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Dinosaur boners... I mean bones!; No seriously, it's about the pe... pelvis.
Topic Started: Nov 8 2011, 07:46 PM (720 Views)
Flisch
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So, everyone knows these dinosaur reconstructions with that huge pelvis sticking out from the base of their tail. (Mainly, because all reconstructions are like that.)

Now, usually I'm not one to question reconstructions that have been used for decades and never changed, but this is really bugging me... What the hell is its purpose? It doesn't seem that there are any muscles attached to it, and it also seems to get in the way when the animal would try to sit/lay down. So, why is it there in the first place, and why is it never covered in tissue in any reconstructions?

Image attached, if you don't know what I am talking about. >_>
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Mish
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Robert Bakker theorized that raptors used that pubic bone as a seat. While it was interesting, if you are in possession of a bony backside like myself, sitting on it is not a picnic.

Good question. I always figured that if they rested, they settled more on their sides, because of that bone. *goes hunting for Raptor Red illustrations*
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JohnFaa
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It seems to play a role in leg muscle attachment, but I don't know why exactly.
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Venatosaurus
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Well it's possible that bone was much more well padded in real-life, either with fat or thick muscle. It could've also served an an anchor point for fat reserves. In reality it could've served a function beyond our imagination...



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Flisch
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Could it be that the leg muscles attached to the bone and basically obscures the upper leg, similarly to how the upper leg usually doesn't stick out of the body in most mammals? This would of course mean, that dinosaurs were slightly more bulky than recent reconstructions make them out to be. >_>
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JohnFaa
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They also seem to play a role in housing the guts; ornithischians and therizinosaurs famously have the backward's pointing pubis, but sauropods, oviraptors, troodontids and ornithomimosaurs have the pubis pointing forewards.
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Empyreon
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Are you plausible?

Am I way off in theorizing that it could play a role in copulation? Sort of a strut on which reproductive organs can sit so they aren't tucked away too deep to access?

I'm looking around for bird anatomy pictures to see why bird hips have a reverse pointing pelvic bone and I found this website. It points out that the bird pelvis actually plays a role in the tail musculature. Now, since ornithischians aren't descendant of modern birds the structure is convergent and doesn't necessarily serve the same purpose, but I think the comparison is informative.
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Take a look at my exobiology subforum of the planet Nereus!

food for thought
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JohnFaa
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While I think it would explain why maniraptors had such a hip arrangement, I doubt it is the answer for the ornithischian arrangement, which don't seem to have had an unique leg musculature arrangement.
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Kamineigh
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Flisch
Nov 8 2011, 07:46 PM
So, everyone knows these dinosaur reconstructions with that huge pelvis sticking out from the base of their tail. (Mainly, because all reconstructions are like that.)

Now, usually I'm not one to question reconstructions that have been used for decades and never changed, but this is really bugging me... What the hell is its purpose? It doesn't seem that there are any muscles attached to it, and it also seems to get in the way when the animal would try to sit/lay down. So, why is it there in the first place, and why is it never covered in tissue in any reconstructions?

Image attached, if you don't know what I am talking about. >_>


That reconstruction is inaccurate. Has been ever since that dinosaur mummy was found. To paraphrase how Bob Bakker put it "This dinosaur had a fatter ass than we previously thought." I know this because I remember when one of my idols says dinosaur and fatass in the same sentence. But yeah, it's been proven that dinosaurs had much thicker tails than what your picture shows.

Flisch
Nov 9 2011, 04:45 AM
This would of course mean, that dinosaurs were slightly more bulky than recent reconstructions make them out to be. >_>


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jasonguppy
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JohnFaa
Nov 8 2011, 08:09 PM
It seems to play a role in leg muscle attachment, but I don't know why exactly.
HE DOESN'T KNOW WHY!!!!!!!!!!!!!!
JOHNFAA DOESN'T KNOW!!!!!!!!
RUN FOR YOUR LIVES!!!!!!!!!!!!!!!
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JohnFaa
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If you know then explain, Mr All Caps.
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lamna
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No you see the joke is, you have an answer for everything paleontological, so if you don't know something must be wrong.
T.Neo
 
Are nipples or genitals necessary, lamna?
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jasonguppy
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^exactamundo
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Dragon
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It would have most definitely been an anchor for the inner leg muscles like our vestigial tailbones. Without it, these dinosaurs probably wouldn't have been able to walk or run, or do anything really. There would definitely nave been some sort of fat or thick muscle on or near that hip bone, since it's pretty awkward for them to sit on that.
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I think this describes what dinosaurs are like now

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