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Post by spinodontosaurus on Aug 19, 2015 4:56:54 GMT 5
Oops, the text colour made me miss the hyper link. I do agree with you too.
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Post by theropod on Sept 26, 2015 14:22:38 GMT 5
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Post by theropod on Mar 3, 2016 1:01:55 GMT 5
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Post by Deleted on Mar 3, 2016 1:36:00 GMT 5
Except that Tyrannosaurus itself preserves birdlike skin, and tyrannosauroids have been found with feather impressions. Same goes for all of Coelurosauria. The same cannot be said for ceratosaurs, or, well, anything that isn't a coelurosaur. You can't just fluff up everything like a coelurosaur, that's akin to putting mammaries on Edaphosaurus. And as for Tianyulong/Kulindadromeus/etc...here's something from the 2013 SVP: "DINOSAUR INTEGUMENT: WHAT DO WE REALLY KNOW?
Osteoderms and scaly skin impressions are historically well known in non-avian dinosaurs. Recent discoveries have demonstrated that in addition to these structures,
many dinosaur taxa possessed other integumentary features, including a range of "quills", filaments, and feathers in non-avian theropods and ornithischians. Feathers and their homologs are commonly regarded as a synapomorphy of either coelurosaurian or tetanuran theropods, but some authors have gone further, using the presence of ornithischian feather-like structures to suggest that these structures are plesiomorphic for Dinosauria. This inference has wide-ranging implications for dinosaur biology and evolution.
However, to date, no studies have attempted to assess rigorously the evolution of dinosaur integumentary structures within a broad phylogenetic context. We compiled a complete database of all epidermal integumentary structures reported in dinosaurs, by major body region, in order to investigate the origin of feather homologs and the evolution of integumentary structures in the clade. Scales are definitively present in virtually all major ornithischian clades. This, and the presence of extensive armour in thyreophorans suggests that genasaurian skins were primitively scaly. Similarly, sauropodomorphs lack evidence for anything other than scales or osteoderms. Fitch optimization of integument types on dinosaur phylogenies shows that there is no unequivocal support for inferring a deep origin of feather-like structures, a result supported by maximum likelihood ancestral state reconstructions for these characters. The structures in Tianyulong and Psittacosaurus are best regarded as autapomorphic integumentary modifications, and there is currently no strong evidence that these features are feather homologs. Further work on the chemical composition of these structures, and those in several non-coelurosaurian theropods, is needed. Although ornithodirans exhibit a range of integumentary novelties that may be related to the origin of feathers, theropods are currently the only dinosaurs that display unequivocal evidence of feathers and their direct homologs." |
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Post by theropod on Mar 3, 2016 2:07:36 GMT 5
Don’t forget what was already addressed about the follow-up study by the same authors.
The thing is that there is no strong evidence that they aren’t feather homologues either, yet Barrett and Evans seem eager to assume non-homology as some sort of default when it isn’t.
Also it’s too easy to confuse factual knowledge (what Barrett & Evans talk about in the conference abstract) with parsimonious inference (what predicts the presence of feathers on the majority of dinosaurs that are commonly acknowledged to have been feathered, as well as on many that aren’t).
And Kulindadromeus wasn’t even known back then, while it’s certainly relevant to the discussion, with its integument being the most diverse of any ornitischian.
And yes, there are other non-coelurosaurs with direct evidence of feathers; Sciurumimus and Concavenator. Of course you can extend the same claims to them; there is no unequivocal evidence that their integumentary filaments are homologues of coelurosaur feathers. That doesn’t make it probable, or relevant for that matter.
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Post by Deleted on Mar 3, 2016 7:24:27 GMT 5
Don’t forget what was already addressed about the follow-up study by the same authors. The thing is that there is no strong evidence that they aren’t feather homologues either, yet Barrett and Evans seem eager to assume non-homology as some sort of default when it isn’t. Also it’s too easy to confuse factual knowledge (what Barrett & Evans talk about in the conference abstract) with parsimonious inference (what predicts the presence of feathers on the majority of dinosaurs that are commonly acknowledged to have been feathered, as well as on many that aren’t). And Kulindadromeus wasn’t even known back then, while it’s certainly relevant to the discussion, with its integument being the most diverse of any ornitischian. And yes, there are other non-coelurosaurs with direct evidence of feathers; Sciurumimus and Concavenator. Of course you can extend the same claims to them; there is no unequivocal evidence that their integumentary filaments are homologues of coelurosaur feathers. That doesn’t make it probable, or relevant for that matter. Parsimonious inference suggests the presence of feathers only on Coelurosauria, with other dinosaurs just having the quills that are the precursors of both feathers and Tianyulong/Kulindadromeus fuzz. They're probably homologous, (like how bat and bird wings are homologous, both are derived arms), but you can't really put coelurosaur feathers on an abelisaur like what the palaeoartist who made the life reconstruction of the new Kem Kem abelisaur did, just because non-theropods have been found with structures that simply share a common ancestry with coelurosaurian feathers. Some quills sticking out, similar to the conditions found in Concavenator and Psittacosaurus, could probably be present in some abelisaurs, but feathers as if you've ripped them off a basal coelurosaur or a tyrannosaur, put on an abelisaur? Sciurumimus is a coelurosaur. Concavenator's filaments are probably just simple quills, carnosaurs don't have anything that suggests anything as derived as coelurosaur-like feathers. |
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Post by theropod on Mar 3, 2016 15:56:55 GMT 5
What characterises feathers "ripped off a basal coelurosaur or a tyrannosaur" when compared to "quills"? And if "quills" can evolve into a similar body covering (independently, in your opinion) in ornithischians, why should they not be able to do the same in ceratosaurs? What relevance is how you call it, if its evidently capable of doing what you say it shouldn’t do?
This feather/quill distinction is arbitrary (but I’m repeating myself…), there’s nothing that sets apart certain forms of coelurosaur integument from the morphologically very similar integument of non-coelurosaurs. By your own nomenclature, the integument of Beipiaosaurus, Sinosauropteryx, Dilong or Sciurumimus qualifies as "quills", just like the integument of Psittacosaurus, Tianyulong or pterosaurs. And yes, the similarities between these filaments have been noted repeatedly in the relevant publications.
We can be pretty confident that at least the former four are homologues of the filaments of maniraptorans, including the more complex ones. So why not make that clear and call all of them feathers (respectively, stage-1-feathers and higher-stage-feathers)?
In short, there’s no reason "quills" can’t look like portrayed in the artwork in question, looking too much like "feathers" isn’t a point of criticism since there’s no actual difference between quills and the feathers they look like to begin with. They look alike because they are the same thing, you just call them differently based on what animal has them.
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Post by Infinity Blade on Jun 7, 2017 9:50:06 GMT 5
So, apparently, a recent study about tyrannosaur skin has been published, and it paints a picture of mostly scaly animals. Feathers, if present, were supposedly only on the dorsal surfaces of the animals. From looking at the abdomen, chest, pelvis, neck, and tail, there were just scales. Here's a couple news reports about it. www.washingtonpost.com/news/speaking-of-science/wp/2017/06/06/tyrannosaurus-rex-had-scaly-skin-and-wasnt-covered-in-feathers-a-new-study-says/?utm_term=.03d35e702a9bnews.nationalgeographic.com/2017/06/tyrannosaurus-rex-skin-fossils-feathers-scales-science/It was published in Biology Letters. I wanted to take a look at it to see just how extensive this scaly integument really was and how they address the supposed plucked feather skin people have brought up on the Internet (if at all), but frustratingly, I was denied access to anything from the study. Not even so much as the measly abstract, nothing (  ). |
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Post by spartan on Jun 7, 2017 15:10:05 GMT 5
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Post by Infinity Blade on Jun 7, 2017 17:23:33 GMT 5
Oh wow...maybe I just tried looking for it too early.
Anyway, yes!
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Post by Infinity Blade on Jun 8, 2017 0:54:46 GMT 5
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Post by theropod on Mar 21, 2019 20:32:20 GMT 5
^Thanks for that insight theropod, and great to see you posting. Was the Yutyrannus considered to be fully covered, or was its coat bare in some places? And what do you think as to if/how much T-Rex was feathered? According to Xu et al., and I’m strongly inclined to agree with them, the fossil material of Yutyrannus suggests an extensive coat of feathers (i.e. similar to birds and other derived Maniraptorans, and to its relative Dilong). The feathers in the fossils are patchy, but that is a preservational artifact also found in birds. That all three specimens preserve feathers in different regions (distal tail in one, pelvis and pes in the second, neck and forelimb in the last one) suggest a wide distribution over the body. Where they are preserved, the feathers are also large (up to 20cm) and dense, so densely packed their individual structure was not discernable to the describers. That to me suggests they served for insulation, not primarily display, although a patchy distribution and display function can not be totally ruled out. I don’t have a strong opinion on how much T. rex was feathered, except that I find it unlikely feathers would have been completely lost on account of complete loss of integumentary appendages being essentially unprecedented among vertebrates. We know T. rex had some patches of scaly skin devoid of large feathers, mostly on the tail and ventral side. That remains all we know. T. rex is generally considered to have lived in "warm climates", however it did have a significant latitudinal range from Canada to Mexico, and it is entirely possible that the climate and its integument varied throughout that range. For a tyrannosaur that lived in an arctic setting, like Nanuqsaurus, I’d consider everything but a rather dense coat of feathers to be a ridiculous suggestion at this point, at least unless someone can credibly suggest that similar-sized (and more compact, i.e. geometrically more favourable) mammoths living in similar climates also lacked such a coat (which totally runs against all available fossil evidence). Xu, X., Wang, K., Zhang, K., Ma, Q., Xing, L., Sullivan, C., Hu, D., Cheng, S. and Wang, S. 2012. A gigantic feathered dinosaur from the Lower Cretaceous of China. Nature 484 (7392): 92. |
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Post by creature386 on Mar 21, 2019 22:41:26 GMT 5
Creature386 and Theropod. You both mentioned fur as well as feathers. Is there reason to believe dino feathers may have been different than bird feathers and more closely akin to mammal fur? I'm no expert on this, but I had thought from a few articles I read on fossilized dino "feathers" that they were quite similar to modern feathers. I mentioned fur because there are no recent birds that can rival Utahraptor's size. My point was more ecological than phylogenetic. Plus, featherless birds are harder to find. Dromaeosaurids had pennaceous feathers, i.e. their feathers were much more similar to those of birds than mammal fur:  |
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Post by dinosauria101 on Mar 21, 2019 23:39:45 GMT 5
Just so everybody knows why I said what I did in Polar bear vs Utahraptor:
In retrospect, Carnivora was probably feeding me garbage info, and now I'd be happy to take in the truth
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Post by theropod on Mar 21, 2019 23:42:14 GMT 5
elosha11: We mentioned fur because the physiological argument that sometimes comes up in favour for or against feathers (insulation and surface-area/volume problem), equally applies to hair. This argument essentially based on mammals to begin with, because there are no extant birds in a size range where they could be expected to reduce their feathers, but there are mammals that large (elephants, rhinos, hippos). Very roughly speaking, we only see reduction of the integument in mammals that are well above a ton, quite a bit larger than Utahraptor, and only in animals that are living in very hot climates and/or aquatic. In addition, none of those mammals have an air sac system, which contributes to shedding excess body heat in birds, and presumbly did the same in other dinosaurs, notably contributing to allowing sauropods to reach sizes far larger than terrestrial mammals ever could. Whether dinosaur feathers were similar to hair depends on the dinosaur. Most Maniraptorans tend have fairly derived feathers, and Utahraptor is a derived maniraptoran, much more closely related to birds than to most other dinosaurs. It’s just that there are no (extant) half-tonne birds out there to compare it to, so I used Yutyrannus as a comparison: it’s a taxon where we can be certain that it was feathered, unlike other bird-line archosaurs that size. Intriguingly I’ve never read any doubts anywhere about Dromornis or Vorombe being feathered, even though those were similar in mass to Utahraptor and lived in warm climates. That being said, I don’t think there are any actual feathers preserved for either taxon, but I’d be extremely surprised if they turned out to have been naked.
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