The Jablonski article is not itself on the topic of pterosaurs to birds. But there are a few points of interest:
1. Jablonski has noted the similarities between specific pterosaurs and specific categories of modern birds. That is something I had noted as well.
2. Jablonski says that pterosaurs "vacated".
In line with what I am saying, the pterosaurs developed into primitive birds - either through anagenesis or cladogenesis followed by extinction of the pterosaurs.
3. It is worth noting that primitive pterosaurs (Rhamphorhynchus) developed into the advanced pterosaurs (Pterodactylus) presumably in the same way.
It's significant that you started your Jablonsky quote where you did. Why didn't you include the previous sentence?
ReplyDelete"Note also that these carnivorous birds opportunistically converged on theropod dinosaurs rather than adhering to the pterosaur models that might have been the most likely targets for convergence given a flying avian starting point (62)."
Anonymous could you please indicate the relevance of that sentence to what I am saying and why you think it is significant?
ReplyDeleteIf Jablonski noting similarities between long extinct pterosaurs and modern birds supports birds being descended from pterosaurs, then Jablonski noting similarities between theropod dinosaurs and early Cenozoic birds supports birds being descended from dinosaurs even more.
ReplyDeleteDid he do that? I don't see that. Could you please detail out why you say that please.
ReplyDeleteI already did. But I will do so again, since you ask.
ReplyDelete"To drive home these important but somewhat abstract points on the long-term prospects for evolutionary replacements, consider the Cenozoic history of birds. The large, flightless phorusrhacid and diatrymid birds, probably the top carnivores of early Cenozoic terrestrial communities (62, 63), interfered with the triumphant mammalian ascent to center stage in the postdinosaurian world, and probably were not replaced by an exact mammalian analog once they disappeared. Note also that these carnivorous birds opportunistically converged on theropod dinosaurs rather than adhering to the pterosaur models that might have been the most likely targets for convergence given a flying avian starting point (62)."
He's saying that the early Cenozoic phorusrhacid and diatrymid birds converged on theropod dinosaurs rather than adhering to pterosaur models.
Early Cenozoic is right after late Cretaceous, when the (non-avian) theropod dinosaurs went extinct. Jablonski's words support a theropod ancestry of birds far more than they do a pterosaur ancestry.
How do you interpret this:
ReplyDeleteconverged on theropod dinosaurs.
Is he saying they converged on actual dinosaurs like Compsognathus and Tyrannosaurus or on Maniraptors.
Since you have read this site you ought to see what I am getting at.
Anonymous posted:
ReplyDeleteYes I do see what you're getting at. But since you've failed to make a convincing argument that maniraptors should be excluded from the rest of the theropod dinosaurs, what you are getting at is irrelevant.
Possibly Anonymous sees that the label `theropod dinosaurs` is not very helpful because it does not make the key distinction that this site is about. It incorrectly lumps in the Maniraptors with the actual dinosaurs. As we have seen from Senter, Maniraptors are not related to dinosaurs.
ReplyDeleteSo the Jablonski article in fact is likely saying:
``Note also that these carnivorous birds opportunistically converged on MANIRAPTORS WHICH IS adhering to the pterosaur models that might have been the most likely targets for convergence given a flying avian starting point.``
That is 100% consistent with what I have been proposing.
Pteroaurs developed into maniraptors (primitive birds) and maniraptors developed into modern birds.
If anyone is not clear on this point please let me know.
Note:
Jablonski`s quote is based on Feduccia. (Reference 62 in the article)
Anonymous made the comment:
ReplyDelete``But since you've failed to make a convincing argument...``.
That is just a mindless type of comment that people make when faced with something that they disagree with. It actually means nothing and certainly is off the mark in relation to what I have been posting now for months.
My suggestion to anyone who encounters that phrase is to realize it is just a statement of that person`s bias.
We can see from this discussion how misleading and unhelpful the phrase "theropod dinosaurs" is.
ReplyDeleteIt does not make the distinction between actual dinosaurs such as Tyrannosaurs etc. and maniraptors.
This is one of the major failings of cladistics concepts.
That is why it was only when Senter used scientific baraminology concepts, that the important distinction came forcefully into the light.
Senter referred to the categories as the "tyrannosaur cluster" and the "birdlike cluster".