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20-07-2019, 08:24   #46
Adam Khor
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Hadrosaurs had great variety. Differential reproduction?
Actually what I find intriguing about them is that postcranially, most of them look VERY much alike, and the head/crest is about the only thing that allows one to tell them apart. Something similar happens with ceratopsians. In both hadrosaurs and ceratopsians it can be extremely difficult even for paleontologists to determine what genus or species they're looking at unless there's a skull, and juveniles (which are yet to develop their distinctive crests) are even more problematic.

Although I suppose the same would be true of say, many antelopes if all we had to go by were the bones...
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20-07-2019, 19:31   #47
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... the head/crest is about the only thing that allows one to tell them apart.
Did one species have a snorkel on the top of its head? For breathing at waterline, with rest of animal below surface?
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20-07-2019, 20:22   #48
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Did one species have a snorkel on the top of its head? For breathing at waterline, with rest of animal below surface?
The snorkel idea was once suggested for Parasaurolophus, perhaps the most iconic of the hadrosaurs (although one relatively rare in the fossil record):



The idea has long been discarded due to several reasons:

1. One would expect a snorkel to project more vertically; instead, the crest grows backwards and downwards at the tip.

2. Not all Parasaurolophus specimens have a long crest; in fact, it has been suggested that only adult males did, whereas females and juveniles had much shorter crests. This strongly suggests a role in courtship and social interaction. If the crest was a snorkel we would expect all Parasaurolophus to have the same equipment.

3. Most importantly, there is no opening at the tip of the crest. The animal's nasal passages DO go into the crest but it's just a detour; it is currently believed that the crest functioned not just as a visual display but also as a trombone of sorts, amplifying the dinosaur's calls.

In the 90s, scientists used a computer simulation to calculate how much air a Parasaurolophus would've been able to blow from its lungs, and reconstructed its possible voice. Check it out, it's rather eerie:



Keep in mind that Parasaurolophus is believed to have prefered more forested areas than other hadrosaurs, so it makes sense that sound would've been an important part of its communication.

Also worth mentioning that hadrosaurs as a whole are no longer believed to have been semiaquatic, as was once proposed. The idea was that since they had duck-like beaks, they probably dived to feed on aquatic plants, but this has long been disproven; the beaks were only vaguely reminiscent of those of ducks; in life, they were covered by a rather hooked, sharp keratinous cover to crop vegetation, and they had batteries of thousands of tiny teeth to grind hard food. They weren´t feeding on soft water plants.

Another piece of supposed evidence for their aquatic lifestyle was the fact that a "mummified" hadrosaur was once found which showed what was interpreted to be webbing between its fingers. However, later it was found that this supposed membrane was actually a sort of "mitten" of skin that kept the three central fingers bound tightly together, an adaptation for supporting the animal's weight as it walked on four legs.

Their tail was also not flexible, but rigid and very heavy, and probably one of their main means of defense against predators (they could use it like a sledghammer to strike a predator ). It was not sinuous and crocodile-like as suggested by early paleontologists.

So in short, we have no evidence of aquatic or semiaquatic hadrosaurs as of this moment, and absolutely no evidence of any dinosaurs having snorkel-like crests.
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21-07-2019, 16:28   #49
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The snorkel idea was once suggested for Parasaurolophus, perhaps the most iconic of the hadrosaurs (although one relatively rare in the fossil record).

The idea has long been discarded due to several reasons...
Good to know. Thanks Adam.
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27-07-2019, 22:30   #50
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Did one species have a snorkel on the top of its head? For breathing at waterline, with rest of animal below surface?
IIRC 2 meters is the maximum depth underwater humans can breath through a tube to the surface.

And the guy who tried it died shortly afterwards, so do not try at home.


Human lungs aren't made for that differential.
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27-07-2019, 23:12   #51
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I wonder what would happen in this scenario then :B
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27-07-2019, 23:14   #52
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https://dino.lindahall.org/img/bur1m.jpg

I wonder what would happen in this scenario then :B

In two words I can tell you what's the matter with it: It's im-possible.

- Samuel Goldwyn
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05-08-2019, 20:37   #53
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Hapless Prosaurolophus ended up at sea

But that's good news for fossil preservation:

https://royaltyrrellmuseum.wpcomstag...play-features/

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05-08-2019, 20:41   #54
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Gobihadros, a new hadrosaur from Mongolia

Or hadrosauroid. Skeleton said to be nearly complete and as well preserved as if it had died days ago, thus allowing for great, accurate reconstruction:

https://journals.plos.org/plosone/ar...l.pone.0208480

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19-10-2019, 20:24   #55
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From the North Dakota Geological Survey's Paleontology Resource Protection Program's Twitter account, comes this very interesting picture which shows the hand of famous Edmontosaurus "mummy" Dakota, one of the best preserved dinosaurs in the world.

The picture shows that we have been reconstructing hadrosaur "hands" the wrong way; instead of three separate digits each ending in one small hoof, it appears these animals had all three main digits completely covered on a skin and flesh "mitten", and only the third digit had a big, horse-like, weight-bearing hoof. So, externally, the creature would only have one apparent hoofed toe, and a small, spike-like "pinky" that didn´t touch the ground.



Yet another example of how little we actually know about dinosaurs- even "classic" ones like Edmontosaurus-, and how different they would look with all their fleshy bits on.

Last edited by Adam Khor; 19-10-2019 at 20:31.
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