This site presents the idea that birds developed from flying pterosaurs.
This is a credible alternative to the current, mainstream idea that birds developed from land-based dinosaurs.
As people know, I am proposing that pterosaurs developed into modern birds in a series of steps. There were changes at each step of course. Because I propose specific taxa on the lineage lines, we can see and evaluate the changes that took place along the lines.
Note: I dearly wish that the dino to bird folk did something similar, so we could see the changes that they propose. Then we could compare. As it is, the dino to bird linage is completely imaginary, so it is impossible to evaluate it.
They show a significant similarity between the feet of dromeosaurs, tyrannosaurs, coelurosaurs and birds. The pterosaur foot, on the other hand, looks quite different, not only in the shape and orientation of the metatarsals and toes, but also in the fact that it lies flat in contact with the ground. Perhaps you do not consider this as something against your theory, and attribute it to saltation, and perhaps you would like to dismiss all similarity of coelurosaur feet and bird feet as convergence. But the similarities and differences are there; it's up to you to explain them as you please.
This post of yours was about comparison. There is your comparison, make what you want of it.
Why do you not think that? I told you about the difference of the pterosaur foot in relation to the orientation of the metatarsals and toes. Tell me where you disagree exactly, and I will elaborate.
As for the comment you quoted, allow me to quote the next sentence:
"You could call this parallelism [B]as they are ancestrally quite similar,[/B] but that’s pretty subject too. I certainly don't think it’s *wrong* to call it convergence".
As you see, the discussion is an issue of term definition. The similarity itself is not disputed. And as I said, you can call it convergence too, if you like, but you should check all pictures first and then provide an explanation.
Harry Seeley, you do not seem to understand the point that Hone is making.
http://archosaurmusings.wordpress.com/2011/04/30/functional-feet/ "Despite the fact that there’s quite an evolutionary distance between the two, and of course that after the tyrannosaurs came long theropods had kinda become birds and been living in trees and flying for a good few million years before coming back down. But again we see similar adaptations, the metatarsals are now fused fully into a single unit, and the toes are rather well spread out."
Here is the joke with what Hone is saying. The claim is that the Tyrannosaur became a flying bird and then became a flightless Moa. The Tyrannosaur foot looks like a flightless Moa but it had changed into something else first (some kind of flying bird) then changed back to the shape of the Tyrannosaur. If this was not so funny it would be sad.
"It is of course inevitable that similar features undergoing similar evolutionary pressures will convergently acquire similar form. Here’s a nice example from the theropods."
This is at most claiming an analagous (convergent) relationship, not a homologous one, between tyrannosaurs and moas.
This argues against the dino to bird idea.
I have a feeling that Harry Seeley just throws things against the wall, no matter how contradictory, just to see if something will stick.
Would anyone care to compare these feet to pterosaur feet? to dromaeosaur feet?
ReplyDeleteHmm. Doesn't look much like a pterosaur foot:
ReplyDeletehttp://archosaurmusings.files.wordpress.com/2011/02/ptero-ft.jpg
Why do you say that?
ReplyDeleteAs people know, I am proposing that pterosaurs developed into modern birds in a series of steps. There were changes at each step of course.
ReplyDeleteBecause I propose specific taxa on the lineage lines, we can see and evaluate the changes that took place along the lines.
Note:
I dearly wish that the dino to bird folk did something similar, so we could see the changes that they propose. Then we could compare.
As it is, the dino to bird linage is completely imaginary, so it is impossible to evaluate it.
Some more feet:
ReplyDeleteDromeosaur
http://upload.wikimedia.org/wikipedia/commons/thumb/9/9d/Dromaeosaurus_feet.JPG/800px-Dromaeosaurus_feet.JPG
Coelurosaur (whole skeleton, but foot visible)
http://azmnh.org/exhibits/dinohall/images/Coelurosaur.jpg
Tyrannosaurus ("Sue")
http://hiddencause.files.wordpress.com/2011/02/sue-foot.jpg
A comparison of an eagle foot and a dromeosaur foot:
http://farm7.static.flickr.com/6067/6129088745_cac20a4b85.jpg
A comparison of a pigeon foot to a Deinonychus foot:
http://www.ucmp.berkeley.edu/diapsids/saurischia/deinon_pes_skrep.jpg
Another Tyrannosaur foot
http://t3.gstatic.com/images?q=tbn:ANd9GcS0sxItS_EAgvdMpykbhvDvwGCFe9Bn-xQarFWILXGYRk0vIbdMSw
And a comparison of a T-Rex foot to the foot of a Moa:
http://archosaurmusings.wordpress.com/2011/04/30/functional-feet/
Harry Seeley.
ReplyDeleteWould you please describe what problem(s) you see in these pictures. Are they contrary to the ideas I have been proposing?
Do they support the dino to bird idea? If you think so, please indicate how.
Thanks.
They show a significant similarity between the feet of dromeosaurs, tyrannosaurs, coelurosaurs and birds. The pterosaur foot, on the other hand, looks quite different, not only in the shape and orientation of the metatarsals and toes, but also in the fact that it lies flat in contact with the ground. Perhaps you do not consider this as something against your theory, and attribute it to saltation, and perhaps you would like to dismiss all similarity of coelurosaur feet and bird feet as convergence. But the similarities and differences are there; it's up to you to explain them as you please.
ReplyDeleteThis post of yours was about comparison. There is your comparison, make what you want of it.
Let's look at this one (I only looked at one):
ReplyDelete"And a comparison of a T-Rex foot to the foot of a Moa:
http://archosaurmusings.wordpress.com/2011/04/30/functional-feet/"
David Hone:
"Well as you say there is a divergence in foot form between tyrannosaurs and moas before the return of the shape in a moa."
Harry Seeley, I do not think things are as you are saying.
Can you explicitly support your point of view with reference to the exact toes etc?
Thanks.
Why do you not think that? I told you about the difference of the pterosaur foot in relation to the orientation of the metatarsals and toes. Tell me where you disagree exactly, and I will elaborate.
ReplyDeleteAs for the comment you quoted, allow me to quote the next sentence:
"You could call this parallelism [B]as they are ancestrally quite similar,[/B] but that’s pretty subject too. I certainly don't think it’s *wrong* to call it convergence".
As you see, the discussion is an issue of term definition. The similarity itself is not disputed. And as I said, you can call it convergence too, if you like, but you should check all pictures first and then provide an explanation.
Harry Seeley, you do not seem to understand the point that Hone is making.
ReplyDeletehttp://archosaurmusings.wordpress.com/2011/04/30/functional-feet/
"Despite the fact that there’s quite an evolutionary distance between the two, and of course that after the tyrannosaurs came long theropods had kinda become birds and been living in trees and flying for a good few million years before coming back down. But again we see similar adaptations, the metatarsals are now fused fully into a single unit, and the toes are rather well spread out."
Here is the joke with what Hone is saying. The claim is that the Tyrannosaur became a flying bird and then became a flightless Moa. The Tyrannosaur foot looks like a flightless Moa but it had changed into something else first (some kind of flying bird) then changed back to the shape of the Tyrannosaur.
If this was not so funny it would be sad.
I am not wasting time on you.
I was just reading that bit again:
ReplyDeletehttp://upload.wikimedia.org/wikipedia/commons/thumb/9/9d/Dromaeosaurus_feet.JPG/800px-Dromaeosaurus_feet.JPG
"It is of course inevitable that similar features undergoing similar evolutionary pressures will convergently acquire similar form. Here’s a nice example from the theropods."
This is at most claiming an analagous (convergent) relationship, not a homologous one, between tyrannosaurs and moas.
This argues against the dino to bird idea.
I have a feeling that Harry Seeley just throws things against the wall, no matter how contradictory, just to see if something will stick.