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Extinct Animal Questions
Topic Started: Nov 26 2013, 10:24 PM (193,245 Views)
magpiealamode
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No good hero is a one-trick phony.

While we're on sauropods, what is the common opinion of Amphicoelias fragillimus? Or, what is your opinion at least?
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BossMan, Jake
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I've heard that it's just been lumped into A. Altus, I have a hard time believing it was actually true though despite the illustrations, kinda strange that fossils of perhaps the largest animal to walk the earth just suddenly disappeared during transit
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Acinonyx Jubatus
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magpiealamode
Mar 7 2017, 11:28 PM
While we're on sauropods, what is the common opinion of Amphicoelias fragillimus? Or, what is your opinion at least?
My opinion is that there's pretty much zero evidence for it; HOWEVER, a sauropod of that size is well within the realm of possibility (A collection of footprints support this, and the new Barosaurus measurements put that animal closer in length than any other dinosaur thus far.)
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Paleop
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I have spent a lot of time scaling Barosaurus sp. (BYU 9024)

Assuming there is no frther alometry from Barosaurus, and ignoring potential species diferences:
The whole creature is roughly 180ft long
Scaled BYU 9024



Some Friends of mine have done a gdi concluding the creature to weigh roughly 40 tones (without skin and a substantial amount of fat).

Some of the largest Titanosaurs crap on this weight estimate. IIRC the largest titanosaurs were around 50-60 tones or so.


There is a theory that Amphicoellias is a rebachisaur.
Edited by Paleop, Mar 8 2017, 10:37 AM.
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Furka
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So this is just a thought that popped out in my mind, what if Diplodocus was "thinner" than other contemporary sauropods like Apatosaurus because it was more of a forest dwelling animal ? (ofc relatively open forests, considering the size of the thing).
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PrimevalBrony
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Hmmmm, well a less broad body would definitely be needed in that sort of idea, which means a smaller gut. Thus stone-swallowing might have been more common to help digest.
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magpiealamode
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No good hero is a one-trick phony.

How come all of the fastest dinosaurs were bipedal? Today our fastest land animal is a quadruped, so what's going on there? When I consider quadrupedal dinosaurs, there's thyreophorans and sauropods which couldn't have been too quick, and then the ceratopsians which I guess were faster? But maybe not. Then there are the iguanodontids which apparently reared up onto two legs to go faster?
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Acinonyx Jubatus
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magpiealamode
Mar 18 2017, 12:05 PM
How come all of the fastest dinosaurs were bipedal? Today our fastest land animal is a quadruped, so what's going on there? When I consider quadrupedal dinosaurs, there's thyreophorans and sauropods which couldn't have been too quick, and then the ceratopsians which I guess were faster? But maybe not. Then there are the iguanodontids which apparently reared up onto two legs to go faster?
As I understand it, Cheetahs are only fast because they have this flexible, hyperextensible backbone that basically slingshots them forward while running. Dinosaurs had somewhat more rigid backbone and had to rely on other means.

Aside from this, it seems the ancestral condition for dinosaurs is bipedalism; all the quadrupedal herbivores got that way because they were getting big, and bulky, and it became easier to support their weight on their front as well as their back feet. That kind of lifestyle is not conducive to fast running anyway, but it does mean that it's simpler just to temporarily revert back to bipedalism when you want to go faster.
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BossAggron
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There's also (possibly) the matter of all the power in Archosaur legs are in the back legs and tail when it comes to movement. Since not as much power can be routed using forelimbs, it would probably just be easier to leave high speeds to the back legs.
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Incinerox
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Āeksiot Zaldrīzoti

Fast moving squamates provide an interesting model on how bipedalism may have happened in archosaurs in the first place. Short front legs, long back legs, powerful tails and stiffer spines meant that to move faster, they could lift their front legs off the ground and let their back legs do all the work since their front legs couldn't keep up. This shifts their COG backwards and adds to the usefulness of their rear limbs. It kinda begets itself.

Meanwhile, mammals, with their equal sized limbs, long, flexible (and flimsy) spines and useless tails means that it takes more for them to keep their front limbs off the ground. So they're more inclined to develop their front limbs and spines and incorporate them into movement. Some DID take to some kind of bipedalism (kangaroos most notably), but it's less common.

Though it interests me why crocodilians never explored more mammalian like means of movement in their evolutionary history. Longer spines, longer front limbs, they were far more quadrupedal than dinosaurs collectively. So why not? Did they just not ever got the chance? I know there were some pretty small, long limbed crocodilians but none could be compared with, say, big cats.
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magpiealamode
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No good hero is a one-trick phony.

Well there was Quinkana, which if I'm reading correctly was actually a crocodile. Then there's the Notosuchia, not crocodilians per se, but a sister group to the Neosuchia I think? Which provides us with such genera as Baurusuchus and Simosuchus.
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heliosphoros
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Incinerox
Mar 22 2017, 09:39 AM
Fast moving squamates provide an interesting model on how bipedalism may have happened in archosaurs in the first place. Short front legs, long back legs, powerful tails and stiffer spines meant that to move faster, they could lift their front legs off the ground and let their back legs do all the work since their front legs couldn't keep up. This shifts their COG backwards and adds to the usefulness of their rear limbs. It kinda begets itself.

Meanwhile, mammals, with their equal sized limbs, long, flexible (and flimsy) spines and useless tails means that it takes more for them to keep their front limbs off the ground. So they're more inclined to develop their front limbs and spines and incorporate them into movement. Some DID take to some kind of bipedalism (kangaroos most notably), but it's less common.

Though it interests me why crocodilians never explored more mammalian like means of movement in their evolutionary history. Longer spines, longer front limbs, they were far more quadrupedal than dinosaurs collectively. So why not? Did they just not ever got the chance? I know there were some pretty small, long limbed crocodilians but none could be compared with, say, big cats.

Quinkana

Sebecids (some to theropod-size)

Pristichampsids
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Acinonyx Jubatus
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What was Dimetrodon's sense of smell like? And did it have ear-holes?
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TheNotFakeDK
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I'm having trouble finding anything about its sense of smell, but I can tell you that Dimetrodon did not have ear holes.
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Acinonyx Jubatus
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TheNotFakeDK
Mar 23 2017, 02:03 PM
I'm having trouble finding anything about its sense of smell, but I can tell you that Dimetrodon did not have ear holes.
This seems really weird to me for some reason. Oh well.
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