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Extinct Animal Questions
Topic Started: Nov 26 2013, 10:24 PM (193,231 Views)
magpiealamode
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No good hero is a one-trick phony.

Perhaps I spoke a little too strongly. We just don't have enough data to confirm. Unfortunately bias plays very much into this discussion; I personally try not to have opinions about whether or not T. rex had a coat of feathers, just hypotheses. Right now the mostly-bald-some-feathers model makes the most sense to me; I would be shocked if T. rex was truly featherless, but if you want a solid answer past that I can't give one and I don't know anyone who can.
Edited by magpiealamode, Jan 5 2018, 06:15 PM.
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heliosphoros
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Kind of late, but my cents:

- Modern ratites are built for speed, and even then they bear dense coats.

- Modern giant mammals are mostly either semi-aquatic or descended from semi-aquatic ancestors. Elephants also rely on what hair they have to cool themselves down, and their tendency to form dense coats is well established as well. Note that, for example, we have no evidence of skin of american elephants, which evolved from ancestors that re-acquired their wooliness.
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Jannick
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Papua merdeka!

heliosphoros
Jan 8 2018, 03:04 AM
- Modern giant mammals are mostly either semi-aquatic or descended from semi-aquatic ancestors. Elephants also rely on what hair they have to cool themselves down, and their tendency to form dense coats is well established as well.
I'll not go into the merits of T. rex integument here since I have nothing meaningful to add, but isn't this line of reasoning kind of self-defeating? Seeing as we know that elephants and rhinoceroses can develop or lose fur coats rather easily depending on their environment, is their semi-aquatic ancestry really relevant to their present-day integument? I.e. knowing that they're quite flexible in this regard, is it really sensible to assume that the lack of fur (in modern day species) is a holdover from semi-aquatic ancestors rather than a 'genuine' thermoregulatory adaptation?
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heliosphoros
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Basically, since they didn't have the need to redevelop dense coats, they didn't. For instance, sumatran rhinos run the gambit from borderline hairless to woolly, depending on the individual.
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Jannick
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Papua merdeka!

Ah okay, I see what you mean now. Thanks for clarifying.
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Ulquiorra
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Did all Ichthyosaurs had a dorsal fin? Some reconstructions show Ichthyosaurs with a dorsal fin, other reconstructions lack a dorsal fin.
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magpiealamode
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No good hero is a one-trick phony.

I think more basal ichthyosaurs lacked dorsal fins, while more derived icthyosaurs evolved them, but don't quote me on that. I don't think it's a rule
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stargatedalek
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I'm not slow! That's just my moe!

magpiealamode
Jan 11 2018, 06:38 PM
I think more basal ichthyosaurs lacked dorsal fins, while more derived icthyosaurs evolved them, but don't quote me on that. I don't think it's a rule
More or less the opposite actually.

Larger species simply didn't need dorsal fins anymore, as we see in whales.
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magpiealamode
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No good hero is a one-trick phony.

Well I don't think that's exactly a rule either. After some cursory research my best guess is that the most basal forms lacked dorsal fins, later taxa evolved them them, but some of the bigger forms lost them again. I'm no icthyosaur expert but that seems quite parsimonious to me and it follows general guidelines we've seen in aquatic forms.
Edited by magpiealamode, Jan 11 2018, 09:24 PM.
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Incinerox
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Āeksiot Zaldrīzoti

Also worth noting that the biggest ichthyosaurs (by quite some margin) are also quite basal too...
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magpiealamode
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No good hero is a one-trick phony.

Why are South Africa and Russia so popular with Permian fossils? It seems to me that those two areas yield fossils from the Permian far more than any other area on Earth.
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Acinonyx Jubatus
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magpiealamode
Jan 13 2018, 09:00 PM
Why are South Africa and Russia so popular with Permian fossils? It seems to me that those two areas yield fossils from the Permian far more than any other area on Earth.
That's because that's where the major fossil sits for the middle and late Permian are located. There's smaller sites in South America, Antarctica, China, North America and Madagascar, among others, but they don't produce the kinds of megafauna that Siberia and the Karoo are famed for- either because they're from marine deposits, or else there's some kind of bias that prevents larger fossils from being preserved and/or collected.
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Incinerox
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Āeksiot Zaldrīzoti

The Karoo supergroup spans from the Carboniferous to the early Jurassic, so at least in South Africa, there's LOTS to be found, and it's not just Permian. It just so happens that it has a fossil record spanning the entirety of the Permian in that region. More fossil beds for a particular time, more fossils to be found.

I guess why it covers that time span, as opposed to, say, the Cretaceous, is a bit to do with tectonic upheaval, a bit of erosion and a bit of luck. Just like for every other fossil bed everywhere else.

Also worth noting for Russia's fossil finds: Russia is HUGE, and most of it is completely unexplored. The Cretaceous beds which are proving to be quite fruitful are on the other side of the country, about 5000km away in the Amur region.

But yeah, the same question could be asked for any continent for any strata: Why does Scotland have good Carboniferous beds? Why does America have such a complete Cretaceous fossil record? The list goes on.
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54godamora
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question: would any extinct animal mainly carnivorous ones be able to smell smoke and identify where it would be? im not asking if they could identify it based on smell but could they detect the smell of smoke?
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Acinonyx Jubatus
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54godamora
Jan 14 2018, 04:29 PM
question: would any extinct animal mainly carnivorous ones be able to smell smoke and identify where it would be? im not asking if they could identify it based on smell but could they detect the smell of smoke?
Almost certainly. In case you haven't noticed, smoke has a very strong scent, even to us humans who have really pathetic noses. The ability to use scent to locate prey is pretty much universal among scent-based predators like canids, sharks, snakes, mustelids, and probably large tyrannosaurs; and fire is a common enough element in most ecosystems that the ability to detect and identify smoke (and the direction it's coming from) would be beneficial.
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