Anything Psittacosaurus

[amargasaurus cazaui]

I appreciate all the papers, and information. Keep posting, I will sort it all.

[amargasaurus cazaui]

I learned something this evening that somewhat amused me. I inquired of the man who sold me my Psittacosaurus, why the actual pubic bone is not present. I had also noticed in every skeleton of the dinosaur I had seen it was missing as well. The only ones seemingly with intact pubic bone were casts and replicas. His reply was somewhat  of an eye opener.

"The pubic bone, forming part of the pelvic assembly, is virtually never presented in commercially available specimens and rarely seen in mounted examples generally.
In 10 years and handling over 300 specimens, I have never seen one with the bone.
The Chinese use this bone in particular, for medicinal treatments, so by the time the specimen gets to market or museum, the bone has been removed."

huh what.........

   So lets compare notes. The Psittacosaurus was perhaps the most populace and commonly found dinosaur known to date. And China has perhaps the largest population in the world...what do they have in common? Psittacosaur pubic bones !!! Does anyone else see the connection?

[Gryphoceratops]

The specimen I have mounted in my living room somewhat disagrees, at least in regards to general cranial shape, and more specifiically the Carnegie model seems to portray very subdued jugals. Even given those minor issues, I am unsure how anyone can defend the paint scheme used.I think its how they did the eyes and face that make the dinosaur look like an oversized tree squirrel or something.

Take a moment to look at Copper's custom he did, and it shows somewhat the issues with the paint on the factory version in compare. I just wish someone would attempt a more realistic paint pattern I guess.

Keep in mind that psittacosaurus is known from MANY individuals from hatchlings all the way up to adults.  There are also many different individual species that all looked physically different from each other as shown in the diagram.  That being said just because the carnegie model doesn't exactly match one individual specimen doesn't mean its wrong.  I don't mind the surprised, wide-eyed look.  Lots of animals, especially birds, have that look to them which i don't think takes away from their "cool" factor at all haha. 



I dunno its always been one of MY favorites so I guess I feel compelled to defend it.    

Back to the task at hand though.  I'm interested to see other shots of the new concavinator.  I want to see how pronounced the arm quill thingies are.  (still on the fence about those anyway). 

[Seijun]

My problem with the carnegie psitta is the pose and proportions. It looks as though it was intended to represent a strictly bipedal animal. The body looks much to long (and head too small?). Overall, it is sculpted like your standard carnegie theropod, but with a psitta head and hands stuck on.

[Patrx]

My problem with the carnegie psitta is the pose and proportions. It looks as though it was intended to represent a strictly bipedal animal. The body looks much to long (and head too small?). Overall, it is sculpted like your standard carnegie theropod, but with a psitta head and hands stuck on.

Wait, is Psittacosaurus not currently regarded to have been a strict biped?

[SBell]

My problem with the carnegie psitta is the pose and proportions. It looks as though it was intended to represent a strictly bipedal animal. The body looks much to long (and head too small?). Overall, it is sculpted like your standard carnegie theropod, but with a psitta head and hands stuck on.

Wait, is Psittacosaurus not currently regarded to have been a strict biped?

Not that I'm aware of--recent reconstructions have it as a quadruped.

[Patrx]

Wait, is Psittacosaurus not currently regarded to have been a strict biped?

Not that I'm aware of--recent reconstructions have it as a quadruped.

Hm, I did not know that. Has this study by P. Senter been invalidated, then?

[SBell]

Wait, is Psittacosaurus not currently regarded to have been a strict biped?

Not that I'm aware of--recent reconstructions have it as a quadruped.

Hm, I did not know that. Has this study by P. Senter been invalidated, then?

As I said, it's as far as I know. Often, studies aren't so much 'invalidated' as just either not accepted universally, or there hasn't been a lot of following/following up on the results.

[Patrx]

Wait, is Psittacosaurus not currently regarded to have been a strict biped?

Not that I'm aware of--recent reconstructions have it as a quadruped.

Hm, I did not know that. Has this study by P. Senter been invalidated, then?

As I said, it's as far as I know. Often, studies aren't so much 'invalidated' as just either not accepted universally, or there hasn't been a lot of following/following up on the results.

Good point. I suppose a consensus is rarely reached when it comes to stuff like that.

[amargasaurus cazaui]

In having my Psittacosaurus mounted this was one portion of the discussion that was held between the lab owner and myself. It had its roots in wether Psittacosaurus hands should be pronated or neutral, so it was not strictly a discussion about the dinosaur and its stance..but his reponse does speak somewhat to the state of the understanding of this.


      " It seems highly doubtful to me that Psittacosaurus could not place its forefeet on the ground.  Certainly,  the species was obligate biped –bipedal locomotion being the norm. I'm certain however that grounding the forefeet would be necessary for numerous essential functions. One paper stating otherwise, does not prove the point. I could elucidate further, but  unfortunately time presses - e.g. validity of preservation robustness of  articulating joints is questionable.. quality of specimens used in the study...does  this mean other obligate bipedal dinosaurs couldn't ground their forefeet? "
           
      Myself I think it likely it was bi-pedal for the most part, but did come down on all fours, as needed. Perhaps in times when it needed to hide, build a nest, or perhaps for extra balance.

[Gryphoceratops]

My problem with the carnegie psitta is the pose and proportions. It looks as though it was intended to represent a strictly bipedal animal. The body looks much to long (and head too small?). Overall, it is sculpted like your standard carnegie theropod, but with a psitta head and hands stuck on.

The head and body size looks okay to me if its intended to be an adult animal. 

In having my Psittacosaurus mounted this was one portion of the discussion that was held between the lab owner and myself. It had its roots in wether Psittacosaurus hands should be pronated or neutral, so it was not strictly a discussion about the dinosaur and its stance..but his reponse does speak somewhat to the state of the understanding of this.


      " It seems highly doubtful to me that Psittacosaurus could not place its forefeet on the ground.  Certainly,  the species was obligate biped –bipedal locomotion being the norm. I'm certain however that grounding the forefeet would be necessary for numerous essential functions. One paper stating otherwise, does not prove the point. I could elucidate further, but  unfortunately time presses - e.g. validity of preservation robustness of  articulating joints is questionable.. quality of specimens used in the study...does  this mean other obligate bipedal dinosaurs couldn't ground their forefeet? "
           
      Myself I think it likely it was bi-pedal for the most part, but did come down on all fours, as needed. Perhaps in times when it needed to hide, build a nest, or perhaps for extra balance.

Unless I'm misreading what he said, I think your friend from the lab is misusing the term "obligate biped".  An obligate biped cannot drop to all fours.  It can only move on its hind legs.  The only animals that are true obligate bipeds that we know of so far are theropods and most likely some ornithopods.  I think he/she means facultative biped- an animal that normally walks around on two limbs but can drop down to all fours if need be.  An example of a facultative biped can be something like us humans. 

Should this be moved to the psittacosaurus thread? 

[amargasaurus cazaui]

Your comment makes great sense Gryph, and that would seem his likely meaning. I did paste it word for word, so I will go with a typo on his part, so that the comment is more correct. I agree with you.

And yes, perhaps this should all move to the Psittacosaurus thread, if some kind admin would do so.

[wings]

In having my Psittacosaurus mounted this was one portion of the discussion that was held between the lab owner and myself. It had its roots in wether Psittacosaurus hands should be pronated or neutral, so it was not strictly a discussion about the dinosaur and its stance..but his reponse does speak somewhat to the state of the understanding of this.


      " It seems highly doubtful to me that Psittacosaurus could not place its forefeet on the ground.  Certainly,  the species was obligate biped –bipedal locomotion being the norm. I'm certain however that grounding the forefeet would be necessary for numerous essential functions. One paper stating otherwise, does not prove the point. I could elucidate further, but  unfortunately time presses - e.g. validity of preservation robustness of  articulating joints is questionable.. quality of specimens used in the study...does  this mean other obligate bipedal dinosaurs couldn't ground their forefeet? "
           
      Myself I think it likely it was bi-pedal for the most part, but did come down on all fours, as needed. Perhaps in times when it needed to hide, build a nest, or perhaps for extra balance.

Perhaps the lab owner that you've spoken to agrees with Senter's paper because if you read the abstract of Senter's paper from SBell's link above. Senter does use the term "obligate biped" in his paper (from the abstract: "...Forelimb morphology and range of motion indicate that Psittacosaurus was an obligate biped and that Leptoceratops and Protoceratops were capable of quadrupedal locomotion. Forelimb mobility was too limited in Psittacosaurus for the hands to reach the mouth..."). Here is an interesting comment from Heinrich Mallison at http://dinosaurpalaeo.wordpress.com/2011/11/08/dinopic-of-the-day-15-find-the-flaws/. He reckons that there are variation among the shape of psittacosaurus radii and ulnae on different individuals, some are curvy (permanently pronated) while others are quite straight (no pronation). Apart from Gryphoceratops's comment on theropods and some ornithopods are being obligate bipeds. There is evidence that shows some prosauropods are also obligate bipeds as discussed in Mallison's paper (http://palaeo-electronica.org/2010_2/198/198.pdf). I've never read Senter's paper but maybe he came to the same conclusion on Psittacosaurus because his finding is very similar to Mallison's paper on Plateosaurus.

[amargasaurus cazaui]

               
     

Perhaps the lab owner that you've spoken to agrees with Senter's paper because if you read the abstract of Senter's paper from SBell's link above. Senter does use the term "obligate biped" in his paper (from the abstract: "...Forelimb morphology and range of motion indicate that Psittacosaurus was an obligate biped and that Leptoceratops and Protoceratops were capable of quadrupedal locomotion. Forelimb mobility was too limited in Psittacosaurus for the hands to reach the mouth..."). Here is an interesting comment from Heinrich Mallison at http://dinosaurpalaeo.wordpress.com/2011/11/08/dinopic-of-the-day-15-find-the-flaws/. He reckons that there are variation among the shape of psittacosaurus radii and ulnae on different individuals, some are curvy (permanently pronated) while others are quite straight (no pronation). Apart from Gryphoceratops's comment on theropods and some ornithopods are being obligate bipeds. There is evidence that shows some prosauropods are also obligate bipeds as discussed in Mallison's paper (http://palaeo-electronica.org/2010_2/198/198.pdf). I've never read Senter's paper but maybe he came to the same conclusion on Psittacosaurus because his finding is very similar to Mallison's paper on Plateosaurus.

He seems to almost directly quote from that abstract, with the same precise term. I did take a minute to glance at my mount, and the ulna and radius for both arms seem quite straight...although the dinosaur was mounted with pronated hands, and the arm bones being side by side rather than top to bottom.

[wings]

He seems to almost directly quote from that abstract, with the same precise term. I did take a minute to glance at my mount, and the ulna and radius for both arms seem quite straight...although the dinosaur was mounted with pronated hands, and the arm bones being side by side rather than top to bottom.

Let's start with a simple recap from the pronation and supination thread. For human, in neutral pose (no rotation) when face to the front, your palms will face forward (ulna, radius parallel to each other, no crossing), not many dinosaurs have this configuration (maybe except Carnotaurus or some other abelisaurs). At the elbow, the lower arm bone on the outer (lateral) side is the radius while the one on the inner (medial) side is the ulna. Due to the length and shape of these elements in general the radius would tend to set in front and overlap the ulna at the distal (away from the body) end, resulting in the palm facing medially in most "dinosaurs". In order for the palm to face to the back, the ulna and radius have to cross more still, where now the distal end of the ulna would be on the lateral side and the distal end of the radius would be on the medial side (or this could be achieved by having these element to curve (grow) around one another, as seen in a lot of articulated hadrosaur specimens where their radii and ulnae are permanently "crossed"). So this crossing movement is mainly accomplish by the rotation of the radius at the elbow, however due to the shape of the radius head (not quite circular in "most" dinosaurs), the radius and ulna appear to be bonded together tightly with limited movement between them.

Now getting back to your question. If the radii and ulnae on your specimen are running parallel, to me that just implies the palms are facing forward when view from the front (deltoid crest pointing forward on the humerus) which is very odd...
Are the radii and ulnae on your animal in one piece? or these elements are separated that you can make adjustment to them? Are any parts of the lower arms fabricated (reconstructed)? Without seeing the elbow end of the radius and ulna it is hard to make suggestions on how much you can tweak the lower arm and not violating its anatomy. Sometime museum would cheat this problem by swapping the position of the radii and ulnae of their specimen mounts.
In closing, here is an example of a well articulated individual which have its palms facing medially (http://upload.wikimedia.org/wikipedia/commons/3/3c/Psittacosaurus_holotype.jpg). This is not intended to say that the "only" orientation for their hands is facing medially but just to show what the elbow joint looks like when articulated properly.

[amargasaurus cazaui]

This picture might help , it is the feet and hands of my mount. I had been given quite a bit of help and suggestion from Niroot, and he has helped me understand to the degree. I believe what I need to do is simply remove all four arm bones, then stack them, radius or larger to the bottom, and ulna at the top, rather than laying side by side. Once done this should allow me to simply twist the hands to a more neutral positioning, and if I am understandng correctly it would be then considered correct.

[attachment msg=18102][/attachment]

[wings]

If you can separate them then that would be good. Perhaps something similar to this (http://ornithodira.narod.ru/Exposition/catalog/verybig/31.jpg) maybe?

[amargasaurus cazaui]

The two arm bones for my specimen have a simple length of stiff wire between them and are glued in place. Using a little super glue remover, they fall right off, so I am sure I can get the radius and ulna to come lose. That link you posted looks like a massive specimen...six footer I would guess. I like the hands on my specimen better !!!(not the mounting , the preservation)
   From how that mount is done, I would assume to mount the radius to the crest of the humerus and then I can cross the ulna from the inside upper end crest of the radius  to the distal outter edge of the radius. This would allow the hands to be posed in a fully neutral (note Niroot, not SUPINATED) position.

[amargasaurus cazaui]

I find all the help and suggestions most useful. I had posed the question earlier in this thread and will again...what else have I missed about this dinosaur? Is anything else incorrect or missing? Thoughts and suggestions would be appreciated. I had already pointed out the processes are missing for the verts. The coracoids were not preserved either. The pubic bone, as with most psittacosaurus mounts is not there either. I also made note the actual ankle bones were not intact. The ribs are of course replicas made from resin.Other than that, the fossil should be entirely original or at least genuine fossil. I believe there are some elements composited. The skull suffers from serious compression that collapsed the side and rear of the skull and had to be repaired. (lower orbital fenestrae) This makes the skull look asymetrical in top view. There are some teeth present in the jaws, however the mouth was fossilized shut and to attempt to open it would destroy the teeth present. The skull fossilized in a gorgeous purplish lavendar tint, making the teeth appear bright purple. The dinosaur is 25 inches long. I counted 67 verts down his back. Anything else? thoughts, suggestions?

[Gryphoceratops]

Yeah I was hesitant to include prosauropods but sure I guess we can consider some of them obligatory bipeds too.  A while back I was working on an illustration of plateosaurus and didn't know whether or not to depict the female on all fours or standing on her hind legs.  I asked around and actually conversed with Heinrich Mallison via interwebs.  Here is what he had to say.

"Chris,
this is a tricky question, because it depends on how you use the term "prosauropods". Let's use it in the classic sense: covering all the basal sauropodomorphs. In that case, the answer is "some could, some could not".

The "Prosauropoda" is a fairly varied group, and if you just look at Plateosaurus and Riojasaurus in comparison it's fairly obvious that they have a high overall similarity, but quite different limb and body proportions. Plateosaurus was, as Bonnan and Senter (2007) and a certain German biomech guy showed, incapable of pronating its hands, had very short front limbs, with a very limited range of motion (Mallison 2010a, b, c). Add to that a short trunk, and you get an animal that is well balanced over the hind limbs.
Riojasaurus, in contrast, has a much longer upper arm, very likely (working off drawings here, have not seen the specimens) a differnetly arranged shoulder girdle and thus more motion range in the shoulder, and a longer trunk. That's a quadruped we're seeing. I made a nice comparative figure for Mallison (2010d), which I now uploaded here on my blog:
http://dinosaurpalaeo.files.wordpress.c ... plateo.jpg
That's the skeleton of Plateosaurus, with the arms scaled to the proportions of Riojasaurus. Note that I did not even scale the trunk!

So were prosauropods bipedal? Some of them were, some were not, and some certainly were capable of changing from bipedal to quadrupedal.

There is also a very nice paper by Jeff Wilson and colleagues (2009) on a trackway of an ornithiopod that might interest you: the animal was crossing a slippery slope, and changed from a bipedal, narrow-gauge walk to a quadrupedal, wide-gauge crawl! The feet even left drag marks from protraction! A threopod crsooing the same terrain simply dug in its claws, but otherwise didn't change its behavior much.

References

Bonnan, M.F. and Senter, P. 2007. Were the basal sauropodomorph dinosaurs Plateosaurus and Massospondylus habitual quadrupeds? In: P.M. Barrett and D.J. Batten (eds.), Evolution and Palaeobiology of Early Sauropodomorph Dinosaurs. Special Papers in Palaeontology 77: 139–155

Mallison, H. (2010a). The digital Plateosaurus I: body mass, mass distribution and posture assessed using CAD and CAE on a digitally mounted complete skeleton. Palaeontologia Electronica 13.2.8A (open access: HTML, PDF) FOR 533

Mallison, H. (2010b). The digital Plateosaurus II: an assessment of the range of motion of the limbs and vertebral column and of previous reconstructions using a digital skeletal mount. Acta Palaeontologica Polonica 55(3): 433-458; doi:10.4202/app.2009.0075 (open access: access to PDF) FOR 533

Mallison, H. (2011). Plateosaurus in 3D: how CAD models and kinetic-dynamic modeling bring an extinct animal to life. Pp. 219-236 in Klein, N., Remes, K., Gee, C. & Sander M. (eds): Biology of the Sauropod Dinosaurs: Understanding the life of giants. Life of the Past (series ed. Farlow, J.) Indiana University Press.

Mallison, H. (2011). Digitizing methods for paleontology – applications, benefits and limitations. Pp. 7-44 in Elewa, A.M.T. (ed.): Computational Paleontology. Springer.

Wilson JA, Marsicano CA, Smith RMH (2009) Dynamic Locomotor Capabilities Revealed by Early Dinosaur Trackmakers from Southern Africa. PLoS ONE 4(10): e7331. doi:10.1371/journal.pone.0007331"

I later found out from other sources that a few seemingly bipedal prosauropods were at least able to rest on all fours.  There are tracks from plateosaurus that show it resting its hands on the ground.  At the museum I used to illustrate for in NJ there was a trackway that included a resting prosauropod as well (hands on the ground beside the body, palms facing inward). 

Since my illustration was of plateosaurus I decided to let her hands touch the ground.  Doesn't mean she could walk that way though.  Does that make it an obligatory biped still?  I dunno haha.