Discussion of everything related to the Theory of Evolution.
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I'm interested in finding out what is the theory on feather evolution. The earliest fossil record of a wing is from archeopteryx and the feathers are already fully developed; no transitional evidence. Their aerodinamical complexity is astounding, the only thing i can imagine could be in it's origin is a fish's fin. Do you have any info on this? i can't find it anywhere...
*EDIT: not archeopteryx as you can read here.
Last edited by lifemare on Mon Jul 28, 2008 6:40 pm, edited 1 time in total.
thank you very much for the links. i feel kind of dumb for not having found it myself on google (never used those search terms)
have to say i'm very disappointed with the suggested timeline for feather evolution, it's so inelegant and unsubstantiated. Is it even chemically possible for a reptile scale to develop into a callamus? It's this kind of fragile constructions that give credit to more speculative and metaphysical hypothesis... looking at these drawings is like looking at Haeckel's rendition of the ontogenic process - they may be a very valid attempt, but in comparison to reality are just awfully grotesque.
One thing to remember is that birds often have scaled legs, so the connection is fairly obvious.
Even reptiles have a decently wide range of scale types. If you think of an early feather being a broad scale whose ridges (there's often a projection of thicker ridges from the central "rod") become actual separate projections, it's not hard to see the progression.
I'm just questioning the evolutionary steps here. It's an occam's razor situation. If you're speculating without any hard evidence as it seems to be the case with feather evolution and considering all fossil records of the earliest aves (oldest being triassic afaik) show fully evolved feathers (ie: same as today), it's not more arbitrary (although more far-fetched) to consider birds offsprings of the Carboniferous fish. The scales (if you must) were also present and most importantly the necessary environmental pressure for such a leap was occuring at the time (sea exodus). Fish are more suitable candidates in my view, not only because their hydrodynamic bodies would migrate better to an aerodynamical system than to land, but also because we have already witnessed flight among a particular fish family. It just sounds contradictory when you think about it. Fins are at the genesis of both limbs and wings, yet somehow paleontology wants us to believe that after(!) adapting to land and growing limbs the reptiles then decided to leave it and grow wings just because they were bored, when they should, by darwinian terms, be enjoying their newfound freedom, relative lack of predators and abundant resources (assuming Permian period for first ave here, since later doesn't seem possible). But hey, i'm no biologist, just an enthusiast, so i may be talking nonsense here. Besides i have even less proof of this theory than the one commonly accepted, but if you ask me, the one currently being taught is just plain ugly.
I'm not quite sure what you mean. The only Exodus I've ever read is the book in the Bible, and it says nothing about fish evolution. Could you please explain what you are talking about here?
If you'll forgive me for saying so, your logic is a bit flawed. Vertebrates did not start flying until a couple hundred million years after moving onto land, by which time the land was getting pretty crowded and there were plenty of good reasons to take to the air. Believe, it wasn't a matter of a bunch of dinosaurs sitting around one day saying, "Hey, I'm bored, let's figure out how to fly."
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lol! give me some credit man! I was just refering to the evolution into the first land-based reptiles.
But that's what i'm questioning, the first flying insects were pretty simultaneous with the first land reptiles, who's to say wings didn't evolve in parallel with limbs giving birth to the first primitive ave around the same time. Specially considering there's fossil record of already very sophisticated feathers around 200mya (pre-jurassic = very early mesozoic = boring paradigm, lol).
I'm not sure how much flying insects has to do with flying vertebrates. Arthropods, like vertebrates, had been living on land for millions of years before taking to the air. I would expect the same from vertebrates. Also, if feathers are necessary for flight, I likewise wouldn't be surprised if they were already around for some time before the first birds evolved. There are plenty of good reasons for a land-dwelling reptile to evolve feathers, such as insulation, that might explain their evolution before the development of flight.
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you are correct Alex infact so called Proto feathers have been found[well they look like fibres or filaments] but the transition from the proto feather to a aero dynamically perfect feather is still a mystery[Although I know remember a theory was proposed about it] yes infact feather at first would have never evolved for flight but as you said for insulation or may be for attracting mates.Also symmetric feathers were found in Dinos these feathers are not capable of flight.But Fishes have 0% chance for being their direct ancestors of birds as the genetic difference between birds and fishes is too large.
"Nothing in biology makes sense except in the light of evolution"
The evolution of birds is thought to have begun in the Jurassic Period, with the earliest birds derived from theropod dinosaurs. Birds are categorized as a biological class, Aves. The earliest known species of class Aves is Archaeopteryx lithographica, from the Late Jurassic period, though Archaepteryx is not commonly considered to have been a true bird.
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