Naked Science Forum
Non Life Sciences => Geology, Palaeontology & Archaeology => Topic started by: Xule on 03/03/2006 19:33:04
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I heard about the theory that raptors and their relatives are thought to have been like flightless birds, with useless wings. But I do not understand how they would have wings. My reasons are:
If they had wings, their fingers would be bent downwards in order to accommodate the membrane, and would not be likely to have claws.
If, however, they had wings with hands attatched (like a bat or most of the air-reptiles of that time), they would have another bone extending downward from the wrist, once again to accommodate the membrane.
Please explain this theory to me. It's really annoying me.[:p]
"Never tell the same lie twice."
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The theory is almost right - most raptor's do not have wings, just small arms. Feathers come next and then the wings. These raptors are Cretaceous and upper Jurassic dinosaurs I am speaking of, not Lower to Mid-Jurassic or any Triassic fauna. And there is controversy about birds comming from raptors - but as the old geezers (like me)are getting out of Paleontology, the issue is faily well settled. Sort of like the Plate Tectonic theory - when A.A. Meyerhoff died and stopped publishing in the AAPG Bulliten, it was accepted theory.
As this is my first post I am putting everyone on notice - I don't spel reel gud. Please forgive the fact that a highly educated person could be that inattitive to his communiqués but it happens.
JimBob
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quote:
Originally posted by JimBob
The theory is almost right - most raptor's do not have wings, just small arms. Feathers come next and then the wings. These raptors are Cretaceous and upper Jurassic dinosaurs I am speaking of, not Lower to Mid-Jurassic or any Triassic fauna. And there is controversy about birds comming from raptors - but as the old geezers (like me)are getting out of Paleontology, the issue is faily well settled. Sort of like the Plate Tectonic theory - when A.A. Meyerhoff died and stopped publishing in the AAPG Bulliten, it was accepted theory.
As this is my first post I am putting everyone on notice - I don't spel reel gud. Please forgive the fact that a highly educated person could be that inattitive to his communiqués but it happens.
JimBob
Ah right. That makes so much more sense. Thank you
"Never tell the same lie twice."
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It's likely that wings on the raptors relatives developed for reasons other than flight. They attacked with claws and teeth. If they attacked feet first (which is likely) there would be a competetive advantage to those with an ability run lunge at prey faster.
I hope you can imagine how these psuedo-wings would help. A couple of quick wing thrusts as the animal lunged at its prey would make a swifter more accurate attack when going in feet first, maybe balanced on the tail.
Your question can then be answered. The differences in morphology between these raptor relatives and flying animals can be attributed to purpose. These were to help in an attack not to fly, at least initially.
It is good to remember when dealing with evolution that the key is the competitive advantage. With a creature that is obviously a top predator start by looking at how it attacks prey. In an attack of the method I described a wing type appendage with claws would be the best. Get the idea.
Enjoy diversity.
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I don't know if this is an accepted theory, but from the fact that flight has evolved several times - in lizards, squirrels, frogs etc. I would have though that birds evolved from very small raptors that lived in trees. Just because the raptors we have bones of are 10 feet tall doesn't mean that there weren't other small ones chasing things in trees. This would also give an advantage for larger arms for climbing with (It has allways worried me that the big raptors had tiny arms, but birds have huge ones), and then feathers could evolve to increase the distance they could jump.... a few million years...-> a bird
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I don't see how wings could have evolved from jumping out of a tree. They would die or at least injure himself. This offers no competitive advantage for anything. Unless of course the young bird made the jump and this made him very succesful with the ladies. Or the nasty little carnivores were nurturing their wounded and mated out of mercy. Truly a mammalian phenomena. And I am pretty sure there is good evidence that feathers came before wings.
A much more plausible cause is the attacking theory. Eventually the small light reptiles could fly for a short distance giving them extra advantage in attacking prey by surprise from above. As evolution forced prey to get faster and smarter only the best flyers would survive. Watch an owl attack it's prey. It has a huge advantage in silent attack from above.
Enjoy diversity.
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For a start if you have a bit of a parachute going you will survive more often if you fall out of a tree, but the real advantage is jumping between branches/trees. Look at how flying squirrels, tree frogs, flying snakes etc behave. gliding has evolved like this at least three times independently, and surely once you can glide, powered flight is a natural next step.
You are right feathers came before flight, they would have had to, but I seriously doubt that the big flight feathers came before some sort of evolutionary process towards flight.
I don't see the attacking theory. You don't get an advantage from attacking from above until you can actually fly. Have you ever seen anything that isn't very good at flying like say a chicken trying to go fast by flapping it's wings - it makes a huge racket ruining any surprise it could possibly have. Powering yourself by moving light stuff like air around is a horribly inefficient thing to do, why bother when you have a nice heavy ground to push off. Just evolve bigger leg muscles.
If you are in trees on the other hand, jumping is increadibly important. Now if you are in mid jump you have no ground to push off so pushing off the air suddenly makes sense.
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Ok Dave you might have a point about the chicken thing. But have you ever pissed off a chicken, they attack pretty heartily, feet first with flapping wings. If they had claws on the end of their wings they might be dangerous.
And all your examples are wingless. None of them have evolved anything that even resembles a wing structure. To evolve a wing structure I would guess that a flap of skin would be a bad precursor.
But since great minds don't always think alike I am going to propose this. Maybe small reptile jumped up into the tree to surprise attack from above. Then attacked like a chicken. How's that. You have to have to attacking thing in there for a predator.
Oh god, not squirrels with wings. How will I protect my nuts.
Enjoy diversity.