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Sooo, dinosaurs have officially turned into birds
Topic Started: Nov 3 2012, 08:13 AM (10,709 Views)
Godzillasaurus
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Not in the evolutionary sense, but in the sarcastic sense. Dinosaurs used to be large, scaly, beasts. Now, everyone thinks they all (yes, including sauropods) had feathers. If there have been countless dinosaur skin-impressions, and only a couple feathered non-ceoulosaur theropods, I guess that just puts feathers on every dinosaur, even when the evidence states otherwise. Anyone else bothered by this? :angry:
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theropod
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You have yet to provide evidence against that. Homology in similar structures in related animals should also be assumed by default unless there is counterindication (such as with mammal hair and dinosaur feathers, were we know they evolved independently).
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SpinoInWonderland
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theropod
Oct 15 2013, 09:48 PM
You have yet to provide evidence against that.
I have already done so for a long time, do I need to dig them up and post them all again?

theropod
Oct 15 2013, 09:48 PM
Homology in similar structures in related animals should also be assumed by default
Why? Can you provide a reason? So we can state that the common ancestor of Dimetrodon and Edaphosaurus should have a sail?

theropod
Oct 15 2013, 09:48 PM
unless there is counterindication (such as with mammal hair and dinosaur feathers, were we know they evolved independently).
Sauropodomorph and Carnotaurus skin impressions, all scaly and no signs of feathers at all
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theropod
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Quote:
 
I have already done so for a long time, do I need to dig them up and post them all again?

Since you require me to post my evidence over and over again, why not?

Quote:
 
Why? Can you provide a reason? So we can state that the common ancestor of Dimetrodon and Edaphosaurus should have a sail?
See my responses/comments and examples on deviantart and you know-where-else. it's simply phylogenetic bracketing "the same that makes us conclude dinosaurs had eyeballs"

Quote:
 
Sauropodomorph and Carnotaurus skin impressions, all scaly and no signs of feathers at all
Because, as I have told you for soooooo many times, if there were filaments of the kind seen in extant megafauna or on scaly mammals (eg. armadillos, were hair grows between the scales), highly likely as I already demonstrated to you multiple times, it wouldn't be preserved.
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SpinoInWonderland
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My replies are in orange

theropod
Oct 16 2013, 01:38 AM
Quote:
 
Why? Can you provide a reason? So we can state that the common ancestor of Dimetrodon and Edaphosaurus should have a sail?
See my responses/comments and examples on deviantart and you know-where-else. it's simply phylogenetic bracketing "the same that makes us conclude dinosaurs had eyeballs"

I think we should be more conservative about those phylogenetic brackets, constraining them to the structures which actually show evidence of homology.

Do you believe Kannemeyeria had hair?


Quote:
 
Sauropodomorph and Carnotaurus skin impressions, all scaly and no signs of feathers at all
Because, as I have told you for soooooo many times, if there were filaments of the kind seen in extant megafauna or on scaly mammals (eg. armadillos, were hair grows between the scales), highly likely as I already demonstrated to you multiple times, it wouldn't be preserved.

But that's because we already know that such had hair. For something with no further evidence, like feathered sauropodomorphs, we're making monstrous bets larger than Godzilla's size.
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Jinfengopteryx
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SpinoInWonderland
Oct 16 2013, 01:48 AM
But that's because we already know that such had hair. For something with no further evidence, like feathered sauropodomorphs, we're making monstrous bets larger than Godzilla's size.
His point was that the skin impressions don't invalidate the theory.
Wether we need hard evidence is another discussion, but it has nothing to do with the skin impressions.
Edited by Jinfengopteryx, Oct 16 2013, 02:12 AM.
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theropod
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Quote:
 

I think we should be more conservative about those phylogenetic brackets, constraining them to the structures which actually show evidence of homology.

Do you believe Kannemeyeria had hair?

What do you consider "evidence of homology"? What evidence of homology do you find between the femora of T. rex and Alamosaurus for example?

And what the hell does my opinion on Kannemeyria's integument have to do with this? We're talking about Reptiles, not synapsids.

Quote:
 
But that's because we already know that such had hair. For something with no further evidence, like feathered sauropodomorphs, we're making monstrous bets larger than Godzilla's size.

What's because of that?

In the lack of concrete evidence, we do the next best thing; Phylogenetic bracketing. In doing so, one must conclude feathers are a plesiomorphy of ornithodira, or even archosauria, because we have no reason to suspect The filaments found among various taxa within these clades are not homologous.
That's no monstrous bet, it's the most parsimonous and most probable assumption we can make.

It's the same way that we can conclude that an extinct squamate was scaly, and that an extinct mammal was furred (and yes, that IS the exact same thing; we know extant mammals have fur, ergo we know mammals from various clades have fur. in between, there are extinct mammals that we have no direct evidence of fur in. What should be assumed, that they had fur or that they didn't? Or do you think the fur of porcupines isn't homologous with that of other mammals?).
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SpinoInWonderland
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theropod
Oct 16 2013, 05:58 AM
What do you consider "evidence of homology"?
When the same or very similar structures are found consistently in a clade, like with coelurosaurian feathers.

theropod
Oct 16 2013, 05:58 AM
And what the hell does my opinion on Kannemeyria's integument have to do with this?
It would show whether you're conservative or liberal with integumentary structures.

theropod
Oct 16 2013, 05:58 AM
In the lack of concrete evidence, we do the next best thing; Phylogenetic bracketing.
I already do that.

theropod
Oct 16 2013, 05:58 AM
In doing so, one must conclude feathers are a plesiomorphy of ornithodira
As I already said somewhere else, I think you're being a bit too liberal with those brackets. There is no known evidence for the homology of quills and pycnofibres, just very loose speculation. I don't think even All Yesterdays is that speculative.


theropod
Oct 16 2013, 05:58 AM
or even archosauria
Wait, what? Phylogenetic bracketing won't get you anywhere near that far! When you suggested this, you should have seen the real point behind that question of a dicynodont's integument that I've asked you. What taxon are you using to bracket feathers, even in the most liberal sensible definition, as the plesiomorphy of Archosauria?

theropod
Oct 16 2013, 05:58 AM
because we have no reason to suspect The filaments found among various taxa within these clades are not homologous.
There is also no reason to suspect that pterosaur pycnofibres and dinosaur quills/feathers are homologues.

theropod
Oct 16 2013, 05:58 AM
That's no monstrous bet, it's the most parsimonous and most probable assumption we can make.
Supporting a homology that is only very very loose speculation, and even suggesting a ridiculous phylogenetic spread of feathers(because really, feathers as an archosaurian plesiomorphy is ridiculous, not supported at all, and works on -0 evidence, can you show me a feathered or even quilled pseudosuchian?), is making a very, very, very monstrous bet. The suggestion of feathers as a plesiomorphy of archosaurs already makes an incomprehensible bet larger than the estimated size of the entire universe.


theropod
Oct 16 2013, 05:58 AM
It's the same way that we can conclude that an extinct squamate was scaly, and that an extinct mammal was furred (and yes, that IS the exact same thing; we know extant mammals have fur, ergo we know mammals from various clades have fur. in between, there are extinct mammals that we have no direct evidence of fur in. What should be assumed, that they had fur or that they didn't? Or do you think the fur of porcupines isn't homologous with that of other mammals?).
The difference there is that we have strong evidence for homology there, in the form of living animals.

The same cannot be said for the alleged homology of pycnofibres and quills/feathers, and no need to mention that very ridiculous idea of feathers as archosaur plesiomorphy, well no offense to you intended for calling out on that idea but I think if you ask the scientific community the question "Are feathers a plesiomorphic trait of Archosauria?", I'm pretty sure that they will all say no.
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Spinodontosaurus
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SpinoInWonderland
Oct 15 2013, 12:59 PM
theropod
Feb 11 2013, 09:13 AM
filaments are the integument that should be automatically assumed and only doubted on the basis of hard evidence, not the other way around.
You still believe this so I can reply.

Well the answer for that is...


N O

SpinoInWonderland
Sep 21 2013, 02:59 AM
A new scenario for the evolutionary origin of hair, feather, and avian scales

"A few samples of the skin of dinosaurs which have been fossilized, consist of granulated scales, not overlapping scales (Gohlih & Chiappe, 2006). In my view it is not necessary to have overlapping scales to form feathers. More probably, feathers may have evolved from the tuberculate scales of the first archosaurs, possibly made of beta-keratins, and even more precisely of feather-type beta-keratins. Recent results (Dalla Valle et al. 2008) strongly suggest that feather beta-keratins originated deep in archosaur evolution, before the split between birds and crocodiles."

"The first archosaurs may have developed symmetrical tuberculate beta-keratinized scales, then, in theropod dinosaurs, the increase of the Wnt/beta-catenin pathway and the formation of dermal condensations, favored long proto-feather to develop, followed by the formation of branched structures, a rachis, barbules, and finally an asymmetry developed in the vane, as in modern feathers."

Posted Image

Tuberculate scales came first. The feather thing was only applied to theropods. And to take this further, all known feathers were found only in Coelurosauria. For all other dinosaurs, we only get tuberculate scales and quills.

And after all this time, you have yet to provide evidence of pterosaur pycnofibres being homologous to coelurosaurian feathers.


Please stop quote mining that study. You are using it to portray a different argument than what it actually presents. It makes you look incompetent when the foundation of your argument disagrees with you.
Heres a fun quote for you, from the same study:
"Concerning feathers, they may have evolved independently of squamate scales, each originating from the hypothetical roughened beta-keratinized integument of the first sauropsids. The avian overlapping scales, which cover the feet in some bird species, may have developed later in evolution, being secondarily derived from feathers."
Edited by Spinodontosaurus, Oct 16 2013, 01:52 PM.
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theropod
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Quote:
 
When the same or very similar structures are found consistently in a clade, like with coelurosaurian feathers.
These are also found consistently in all of ornithodira.

Quote:
 
It would show whether you're conservative or liberal with integumentary structures.

OK then. I must admit I have no clue, It has been a long time since my last intensive research on synapsids. For answering your question I´d first have to do a literature survey on the evidence at hand.


Quote:
 
I already do that.
Well, phylogenetic bracketing tells us non-avian dinosaurs had stage one or higher filaments.

Quote:
 
As I already said somewhere else, I think you're being a bit too liberal with those brackets. There is no known evidence for the homology of quills and pycnofibres, just very loose speculation. I don't think even All Yesterdays is that speculative.
Again, is there anything suggestive of them NOT being momologous? No! So what´s so speculative about it? It´s the same reasoning that also makes us concldue coelurosaurs had feathers!

Quote:
 
Wait, what? Phylogenetic bracketing won't get you anywhere near that far!
Explain that to the scientists!

Quote:
 
When you suggested this, you should have seen the real point behind that question of a dicynodont's integument that I've asked you. What taxon are you using to bracket feathers, even in the most liberal sensible definition, as the plesiomorphy of Archosauria?
Alligator missisipiensis, a derived member of crurotarsi whose genes contain the information for developing feathers. this makes it likely its a plesiomorphic condition secondarily lost in adult crurotarsi.

Quote:
 
There is also no reason to suspect that pterosaur pycnofibres and dinosaur quills/feathers are homologues.
For all we know they could be, and since that explanation requires only a single evolutionary step as opposed to two, it should be preferred.

Quote:
 
Supporting a homology that is only very very loose speculation, and even suggesting a ridiculous phylogenetic spread of feathers(because really, feathers as an archosaurian plesiomorphy is ridiculous, not supported at all, and works on -0 evidence, can you show me a feathered or even quilled pseudosuchian?), is making a very, very, very monstrous bet. The suggestion of feathers as a plesiomorphy of archosaurs already makes an incomprehensible bet larger than the estimated size of the entire universe.
Sorry if I hurt your feelings that much by suggesting Archosaurs could plesiomorphically have had feathers (again, real definition, not your "pennaceous feather=the only proper feather"). Are you OK now?

Quote:
 
The difference there is that we have strong evidence for homology there, in the form of living animals.
We also have strong homology in the case of archosaurs, in the form of both living animals and extinct taxa with unambigous evidence for feathers.

Quote:
 
The same cannot be said for the alleged homology of pycnofibres and quills/feathers, and no need to mention that very ridiculous idea of feathers as archosaur plesiomorphy, well no offense to you intended for calling out on that idea but I think if you ask the scientific community the question "Are feathers a plesiomorphic trait of Archosauria?", I'm pretty sure that they will all say no.

I´m pretty sure they won´t.

At least I know this study doesn´t: "Beta-keratin localization in developing alligator scales and feathers in relation to the development and evolution of feathers"
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Jinfengopteryx
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theropod
Oct 16 2013, 09:36 PM
Alligator missisipiensis, a derived member of crurotarsi whose genes contain the information for developing feathers. this makes it likely its a plesiomorphic condition secondarily lost in adult crurotarsi.
Could you show a source for that? Because this is somehow amazing to me.
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SpinoInWonderland
The madness has come back...
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Spinodontosaurus
Oct 16 2013, 01:51 PM
Concerning feathers, they may have evolved independently of squamate scales, each originating from the hypothetical roughened beta-keratinized integument of the first sauropsids. The avian overlapping scales, which cover the feet in some bird species, may have developed later in evolution, being secondarily derived from feathers.
I am not talking about those, I am talking about the ancestral non-overlapping archosaurian scales.

theropod
Oct 16 2013, 09:36 PM
These are also found consistently in all of ornithodira.
Can you show me a non-dinosaur dinosauromorph confirmed with such?

theropod
Oct 16 2013, 09:36 PM
Alligator missisipiensis, a derived member of crurotarsi whose genes contain the information for developing feathers. this makes it likely its a plesiomorphic condition secondarily lost in adult crurotarsi.
A more likely explanation is that those genes weren't originally "feather genes". Keep in mind that the same genes that allow the development of hair is also used to develop teeth and fish scales.

theropod
Oct 16 2013, 09:36 PM
For all we know they could be, and since that explanation requires only a single evolutionary step as opposed to two, it should be preferred.
Well pterosaur pycnofibres are usually compared with mammalian hair and are structured differently from even primitive feathers.

theropod
Oct 16 2013, 09:36 PM
Sorry if I hurt your feelings that much by suggesting Archosaurs could plesiomorphically have had feathers (again, real definition, not your "pennaceous feather=the only proper feather"). Are you OK now?
Can you please provide me even a single actual case of a feathered/quilled pseudosuchian?

theropod
Oct 16 2013, 09:36 PM
I´m pretty sure they won´t.

At least I know this study doesn´t: "Beta-keratin localization in developing alligator scales and feathers in relation to the development and evolution of feathers"
Dude, that says that alligator scales are similar in composition and comes from the same genes as feathers, it does not mean that pseudosuchians have actual feathers.
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Fist of the North Shrimp
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@Jingfengopteryx: http://www.ncbi.nlm.nih.gov/pubmed/17784647
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Fist of the North Shrimp
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SpinoInWonderland
Oct 16 2013, 10:57 PM
Spinodontosaurus
Oct 16 2013, 01:51 PM
Concerning feathers, they may have evolved independently of squamate scales, each originating from the hypothetical roughened beta-keratinized integument of the first sauropsids. The avian overlapping scales, which cover the feet in some bird species, may have developed later in evolution, being secondarily derived from feathers.
I am not talking about those, I am talking about the ancestral non-overlapping archosaurian scales.

theropod
Oct 16 2013, 09:36 PM
These are also found consistently in all of ornithodira.
Can you show me a non-dinosaur dinosauromorph confirmed with such?

theropod
Oct 16 2013, 09:36 PM
Alligator missisipiensis, a derived member of crurotarsi whose genes contain the information for developing feathers. this makes it likely its a plesiomorphic condition secondarily lost in adult crurotarsi.
A more likely explanation is that those genes weren't originally "feather genes". Keep in mind that the same genes that allow the development of hair is also used to develop teeth and fish scales.

theropod
Oct 16 2013, 09:36 PM
For all we know they could be, and since that explanation requires only a single evolutionary step as opposed to two, it should be preferred.
Well pterosaur pycnofibres are usually compared with mammalian hair and are structured differently from even primitive feathers.

theropod
Oct 16 2013, 09:36 PM
Sorry if I hurt your feelings that much by suggesting Archosaurs could plesiomorphically have had feathers (again, real definition, not your "pennaceous feather=the only proper feather"). Are you OK now?
Can you please provide me even a single actual case of a feathered/quilled pseudosuchian?

theropod
Oct 16 2013, 09:36 PM
I´m pretty sure they won´t.

At least I know this study doesn´t: "Beta-keratin localization in developing alligator scales and feathers in relation to the development and evolution of feathers"
Dude, that says that alligator scales are similar in composition and comes from the same genes as feathers, it does not mean that pseudosuchians have actual feathers.
Have you read the actual paper, or even the abstract?
It means that Alligators most likely evolved from a ancestor that had integument made of feather keratin, most likely something akin to a filament. But the developement is inhibited, which is most likely is a derived state.
Just like Crocs might be secondary homoitherm. Hell.

Edit: Oh, and concerning the genes that influence the developement of jair and scales, they are not all the same. Of course they share some, but that is because that they are ectodermal structures and develop from the skin.
Same for teeth, they are even homolougous with placoid scales. Please, before you refer to those topics again, learn some basic Cytology and Genetics.
Edited by Fist of the North Shrimp, Oct 17 2013, 01:58 AM.
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theropod
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Jinfengopteryx
Oct 16 2013, 10:45 PM
theropod
Oct 16 2013, 09:36 PM
Alligator missisipiensis, a derived member of crurotarsi whose genes contain the information for developing feathers. this makes it likely its a plesiomorphic condition secondarily lost in adult crurotarsi.
Could you show a source for that? Because this is somehow amazing to me.
See the last line of my last post, that's the paper it's from (it was cited in the wikipedia article about feathers)
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theropod
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Quote:
 
Can you show me a non-dinosaur dinosauromorph confirmed with such?

Dude, slowly I'm starting to question whether you comprehended the basic concept of phylogenetic bracketing.

The question is, is there even the SLIGHTEST reason to suspect they did NOT have them?

Quote:
 
A more likely explanation is that those genes weren't originally "feather genes". Keep in mind that the same genes that allow the development of hair is also used to develop teeth and fish scales.
You know damn well what they meant. Yes, they would totally have done a study to say "Alligator missisipiensis displays the genes for developing scales!". Furthermore, how do you explain they note these genes were Recapitulated, ie. not developed further during ontogeny? How many scaleless alligators do you see swimming or walking around?

Quote:
 
Well pterosaur pycnofibres are usually compared with mammalian hair and are structured differently from even primitive feathers.
Is this sufficient evidence to suggest they were not homologous? Do you even have a source for that, and a proper description? Didn't I already provide you with enough examples of how structure in homologous filaments varies?
Because I know scientists who say they are likely homologous, and in fact none who say they weren't.

Quote:
 
ude, that says that alligator scales are similar in composition and comes from the same genes as feathers, it does not mean that pseudosuchians have actual feathers.
I'm sorry, I can only agree with Mantis shrimp.
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