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| Extinct Animal Questions | |
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| Topic Started: Nov 26 2013, 10:24 PM (193,332 Views) | |
| CyborgIguana | Dec 19 2015, 08:12 PM Post #2431 |
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We actually already know directly of several, notably Brodavis and Potamornis from the Hell Creek formation.
Edited by CyborgIguana, Dec 19 2015, 08:13 PM.
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| Furka | Dec 20 2015, 06:25 AM Post #2432 |
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Do we have any idea about how large Ugrunaaluk was ? |
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| Incinerox | Dec 20 2015, 07:17 AM Post #2433 |
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Āeksiot Zaldrīzoti
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I'll get back to you on this. EDIT: News articles say it got to 30ft. I am very skeptical of this number though, on the basis that it's news articles and we have no adult specimens to confirm this. EDIT 2: OR... I could just read the damn paper and tell you that the largest Ugrunaaluk specimens we have (WHICH ARE ADULTS, so I was WRONG) suggest it was substantially smaller than either E. regalis or E. annectens, and more specifically, adult Ugrunaaluk were only 60% the size of the E. annectens paratype, YPM 2182 (which is an 8m subadult - we know that E. annectens could get to stupidly large sizes). This would make Ugrunaaluk about 5.4m (17.6ft). Which is very small, and sorta corresponds with the small size of Nanuqsaurus. Even assuming the paper undersizes the animal, or I've misinterpreted (which I likely haven't since they split individuals into size class depending on size ranges and ontogenetic stage quite effectively), that puts a MAXIMUM estimate from me at 7.2m (23.4ft). If you wanna take a chance on it, split the difference - go with 6.3m (20.5ft). The first number is your most reliable though. This raises a question I want to ask: In modern animals, things tend to get larger as you move into colder environments - wolves, bears, moose, ducks, geese, grouse, birds of prey, bison etc. all have larger representatives in the north, seemingly because it helps with body heat conservation when it's bitterly cold. This is a principle that applies to all endotherms - dinosaurs included. Hence why many believe the Prince Creek Troodontid to just be a large Troodon, even though it's nearly twice as large. Yet we have a TRUE Dwarf Tyrannosaurine, and a really small version of what should be one of our largest hadrosaurs. Why is life in Prince Creek so small? And why was Pachyrhinosaurus's size unchanged? Edited by Incinerox, Dec 20 2015, 08:44 AM.
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| BossMan, Jake | Dec 20 2015, 11:14 AM Post #2434 |
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Son of God
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Well that last point about Ugrunaaluk raises a good hypothesis. Perhaps the animal didn't need to be larger because it didn't spend the winter months in Alaska. If we look at many of the northern species of some animals they typically have higher fat concentrations and thicker fur. (Which is sometimes why they are larger). Yet it's apparent that this hadrosaur was smaller then it's Southern kin. Chances are during the winter months they probably would've migrated south to avoid the cold weather. As a result of this they didn't need to be so big. There is 0 proof of this but it's an idea |
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| Paleop | Dec 20 2015, 01:05 PM Post #2435 |
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Paleopterix
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maybe the environment 'preferred' smaller animals as opposed to giants atleast in the sense that the area couldn't support very large creatures?
out of curiosity: is there evidence of individuals longer than 12 meters? |
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| Mathius Tyra | Dec 20 2015, 01:09 PM Post #2436 |
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Rat snake is love... Rat snake is life
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Aside from Carnotaurus, Albertosaurines and possibly several Troodontids, are there any other predatory dinosaurs are cursorial hunter that mainly hunt by chasing prey? |
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| Even | Dec 20 2015, 03:08 PM Post #2437 |
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@DG: Perhaps the answer to your question can be found when we observe the trends on birds from northern latitudes to equatorial ones... Do they follow Cope's Law? |
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| Incinerox | Dec 20 2015, 06:12 PM Post #2438 |
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Āeksiot Zaldrīzoti
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I find this unlikely since it wasn't THAT cold up there in the Cretaceous. It was like the UK. And why would you migrate south towards predators 8 times heavier than what you normally put up with?
Uh... Cope's Law is to do with evolutionary trending towards larger sizes. Not a north/south size division. I assume you mean Bergmann's rule, which DOES state that animals tend to get larger in colder conditions. In response to your question though, yes. We're looking at something around 72% of all living bird species (with the sort of distribution which allows for this kind of test) which follow Bergmann's rule, and 65% of mammals (small mammals ignore the rule, but birds seem to abide by it regardless of size - even the size of their eggs changes). Ectothermic reptiles show the reverse - they get larger in warmer climates.
I did consider this hypothesis to be the most plausible. That said, I can't really imagine why this would be the case. Prince Creek back then was basically like the UK is now - gray and miserable, but not particularly bitter with a chance at snow during winter. And the UK is fairly green, so I can't imagine it's a result of food shortage. Also yes, yes there is. MOR V 007. It's tail alone already hit the 10m mark. Also contains traces of an epidermal midline frill along the top of the tail, and presumably back. https://www.researchgate.net/publication/259075531_A_segmented_epidermal_tail_frill_in_a_species_of_hadrosaurian_dinosaur
You've been a bit selective among clades, but that's more or less it. It also depends on what you mean - all theropods likely ran after their prey to some extent. If you mean something a bit more specialist, then you have the following: > Brachyrostran abelisaurs > Most derived tyrannosauroids (essentially anything floating about the middle of the tyrannosauroid family tree from Raptorex, Alectrosaurus and Xiongguanlong right down to Alioramines, Albertosaurines, and juvenile giant tyrannosaurines). > Troodontids. > Phorusrhacids. That's what comes to mind at the moment. Feel free to chime in if I've missed a spot. |
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| Furka | Dec 20 2015, 06:29 PM Post #2439 |
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Maybe I'm wrong, but didn't Allosaurus (or at least the juvenile) have fairly long legs too ?. |
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| BossMan, Jake | Dec 20 2015, 06:51 PM Post #2440 |
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Son of God
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What about the dromaeosaurids like Velociraptor? Weren't they built for at least some form of pursuit? |
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| Incinerox | Dec 20 2015, 07:03 PM Post #2441 |
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Āeksiot Zaldrīzoti
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For Allosaurus, sorta? They did compared to the adults but they weren't exactly specialist runners. When you compare a juvenile allosaurus and a tyrannosaurid of the same ontogenetic stage of their lives, it's more noticable. Dromaeosaurids were actually pretty crap runners. Having enlarged 2nd toe claws meant they needed shorter, more robust metartarsals to support all the ligaments involved in using it. Troodontids get away with this because their 2nd toes aren't anywhere near as developed, or as powerful as a result. And unlike troodontids, the rest of a dromaeosaurid's leg was also built for power, not speed. As a result, these animals likely weren't partaking in drawn out chases. They were STUPENDOUSLY good at LEAPING, however. Which might have implications on how they employed different ambush tactics. |
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| Paleop | Dec 20 2015, 07:29 PM Post #2442 |
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Paleopterix
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doing some scaling in gimp....(the 2 purple squares and the distance between represent the tail length used to scale MOR V 007) ![]() that's practically a sauropod sized hadrosaur EDIT: there's also evidence of a large lambeosaurine in hell creek... Edited by Paleop, Dec 20 2015, 07:35 PM.
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| BossMan, Jake | Dec 20 2015, 11:54 PM Post #2443 |
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Son of God
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Speaking of Hell Creek what other as yet undescribed fossils (besides the lambeosaurine mentioned above) do we have from the formation? Like fragments or trace fossils to be exact
Edited by BossMan, Jake, Dec 20 2015, 11:55 PM.
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| Incinerox | Dec 21 2015, 05:37 AM Post #2444 |
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Āeksiot Zaldrīzoti
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Off the top of my head, some ornithurines and an azhdarchid. |
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| CyborgIguana | Dec 21 2015, 11:19 AM Post #2445 |
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Isn't there also alvarezsaurid material that's yet to be described? |
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