True or false -Derived ceratopsian quills Poll

[amargasaurus cazaui]

Thanks for adding all of this information Gryph, I remember your stating something similar to this once before, but I had lost the precise reference. (@ pegomastax and the reconstruction) I always enjoy hearing your thoughts on these matters, as you generally add something I had not considered or thought of.
    To respond to the above question regarding psittacosaurus and its tail quills...it is not a question of wether I think quills on a psittacosaurus make sense or not. The simple fact is we have a fossil with them, that has seen publication and it was fairly well established exists. (the papers that are posted within this thread , actually)
   I had almost forgotten another thing I neant to establish regarding the quilled specimen. If you review the evidence I provided, the heterodontosaurid family was likely the group of dinosaurs which led into the early basal ceratopsians. We know from fossils that these animals were quilled, but not just their tails, but all over their bodies. This is the science as it is understood today. Then we have a quilled psittacosaurus....but it was preserved with only quills on its tail. It is quite possible the specimen originally had quills on its entire body, and perhaps they were not angled to preserve properly or were torn lose before preservation. We do know this specimen either was attacked and killed by some form of heterodontosaurid, or was fed upon once deceased. The body shows crushing and tooth marks from canines or small tusks consistent with a heterodontosaurid. This makes it feasible the dinosaur might well have had the same style covering as its ancestral family would have, and only the quills present around the tail were favorable for preservation. What this then means for science , is we have a dinosaur that did not have the brush of quills only on its tail or back as it is being depicted and all animals following this example would then likely also be inaccurate.

[Sim]

I think it's most likely ceratopsians with horns used their horns to defend themselves against predators.  The reasons why I think this were covered excellently by Gryphoceratops in his post.  Even Einiosaurus's nose horn looks like it could have been used to deliver a powerful stab into the lower leg of predators.  I think I remember reading ceratopsian beaks would have made strong defensive weapons too.  The Fighting Dinosaurs fossil is a Velociraptor and Protoceratops which are locked in combat with each other and are believed to have died together while fighting.  The Protoceratops's beak is clamped down on the Velociraptor's right arm confirming that it used its beak to fight.  One of the Velociraptor's sickle claws is apparently embedded in the Protoceratops's throat.  That fossil is really amazing as you can actually see behaviour of these two animals!

[Dinoguy2]

Thanks for adding all of this information Gryph, I remember your stating something similar to this once before, but I had lost the precise reference. (@ pegomastax and the reconstruction) I always enjoy hearing your thoughts on these matters, as you generally add something I had not considered or thought of.
    To respond to the above question regarding psittacosaurus and its tail quills...it is not a question of wether I think quills on a psittacosaurus make sense or not. The simple fact is we
   I had almost forgotten another thing I neant to establish regarding the quilled specimen. If you review the evidence I provided, the heterodontosaurid family was likely the group of dinosaurs which led into the early basal ceratopsians. We know from fossils that these animals were quilled, but not just their tails, but all over their bodies. This is the science as it is understood today. Then we have a quilled psittacosaurus....but it was preserved with only quills on its tail. It is quite possible the specimen originally had quills on its entire body, and perhaps they were not angled to preserve properly or were torn lose before preservation. We do know this specimen either was attacked and killed by some form of heterodontosaurid, or was fed upon once deceased. The body shows crushing and tooth marks from canines or small tusks consistent with a heterodontosaurid. This makes it feasible the dinosaur might well have had the same style covering as its ancestral family would have, and only the quills present around the tail were favorable for preservation. What this then means for science , is we have a dinosaur that did not have the brush of quills only on its tail or back as it is being depicted and all animals following this example would then likely also be inaccurate.

Some research in the early 2000s found heterodontosaurids to be close relatives of marginicephalians but this has failed to be replicated. Many later studies found them to be basal ornithischians, so that direct link doesn't seem to be supported by current consensus.

Also, note that the authors of the psittacosaur scale color paper are all notorious BANDits who seemed to be trying to use it to refute the idea of coelurosaur feathers (in short, they said that if color could leech from scales into collagen, it would explain why we find melanin in Sinisauropteryx fibers, which they think are collagen). I'd take anything written by them with a big bag of salt.

And what does a fossil of Yinlong preserved in three dimensional sandstone incapable of preserving feathers have to do with anything? Or a sculpture of  Pegomastax? Or sculptures of psittacosaur foot bones?  I'm not sure what this stuff is supposed to help with.

[amargasaurus cazaui]

Thanks for adding all of this information Gryph, I remember your stating something similar to this once before, but I had lost the precise reference. (@ pegomastax and the reconstruction) I always enjoy hearing your thoughts on these matters, as you generally add something I had not considered or thought of.
    To respond to the above question regarding psittacosaurus and its tail quills...it is not a question of wether I think quills on a psittacosaurus make sense or not. The simple fact is we
   I had almost forgotten another thing I neant to establish regarding the quilled specimen. If you review the evidence I provided, the heterodontosaurid family was likely the group of dinosaurs which led into the early basal ceratopsians. We know from fossils that these animals were quilled, but not just their tails, but all over their bodies. This is the science as it is understood today. Then we have a quilled psittacosaurus....but it was preserved with only quills on its tail. It is quite possible the specimen originally had quills on its entire body, and perhaps they were not angled to preserve properly or were torn lose before preservation. We do know this specimen either was attacked and killed by some form of heterodontosaurid, or was fed upon once deceased. The body shows crushing and tooth marks from canines or small tusks consistent with a heterodontosaurid. This makes it feasible the dinosaur might well have had the same style covering as its ancestral family would have, and only the quills present around the tail were favorable for preservation. What this then means for science , is we have a dinosaur that did not have the brush of quills only on its tail or back as it is being depicted and all animals following this example would then likely also be inaccurate.

Some research in the early 2000s found heterodontosaurids to be close relatives of marginicephalians but this has failed to be replicated. Many later studies found them to be basal ornithischians, so that direct link doesn't seem to be supported by current consensus.

Also, note that the authors of the psittacosaur scale color paper are all notorious BANDits who seemed to be trying to use it to refute the idea of coelurosaur feathers (in short, they said that if color could leech from scales into collagen, it would explain why we find melanin in Sinisauropteryx fibers, which they think are collagen). I'd take anything written by them with a big bag of salt.

And what does a fossil of Yinlong preserved in three dimensional sandstone incapable of preserving feathers have to do with anything? Or a sculpture of  Pegomastax? Or sculptures of psittacosaur foot bones?  I'm not sure what this stuff is supposed to help with.

    Responding to your points one by one, first, even Wiki clearly shows the link between heterodontosaurids and margincephalians.

"
  others have suggested that heterodontosaurids instead share a common ancestor with Marginocephalia (ceratopsians and pachycephalosaurs),[27][28] a hypothesis that has found support in a number of recent studies.[29][30] The clade containing heterodontosaurids and marginocephalians has been named Heterodontosauriformes.[31] Heterodontosaurids have also been seen as basal to both ornithopods and marginocephalians.[32][33] In 2007, a cladistic analysis suggested that heterodontosaurids are basal to all known ornithischians except Pisanosaurus, a result that echoes some of the very earliest work on the family."

So in fact the consensus does remain that they were linked quite closely, and many studies have in fact replicated the result.Your statement was reversed, is all.


     Regarding the authors of the two papers regarding psittacosaurus, You may attack them for their beliefs if you choose, but the papers are well written, and do not drift into much speculation. I have also seen the links the authors have with BANDits, but that does not mean everything they write is incorrect. These are in fact peer reviewed papers, and science has accepted their findings regarding the integument, scales, and coloration as correct and not that speculative, despite their views in other papers. The pictures, and information speak for themselves, regardless of the link these people might have with other beliefs that do not fit with accepted ideas. You could do this with nearly every published paper and scientist there is if you like....at some point they all have published a view that turned out incorrect or supported an ideas that was not conventional. That does not negative every single piece of work they have done.
  Yinlong is quite important to the discussion as the most basal known ceratopsian and was found with no quills. Notice quills, not feathers. I only pictured the holotype specimen incidentally, although more remains are known for it, and none to date have posessed quills.
Pegomastax, as I already established is a heterodontosaurid, and by definition is known by many recent studies to be linked to margincephalians . The members of this family were assumed to be quilled based on the specimen of Tianyulong I provided, which do demonstrate quills over the entire body, and not simply the busy tail quills psittacosaurs was found with.
   The psittacosaurus bones pictured are fossils, not sculptures and demonstrate quite clearly another point. The purpose of the discussion is to debunk the science of providing mohawk style quills to more derived ceratopsians. This was begun when psittacosaurus was found to have this type of quill arrangment. The implication was made if psittacosaurus had mohawk of quills on its tail, more derived ceratopsians would as well. The problem with the contention is this........Psittacosaurus had evolved away from having the extra fenestrae between the nasal and eye orbits, and had evolved to the point of no longer having the fifth digit on its hands and feet. Since these are known to be quite basal traits in the family, it clearly establishes that psittacosaurus did not continue onwards into the more derived ceratopsians we have today, and that another type of animal or animals would have of course, been ancestral to more derived ceratopsians. The only way psittacosaurus could have done this, would have been if it had evolved past the extra opening in the skull, and the extra digits, and then re-evolved them to later become the forbear of more derived forms. This is how we known for fact that even if psittacosaurus had quills, and no matter what their type, more derived ceratopsians would not likely have had them
   If you cannot link psittacosaurus with its brushy type tail with more derived ceratopsians, the point is made. And the science clearly demonstrates you cannot. So, each and every picture I presented has a purpose and reason for being present. Thanks for asking

[Gwangi]

I think it's most likely ceratopsians with horns used their horns to defend themselves against predators.  The reasons why I think this were covered excellently by Gryphoceratops in his post.  Even Einiosaurus's nose horn looks like it could have been used to deliver a powerful stab into the lower leg of predators.  I think I remember reading ceratopsian beaks would have made strong defensive weapons too.  The Fighting Dinosaurs fossil is a Velociraptor and Protoceratops which are locked in combat with each other and are believed to have died together while fighting.  The Protoceratops's beak is clamped down on the Velociraptor's right arm confirming that it used its beak to fight.  One of the Velociraptor's sickle claws is apparently embedded in the Protoceratops's throat.  That fossil is really amazing as you can actually see behaviour of these two animals!

If ceratopsian horns were used for defense I think it would have been a secondary function. Most animals alive today that have horns or antlers and similar head gear use them primarily to display rank and impress members of the opposite sex. That's the main purpose of deer antlers, but if they have to they'll use them as weapons too. I imagine ceratopsian horns functioned similarly. Also if defense was the primary function I doubt you would see such diversity in forms from species to species.

[amargasaurus cazaui]

I think it's most likely ceratopsians with horns used their horns to defend themselves against predators.  The reasons why I think this were covered excellently by Gryphoceratops in his post.  Even Einiosaurus's nose horn looks like it could have been used to deliver a powerful stab into the lower leg of predators.  I think I remember reading ceratopsian beaks would have made strong defensive weapons too.  The Fighting Dinosaurs fossil is a Velociraptor and Protoceratops which are locked in combat with each other and are believed to have died together while fighting.  The Protoceratops's beak is clamped down on the Velociraptor's right arm confirming that it used its beak to fight.  One of the Velociraptor's sickle claws is apparently embedded in the Protoceratops's throat.  That fossil is really amazing as you can actually see behaviour of these two animals!

If ceratopsian horns were used for defense I think it would have been a secondary function. Most animals alive today that have horns or antlers and similar head gear use them primarily to display rank and impress members of the opposite sex. That's the main purpose of deer antlers, but if they have to they'll use them as weapons too. I imagine ceratopsian horns functioned similarly. Also if defense was the primary function I doubt you would see such diversity in forms from species to species.

I have always wondered the why of this myself..so many different configurations, and designs in the horns, frills and shapes. It is obvious there was a purpose, but it does make you wonder.

[Gwangi]

I think it's most likely ceratopsians with horns used their horns to defend themselves against predators.  The reasons why I think this were covered excellently by Gryphoceratops in his post.  Even Einiosaurus's nose horn looks like it could have been used to deliver a powerful stab into the lower leg of predators.  I think I remember reading ceratopsian beaks would have made strong defensive weapons too.  The Fighting Dinosaurs fossil is a Velociraptor and Protoceratops which are locked in combat with each other and are believed to have died together while fighting.  The Protoceratops's beak is clamped down on the Velociraptor's right arm confirming that it used its beak to fight.  One of the Velociraptor's sickle claws is apparently embedded in the Protoceratops's throat.  That fossil is really amazing as you can actually see behaviour of these two animals!

If ceratopsian horns were used for defense I think it would have been a secondary function. Most animals alive today that have horns or antlers and similar head gear use them primarily to display rank and impress members of the opposite sex. That's the main purpose of deer antlers, but if they have to they'll use them as weapons too. I imagine ceratopsian horns functioned similarly. Also if defense was the primary function I doubt you would see such diversity in forms from species to species.

I have always wondered the why of this myself..so many different configurations, and designs in the horns, frills and shapes. It is obvious there was a purpose, but it does make you wonder.

I've always figured it had to do with species recognition and display. That's the most logical answer to me anyway, especially when you look at modern animals. It's the same sort of thing you see with the various species of antelope in Africa or the birds of paradise on New Guinea.

[amargasaurus cazaui]

That is an interesting comparison Gwangi...makes me wonder about those African gazelle and how simiar their body size and shapes are .

[Gryphoceratops]

I said all that too! 

"In evolution, most of what we see evolves to help an animal ultimately pass on its genes.  That being said, the horns and frills probably did evolve as a result of display and mate choice (why else would they be so variable?) but don't assume a dinosaur wouldn't turn around and use them to hurt you if you ticked it off!"

I think Jack Horner said it- An individual animal generally wont get attacked by a predator on a frequent regular basis.  But they will want to mate. 

[Dinoguy2]

Thanks for adding all of this information Gryph, I remember your stating something similar to this once before, but I had lost the precise reference. (@ pegomastax and the reconstruction) I always enjoy hearing your thoughts on these matters, as you generally add something I had not considered or thought of.
    To respond to the above question regarding psittacosaurus and its tail quills...it is not a question of wether I think quills on a psittacosaurus make sense or not. The simple fact is we
   I had almost forgotten another thing I neant to establish regarding the quilled specimen. If you review the evidence I provided, the heterodontosaurid family was likely the group of dinosaurs which led into the early basal ceratopsians. We know from fossils that these animals were quilled, but not just their tails, but all over their bodies. This is the science as it is understood today. Then we have a quilled psittacosaurus....but it was preserved with only quills on its tail. It is quite possible the specimen originally had quills on its entire body, and perhaps they were not angled to preserve properly or were torn lose before preservation. We do know this specimen either was attacked and killed by some form of heterodontosaurid, or was fed upon once deceased. The body shows crushing and tooth marks from canines or small tusks consistent with a heterodontosaurid. This makes it feasible the dinosaur might well have had the same style covering as its ancestral family would have, and only the quills present around the tail were favorable for preservation. What this then means for science , is we have a dinosaur that did not have the brush of quills only on its tail or back as it is being depicted and all animals following this example would then likely also be inaccurate.

Some research in the early 2000s found heterodontosaurids to be close relatives of marginicephalians but this has failed to be replicated. Many later studies found them to be basal ornithischians, so that direct link doesn't seem to be supported by current consensus.

Also, note that the authors of the psittacosaur scale color paper are all notorious BANDits who seemed to be trying to use it to refute the idea of coelurosaur feathers (in short, they said that if color could leech from scales into collagen, it would explain why we find melanin in Sinisauropteryx fibers, which they think are collagen). I'd take anything written by them with a big bag of salt.

And what does a fossil of Yinlong preserved in three dimensional sandstone incapable of preserving feathers have to do with anything? Or a sculpture of  Pegomastax? Or sculptures of psittacosaur foot bones?  I'm not sure what this stuff is supposed to help with.

    Responding to your points one by one, first, even Wiki clearly shows the link between heterodontosaurids and margincephalians.

"
  others have suggested that heterodontosaurids instead share a common ancestor with Marginocephalia (ceratopsians and pachycephalosaurs),[27][28] a hypothesis that has found support in a number of recent studies.[29][30] The clade containing heterodontosaurids and marginocephalians has been named Heterodontosauriformes.[31] Heterodontosaurids have also been seen as basal to both ornithopods and marginocephalians.[32][33] In 2007, a cladistic analysis suggested that heterodontosaurids are basal to all known ornithischians except Pisanosaurus, a result that echoes some of the very earliest work on the family."

So in fact the consensus does remain that they were linked quite closely, and many studies have in fact replicated the result.Your statement was reversed, is all.


     Regarding the authors of the two papers regarding psittacosaurus, You may attack them for their beliefs if you choose, but the papers are well written, and do not drift into much speculation. I have also seen the links the authors have with BANDits, but that does not mean everything they write is incorrect. These are in fact peer reviewed papers, and science has accepted their findings regarding the integument, scales, and coloration as correct and not that speculative, despite their views in other papers. The pictures, and information speak for themselves, regardless of the link these people might have with other beliefs that do not fit with accepted ideas. You could do this with nearly every published paper and scientist there is if you like....at some point they all have published a view that turned out incorrect or supported an ideas that was not conventional. That does not negative every single piece of work they have done.
  Yinlong is quite important to the discussion as the most basal known ceratopsian and was found with no quills. Notice quills, not feathers. I only pictured the holotype specimen incidentally, although more remains are known for it, and none to date have posessed quills.
Pegomastax, as I already established is a heterodontosaurid, and by definition is known by many recent studies to be linked to margincephalians . The members of this family were assumed to be quilled based on the specimen of Tianyulong I provided, which do demonstrate quills over the entire body, and not simply the busy tail quills psittacosaurs was found with.
   The psittacosaurus bones pictured are fossils, not sculptures and demonstrate quite clearly another point. The purpose of the discussion is to debunk the science of providing mohawk style quills to more derived ceratopsians. This was begun when psittacosaurus was found to have this type of quill arrangment. The implication was made if psittacosaurus had mohawk of quills on its tail, more derived ceratopsians would as well. The problem with the contention is this........Psittacosaurus had evolved away from having the extra fenestrae between the nasal and eye orbits, and had evolved to the point of no longer having the fifth digit on its hands and feet. Since these are known to be quite basal traits in the family, it clearly establishes that psittacosaurus did not continue onwards into the more derived ceratopsians we have today, and that another type of animal or animals would have of course, been ancestral to more derived ceratopsians. The only way psittacosaurus could have done this, would have been if it had evolved past the extra opening in the skull, and the extra digits, and then re-evolved them to later become the forbear of more derived forms. This is how we known for fact that even if psittacosaurus had quills, and no matter what their type, more derived ceratopsians would not likely have had them
   If you cannot link psittacosaurus with its brushy type tail with more derived ceratopsians, the point is made. And the science clearly demonstrates you cannot. So, each and every picture I presented has a purpose and reason for being present. Thanks for asking

Thanks for your reply. So the point of this "poll" was to convince people you're right about ceratopsid quills? And to do so you posted only evidence that could be used to support your position? That's called cherry picking data

The fact is that we don't know if ceratopsids had quills or not. The correct answer to the poll is C, A and B are factually wrong. To respond to a couple of your points...

"So in fact the consensus does remain that they were linked quite closely, "
No study in the past five years has found heterodontosaurs to clade with Marginocephalia. No study incorporating basal heterodontosaurs like Tianyulong and Pegomastax has found that result. The addition of new data changed the conclusion, so the old studies that don't have the new data are not reliable, even though there are more of them as of right now (because the new data is new). I haven't heard or read any paleontologists even refer to the old "Heterodontosauriformes" hypothesis in years.

"Yinlong is quite important to the discussion as the most basal known ceratopsian and was found with no quills."
Can you explain how quills would be preserved outside of a lagerstatten? Even if they were there? No non-lagerstatten Psittacosaurus specimens preserve quills, and there are thousands of them. The only quilled specimens come from lagerstatten, which strongly supports preservation bias and geology being a major factor.

"The members of this family were assumed to be quilled based on the specimen of Tianyulong I provided, which do demonstrate quills over the entire body, and not simply the busy tail quills psittacosaurs was found with. "
This actually does contradict your argument. The fossils of Pegomastax do NOT preserve quills. They are inferred based on Tianyulong. Therefore we could just as easily infer them for Yinlong, or Styracosaurus.

"The psittacosaurus bones pictured are fossils, not sculptures"
I wasn't aware that Psittacosaurus had a bird-like tarsometatarsus. I thought it had individual metatarsals bound by ligaments, like most other non-avian dinosaurs. The image seems to show all the metatarsals fused into a single unit, as in modern birds. So either I'm wrong and Psittacosaurus actually did have a tarsometatarsus, or the photo is unclear, or this is a sculpture... easy mistake to make.


"If you cannot link psittacosaurus with its brushy type tail with more derived ceratopsians, the point is made. And the science clearly demonstrates you cannot."
Sure you can. Heterodontosaurids are primitive to both ceratopsids and psittacosaurids. Heterodontosauruids had quills. Psittacosaurids had quills. Therefore ceratopsids could also have had quills. Science just demonstrated you can (of course that's sarcastic, none of this is science, we're just cherry picking data to support an unprovable hypothesis).

[Sim]

I too think ceratopsian horns and frills evolved as a result of display and mate choice, which is why they were so variable.  I agree with what Gryphoceratops said in his post on the previous page, so I thought I'd just focus on how a ceratopsian might defend itself.  In case there was any misunderstanding, when I said, "I think it's most likely ceratopsians with horns used their horns to defend themselves against predators", I meant it's much more likely they used their horns in defence than that they didn't use them in defence.  I didn't mean I think that's all the horns were used for, or that defence was their primary function.

[Dinoguy2]

I too think ceratopsian horns and frills evolved as a result of display and mate choice, which is why they were so variable.  I agree with what Gryphoceratops said in his post on the previous page, so I thought I'd just focus on how a ceratopsian might defend itself.  In case there was any misunderstanding, when I said, "I think it's most likely ceratopsians with horns used their horns to defend themselves against predators", I meant it's much more likely they used their horns in defence than that they didn't use them in defence.  I didn't mean I think that's all the horns were used for, or that defence was their primary function.

Agreed, everything will use whatever it can for defense, even if the purpose is display and/or competition. I think the fact that the horns are so variable is extremely good evidence they were mainly for display, and I think the fact they change so much with growth shows there may also have been a competition aspect to them, especially in species where the nasal horn turns into more of a boss with growth, like advanced centrosaurines.

On the other hand, I don't think the filaments of psittacosaurus could be used for defense. They're way too flexible. I's a shame people started calling them quills at all, since that implies stiff, porcupine-like structures. These have more like the flexibility of whiskers.

[suspsy]

Excellent posts there, Dinoguy2. 100% agreement.

For myself, I went with Option C. I think ceratopsids with filaments look neat, but I can take them or leave them. There's no solid fossil evidence one way or the other. Some paleontologists like Darren Naish and Robert Bakker are quite open to the possibility while others like James Kirkland are inclined to say no. In the mean time, there's no real harm in an artist choosing to depict a ceratopsid that way. I especially like the prickly Triceratops John Conway did for All Yesterdays.

[amargasaurus cazaui]

I do think you should vote as you feel inclined to do so , based on your view of the evidence.I strongly encourage this in fact  I stated at the start of my posting that I was attempting to debunk the science that might justify placing MOHWAK style quills on more derived ceratopsians. I then posted the evidence as I saw it that , again as I see it, does prove without a doubt that premise is not accurate.I also posted evidence....not assertions, I never stated I was posting an open view or everything known on the topic...I stated clearly I was attmpting to debunk a point of view. I then asked others to provide evidence, papers, fossils or contradictory science to disprove the assertion. I asked for evidence, papers, articles, anything that can be confirmed. If I were cherry picking then every paper ever released is cherry picking, as I chose a point I felt was supported and provided by the evidence that I can see for that idea. This statement was made at the outset of the post. I really see no point in the constant back and forth speculation and inference. I am looking for evidence, that was my original proposition. I also wish to keep this civil and polite please.


So in fact the consensus does remain that they were linked quite closely, "
No study in the past five years has found heterodontosaurs to clade with Marginocephalia. No study incorporating basal heterodontosaurs like Tianyulong and Pegomastax has found that result. The addition of new data changed the conclusion, so the old studies that don't have the new data are not reliable, even though there are more of them as of right now (because the new data is new). I haven't heard or read any paleontologists even refer to the old "Heterodontosauriformes" hypothesis in years.

            Back this up, show evidence.Support it as I have done Until then this is not evidence, its an assertion. This is called negative evidence as it stands. It is the entire point of what i have done here. To find the missing piece that I do not have and perhaps learn from them. Can you cite these studies? Articles? Books? give something helpful here please , I would love to see it and read it and have that information.



"Yinlong is quite important to the discussion as the most basal known ceratopsian and was found with no quills."
Can you explain how quills would be preserved outside of a lagerstatten? Even if they were there? No non-lagerstatten Psittacosaurus specimens preserve quills, and there are thousands of them. The only quilled specimens come from lagerstatten, which strongly supports preservation bias and geology being a major factor.

  Your conclusions here are an inference, and only one possibe intepretation ...and there are several possible interpretations for them. The quick answer for this question you posed was...Can you then explain why so many other psittacosaurus and other type animals that were found within the Jehol Biota do NOT have quills? Given the enormous numbers of psittacosaurus specimens found within  that Lagersttten, there is one fossil with quills. It seems far more likely based on that question that it is in fact not a preservational bias based on Lagerstatten environment so much as something related to wether they were present in only one or a few species or even only this one animal, which is also possible. So you cannot state categorically that preservational aspect is the basis for this. You have to allow for the possibilities that could be based outside preservational bias as well.If you are going to dwell in possibilities and inference you have to allow for all of them.
Aside from that, I do not need to explain if and why Yinlong did or did not have quills. I displayed the fossil and stated clearly...that it is an evidence based presentation and at this point the evidence shows no quills for the dinosaur right? It does not...I did not say it could not have existed..I refused to speculate.
      Here is my original comment in the posting , for the record.   


"  While the oldest known and most basal ceratopsian found, Yinlong was not found with quills, that may be a preservational relic or simply the effects of the taphonic processes for its burial. So far we have no direct fossil evidence for quills in Yinlong."

      I covered your point of view from the start.


""The members of this family were assumed to be quilled based on the specimen of Tianyulong I provided, which do demonstrate quills over the entire body, and not simply the busy tail quills psittacosaurs was found with. "
This actually does contradict your argument. The fossils of Pegomastax do NOT preserve quills. They are inferred based on Tianyulong. Therefore we could just as easily infer them for Yinlong, or Styracosaurus."

Your assertion vs my original comments


  Of further interest is the heterodontosaurid line which is considered by many to have given rise to the early basal ceratopsians. A fossil belonging to a dinosaur named Tianyulong was discovered, and is indeed covered in places with what appear to be similar quills. When Paul Sereno reconstructed Sam, or Pegomastax as it was named, despite the fossil being based only on jaw elements, as it was a heterodontosaurid, he chose to have the reconstruction quilled heavily.
   That was my original posting. I stated the quills for pegomastax were inferred in the reconstructions and the fossil was only jaw elements. The proposition of my posting was again..evidence, not inference. The evidence shows quills for Tianyulong and Paul Sereno felt the evidence supported Pegomastax being quilled despite the limited fossil remains. Inferring them randomly for other species is not evidence based, but only an inference.
   


    About the psittacossaurus elements I pictured, they are all portions of entire skeleton recovered from the same area as the quilled specimen and it is mounted and sitting behind me. It was prepared and mounted by perhaps the foremost laboratory in the world for psittacosaurus commericial specimens. The owner, Mike Holmes, is a prominent fossil dealer with an impeccable set of references and he provided a guarantee in writing with the dinosaur that the only elements within it that are restored, or in way replicas are of course the ribs, which is common practice for these particular dinosaurs. Most rib fragments that are found for these dinosaurs, even if recovered and restored , are so fragile they would not survive the mounting process.
     I believe the shape and structure of the hands and feet you are referring to are caused by two things, the first is this specimen is a sub-adult and not fully grown yet, and the other is when these specimens come to market, they are generally in a packing box, with the skull infilled, all limbs and verts present , but the hands and feet are generally already restored to keep them intact and also to allow for any compositing necessary, as often smaller verts, and various elements of the hands have to be composited from several like dinosaurs to create a single mount. I encourage if you have questions about the shape of the hands and feet elements for you to speak with him, he is promiment on both ebay as Triassica , and on Facebook and is always quite helpful in such things. As it stands I accept that the skeleton is in fact real and nothing has been ...sculpted beyond the ribs. I do accept that it is an easy mistake to make, very easy to make. I also for my part failed to mention the animal is sub adult, although that should prove little bearing to number of digits, which was my point.

   
"If you cannot link psittacosaurus with its brushy type tail with more derived ceratopsians, the point is made. And the science clearly demonstrates you cannot."
Sure you can. Heterodontosaurids are primitive to both ceratopsids and psittacosaurids. Heterodontosauruids had quills. Psittacosaurids had quills. Therefore ceratopsids could also have had quills. Science just demonstrated you can (of course that's sarcastic, none of this is science, we're just cherry picking data to support an unprovable hypothesis).

    Your final point. You cannot link psittacosaurus to more dervied ceratopsians as I proved quite adequately. That portion of the evidence , I do not believe is even in question.  I know of no paleontologist today that feels that psittacosaurus with its quilled tail was a distant but direct ancestor to more derived ceratopsians.
The contention of my point has always been ...that you cannot provide any form of evidence that more derived ceratopsians have mohawk type quills correct? I allowed they may have had body covering style quills or even the Lane mount suggested type. I concurr that the evidence is inconclusive for that argument. What I have said and supported is the MOHAWK type quills are not evidence supported. Heterodnotsaurids had a body covering of quills...the evidence shows psittacosaurs with a Mohawk style on its tail. Ceratopsids could very possible have had quills, but they would not resemble the shape and style being coped from a species proven unrelated to them that proceeded them by tens of millions of years in evoloution That is the science, not cherry picking, and more to the point it is evidence based.
    You are one of the most well thought and informed dinosaur fans in this forum. I have no issue there may be other facts that I missed here or evidence I have not seen. I also think you may posses them or know where to look, and if you do I would love to read them. I am not stating the science I gave is complete, i offered a proposition that seems supported based on evidence. But I also feel I gave a lot of evidence and effort, not just inference and speculation and that is what I am hoping to get in return. Either way it is my hope we can avoid going back and forth like this, and keep the poll polite and civil rather than exchanging sarcasm.

[Patrx]

Option "C" for me as well. It's within the realm of possibility that some ceratopsids were totally devoid of filamentous integument. I'm always drawn to more interesting reconstructions, though (i.e. different from what I'm used to seeing), so bring on the bristles 

There is indeed a bit of snark and aggression going around, so I'd like to remind everyone to keep things as peaceful as possible 

[amargasaurus cazaui]

   I was somewhat concerned when reading the comments regarding my psittacsosaurus elements and the suggestiong they were sculpts , and were incorrect. This was due to the heavy investment I have made in the specimen moreson , but I took the time to wander through some of the hundreds of psittacosaurus skeletal mounts I have pictures for.

    I think it is clear from the large number of mounts with practically identical hands and feet to my own that they are correct, but I offer some of the images for others to see. There are some museum pieces represented, including the quilled specimen and many different species and age groups. (warning, image intensive post)


In situ specimen, Chinese museum collection



Famous quilled specimen


Six foot long, adult











Infant








Indianapolis Children's Museum , this one is a cast and retains many of the features not found in most commercial mounts, like the pubic bone, and coracoids by example

[Sim]

On the other hand, I don't think the filaments of psittacosaurus could be used for defense. They're way too flexible. I's a shame people started calling them quills at all, since that implies stiff, porcupine-like structures. These have more like the flexibility of whiskers.

I'm glad you brought this up.  Calling the filaments on Psittacosaurus and Tianyulong "quills" doesn't seem appropriate and it can be misleading.

[amargasaurus cazaui]

On the other hand, I don't think the filaments of psittacosaurus could be used for defense. They're way too flexible. I's a shame people started calling them quills at all, since that implies stiff, porcupine-like structures. These have more like the flexibility of whiskers.

I'm glad you brought this up.  Calling the filaments on Psittacosaurus and Tianyulong "quills" doesn't seem appropriate and it can be misleading.

The authors of the original studies on the psittacosaurus specimen at least, stated they were more like bristles...they measured 160 mm long and were 1 mm wide, and were pointed at the tips, and were coming from an area of the body in close relationship to the vertebrae. Speculation suggested they  may have been covered in keratin, which would have then made them quite quill-like to be sure, but there is no proof of this.

. Under ultraviolet light they show the same fluorescence as the epidermal scales, which indicates that they might have been keratinized.

That is probably how the idea got started....but if there was no keratin covering they were quite flexible and thin.

[stargatedalek]

They seem almost like iguana crests/spines to me, but longer and more dense.

[amargasaurus cazaui]

They seem almost like iguana crests/spines to me, but longer and more dense.

When I look at the fossil and how it is preserved I get the idea that it had more quills which did not preserve...which would have made for a very odd looking little character for sure,somewhat along the lines of Tianyulong. I believe that soon a specimen will come to light entirely covered, which will establish that the small brush along the tail might have continued in places along the spine and around the face. Either way, the published specimen has proven one of the golden finds of modern science, between preserved integument, scales, scale patterns, colors, predation and other evidence. I think viewing one of these little guys had to be a something special..especially if the bristles were colored or highly patterned