General Prehistoric Animal Anatomy Request Thread

[Tyto_Theropod]

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

I wasn't implying that palaeoart memes were inherently wrong. I'm sorry if I was prickly - I'd had a bad day and was feeling pretty embittered about things.

[DinoLord]

One thing I'm curious about is the effect of the long, muscular tail on posture - sure birds usually don't hold themselves horizontally most of the time, but then they don't have much of a tail asides from the tail feathers.

[Dinoguy2]

One thing I'm curious about is the effect of the long, muscular tail on posture - sure birds usually don't hold themselves horizontally most of the time, but then they don't have much of a tail asides from the tail feathers.

I think the general consensus is that the more hefty the tail (not necessarily long, but massive), the more horizontal the posture would have to be to maintain balance. Things like T. rex, which had massive but relatively short tails together with massive heads, may have actually walked more diagonally than usually depicted. Here's an article on the London specimen of T. rex (the original Dynamosaurus), which was mounted by Newman, the guy who also happened to be the one that published the study getting rid of tail-dragging dinosaurs:
http://scienceblogs.com/tetrapodzoology/2008/10/13/american-tyrant-in-london/

The idea that dinosaurs didn't drag their tails was popularized by Bakker based on Newman's work. But Newman didn't have them horizontal, he had them diagonal.

[DinoToyForum]

I have a topic you might be able to help with. I'd like to know about the anatomy of the hand in feathered theropods and how the feathers attached in this region.  I know this has come up on the forum before, probably several times, but I can't recall where. I'm sure I've seen an illustration showing how the primaries, secondaries, and tertiary feathers are supposed to be arranged. I'm interested, in particular, if the digits bear feathers, and if so, which digit(s). Can anyone point me to a previous forum thread where this is discussed or a paper where this issue is explored? My search of the literature hasn't turned up anything too useful - there's so much published on this topic! Thanks muchly!

[stargatedalek]

I'm not sure how helpful these diagrams will be to you (I swear I've seen labelled versions of them somewhere), but they are pretty well the standard (except for therizinosaurs which probably had reduced wings to give their fingers more versatility). I can't recall any particular papers on the subject but I always prefer to feather the fingers, and I would personally recommend an alula for paraves. There isn't (to my knowledge) any specific papers on the presence of feathers (or an alula) on the fingers, but given most don't show signs of using their forelimbs to attack I'd say an alula would have been very useful to them, its a structure that is practically tailor fit to the tactic of standing on ones prey pinning it to the ground and balancing with ones wings while attacking it.

[DinoToyForum]

Helpful indeed! Many thanks. I think this must have been what I was thinking of. If anyone knows some supporting references for this then all the better!

[Tyto_Theropod]

Thanks for these, star - they'll be helpful when I get round to sculpting the wings on my custom WS Velociraptor.

[Doug Watson]

I have a topic you might be able to help with. I'd like to know about the anatomy of the hand in feathered theropods and how the feathers attached in this region.  I know this has come up on the forum before, probably several times, but I can't recall where. I'm sure I've seen an illustration showing how the primaries, secondaries, and tertiary feathers are supposed to be arranged. I'm interested, in particular, if the digits bear feathers, and if so, which digit(s). Can anyone point me to a previous forum thread where this is discussed or a paper where this issue is explored? My search of the literature hasn't turned up anything too useful - there's so much published on this topic! Thanks muchly!

Edit: Oops I just noticed you were asking specifically about theropods, from what I know most reconstructions are based on Archaeopteryx. I believe the quill knobs found on the velociraptor specimen were on the ulna. I don't believe any fossil evidence shows those knobs on any theropod digits but I could be wrong. That is why I believe most base their reconstructions on Archaeopteryx since there is actual evidence of feather insertion on the digits.

This paper that describes what is considered to be the most complete specimen of archeopteryx has a section on feathers that describes how many primaries are inserted into the second digit and where. You actually provided the paper for me so if you want I can send you the PDF. I'll check my file for anything else that might help.

Mayr,G.etal.The tenth skeletal specimen of Archaeopteryx.Zool.J.Linn.Soc.149, 97–116 (2007).

I just noticed there is a 2014 paper out on PLOS one that disputes the assertion that the primaries were covered by dorsal coverts: Reassessment of the Wing Feathers of Archaeopteryx lithographica Suggests No Robust Evidence for the Presence of Elongated Dorsal Wing Coverts by Robert L. Nudds

Those coloured illustrations that Star provided are from a blog by Elijah Shandseight who describes himself as a student and freelance artist in Italy. His blog is http://ktboundary-smnt2000.blogspot.ca/

[Patrx]

Just spotting this topic! Those diagrams are part of a series by Elijah Shandseight, from his blog. Here's the most recent post in the series, with a pretty thorough write-up: http://ktboundary-smnt2000.blogspot.it/2014/02/how-to-properly-restore-winged-arms-of.html. Links to previous posts are available there, and, perhaps more importantly, a full list of references. Invaluable stuff!

EDIT: It seems Doug is a step ahead of me 

[Dinoguy2]

I have a topic you might be able to help with. I'd like to know about the anatomy of the hand in feathered theropods and how the feathers attached in this region.  I know this has come up on the forum before, probably several times, but I can't recall where. I'm sure I've seen an illustration showing how the primaries, secondaries, and tertiary feathers are supposed to be arranged. I'm interested, in particular, if the digits bear feathers, and if so, which digit(s). Can anyone point me to a previous forum thread where this is discussed or a paper where this issue is explored? My search of the literature hasn't turned up anything too useful - there's so much published on this topic! Thanks muchly!

Edit: Oops I just noticed you were asking specifically about theropods, from what I know most reconstructions are based on Archaeopteryx. I believe the quill knobs found on the velociraptor specimen were on the ulna. I don't believe any fossil evidence shows those knobs on any theropod digits but I could be wrong. That is why I believe most base their reconstructions on Archaeopteryx since there is actual evidence of feather insertion on the digits.

This paper that describes what is considered to be the most complete specimen of archeopteryx has a section on feathers that describes how many primaries are inserted into the second digit and where. You actually provided the paper for me so if you want I can send you the PDF. I'll check my file for anything else that might help.

Mayr,G.etal.The tenth skeletal specimen of Archaeopteryx.Zool.J.Linn.Soc.149, 97–116 (2007).

I just noticed there is a 2014 paper out on PLOS one that disputes the assertion that the primaries were covered by dorsal coverts: Reassessment of the Wing Feathers of Archaeopteryx lithographica Suggests No Robust Evidence for the Presence of Elongated Dorsal Wing Coverts by Robert L. Nudds

Those coloured illustrations that Star provided are from a blog by Elijah Shandseight who describes himself as a student and freelance artist in Italy. His blog is http://ktboundary-smnt2000.blogspot.ca/

For the record, the paper isn't disputing the presence of coverts but if long coverts that reach near the ends of the primaries, which had been argued by some recent papers.

No birds have quill knobs on the fingers as far as I know, instead the fingers are flattened into a broad, fused phalange. Greg Paul used the presence of such a structure in Dromaeosaurs to argue for secondary flightless ness, but this may simply be there to support large primaries. Note that quill knobs are only present at all in a few species that have particularly high stresses on the feathers. Not even all or most flying birds have quill knobs. The feathers usually anchor into the patagium that wraps around the arm and hand, as seen in Microraptor (which lacks quill knobs, as does Archaeopteryx).

[Doug Watson]

For the record, the paper isn't disputing the presence of coverts but if long coverts that reach near the ends of the primaries, which had been argued by some recent papers.

No birds have quill knobs on the fingers as far as I know, instead the fingers are flattened into a broad, fused phalange. Greg Paul used the presence of such a structure in Dromaeosaurs to argue for secondary flightless ness, but this may simply be there to support large primaries. Note that quill knobs are only present at all in a few species that have particularly high stresses on the feathers. Not even all or most flying birds have quill knobs. The feathers usually anchor into the patagium that wraps around the arm and hand, as seen in Microraptor (which lacks quill knobs, as does Archaeopteryx).

You are correct, my bad for leaving "elongated" out of my summary. But anyone reading the paper's title should have caught that. I'll blame that on the sinus infection I am fighting and all the drugs I am on.

I am well aware that many flying birds lack quill knobs. My assertion is as far as I know archaeopteryx is the only example we have that shows physical evidence of the feather insertion on the fingers in the actual fossil and only shows those feathers on the second digit, the other digits would be featherless and that also contradicts those illustrations. The specimen described in the paper I cited also shows that the "distalmost primary apparently inserted into the midsection of the second phalanx, which indicates that the ungual phalanx of the second digit was not covered by feathers and was therefore functional." The feathers in those illustrations appear to cover the ungual phalanx.  Again I guess I wasn't clear in my foggy state.

[Pachyrhinosaurus]

It's been a while since this thread has been used. I was just wondering if anyone had good references for europasaurus. I'm particularly interested in neck posture, since it seems to vary in most reconstructions. Some show it held out forwards, others show it held upright (like the typical brachiosaur) and then there are those which are in between (Bullyland). Are they equally likely or is one more plausible than the rest?

[Balaur]

From what I know, a lot of palaeontologists thought that most sauropods held their necks horizontally. However, they probably all held their necks up high when they were awake, so I would say Europasaurus did hold its neck vertically.

[Yutyrannus]

It's been a while since this thread has been used. I was just wondering if anyone had good references for europasaurus. I'm particularly interested in neck posture, since it seems to vary in most reconstructions. Some show it held out forwards, others show it held upright (like the typical brachiosaur) and then there are those which are in between (Bullyland). Are they equally likely or is one more plausible than the rest?

Here you are .
http://paleo-king.deviantart.com/art/Europasaurus-holgeri-skeletal-412249463

[Pachyrhinosaurus]

Those are some strange proportions! All the more fun to sculpt it. Thanks for the information. I'm guessing the neck would have been better-muscled than the diagram indicates? Or at least near the base.

[Newt]

Do yourself a favor. Go to svpow.com/category/necks/ and start reading! Lots of great information there about sauropod neck anatomy and posture.

The short of it is, different workers disagree on how sauropods held their necks and how the soft tissues were arranged, so this gives you a fairly broad range of interpretations to choose from. Of course the authors of SV-POW promote their own interpretations, but they also discuss the alternatives, so that's a great place to start.

[hmcgill]

Hi! I'm looking for a diagram of a single, zoomed-in pycnofiber. Anybody know of something I can reference?

[Dinoguy2]

It's been a while since this thread has been used. I was just wondering if anyone had good references for europasaurus. I'm particularly interested in neck posture, since it seems to vary in most reconstructions. Some show it held out forwards, others show it held upright (like the typical brachiosaur) and then there are those which are in between (Bullyland). Are they equally likely or is one more plausible than the rest?

All of them are correct! The forward position would be used any time the animal needed to lower its head (lower browsing, drinking, etc.).

There's no one correct posture for any animal, just a range of postures with extremes, and a certain point past the extreme where a posture would become impossible without breaking bones or ligaments.

[Newt]

Mosasaur lips: thoughts?

Obviously their modern cousins have lips of a sort, enough to conceal the teeth and provide a sleek mouthline. But - I'm guessing lips for totally marine lizards are at best useless (their main function, I reckon, being to reduce water loss by sealing the mouth from the atmosphere) and at worst maladaptive (a sealed mouth being harder to open underwater). It would make sense, to me at least, for them to have lipless, crocodilian-like mouths. Then again, aquatic snakes manage to feed underwater despite their lips, and lips might provide marginally better hydrodynamics. I'm stumped.

Is there any relevant fossil evidence?

[stargatedalek]

I can't think of anything from the fossils, but there are several species of monitor lizards today that will hunt underwater and they don't seem to have any difficulties opening their mouths fast enough to catch fish. Given that the basic shape of a mosasaur head is still similar to a monitors and shows no further adaptations to counteract the changes to shape loosing the lips would cause I think the safe assumption is that they never lost them.