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Post by kuni on Jan 8, 2009 18:04:50 GMT
www.youtube.com/user/flightlabApparently, birds can use their wings not just for flying, but to increase traction while rapidly climbing, and this allows them to reach angles of not just 90 degrees vertical, but 120! Really awesome stuff. This is a major insight into the evolutionary origins of flight -- you don't use wings to fly right of the bat, you use them to improve climbing ability Also, apparently this ability is basal to the maniraptorans, so it's quite likely that young therizinosaurs, oviraptorosaurs, and dromeaosaurs used this behavior, and possibly some adults, depending on size, arm length, feather length etc etc. This lab may also look into whether the "killing claw" of raptor dinosaurs was actually an adaptation to increase climbing ability, but nobody knows yet. The wings are apparently also useful at slowing falls and aiming when leaping, so I've got this great picture of a velociraptor as a solitary ambusher, hanging out up in a tree (which it got to by running straight up the trunk), then leaping onto the back of unsuspecting prey.
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Post by arioch on Jan 8, 2009 20:38:20 GMT
Interesting. But the arms of "big" -larger than microraptor, since 15kg- dromaeosaurids were too short to achieve something no matter how much they flap, or how long were the arm feathers. They were too "bulky" for that. And in a fall from a tree, they could injure too easily, unlike felines. I think only babies could be good climbers, in an adaptation for survival.
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Post by kuni on Jan 8, 2009 20:46:10 GMT
I don't think this behavior is understood well enough to know how much of a wing surface area you need.
It would be nice to have a growth series for a lot of these guys to get an idea of how forearm length scales with age.
Your fall from a tree bit is likely incorrect, as chicks with a very small ratio of wing area to body mass manage to significantly cushion their falls with flapping. Even so, I don't think this lab has looked into that in detail.
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Post by sid on Jan 8, 2009 21:08:37 GMT
I have a theory about that (actually it's floating in my mind from a long time)... ...What if young,very young Dromeosaurids had feathers on their arms BECAUSE they lived on trees,either to avoid predators (like young Komodo Dragons,which are arboreal) or due to some form of atavism (Microraptor and other tree-climbing ancestors),and then,once grown up,the lost 'em all and became terrestrial (Velociraptor,Deinonychus and other "classic" Raptors)? Considering that,it could be speculated that the Sinornithosaurus' specimens we found in China were actually juveniles of that species... But that's just my two cents,and i think a theory like that could bring peace among the "anti-feathers people" (like me ;D) and the "Pro-feathers" ones  |
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Post by arioch on Jan 8, 2009 21:47:22 GMT
The arms of sinornithosaurus are so long than the legs, or a little more. There´s no way he could be a juvenile velociraptor, the anathomy is too different.
What is the motivation of this anti feathers people? nostalgia and JP movies? they just cant get over it?
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Post by sid on Jan 8, 2009 22:07:51 GMT
The arms of sinornithosaurus are so long than the legs, or a little more. There´s no way he could be a juvenile velociraptor, the anathomy is too different. What is the motivation of this anti feathers people? nostalgia and JP movies? they just cant get over it? I didn't say that Sinornithosaurus was a juvenile of Velociraptor...Only that the skeletons we found of Sinornithosaurus could have been juveniles of the species S.Millenii itself  And regarding the motivations of Anti-feathers people ( ;D)...Heck,at least for me the motivations are the following: - Feathers are the basal condition for Dromies'skin,granted...In 100 million of years of evolution is possible that some species of advanced "Raptors" could have lost 'em and regained scales - for animals like the medium/big-sized Raptors long feathers,especially on the arms,should have been only a problem,considering the life they lived and the way they hunted - even if they were related to birds,they were STILL reptiles,from the tip of the tail to the snout...Again,in 100 million of years of evolution is highly probable that the original,"scaly" condition of the Archosaurian lineage reappered here and there,in different taxa (for example Utahraptor) - Scaly Raptors RULE ;D |
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Post by arioch on Jan 8, 2009 23:37:31 GMT
That is like suggesting that the present chickens will evolve losing the feathers and turning in little lizards in a few million years. Too absurd to consider it. The feathers only grow in the nude skin like the chicken one (which have some lizard-like scales in legs, by the way), and once evolution develop it, theres no way back. A involution like that cannot exist in nature.
The only thing dromaesaurids have in common with reptiles are the teeth and the long tail (atrofied in birds), wich isnt even flexible like the lizard ones: vestigial features. For any purpose, they are birds.
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Post by sid on Jan 9, 2009 0:14:21 GMT
That is like suggesting that the present chickens will evolve losing the feathers and turning in little lizards in a few million years. Too absurd to consider it. The feathers only grow in the nude skin like the chicken one (which have some lizard-like scales in legs, by the way), and once evolution develop it, theres no way back. A involution like that cannot exist in nature. The only thing dromaesaurids have in common with reptiles are the teeth and the long tail (atrofied in birds), wich isnt even flexible like the lizard ones: vestigial features. For any purpose, they are birds. It's official: Arioch is the "Anti-Piltdown" ;D |
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Post by arioch on Jan 9, 2009 0:21:56 GMT
Is that bad or not very bad? :/
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Post by kuni on Jan 9, 2009 0:26:55 GMT
Kinda both |
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