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| Extinct Animal Questions | |
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| Topic Started: Nov 26 2013, 10:24 PM (193,441 Views) | |
| stargatedalek | Nov 17 2014, 04:39 PM Post #796 |
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I'm not slow! That's just my moe!
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in select cases size is a perfectly valid reason to loose integument, not with things like large theropods, but how do you expect a brachiosaurus or stegosaurus to groom itself? as some members grew larger and less able to groom themselves it makes sense they would loose soft integument this makes a great deal of sense for things like sauropods, stegosauria, and ceratopsians and I seem to recall a theory that some prosauropods may have been semi aquatic (don't quote me on this), perhaps that could draw a parallel to modern (nearly) hairless mammals the only evidence that doesn't make sense with soft integument being basal to ornithodira would be the few scaled saurischians we have, but I see no reason to assume they weren't the abnormality amongst the group as a whole (of course there's no reason to assume they were, but they are hardly convincing evidence on their own) to sum up, I believe soft integument was basal to ornithodira and that sauropods and the larger members of ornithischia lost it due to their body shapes, with a parallel perhaps being true of some saurischians also but there's just not enough evidence to claim that this theory is wright or wrong, thus its still that, a theory, as is the contrary idea of soft integument evolving several times independently, neither is objectively correct or incorrect (yet) and so either assertion is relatively valid *edit* feathers can indeed grow in between scales, some species of owls show this, but to even greater effect would be the breeds of chicken and pigeon with this trait since the trait was specifically bred rather than occurring naturally, its possible to see the process at work, we can see through generations feathers forming between (not instead of) the scales on pigeon feet Edited by stargatedalek, Nov 17 2014, 04:44 PM.
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Nov 17 2014, 04:45 PM Post #797 |
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The Ectotherm
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Thing is, again 3D fossils almost never make feathers. So most scale impressions are moot. Then there's that feathers and scales preserve under different conditions (look at Scipionyx). Also, I must nitpick feathers are not known from Ornithopoda. Kulindadromeus was basal to Cerapoda. That also fails to explain Heterodontosaurs, or that Sciurumimus and Juravenator are probably basal to Coelurosauria (SVP abstracts). Lastly, this means we have three very similar structures evolving three times in ornithodira. RE Ammonites: Haven't got an answer yet, but y best guess is that the CTM hit them very hard (and it would, as it hit aquatic life much harder), and never recovered for some reason. Why is beyond me. They'd recovered form whatever nature hit them with before. One question leads into anther, and I'm not very sure about my first answer either... edit (ninja'd):Stargatedalek, that is indeed a good point I'd not thought of (although dromaeosaur tails might be of note here.). I think I've heard that about primitive sauropodomorphs at one point to, but I think it's been confidently dismissed as unlikely at best. Edited by Myotragus, Nov 17 2014, 04:48 PM.
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| stargatedalek | Nov 17 2014, 05:02 PM Post #798 |
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I'm not slow! That's just my moe!
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dromaeosaur tails were still relatively flexible, and more importantly so were their necks and for ammonites, I think the plankton die-off theory makes a lot of sense, less sun and rapidly changing water quality would have a huge impact on plankton populations, and as such ammonite larva, it still doesn't explain why things like lobsters are still around and ammonites aren't, but it could be that (like the dinosaurs) they were already beginning to dwindle in diversity, and thus the whole group was at higher risk |
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Nov 17 2014, 05:10 PM Post #799 |
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The Ectotherm
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They were chalk full of tendons. So quite stiff. Although yes, still flexible enough, I do wonder whether they could reach a fan on the end. |
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| CyborgIguana | Nov 17 2014, 05:12 PM Post #800 |
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Also remember that a lot of dinosaurs had scutes and osteoderms that are hard to visualize (at least for me) as co-existing with feathers. |
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Nov 17 2014, 05:28 PM Post #801 |
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![]() Easily.
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| stargatedalek | Nov 17 2014, 05:30 PM Post #802 |
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I'm not slow! That's just my moe!
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personally I don't find that hard to visualize at least no harder to visualize than the large broad scales of chicken feet *ninja'd by Flish* Edited by stargatedalek, Nov 17 2014, 05:31 PM.
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Nov 17 2014, 05:39 PM Post #803 |
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The Ectotherm
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Well, condors do it and that would look impossible to the naked eye (never mind terratorns...), so I guess they got about it somehow. |
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| CyborgIguana | Nov 17 2014, 07:21 PM Post #804 |
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I still can't really imagine things like ankylosaurs or Carnotaurus being feathered, and I will remain convinced that they were scaly until I see some concrete evidence suggesting otherwise, but I admit that you two do bring up some good points.
Edited by CyborgIguana, Nov 17 2014, 07:23 PM.
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| stargatedalek | Nov 17 2014, 07:44 PM Post #805 |
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I'm not slow! That's just my moe!
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don't forget, the "non armored" areas of ankylosaurs are still somewhat of a mystery |
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| CyborgIguana | Nov 17 2014, 07:50 PM Post #806 |
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That's true, and I suppose it's not that difficult to imagine feathers growing around the armour. I still think Carnotaurus was scaly though, since what we have of it (which is quite a lot) shows entirely scales. Scales in birds today are restricted to the feet usually, so it's relatively easy for feathers to grow around them when necessary. It would be more difficult IMO for an animal that was almost entirely scaly to have soft integument. |
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Nov 17 2014, 07:53 PM Post #807 |
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The Ectotherm
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I think they're feathered, but I won't dismiss scales in certain groups. |
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| CyborgIguana | Nov 17 2014, 07:56 PM Post #808 |
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Note that I have nothing against these animals being feathered, I'd just prefer to stick to what we know from the fossils, at least for now. |
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| Incinerox | Nov 17 2014, 10:10 PM Post #809 |
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Āeksiot Zaldrīzoti
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Size is less a factor and probably more their physical shape. But I agree with you here. Also the idea that prosauropods may have been semiaquatic is extremely unlikely. To my knowledge, none have shown any kind of adaptations for such a lifestyle. Also can I just point out this word regarding scaled saurischians: "Few". Now, assuming you actually follow the rules of paleontological science, cladistics and phylogenetic bracketing, the "few" saurischians we can safely bet were scaly turns into "everything outside coelurosauria", which is what I made a really big point of in my last big post. Good to see people paid attention to that one. Good to see you also paid attention to the many posts that stated that pterosaur fluff, ornithischian fluff and theropod fluff were actually different structurally. If you consider that each of these is in turn different from mammal fur as well as each other, mammal fluff evolving in a completely different line of tetrapods, it doesn't actually become much of a stretch to assume that animals that shared similar base genes could repeat similar traits given the time. The point I've been making several times in this arc of the topic discussion is that according to the rules of phylogenetic bracketing, we kinda have to assume that the majority of saurischians were scaly and that the most likely integument for the basal ornithodiran was most likely scales. Credit is due where it's due though, I did manage to confirm that you are correct on filamentous integument growing between scales: ![]() I had it in my mind you were referring to Snowy Owls, and I thought they didn't actually have scaled feet because of the presence of feathers but there ya go. But there is still a problem. The problem with this is that the scales on theropod feet are structurally different again from the standard mosaic/scuted scales seen in Carnotaurus, Allosaurus, all known sauropod skin and the big derived ornithischians, which are more akin to the bog standard scales you see in most reptiles anyway. So while you could have fine filaments growing between the scales of Kulindadromeus's feet, or even those of Tyrannosaurus's big, heavy plated feet, you won't see them growing in early theropods, thyreophorans, iguanodonts or ceratopsians. Unless you wish to draw Carnotaurus essentially wearing inbuilt Ugg boots. But that's unlikely AND silly. But yeah, we lack enough data to say with certainty what every species' integument was. So bla bla no right or wrong answer bla bla reasonable hypotheses bla bla bla. But that's why we establish rules based on what we can observe. And what we observe is that related species are more likely to share physical traits. And that if we wish to fill a gap in the knowledge of one species, we turn to the nearest available options. And that's why we stick with phylogenetic bracketing. We can temporarily fill in gaps with the least required assumptions that way. And it bloody annoys me when people decide to do the opposite because "there's no concrete evidence suggesting otherwise". It's like them saying Bigfoot might exist because we can't prove it never did at all ever.
Well obviously scales are more likely to fossilise than feathers in 3D preservations, simply because they're more robust structures which can't be plucked, shed or washed off post mortem. But you can tell which kind of scales on which species may allow for feather growth between them, and which can't. Mosaic scales in iguanodontians or Carnotaurus can't while the small, tiny rounded ones on raptor feet certainly CAN. More importantly, scales and fully plumed feathers or dense fuzzy integument are indeed mutually exclusive. Especially for plumed feathers of maniraptorans. You'll find that the skin under them is all leathery and almost pimply and, key word here, scaleless. A bit like the undersides and throats of tyrannosaurids, which in life would've appeared very elephantine in nature. Heterodontosaurs probably shares integument form with the likes of Kulindadromeus. As for Juravenator and Sciurumimus, they're probably compsognathids. If not, they're probably near the origins of the coelurosaurs, not baby goddamn megalosaurs like they were originally hyped up to be (sorry to disappoint). To sum up: 1) Lrn2PhylogeneticalBracketing. 2) Certain scales can allow for filamentous growth, and some can't. 3) Lrn2PhylogeneticalBracketing. 4) For more information, please see my initial rants on "FUZZ ALL THE THINGS" in either this topic, or the "Things that annoy you about Paleontology" topic. I'd like to make a special note: I swear I read something about the possibility of ankylosaurs being fluffed in the unarmoured areas. So tell me, where exactly do you plan to put fuzz when we know them to have bigass plates on their backs and big, heavy, mosaic scales and scutes covering basically everything down to its forearms and just above its belly?
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| CyborgIguana | Nov 18 2014, 06:13 AM Post #810 |
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I wasn't aware we had any evidence of the integument of Allosaurus. Do you have a source for this? I'm not questioning you, just curious. |
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