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Extinct Animal Questions
Topic Started: Nov 26 2013, 10:24 PM (193,397 Views)
Consultant
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When did cacti evolve?
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Incinerox
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Āeksiot Zaldrīzoti

35 million years ago in South America.
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Consultant
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Damn it! Well there goes some speculative evolution. Thanks though.
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Joe99
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how did spinosaurus walk, the legs look like there not build to walk and it look kinda to front heavy to be on to I wanna know
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Paleop
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Paleopterix

this is a weird answer but, maybe it didn't or maybe it dragged its hind legs across the ground using it's front legs to move. though its legs were solid bone (if I remember correctly) so that and thick muscle may have allowed them to use their legs for foot walking (Bionicle ref intended :P )







Incinerox can give you a better answer though :)
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Zoo Tycooner FR
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#Lithopédion

Why there is so sparsely information of the Saotherium mingoz and where can i found some english or french information ?
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Incinerox
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Paleop
May 24 2015, 10:00 AM
this is a weird answer but, maybe it didn't or maybe it dragged its hind legs across the ground using it's front legs to move. though its legs were solid bone (if I remember correctly) so that and thick muscle may have allowed them to use their legs for foot walking (Bionicle ref intended :P )







Incinerox can give you a better answer though :)
Honestly, I can't actually provide an answer to this because nobody has an idea of what was going on.

Sereno and co thought that it might've been a quadruped after all, supporting the front half of its body on its knuckles. How that fares as a valid hypothesis is completely dependent on how specialised its wrist and fingers were. Bits of the animal we still don't actually have yet. But the logic is sound - it was WAY too front heavy to walk like a standard theropod. Hell, even Majungasaurus had absurdly robust legs and tail to counter its elongated front end.

Cau says it COULD walk on 2 legs, but on the basis that it waddled more like a pelican, with its head pulled back (a perfectly reasonable assumption given the new neck material), and its body held at an angle. I'm personally against this on the basis that it'd put an unneccesary amount of strain on its legs, and maybe break the tail at its base. And I doubt it solves the centre of gravity problem Spinosaurus had.

Then you have some like Hartman that are convinced that there's been some kind of error. Several thought the same but were swayed back into Sereno and Ibrahim's field of thought. I don't know if Hartman was ever convinced. But if Hartman's calculations are true, then the legs of Spinosaurus were under scaled, and perhaps it could indeed walk like a normal theropod. Given that Ibrahim's conclusion was reached from multiple independent paleontologists, I'm pretty sure their original calculations were legit.

There's that, or there's an idea that the sail was restored wrong. Can't remember who it was (might've been Hadden) suggested that the sail should be restored with more of it over the hips and top of the tail, rather than at its highest on the lower back. If he's right, the cluster of muscles over the tail MIGHT make Cau's hypothesis more reasonable (it'd also give the head and neck more space to move backward).

Then some just insist that it wasn't walking at all, and that it was sliding around on mud like a crocodile-mudskipper. It'd make for a really interesting analogy, but I'm not convinced it'd be a reasonably comfortable position for a 9 ton theropod to take on, spending its entire time sliding on a not-particularly-reinforced belly.

I'm currently more in favour of quadrupedal walking on land, if I'm honest simply because it relies on the least number of physical and behavioural assumptions about the way Ibrahim and Sereno restored Spinosaurus, even if it's a fairly big assumption to make.




Also I have no idea. Google HK has the same problem. I managed to figure out that it's a hippo of some kind. Beyond that, it's all french.
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Iben
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There'll be no foot-walking! Just air-flying!

Incinerox
May 24 2015, 10:42 AM


There's that, or there's an idea that the sail was restored wrong. Can't remember who it was (might've been Hadden) suggested that the sail should be restored with more of it over the hips and top of the tail, rather than at its highest on the lower back. If he's right, the cluster of muscles over the tail MIGHT make Cau's hypothesis more reasonable (it'd also give the head and neck more space to move backward).

It was indeed Headden. He mentions it, amongst other valid points.

Jaime A. Headden
 
Ibrahim et al. (2014) reverse the trend recently to see the last, tallest vertebral spine as a caudal (Andrea Cau, Scott Hartman, and myself) and pull the arch of the sail over the hips, and plop it right back into von Stromer’s and Lydekker’s last-dorsal position with corresponding sharp drop-off in height over the hips and into the tail. Ibrahim et al. (2014) describe new caudal material, but as it turns out none of the material represents anterior caudals, and instead the authors place the ambiguous caudal of the holotype into the most anterior (read, first caudal) position possible. As I discussed here, this is unlikely. As it is, none of the caudal vertebrae seem to be anterior further anterior than about half of the tail’s length, assuming about 50 caudals.


Now I do believe there was someone else who mentioned errors in the sail reconstruction in a more elaborate blogpost, but I'm not sure who it was...
Edited by Iben, May 24 2015, 11:02 AM.
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Even
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Both Headden and Cau had discussed about it
Edited by Even, May 24 2015, 11:46 AM.
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DinoBear
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Weren't theropod shoulder girdles poorly adapted for any sort of quadrupedal movement?
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Paleop
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Paleopterix

where may I find the most accurate and up to date skeletal of t rex

thanks :)
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Anas Platyrhynchos
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The Quacky Canine

Is it possible that Dilophosaurus could have hacked up mucus and spit it in the eyes of a competitor while in a fight
Edited by Anas Platyrhynchos, May 24 2015, 05:45 PM.
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BossAggron
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Formerly Dilophoraptor

I kinda doubt it.
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Incinerox
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Paleop
May 24 2015, 04:58 PM
where may I find the most accurate and up to date skeletal of t rex

thanks :)
Scott Hartman's stuff.

He's got multiple specimens too.
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Anas platyrhynchos
May 24 2015, 05:44 PM
Is it possible that Dilophosaurus could have hacked up mucus and spit it in the eyes of a competitor while in a fight
No modern animal I know of does that so I really doubt it would do that.
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