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Extinct Animal Questions
Topic Started: Nov 26 2013, 10:24 PM (193,442 Views)
Incinerox
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Āeksiot Zaldrīzoti

Kulindadromeus had scales AND fluff, yes. But they were distinctly separated. The neck and body had short dense fur-like fluff. The upper arms and lower legs had a different kind of shaggier fluff. The forearms and feet had typically bird like scales (small, round etc.). The tail was weird in having large, rectangular scales.

http://cdn4.sci-news.com/images/enlarge/image_2079e-Kulindadromeus-zabaikalicus.jpg

This is pretty accurate.

The whole hype was that it showed that a dinosaur could significant amounts of scales AND fluff on the same species, and that integument could be so variable in an individual dinosaur.

But scales and feathers do not exist on the same surface. It doesn't work like pangolin scales.
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Posted Image Guat
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Wait Sauropod scales aren't anything like those on birds?
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CyborgIguana
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The fact is that dinosaurs were an astonishingly diverse group of animals, and there's little reason to assume that absolutely all of them were fluffy.
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Incinerox
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Āeksiot Zaldrīzoti

I've made many a rant making that exact point here. Two of them in particular posted over a month ago come to mind.

I'm glad people seem to agree.
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Myotragus
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The Ectotherm

Firstly, there isn't really any extant creature with extensive feathers and scales, so that point's a little redundant.

True, but how many actually hairless mammals or actually scaleless squamates can you name?
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Incinerox
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Āeksiot Zaldrīzoti

You won't find scaleless squamates at all.

As for hairless mammals, things like cetaceans and manatees come to mind. Some of the larger rhino species I THINK, hippos too I THINK. Naked mole-rats too aside from whiskers.
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Furka
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Warthogs have lost a good amount of hair too, compared to their relatives.
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Yi Qi
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Incinerox
Nov 17 2014, 03:28 PM
As for hairless mammals, things like cetaceans and manatees come to mind. Some of the larger rhino species I THINK, hippos too I THINK. Naked mole-rats too aside from whiskers.
They all have some sort of minor fur, even baby cetaceans have whiskers, which they loose as they grow, besides they all follow a pattern, they're either aquatic, had aquatic ancestors or are exclusively underground dwellers.

that and humans who lost fur primarily because of fire, clothes and lice, but thats a subject for another topic.

but the point you mentioned stands.

Scales and feathers can't coexist in the same species mainly because a feather is nothing more than a highly derived scale, they are, genetically and embriologically the same structure, thus they can't just grow over the other, that'd be like hair growing over fingernails.
Edited by Yi Qi, Nov 17 2014, 03:43 PM.
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CyborgIguana
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Not that I disagree with you, but don't owls have scaly feet with feathers growing over or between them?
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Myotragus
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The Ectotherm

Cetaceans and Sirenians are aquatic, which is the most likely explanation for hair loss. Hippos are semi-aquatic. Naked mole rats are naked mole rats, enough said. So that's one large terrestrial mammal without them. And fuzz goes back to pterosaurs at least... so it seems likely they were very widespread in ornithodira.

I agree, which I why I never said on top of scales; I said between them (as have others earlier, I take no credit). So it's certainly anatomically possible.

You also need a reason why they'd lose fuzz. Unlike hair, it doesn't just warm, but can cool a creature as well, so temperature isn't a reason. So what motive would evolution possibly have to lose them?
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CyborgIguana
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No one ever said they lost fuzz, it's entirely possible that some dinosaur lineages never evolved it in the first place.
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Ulquiorra
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CyborgIguana
Nov 17 2014, 03:49 PM
Not that I disagree with you, but don't owls have scaly feet with feathers growing over or between them?
If I remember correctly, the scales on birds legs/feet are modified feathers.
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Myotragus
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The Ectotherm

It currently looks like it's basal to ornithodira, so I don't see how they would've not evolved it they had it ancestrally.
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CyborgIguana
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Except that (as previously pointed out), feathers are just highly modified scales anyway. So they wouldn't be LOSING anything, just modifying what they already have to respond to a variety of environmental pressures.
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Yi Qi
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CyborgIguana
Nov 17 2014, 03:49 PM
Not that I disagree with you, but don't owls have scaly feet with feathers growing over or between them?
yes, but the feathers grow inbetween the scales, not over them.

@Myotragus: The reasons for an animal to loose fur are

1- Aquatic life (the case of Hippos,sirenians and cetaceans and the reason rhinos and elephants are bald, mainly because they had aquatic ancestors, which also explains their internal testicles, and even then, whenever things get A LITTLE colder they start sprouting fur all over again, mammoths and wooly rhinos are just the more extreme examples, you don't need that much cold, rainy southeast asian rainforests http://upload.wikimedia.org/wikipedia/commons/f/fa/SumatranRhino3_CincinnatiZoo.jpg and the rather sunny but temperate prairies of sicily and malta http://scienceblogs.com/tetrapodzoology/wp-content/blogs.dir/471/files/2012/05/i-24afe03f5f7d97ff057d6d997dcc2e0e-Rekhmire-tomb-elephant-closeup-Jan-2011.jpg http://fc03.deviantart.net/fs70/i/2010/194/7/b/Sicilian_Dwarf_Elephant_by_Eurwentala.jpg are already enough ).

2- An EXCLUSIVELY subterranean lifestyle (the case of mole rats)


3- The animal starts sitting around campfires at night AT the exact same time its starts making artificial coats, aswell as being evolutionarily pressioned by lice infestations to loose hair (our case)

Size is absolutely NO argument for the loss of animal integument whatsoever, you see, we know mylodontids often lived in arid climates and were the same size range as most elephants .

This is what their skin impressions look like:

http://upload.wikimedia.org/wikipedia/commons/f/f2/Mylodon_fur.jpg

infact thats actually the norm among sloths, granted xenarthrans have slower metabolisms than most animals, nevertheless this would be a massive warm blooded creature still.

The only sloths that may have possibly lost integument are Thalassocnids and some river dwellling megalonychids, but for those check point 1.

now dinosaurs are a different case, from all we can gather feathers appeared on coelurosauria and got more complex the most the group derived

everything else sans basal ornithopods show scales, and this "ornithopod fur" is likely an evolutionary
excentricity that evolved independently in heterodontosaurs and some ornithischians, while the rest of them stayed scaly.


Edited by Yi Qi, Nov 17 2014, 04:31 PM.
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