General Prehistoric Animal Anatomy Request Thread

[Pachyrhinosaurus]

I had some questions and I didn't think they'd be enough for an entire thread and the idea came to me to make a general thread for simple questions and answers about dinosaur or prehistoric animal anatomy, particularly for drawings or sculpture. The kind of questions I had in mind are ones which would only take up a page or two, if that, not calling it a 'rule' or anything.
My first questions which inspired this thread relate to Parasaurolophus cyrtocristatus. Firstly, I was wondering about hadrosaur thighs. How would they have been attatched to the body? I've seen different restorations do it differently. In some cases the thigh is completely distinct from the torso and in others there is no gap between them, under a more smooth piece of skin, like this:

Versus this:

Is either right or wrong, or is it pure speculation, and what evidence is there for the 'attached-thigh' theory?
Something else which had interested me was the known skin of relatives of parasaurolophus (unless there is known parasaurolophus skin). Is there any reliable source out there which provides the size of the scales, or pictures where the pattern can be seen clearly?
If this thread does not work out I will gladly change its name and purpose to be more of a thread for questions I have about lambeosaurines.

[Newt]

There is a specimen of Lambeosaurus (iirc) where the body skin appears to cover the upper leg, as in birds. There are several edmontosaur specimens with skin impressions; you can see a photo on the Edmontosaurus wikipedia page. The scales are very small (a few millimeters), round, and non-overlapping, similar to Gila monster skin.

[Gryphoceratops]

The back of the thigh would have blended into the tail base since we know there was a big muscle attachment there just like in birds.  Next time you go to a grocery store check out the chickens.  even though they don't have a long tail, the muscle is there.  As for the rest of the limb, you must remember that mummies don't reflect how the skin was on the animal in life.  The skin shifts around as decomposition of certain internal parts takes place.  Either look you suggested is probably okay since nobody knows for sure. 

The known scales of hadrosaurs are small and look like mosaics tiles.  You would not have been able to see individual scales unless you were up close to the animal.  (big pet peeve of mine in paleoart is when artists think they are being accurate by illustrating every itty bitty scale when the hadrosaur is over 100 meters away from the viewer!)

[Dinoguy2]

The back of the thigh would have blended into the tail base since we know there was a big muscle attachment there just like in birds.  Next time you go to a grocery store check out the chickens.  even though they don't have a long tail, the muscle is there.  As for the rest of the limb, you must remember that mummies don't reflect how the skin was on the animal in life.  The skin shifts around as decomposition of certain internal parts takes place.  Either look you suggested is probably okay since nobody knows for sure. 

The known scales of hadrosaurs are small and look like mosaics tiles.  You would not have been able to see individual scales unless you were up close to the animal.  (big pet peeve of mine in paleoart is when artists think they are being accurate by illustrating every itty bitty scale when the hadrosaur is over 100 meters away from the viewer!)

The better question is, why do artists show these with separate thighs at all? I ca't think of any modern animals with huge "thigh pits" except for sprawlers.





That first pic you posted is too shrink-wrapped, and is missing the muscles connecting the thigh to the tail (modern birds lack this, so some pics of naked chickens you can see a distinct back to the thigh).

[Gryphoceratops]

I suppose the biggest example of a living animal that shows separation between upper limb and body are crocodilians, which are semi-erect in posture. (There are surely others like camels and some primates but crocs are closest to dinosaurs out of these)  It depends on what you want to use for a reference.  There could have been (and probably were) examples of each for all anyone knows.  I know birds are living dinosaurs but they may not be the best reference for every kind of nonavian dinosaur, especially ones that weren't theropods, for everything.  I don't criticize either method in art. 

[Pachyrhinosaurus]

Thanks for the information. So the thigh should be restored more fleshy than in the first picture, like the skin folds seen in some of the Carnegie models? The featherless chicken sounds good, too. I guess my confusion lies in the posterior end, as mammals do not have such large tails.  As for scales, I'd be doing this in 1:12, and usually I do have the pet peeve of oversized scales in smaller scales, but I wasn't sure about something so large compared to what I normally see.

[Dinoguy2]

I suppose the biggest example of a living animal that shows separation between upper limb and body are crocodilians, which are semi-erect in posture. (There are surely others like camels and some primates but crocs are closest to dinosaurs out of these)  It depends on what you want to use for a reference.  There could have been (and probably were) examples of each for all anyone knows.  I know birds are living dinosaurs but they may not be the best reference for every kind of nonavian dinosaur, especially ones that weren't theropods, for everything.  I don't criticize either method in art.

Crocodilians, as sprawlers, need separate thighs so they can sprawl when laying down, swimming, etc. Also, their hips are so shallow that the legs basically erupt closer to the underside of the body anyway, like the forelimbs of dinosaurs. In other words, the knee extends very far beyond the pubis when standing up straight. This is not the case for most dinosaurs, where the knee is at pubis level or above. For a permanently upright limbed animal with a hip socket very high up the flank, a space there serves no purpose other than being able to trap dirt and parasites. The thighs of dinosaurs were (are) basically immobile from side to side and have very limited movement even back and forth, just enough for short, powerful movements to drive the lower leg.

[Tyto_Theropod]

I suppose the biggest example of a living animal that shows separation between upper limb and body are crocodilians, which are semi-erect in posture. (There are surely others like camels and some primates but crocs are closest to dinosaurs out of these)  It depends on what you want to use for a reference.  There could have been (and probably were) examples of each for all anyone knows.  I know birds are living dinosaurs but they may not be the best reference for every kind of nonavian dinosaur, especially ones that weren't theropods, for everything.  I don't criticize either method in art.

Crocodilians, as sprawlers, need separate thighs so they can sprawl when laying down, swimming, etc. Also, their hips are so shallow that the legs basically erupt closer to the underside of the body anyway, like the forelimbs of dinosaurs. In other words, the knee extends very far beyond the pubis when standing up straight. This is not the case for most dinosaurs, where the knee is at pubis level or above. For a permanently upright limbed animal with a hip socket very high up the flank, a space there serves no purpose other than being able to trap dirt and parasites. The thighs of dinosaurs were (are) basically immobile from side to side and have very limited movement even back and forth, just enough for short, powerful movements to drive the lower leg.

Maybe, in light of this, it's a hangover from when dinosaurs were thought of as more reptilian in nature?

[Dinoguy2]

I suppose the biggest example of a living animal that shows separation between upper limb and body are crocodilians, which are semi-erect in posture. (There are surely others like camels and some primates but crocs are closest to dinosaurs out of these)  It depends on what you want to use for a reference.  There could have been (and probably were) examples of each for all anyone knows.  I know birds are living dinosaurs but they may not be the best reference for every kind of nonavian dinosaur, especially ones that weren't theropods, for everything.  I don't criticize either method in art.

Crocodilians, as sprawlers, need separate thighs so they can sprawl when laying down, swimming, etc. Also, their hips are so shallow that the legs basically erupt closer to the underside of the body anyway, like the forelimbs of dinosaurs. In other words, the knee extends very far beyond the pubis when standing up straight. This is not the case for most dinosaurs, where the knee is at pubis level or above. For a permanently upright limbed animal with a hip socket very high up the flank, a space there serves no purpose other than being able to trap dirt and parasites. The thighs of dinosaurs were (are) basically immobile from side to side and have very limited movement even back and forth, just enough for short, powerful movements to drive the lower leg.

Maybe, in light of this, it's a hangover from when dinosaurs were thought of as more reptilian in nature?

Could be, though even Charles R. Knight often (not always) painted them as bonding into the body.


I suspect it's more due to the flurry of Greg Paul copiers in the '90s. Paul basically restored the muscles and then colored those without adding any other soft tissue, and was a big contributor to the trend of shrink wrapping.

[Kayakasaurus]

Camel was a good example I couldn't think of any upright quadrupedal animals with thighs like that. But if you look at camels the body is very skiny right there and there isn't much to attach skin to it just makes sense by looking at them. Their thighs are their rear end. But when seen on hadrosaurs the thighs are up against the body and tail all the way down to the knees. It seems like the legs would constantly be rubbing against the body skin on skin for no reason.

[Dinoguy2]

Camel was a good example I couldn't think of any upright quadrupedal animals with thighs like that. But if you look at camels the body is very skiny right there and there isn't much to attach skin to it just makes sense by looking at them. Their thighs are their rear end. But when seen on hadrosaurs the thighs are up against the body and tail all the way down to the knees. It seems like the legs would constantly be rubbing against the body skin on skin for no reason.

That's a very good point. We're so used to looking at skeletals and other dino pics in side view we forget how wide and barrel chested some of them were. There are many species where the thigh couldn't move forward very much because it would hit the ribs!

[Gryphoceratops]

Camel was a good example I couldn't think of any upright quadrupedal animals with thighs like that. But if you look at camels the body is very skiny right there and there isn't much to attach skin to it just makes sense by looking at them. Their thighs are their rear end. But when seen on hadrosaurs the thighs are up against the body and tail all the way down to the knees. It seems like the legs would constantly be rubbing against the body skin on skin for no reason.

Yes but my point is had you just seen a skeleton of a camel you wouldn't necessarily know it if was skinny right there or if there was more soft tissue covering it.  I'm referring more to the front of the thigh and the midsection.  Most hoofed animals, including horses and zebras also have the thighs basically as the rear end but the front of their thighs are unified with soft tissue to their midsections like the photo Dinoguy put up of the zebra.  Camels on the other hand, are not.  I'm not saying I'm against soft tissue covering limbs.  It makes sense a lot of the time.  I'm saying that if I see a reconstruction that does not exhibit this, I lay off on scientific inaccuracy alarm.  There are certain things in prehistoric animal reconstructions we can confidently say were almost certainly a certain way (feathers on coelurosaurs for instance) but there are others where I feel we can afford to hold off on and remind ourselves there is a lot we really don't know.  Animals, even those that are closely related, can look very different from one another in the soft tissue department.  We don't have to reconstruct them all exactly the same way with certain things.

[Tyto_Theropod]

Camel was a good example I couldn't think of any upright quadrupedal animals with thighs like that. But if you look at camels the body is very skiny right there and there isn't much to attach skin to it just makes sense by looking at them. Their thighs are their rear end. But when seen on hadrosaurs the thighs are up against the body and tail all the way down to the knees. It seems like the legs would constantly be rubbing against the body skin on skin for no reason.

Yes but my point is had you just seen a skeleton of a camel you wouldn't necessarily know it if was skinny right there or if there was more soft tissue covering it.  I'm referring more to the front of the thigh and the midsection.  Most hoofed animals, including horses and zebras also have the thighs basically as the rear end but the front of their thighs are unified with soft tissue to their midsections like the photo Dinoguy put up of the zebra.  Camels on the other hand, are not.  I'm not saying I'm against soft tissue covering limbs.  It makes sense a lot of the time.  I'm saying that if I see a reconstruction that does not exhibit this, I lay off on scientific inaccuracy alarm.  There are certain things in prehistoric animal reconstructions we can confidently say were almost certainly a certain way (feathers on coelurosaurs for instance) but there are others where I feel we can afford to hold off on and remind ourselves there is a lot we really don't know.  Animals, even those that are closely related, can look very different from one another in the soft tissue department.  We don't have to reconstruct them all exactly the same way with certain things.

Good point, but as has been established Hadrosaurs, unlike camels, had big, meaty tails - so in my opinion it's much more likely that their thighs blended smoothly into their bodies as they need some pretty hefty tail muscles too.

[Gryphoceratops]

Camel was a good example I couldn't think of any upright quadrupedal animals with thighs like that. But if you look at camels the body is very skiny right there and there isn't much to attach skin to it just makes sense by looking at them. Their thighs are their rear end. But when seen on hadrosaurs the thighs are up against the body and tail all the way down to the knees. It seems like the legs would constantly be rubbing against the body skin on skin for no reason.

Yes but my point is had you just seen a skeleton of a camel you wouldn't necessarily know it if was skinny right there or if there was more soft tissue covering it.  I'm referring more to the front of the thigh and the midsection.  Most hoofed animals, including horses and zebras also have the thighs basically as the rear end but the front of their thighs are unified with soft tissue to their midsections like the photo Dinoguy put up of the zebra.  Camels on the other hand, are not.  I'm not saying I'm against soft tissue covering limbs.  It makes sense a lot of the time.  I'm saying that if I see a reconstruction that does not exhibit this, I lay off on scientific inaccuracy alarm.  There are certain things in prehistoric animal reconstructions we can confidently say were almost certainly a certain way (feathers on coelurosaurs for instance) but there are others where I feel we can afford to hold off on and remind ourselves there is a lot we really don't know.  Animals, even those that are closely related, can look very different from one another in the soft tissue department.  We don't have to reconstruct them all exactly the same way with certain things.

Good point, but as has been established Hadrosaurs, unlike camels, had big, meaty tails - so in my opinion it's much more likely that their thighs blended smoothly into their bodies as they need some pretty hefty tail muscles too.

Read what I wrote more carefully!  Sure, tail muscles would blend the back of the thigh to the tail.  "I'm referring more to the front of the thigh and the midsection."

[Tyto_Theropod]

Thought I'd keep this thread alive with a query of my own. Recently, I've been seeing reconstructions of Dromaeosauridae in a very different pose from the 'classic tail-up Theropod' we're to. Rather, they have their necks up and their bodies and tales held diagonally. I suppose this is fair enough with short-legged genera like Achillobator, here restored by Matt Martinuik: http://dinogoss.blogspot.co.uk/2011/12/waddle-achillobator-waddle.html, but I've also seen smaller, leggier types like Velociraptor and Dromaeosaurus restored like this as of late. I there any rhyme or reason for this posing in terms of palaeontological evidence that I've missed?

Another example from Emily Willoughby: http://emilywilloughby.com/gallery/paleoart/the-terrible-claw

[Newt]

I don't know about paleontological evidence, but I can give you some neontological anecdotes that may help. Some cursorial birds, such as turkeys, hold their body axis parallel to the ground when running or feeding, but hold the front end higher when walking or looking around. I would guess the artists are trying to show the animals in more sedate poses than were popular in years past, and the more upright posture is a reflection of that.

[Tyto_Theropod]

That would indeed make sense - thanks! The two examples I managed to rustle up are pretty mild instances, though, and I don't mind them, but I did see one Velociraptor that almost looked like a retro Tyrannosaurus! The weird thing was that there was a Troodon illustrated next to it with a more standard pose. Weird. (Unfortunately I can't seem to find the link now) Still, maybe whoever drew those had seen the art I linked, or something similar, and ended up exaggerating the stance.

[Dinoguy2]

Thought I'd keep this thread alive with a query of my own. Recently, I've been seeing reconstructions of Dromaeosauridae in a very different pose from the 'classic tail-up Theropod' we're to. Rather, they have their necks up and their bodies and tales held diagonally. I suppose this is fair enough with short-legged genera like Achillobator, here restored by Matt Martinuik: http://dinogoss.blogspot.co.uk/2011/12/waddle-achillobator-waddle.html, but I've also seen smaller, leggier types like Velociraptor and Dromaeosaurus restored like this as of late. I there any rhyme or reason for this posing in terms of palaeontological evidence that I've missed?

Another example from Emily Willoughby: http://emilywilloughby.com/gallery/paleoart/the-terrible-claw

"Animals move." -Dr. Tom Holtz

There is no such thing as a correct pose for any animal, just a list of a few things they can't do without dislocating something. (And sometimes they would still have done those things, just died a few days or weeks later!)

Since you mention retro Tyrannosaurus, I should mention that I've been doing a lot of research on the history of museum mounts, and paleontologists have known full well that dinosaurs did not drag their tails during normal walking, that they held their bodies either diagonally or horizontally during normal walking, etc., for more than 110 years at least. It's not like trackways are obscure, even back then! But they also knew what most modern dinosaur fans have had drilled out of them by pedants: animals move. The famous AMNH T. rex mount, for example, was meant to be rearing up to fend off a rival, not walking. There's no reason the posture is impossible and nothing was so dislocated that it couldn't be accounted for by cartilage between the joints. Those guys weren't dumb. But the mount was famous, the rival never got mounted, and all other mounts and artists made the rearing up posture a meme when it's no more inaccurate than the current rearing Barosaurus, but nobody assumes that one is supposed to be walking.

Then they remounted the Rex, in a walking posture..., because I guess you can't show a standing, inactive dinosaur without getting called inaccurate...

[Tyto_Theropod]

Thought I'd keep this thread alive with a query of my own. Recently, I've been seeing reconstructions of Dromaeosauridae in a very different pose from the 'classic tail-up Theropod' we're to. Rather, they have their necks up and their bodies and tales held diagonally. I suppose this is fair enough with short-legged genera like Achillobator, here restored by Matt Martinuik: http://dinogoss.blogspot.co.uk/2011/12/waddle-achillobator-waddle.html, but I've also seen smaller, leggier types like Velociraptor and Dromaeosaurus restored like this as of late. I there any rhyme or reason for this posing in terms of palaeontological evidence that I've missed?

Another example from Emily Willoughby: http://emilywilloughby.com/gallery/paleoart/the-terrible-claw

"Animals move." -Dr. Tom Holtz

There is no such thing as a correct pose for any animal, just a list of a few things they can't do without dislocating something. (And sometimes they would still have done those things, just died a few days or weeks later!)

Since you mention retro Tyrannosaurus, I should mention that I've been doing a lot of research on the history of museum mounts, and paleontologists have known full well that dinosaurs did not drag their tails during normal walking, that they held their bodies either diagonally or horizontally during normal walking, etc., for more than 110 years at least. It's not like trackways are obscure, even back then! But they also knew what most modern dinosaur fans have had drilled out of them by pedants: animals move. The famous AMNH T. rex mount, for example, was meant to be rearing up to fend off a rival, not walking. There's no reason the posture is impossible and nothing was so dislocated that it couldn't be accounted for by cartilage between the joints. Those guys weren't dumb. But the mount was famous, the rival never got mounted, and all other mounts and artists made the rearing up posture a meme when it's no more inaccurate than the current rearing Barosaurus, but nobody assumes that one is supposed to be walking.

Then they remounted the Rex, in a walking posture..., because I guess you can't show a standing, inactive dinosaur without getting called inaccurate...

I wasn't implying that I didn't know dinosaurs moved - of course they did. I was just finding it a little strange as some of the restorations I'd seen had them both walking AND holding their bodies that way. I was wondering if there was any evidence that had showed they held their bodies diagonally, whether it was speculation, or whether 'diagonal Dromaeosaur' was new meme. I don't mind saying that I find it very rude to assume people are stupid for asking an honest-to-goodness question.

[Dinoguy2]

Thought I'd keep this thread alive with a query of my own. Recently, I've been seeing reconstructions of Dromaeosauridae in a very different pose from the 'classic tail-up Theropod' we're to. Rather, they have their necks up and their bodies and tales held diagonally. I suppose this is fair enough with short-legged genera like Achillobator, here restored by Matt Martinuik: http://dinogoss.blogspot.co.uk/2011/12/waddle-achillobator-waddle.html, but I've also seen smaller, leggier types like Velociraptor and Dromaeosaurus restored like this as of late. I there any rhyme or reason for this posing in terms of palaeontological evidence that I've missed?

Another example from Emily Willoughby: http://emilywilloughby.com/gallery/paleoart/the-terrible-claw

"Animals move." -Dr. Tom Holtz

There is no such thing as a correct pose for any animal, just a list of a few things they can't do without dislocating something. (And sometimes they would still have done those things, just died a few days or weeks later!)

Since you mention retro Tyrannosaurus, I should mention that I've been doing a lot of research on the history of museum mounts, and paleontologists have known full well that dinosaurs did not drag their tails during normal walking, that they held their bodies either diagonally or horizontally during normal walking, etc., for more than 110 years at least. It's not like trackways are obscure, even back then! But they also knew what most modern dinosaur fans have had drilled out of them by pedants: animals move. The famous AMNH T. rex mount, for example, was meant to be rearing up to fend off a rival, not walking. There's no reason the posture is impossible and nothing was so dislocated that it couldn't be accounted for by cartilage between the joints. Those guys weren't dumb. But the mount was famous, the rival never got mounted, and all other mounts and artists made the rearing up posture a meme when it's no more inaccurate than the current rearing Barosaurus, but nobody assumes that one is supposed to be walking.

Then they remounted the Rex, in a walking posture..., because I guess you can't show a standing, inactive dinosaur without getting called inaccurate...

I wasn't implying that I didn't know dinosaurs moved - of course they did. I was just finding it a little strange as some of the restorations I'd seen had them both walking AND holding their bodies that way. I was wondering if there was any evidence that had showed they held their bodies diagonally, whether it was speculation, or whether 'diagonal Dromaeosaur' was new meme. I don't mind saying that I find it very rude to assume people are stupid for asking an honest-to-goodness question.

I'm not sure where you got the implication that I thought anybody was stupid. I was trying to answer the question. There's nothing in dromeosaurid anatomy to prevent a horizontal, diagonal, or nearly vertical posture, depending on the stance and that the animal is doing. If anything is a meme, it's the idea that there is such thing as a standard pose. The second part of my post was trying to shed light on how the false idea of a standard pose came about.

"I was wondering if there was any evidence that had showed they held their bodies diagonally,"
Nope.

"whether it was speculation,"
Yup, but so is the horizontal tail-up posture. We have no clue how they held their bodies in any given situation.

"or whether 'diagonal Dromaeosaur' was new meme."
Could be developing that way! But that doesn't mean it's wrong.