless birds wouldn't have them, and flighted birds would only have them on their wings and tails. We use down for insulation in ski jackets for the same reason the goose made it in the first place.
A small, warm blooded dinosaur would need insulation. Insulation is lightweight for its bulk, so it would lower the density of the animal as a whole. This would protect the animal from falls, but it would also make it difficult to run, due to the air resistance overcoming the available traction.
Streamlining would be selected for. Small animals would experience higher Reynolds numbers (the air would seem thicker to them) and so flapping their feathered arms would get them more benefit than a larger animal would get.
It would not surprise me to find out that flight developed in several dinosaurs in parallel, given that we see it evolving in several quite different critters today (insects, reptiles, mammals, fish).
Your idea that flight developed as a side effect of temperature control mechanisms doesn't seem far-fetched to me at all. In fact, one might call it near-fletched, if one were a punning fellow.
Re:it's all lies (Score:3, Insightful)
Like I said, I'm not an expert on evidence for the common ancestor theories. That said, while microchanges and adaptions through mutation may not by itself be evidence enough to satisfy, when combined with the DNA/RNA/Protein sequence evidence , it becomes rather compelling, IMO. (once again, I'm a bit out of my area)
It comes down to two options, an intelligent agent (god, aliens, etc) could have created the species' with DNA sequences that fit a mutational model quite well, or every organism could have a common ancestor and these sequences evolved naturally through mutation. If an intelligent agent created the species, why would it engineer the DNA/RNA/Protein sequences such that they looked exactly like they would if they got that way by eons of mutation? Occam's razor would tell you that natural evolution of those sequences is a far, far simpler and more likely explanation, especially in light of the fact that microchanges happen spontaneously and are commonly observed in the laboratory.
-Sean
Re:it's all lies (Score:2, Insightful)
Although this depends on one's interpretation of similarities in DNA between living creatures. On a biological level creatures use similar organs to perform similar functions. The same is logically the case on the molecular level. DNA in similar creatures would be expected to be similar. The molecular evidence, from what I know is no more compelling than morphological based phylogenetic trees. That is to say, molecular evidence shows no inidication of missing links existance. That mutations back to a common ancestor can be thought up is one matter, but the feasability of those mutational, in between forms is still as in question as before.
If an intelligent agent created the species, why would it engineer the DNA/RNA/Protein sequences such that they looked exactly like they would if they got that way by eons of mutation?
Well, it's pretty early still in our understanding of DNA but I'd hazard they wouldn't. Furthermore though, I'm unconvinced that they do appear to look like they have evolved over eons. All the evidence I've seen and found(and I've looked, please show me any you think is compelling), falls into two categories. DNA that looks like it has evolved over a short time within species, or junk DNA we don't yet know the purpose of and we assume similarities in this junk DNA between species is evidence of common descent. I still believe we'll find functional reasons for those similarities. The common descent interpretation is just that, an interpretation. I personally see the evidence and take a different view of what it represents.
Occam's razor would tell you that natural evolution of those sequences is a far, far simpler and more likely explanation, especially in light of the fact that microchanges happen spontaneously and are commonly observed in the laboratory.
Occam's razor is not a cure all magic wand though. It can as easily be turned around to say abiogenesis seems highly improbable(by currently known methods), and depending on how probable you believe God's existance is, one could say God is more likely to exist than a natural method by which abiogenesis occured.
Re: evolution vs. creation (Score:3, Insightful)
> I've yet to see a single pair of fossils that
are close enough to one another to be a single mutation apart
You and your parents are several mutations apart. You won't find that minimal quantum jump in the fossil record.
> We should see all kinds of creatures and
evidence of past creatures that are similar, with relatively smooth transitions from one form to another. The just isn't any evidence of that.
No one is going to make you believe the results of scientific enquiry if you don't want to, but if you want to sound like an informed critic you're going to have to get informed first. There is absolutely nothing in the theory of evolution that implies that we should have the collection of fossils you are demanding to see.