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Extinct Animal Questions
Topic Started: Nov 26 2013, 10:24 PM (193,337 Views)
Paleosaurus
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54godamora
Nov 30 2015, 05:11 PM
what sea reptiles that had flippers excluding turtles could clamber onto land?
Primitive ichthyosauromorphs like Cartorhynchus definitely could. Most marine placodonts were probably mediocre at moving around on land, comparable to sea turtles. Flippered nothosaurs were most likely capable of it too as well as early mosasaurs that had yet to develop full flippers.
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54godamora
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what about plesiosaurs
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Paleosaurus
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A plesiosaur on land would be heavily impaired by its neck and I'm pretty sure the way their limbs moved would make them even slower than sea turtles. That's not even accounting for big species like Elasmosaurus which would likely die from its own weight if it was on a beach. There would be no reason for them to return to land anyway since we know plesiosaurs gave live birth ancestrally.
Edited by Paleosaurus, Nov 30 2015, 05:56 PM.
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BossMan, Jake
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Son of God

AFAIK none of them did unless you could count some more advanced Nothosaurs.
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54godamora
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I was asking because in a story of mine if you already know, the main character offers plesiosaur rides when they're at the beach because RWBY logic.
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Paleop
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Paleopterix

so ive been wondering for a while, is there any evidence to say triceratops cheek bones were exposed/visible like in this reconstruction
Posted Image
or submerged in flesh like mine and at-least a few others?
Posted Image
*note not a plug
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BossMan, Jake
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Son of God

How similar was the Paleofauna in the Prince Creek Formation to the many formations in Canada? And would it have been possible that it served as a Land Bridge between N. America and Asia during that time? (72-66 MYA to be exact)
Edited by BossMan, Jake, Nov 30 2015, 11:45 PM.
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Incinerox
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Āeksiot Zaldrīzoti

Paleop
Nov 30 2015, 09:49 PM
so ive been wondering for a while, is there any evidence to say triceratops cheek bones were exposed/visible like in this reconstruction
Posted Image
or submerged in flesh like mine and at-least a few others?
Posted Image
*note not a plug
Yeah, those cheek bosses would have been visible in life.

Posted Image
Posted Image

Perhaps they'd not have been AS obvious from the side as they are in the top pic you provided, but they'd have ended in a raised calloused pad or a large scale - basically some kind of keratinous coating around the tip of the bosses. How visible it was depends on how much you want to flesh out the cheeks themselves. Point is though, they'd have been visible, so the second pic is simply incorrect.


@Jake: Middle Maastrichtian Prince Creek was actually more similar to the Campanian Horseshoe Canyon formation than anything else, and it's likely that this is not a coincidence. The presence of the youngest Pachyrhinosaurus species and Ugrunaaluk, a younger sister taxon to Edmontosaurus regalis in Prince Creek suggests that these polar regions were a refuge for Horseshoe Canyon type biota when climates shifted and more typical Maastrictian fauna of Laramidia (eg. Hell Creek and Lance biota) moved into Alberta. I can tell you that the weather back then in Prince Creek was like England's weather today - bloody miserable.

As for a land bridge? I... don't think so. Maybe? We know it had to have existed before 70 million years ago (which is why we have Saurolophus in both Nemegt and Horseshoe Canyon). Interchanges between American and Asian species is common throughout the Cretaceous, so either this bridge was very long lasting or it came and went regularly as sea levels rose and fell. As for whether it was there at the time of Prince Creek, I'm getting mixed results. Honestly? I'd roll with it. It's perfectly reasonable to suggest one was there during the later half of the Cretaceous.
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heliosphoros
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Xenarthrans have similar projections:

Posted Image

Yet they're invisible in life:

Posted Image

So there is some precendent for them to be at least less conspicuous
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Incinerox
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Āeksiot Zaldrīzoti

Fair enough. The point is that the texture at the end of those projections on ceratopsians does suggest they were capped in some sort of large scale or calloused pad of some kind.

Also noting that in the sloth, that projection comes downward from the zygomatic arch, rather than outward from the skull itself (that is to say, it appears that the projection in ceratopsian cheeks doesn't seem to be integrated into the skull musculature itself).

So yeah, there is precedent for them to be less conspicuous as a whole projecting thing on the cheeks, but they did end in a distinct hornlet type thing.

ALSO, I was slightly mistaken. Yes, I can confirm that there was a land bridge throughout the post-Aptian Cretaceous.
https://www.kahaku.go.jp/english/research/researcher/papers/165941.pdf
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Rockypockypuff
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Is walkin' with a dead man.

This have been bothering me...

Did the Tyrannosaurus rex have "lips" or were their upper teeth visible (kinda like this: http://vignette3.wikia.nocookie.net/jurassicpark/images/f/fe/T_rex_male_tlw_by_manusaurio-d6ilbfy.jpg/revision/latest?cb=20140103204938 )? Which would make most sense, juding by skeleton finds and now living animals?
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Brach™
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hi

Rockypockypuff
Dec 1 2015, 02:30 PM
This have been bothering me...

Did the Tyrannosaurus rex have "lips" or were their upper teeth visible (kinda like this: http://vignette3.wikia.nocookie.net/jurassicpark/images/f/fe/T_rex_male_tlw_by_manusaurio-d6ilbfy.jpg/revision/latest?cb=20140103204938 )? Which would make most sense, juding by skeleton finds and now living animals?
It's pretty hard to say for sure. There's nothing that suggests they did or didn't have lips. The problem with looking to extant life for inference is that the extant archosaurs we have to look at have adaptations that would negate the need for lips. (no teeth, aquatic life styles).
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Paleop
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Paleopterix

thanks, guys :)
I've corrected the cheek bones to be semi visible:
link
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CyborgIguana
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Braqistan
Dec 1 2015, 04:01 PM
Rockypockypuff
Dec 1 2015, 02:30 PM
This have been bothering me...

Did the Tyrannosaurus rex have "lips" or were their upper teeth visible (kinda like this: http://vignette3.wikia.nocookie.net/jurassicpark/images/f/fe/T_rex_male_tlw_by_manusaurio-d6ilbfy.jpg/revision/latest?cb=20140103204938 )? Which would make most sense, juding by skeleton finds and now living animals?
It's pretty hard to say for sure. There's nothing that suggests they did or didn't have lips. The problem with looking to extant life for inference is that the extant archosaurs we have to look at have adaptations that would negate the need for lips. (no teeth, aquatic life styles).
Personally I'd lean towards the majority of theropods having lips, since most terrestrial tetrapods alive today (aside from the aforementioned highly specialized archosaurs) have them.
Edited by CyborgIguana, Dec 1 2015, 05:50 PM.
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Incinerox
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Āeksiot Zaldrīzoti

Braqistan
Dec 1 2015, 04:01 PM
Rockypockypuff
Dec 1 2015, 02:30 PM
This have been bothering me...

Did the Tyrannosaurus rex have "lips" or were their upper teeth visible (kinda like this: http://vignette3.wikia.nocookie.net/jurassicpark/images/f/fe/T_rex_male_tlw_by_manusaurio-d6ilbfy.jpg/revision/latest?cb=20140103204938 )? Which would make most sense, juding by skeleton finds and now living animals?
It's pretty hard to say for sure. There's nothing that suggests they did or didn't have lips. The problem with looking to extant life for inference is that the extant archosaurs we have to look at have adaptations that would negate the need for lips. (no teeth, aquatic life styles).
They had lips.

You can tell based on the size and distribution of pores along the jaw margins of dinosaur maxillae, premaxillae and dentary bones. Those of most theropods, and indeed most dinosaurs with teeth suggest that they had extensive soft tissues lining their jaws, much like those in modern squamates actually. Likely textured differently but there's that's not relevant. That's a different study entirely.
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