Comments on: Zombie hands to bird wings – the evolution of the dinosaur wrist http://blogs.discovermagazine.com/notrocketscience/2010/03/03/zombie-hands-to-bird-wings-the-evolution-of-the-dinosaur-wrist/ Mon, 26 Nov 2012 12:00:51 +0000 hourly 1 http://wordpress.org/?v=3.4.2 By: Zach Miller http://blogs.discovermagazine.com/notrocketscience/2010/03/03/zombie-hands-to-bird-wings-the-evolution-of-the-dinosaur-wrist/#comment-6715 Zach Miller Sat, 05 Jun 2010 00:15:35 +0000 http://blogs.discovermagazine.com/notrocketscience/2010/03/03/zombie-hands-to-bird-wings-the-evolution-of-the-dinosaur-wrist/#comment-6715 Cal, don't listen to Feduccia. The man has a very mysterious axe to grind regarding bird origins. The idea that a frame shift occured is probably valid, but it didn't have to happen down in the non-avian dinosaur side of the Theropoda. For all we know, it's unique to neornithine birds, or may be variable across Aves. I don't think there's been a strong sample size taken for manual digit formation across living birds (maybe there has and I'm unaware of it). Cal, don’t listen to Feduccia. The man has a very mysterious axe to grind regarding bird origins. The idea that a frame shift occured is probably valid, but it didn’t have to happen down in the non-avian dinosaur side of the Theropoda. For all we know, it’s unique to neornithine birds, or may be variable across Aves. I don’t think there’s been a strong sample size taken for manual digit formation across living birds (maybe there has and I’m unaware of it).

]]> By: Cal King http://blogs.discovermagazine.com/notrocketscience/2010/03/03/zombie-hands-to-bird-wings-the-evolution-of-the-dinosaur-wrist/#comment-6714 Cal King Sun, 09 May 2010 07:00:07 +0000 http://blogs.discovermagazine.com/notrocketscience/2010/03/03/zombie-hands-to-bird-wings-the-evolution-of-the-dinosaur-wrist/#comment-6714 One of the so-called "dinosaurs" in this article is Caudipteryx. Caudipteryx, according to Alan Feduccia of the Univ. of North Carolina, is a flightless bird, not a dinosaur. He says that there is not a single uniquely dinosaurian character in this fossil, but many bird-like characters. The fact that it also has feathers is strong evidence that it is a bird. That shows the claim that the bird wrist evolved before birds did is simply a bad mistake. In fact, the bird hand, which has fingers 2-3-4, is strong evidence that birds did not evolve from a theropod, which has fingers 1-2-3. The evidence is so strong that some cladists had to invent an ad hoc hypothesis called "frame shift" to try to explain how a hand with fingers 1-2-3 can become a hand with fingers 2-3-4. Worse, one of the original authors (namely Mr. Wagner) of the paper claiming a frame shift no longer believes that a frame shift occurred. Just like the emperor in his new clothes, the cladistic emperor continues to march on, even after his clothelessness had been revealed. The cladistic emperor's new clothe is of course the dinosaurian origin of birds. One of the so-called “dinosaurs” in this article is Caudipteryx. Caudipteryx, according to Alan Feduccia of the Univ. of North Carolina, is a flightless bird, not a dinosaur. He says that there is not a single uniquely dinosaurian character in this fossil, but many bird-like characters. The fact that it also has feathers is strong evidence that it is a bird. That shows the claim that the bird wrist evolved before birds did is simply a bad mistake. In fact, the bird hand, which has fingers 2-3-4, is strong evidence that birds did not evolve from a theropod, which has fingers 1-2-3. The evidence is so strong that some cladists had to invent an ad hoc hypothesis called “frame shift” to try to explain how a hand with fingers 1-2-3 can become a hand with fingers 2-3-4. Worse, one of the original authors (namely Mr. Wagner) of the paper claiming a frame shift no longer believes that a frame shift occurred. Just like the emperor in his new clothes, the cladistic emperor continues to march on, even after his clothelessness had been revealed. The cladistic emperor’s new clothe is of course the dinosaurian origin of birds.

]]> By: The Next Twenty Years » Blog Archive » Dramatic restructuring of dinosaur feathers revealed by two youngsters of same species | Not Exactly Rocket Science http://blogs.discovermagazine.com/notrocketscience/2010/03/03/zombie-hands-to-bird-wings-the-evolution-of-the-dinosaur-wrist/#comment-6713 The Next Twenty Years » Blog Archive » Dramatic restructuring of dinosaur feathers revealed by two youngsters of same species | Not Exactly Rocket Science Thu, 29 Apr 2010 04:57:37 +0000 http://blogs.discovermagazine.com/notrocketscience/2010/03/03/zombie-hands-to-bird-wings-the-evolution-of-the-dinosaur-wrist/#comment-6713 [...] Zombie hands to bird wings – the evolution of the dinosaur wrist [...] [...] Zombie hands to bird wings – the evolution of the dinosaur wrist [...]

]]> By: Dramatic restructuring of dinosaur feathers revealed by two youngsters of same species | Not Exactly Rocket Science http://blogs.discovermagazine.com/notrocketscience/2010/03/03/zombie-hands-to-bird-wings-the-evolution-of-the-dinosaur-wrist/#comment-6712 Dramatic restructuring of dinosaur feathers revealed by two youngsters of same species | Not Exactly Rocket Science Wed, 28 Apr 2010 22:14:20 +0000 http://blogs.discovermagazine.com/notrocketscience/2010/03/03/zombie-hands-to-bird-wings-the-evolution-of-the-dinosaur-wrist/#comment-6712 [...] Zombie hands to bird wings – the evolution of the dinosaur wrist [...] [...] Zombie hands to bird wings – the evolution of the dinosaur wrist [...]

]]> By: Nathan Myers http://blogs.discovermagazine.com/notrocketscience/2010/03/03/zombie-hands-to-bird-wings-the-evolution-of-the-dinosaur-wrist/#comment-6711 Nathan Myers Wed, 03 Mar 2010 23:54:11 +0000 http://blogs.discovermagazine.com/notrocketscience/2010/03/03/zombie-hands-to-bird-wings-the-evolution-of-the-dinosaur-wrist/#comment-6711 I found Corwin Sullivan's description of the hand motions involved a little easier (sorry) to follow, despite that he (unlike Ed) has us start out with our hands in a position theropods could never have achieved: <a href="http://archosaurmusings.wordpress.com/2010/03/03/guest-post-birds-in-a-flap-thanks-to-dinosaur-wrists/" rel="nofollow">http://archosaurmusings.wordpress.com/2010/03/03/guest-post-birds-in-a-flap-thanks-to-dinosaur-wrists/</a> I find it helps me to picture the flexibility involved as trying to touch my elbow with my little finger while keeping my thumb pointed forward. (I don't get very close, but hope for improvement with practice. :-) Thank you for the correction: maniraptorans were a big group, since pruned and radiated. Certainly all the extant ones achieve wrist flexibility I can only dream of. I found Corwin Sullivan’s description of the hand motions involved a little easier (sorry) to follow, despite that he (unlike Ed) has us start out with our hands in a position theropods could never have achieved:
http://archosaurmusings.wordpress.com/2010/03/03/guest-post-birds-in-a-flap-thanks-to-dinosaur-wrists/
I find it helps me to picture the flexibility involved as trying to touch my elbow with my little finger while keeping my thumb pointed forward. (I don’t get very close, but hope for improvement with practice. :-)
Thank you for the correction: maniraptorans were a big group, since pruned and radiated. Certainly all the extant ones achieve wrist flexibility I can only dream of.

]]> By: Ed Yong http://blogs.discovermagazine.com/notrocketscience/2010/03/03/zombie-hands-to-bird-wings-the-evolution-of-the-dinosaur-wrist/#comment-6710 Ed Yong Wed, 03 Mar 2010 23:31:42 +0000 http://blogs.discovermagazine.com/notrocketscience/2010/03/03/zombie-hands-to-bird-wings-the-evolution-of-the-dinosaur-wrist/#comment-6710 <blockquote>As I understand the flexible wrists of maniraptorans, they could, like birds, flop their hands back parallel to their forearms.</blockquote> Not quite that far. The paper suggests that most were a lot less flexible than that although they could flop their hands back towards their forearms to some extent. Deinonychus's writst, for example, was actually pretty inflexible.

As I understand the flexible wrists of maniraptorans, they could, like birds, flop their hands back parallel to their forearms.

Not quite that far. The paper suggests that most were a lot less flexible than that although they could flop their hands back towards their forearms to some extent. Deinonychus’s writst, for example, was actually pretty inflexible.

]]> By: Nathan Myers http://blogs.discovermagazine.com/notrocketscience/2010/03/03/zombie-hands-to-bird-wings-the-evolution-of-the-dinosaur-wrist/#comment-6709 Nathan Myers Wed, 03 Mar 2010 23:16:49 +0000 http://blogs.discovermagazine.com/notrocketscience/2010/03/03/zombie-hands-to-bird-wings-the-evolution-of-the-dinosaur-wrist/#comment-6709 I know the left-hand picture position as "<b>bunny hands</b>". Theropods were entirely incapable of getting their hands into such a pose. As I understand the flexible wrists of maniraptorans, they could, like birds, flop their hands back parallel to their forearms. That's clever, but seems more useful to birds folding their wings than to your average theropod. It still seems right to reconstruct theropods stalking around with their palms facing one another, menacingly. Certainly the bunny-hands posture is just as absurd as it ever was. I know the left-hand picture position as “bunny hands“. Theropods were entirely incapable of getting their hands into such a pose. As I understand the flexible wrists of maniraptorans, they could, like birds, flop their hands back parallel to their forearms. That’s clever, but seems more useful to birds folding their wings than to your average theropod.
It still seems right to reconstruct theropods stalking around with their palms facing one another, menacingly. Certainly the bunny-hands posture is just as absurd as it ever was.

]]> By: jdaniel http://blogs.discovermagazine.com/notrocketscience/2010/03/03/zombie-hands-to-bird-wings-the-evolution-of-the-dinosaur-wrist/#comment-6708 jdaniel Wed, 03 Mar 2010 22:29:22 +0000 http://blogs.discovermagazine.com/notrocketscience/2010/03/03/zombie-hands-to-bird-wings-the-evolution-of-the-dinosaur-wrist/#comment-6708 Yes, well we already knew that. The normally pronated position was a layman's misperception and always has been. Don't get me wrong, I like the study, but the importance of the study was not that dinosaurs didn't pronate their hands, but how far could they abduct their hands and how did it change over the evolution of the clade. The reconstructions have been terribly inconsistent and this study provides guidance on what angles are reasonable. The pronated hands has always been a puzzlement to me anyway. We don't even do that. Start with your arms at your sides and bend your forearm, where does your palm end up? At least for me, they end up facing medially, same as anyone jogging down the street. The pronated position only makes sense if one is looking at a quadroped standing on its back legs. I expect that if you tried to walk while keeping your hands pronated, you find quickly find it bothersome because it is not a natural resting position. The difference of course between us and them is that we have a small range of abduction and birds have a much wider range, but how that range developed hasn't really been rigorously examined until now. I guess my issue here is the laxity of terms people are using to describe the motions, confusing the movements and thus confusing the discussion. Yes, well we already knew that. The normally pronated position was a layman’s misperception and always has been. Don’t get me wrong, I like the study, but the importance of the study was not that dinosaurs didn’t pronate their hands, but how far could they abduct their hands and how did it change over the evolution of the clade. The reconstructions have been terribly inconsistent and this study provides guidance on what angles are reasonable.
The pronated hands has always been a puzzlement to me anyway. We don’t even do that. Start with your arms at your sides and bend your forearm, where does your palm end up? At least for me, they end up facing medially, same as anyone jogging down the street. The pronated position only makes sense if one is looking at a quadroped standing on its back legs. I expect that if you tried to walk while keeping your hands pronated, you find quickly find it bothersome because it is not a natural resting position.
The difference of course between us and them is that we have a small range of abduction and birds have a much wider range, but how that range developed hasn’t really been rigorously examined until now.
I guess my issue here is the laxity of terms people are using to describe the motions, confusing the movements and thus confusing the discussion.

]]> By: Science&Honor http://blogs.discovermagazine.com/notrocketscience/2010/03/03/zombie-hands-to-bird-wings-the-evolution-of-the-dinosaur-wrist/#comment-6707 Science&Honor Wed, 03 Mar 2010 22:02:10 +0000 http://blogs.discovermagazine.com/notrocketscience/2010/03/03/zombie-hands-to-bird-wings-the-evolution-of-the-dinosaur-wrist/#comment-6707 @jdaniel The author is essentially saying that evidence shows that the pronated position we typically envisioned for dinosaurs (such as various raptors) was not the case, and that dinosaurs of this type were evolving the ability to increase the range of motion of abduction of the wrist in a backwards facing direction, like a bird wing. @jdaniel The author is essentially saying that evidence shows that the pronated position we typically envisioned for dinosaurs (such as various raptors) was not the case, and that dinosaurs of this type were evolving the ability to increase the range of motion of abduction of the wrist in a backwards facing direction, like a bird wing.

]]> By: jdaniel http://blogs.discovermagazine.com/notrocketscience/2010/03/03/zombie-hands-to-bird-wings-the-evolution-of-the-dinosaur-wrist/#comment-6706 jdaniel Wed, 03 Mar 2010 16:24:39 +0000 http://blogs.discovermagazine.com/notrocketscience/2010/03/03/zombie-hands-to-bird-wings-the-evolution-of-the-dinosaur-wrist/#comment-6706 Just to clarify, are you talking about abduction of the hand (a wrist movement) or pronation of the hand (a forearm movement)? I say it this way, because even though pronation for us is really a forearm movement, most people consider it a hand movement and just wanted to be clear what you meant. The description you gave of the dinosaurs with their palms facing downward is a pronated position, not an abducted position, which is what birds do, and thus makes this discussion confusing. Just to clarify, are you talking about abduction of the hand (a wrist movement) or pronation of the hand (a forearm movement)? I say it this way, because even though pronation for us is really a forearm movement, most people consider it a hand movement and just wanted to be clear what you meant. The description you gave of the dinosaurs with their palms facing downward is a pronated position, not an abducted position, which is what birds do, and thus makes this discussion confusing.

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