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February 4, 2012
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This is the long awaited post for my point of view on this question. I finally finished it inspired by the recent post of the deviantartist karkajou1993.

EDIT: Now there is an updated and corrected blog post of this entry! Check it out: ktboundary-smnt2000.blogspot.i…

EDIT 2: the blog version has been updated with some new infos after an interesting post by Matt Martyniuk (link: dinogoss.blogspot.it/2013/09/y…). Go to read it!

1 - The ancestor of Dinosauria is feathered. Now we have proof that feathers were present both in theropods (Sinosauropteryx, Epidexipteryx, Velociraptor, Beipiaosaurus, Dilong, Anchiornis, etc..) other than ornithischians (Tianyulong, Psittacosaurus). Even if we cant 'rule out that the two groups of animals have developed these structures independently, it is extremely likely that the common ancestor of both possessed 'em. As it is unlikely that ungulates and felines have developed fur each independently from a hairless common ancestor, at the same time we can say that if Rahonavis and Heterodontosaurus were feathered is because even their "ancestor" was. Further evidence in support of this are pterosaurs's pycnofibres. Pycnofibre is nothing else but a bizarre word for structures most likely homologous to the proto-feathers of the dinosaurs. As the ancestor of Dinosauria is the same one of Pterosauria and since both orders are feathered, this archaic animal and all his descendants MUST be feathered.
2 - The polar dinosaurs MUST be feathered dinosaurs, then the categories of animals to which belong MUST be also feathered. Numerous data tell us that all dinosaurs were warm blooded, from gigantic sauropods to tiny Scansoriopterygids. Since every endothermic tetrapod (excluding cetaceans) is covered by thermoregulatory structures in temperate or cold climates, this reasoning can be applied to dinosaurs as well. Then the members of Neovenatoridae, Troodontidae, Dromaeosauridae, Tyrannosauridae (aka Deinodontidae), Ceratopsidae, ornithischian dinosaurs considered as Hypsilophodontidae, Rhabdodontidae, Spinosauridae, etc. are feathered, at least in temperate climates. This leads us to conclude that the ancestor of each group must also be feathered, and also its ancestor and so on. This brings us back to point 1.
3 - At different temperatures, different thickness (but NEVER TOTAL EXCLUSION) of plumage. Derivation of point 2. We said that Hadrosauridae and Ceratopsidae have feathers. But we have the fossil fragments of skin belongin' to both groups (Edmontosaurus, Triceratops) that indicate the presence of scales. So is step 2 wrong? Not necessarily. Just think of today's elephants that live in hot climates (and they still have some hair) and their relatives, the mammoths provided by a thick woolly coat. Or you can even mention rhinoceros and woolly rhinos, warthogs and boars, etc.. From this we can infer that dinosaurs possessed coverings more or less dense depending on climate and latitude. Moreover, the presence of scales does not exclude definitively the presence of proto-feathers small and sparse like the hairs of the current pachyderms. Further confirmation of this point is the skin of the afore-mentioned Triceratops: it's scaly but it presents quill knobs similar to those of his distant relative Psittacosaurus.
4 - Different weights, Different plumages. Derivation of points 2 and 3. Another factor to consider is the weight. In today's warm-blooded animals, in  the EQUATORIAL AREA, species generally weighing more than a ton or a ton and a half have a sparse covering of feathers / fur. Similarly, the dinosaurs of EQUATORIAL CLIMATES that weigh over that threshold should not be heavily coated by integumentary structures. Proof: the small dog-sized Tianyulong has a thick plumage, while Corythosaurus, heavy as a rhino, is "hairless".
5 - If you are a carnivore like T. Rex, you are feathered. Derivation of point 4. So far we have only mentioned large herbivores  big as elephants, but what about theropods of comparable size? Are they also to be considered scaly? Here comes the issue of metabolism. Citing Tyrannosaurus just to make an example (but if you want, you can do the following comparison with any other giant carnivorous dinosaur), this saurischian, despite weights as an African elephant, consumes an amount of energy equal to that of a 1-ton bear. This is because, although there may be a several tons herbivore with a metabolism more or less comparable to those of elephants, a giant carnivore of the weight of T. Rex (or heavier) can exist only in marine environments. Since Tyrannosauridae (and other large theropods of similar tonnage) do not live in oceans, since it seems that no land predator covered in fur actually lose his fur around 1588-1749 kg (like the bear Arctotherium) and since a carnivorous dinosaur that weighs 6 tons generates an amount of heat similar to that of a 1-ton mammal predator, there is no reason that big theropods must loose plumage. EDIT (April 2012): we've got the final proof of giant feathered theropods! Yutyrannus hauli (Xu et. al., 2012) is a giant, maybe Baryonyx sized tyrannosauroid from the Lower Cretaceous of China and it shows the unequivocal proof that big tetanurans had protofeathers. It's not very surprising if you agreed with the many points of mine, but it sure is a pleasant surprise.
6 - Not the whole body is feathered in the same way. When it comes to feathered or furry animals, we generally thought to the tegumentary thickness of the Star Wars's Chewbacca. We must however remember that the length and distribution of these coatings vary not only from species to species, but also from different areas of the animal's body as well. The hairs of the muzzle of some bovids are very short, while in other parts like the chest or shoulders may be long and thick (like in the bison). To also cite birds, vultures have thin feathers on the neck against sunburn, while having a more dense plumage on the body. Among suids and some other related species, some have fur (wild boars, peccaries) while others can be considered almost hairless (pigs, babirusa). Such disparities are also present in many other animals: rodents, insectivores, primates, etc.. so, albeit the previous points are not incorrect (in fact, I think they are not), the feather / fur factor cannot be entirely understood and there may always be some exceptions. In the world of dinosaurs, an example of this exception are Ceratosaurus and Carnotaurus. But you must also remind that exceptions are not the rule.

This post has been written not to impress or manipulate the minds of others or, even worse, indoctrinate forcibly what I think about it, but it is a plain statement that justifies the presence of feathers on my reconstructions of dinosaurs. When I'll put drawings of feathered prosauropods and carcharodontosaurids or whatever in my gallery, you now know that I have an outlandish explanation of why I have portraited 'em in that manner. I'm not absolutely saying that I'm an expert, I'm a genius while you're jerks, I'm smarter or other nonsense stufflike that. I just need to be understood. Or, if you prefer, pitied.
So avoid stupid, negative and quarrelsome comments. I do not need 'em, but most important of all, I do not want them. You want to insult, mock or make me change my mind for having expressed my idea? No thanks. As I do not want to do that to you, I ask you not to do it to me. I know, it's selfish and stupid, but this is my request. Then, critics must abstain.

I'm done with this. Good day to you all.

PS: Sorry for the bad english

  • Listening to: Sherlock Soundtrack
  • Reading: My entry
  • Watching: My sister's dog
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:iconlordofstamps:
LordOfstamps Featured By Owner Sep 23, 2014
Oh and one thing. Large polar dinosaurs could have kept warm with thick layers of fat like whales and walruses. 
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:iconsmnt2000:
Smnt2000 Featured By Owner Sep 24, 2014  Hobbyist Traditional Artist
Which are cetaceans and pinnipeds, respectively. There are no land polar hetherothermic tetrapods without fur or feathers. And many polar seals have fur - the presence of layers of fat is not an excuse for the absence of fur or feathers.
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:iconlordofstamps:
LordOfstamps Featured By Owner Sep 24, 2014
We have numerous skin impressions from Hadrosaurs. No feathers were found on them. So polar Hadrosaurs either migrated or kept warm with fat.
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:iconsmnt2000:
Smnt2000 Featured By Owner Sep 25, 2014  Hobbyist Traditional Artist
We don't have skin impressions of polar hadrosaurs and the known skin patches known belong to specimens which lived in temperate or hot climates. But that doesn't exclude the presence of feathers in polar species - think about the difference between a woolly mammoth and a common elephant.

Polar hadrosaurs were perennial residents (Chinsamy et al. 2012) so migration is not an option.

I still want to know if there is at least one species of terrestrial, endothermic tetrapod without fur or feathers in polar climates
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:iconlordofstamps:
LordOfstamps Featured By Owner Sep 25, 2014
But one known polar hadrosaur is Edmontosaurus which has skin impressions from it (no feathers).  If it was not migratory that only leaves keeping warm with a thick layer of fat.
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:iconsmnt2000:
Smnt2000 Featured By Owner Sep 26, 2014  Hobbyist Traditional Artist
We don't have any skin patches from the polar specimens of the genus Edmontosaurus, just from southern regions. This means that a coat of proto-feathers is still possible for these animals.
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:iconlordofstamps:
LordOfstamps Featured By Owner Sep 26, 2014
Hadrosaurs probably did not have feathers The fact that scaly skin was found in numerous hadrosaur species (Edmontosaurus, Saurolophus, Lambeosaurus, Corythosaurus, Gryposaurus, Parasaurolophus, and Brachylophosaurus) shows that feathers were not present in hadrosaurs.

If a polar Hadrosaur did have fuzz, then it probably isn't Edmontosaurus but a seperate Hadrosaur altoghter.
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:iconsmnt2000:
Smnt2000 Featured By Owner Oct 4, 2014  Hobbyist Traditional Artist
Dinosaur 'scales' could be feathers which arrested their development in their earliest stages: dinogoss.blogspot.pt/2013/09/y…

About the polar hadrosaur question you're probably, althought sometimes different species in the same genus show different pelage thickness (like in the suid babirusa, also known as pig deer)
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(1 Reply)
:iconlordofstamps:
LordOfstamps Featured By Owner Aug 15, 2014
Actually pterosaur pycnofibers are structurally different from protofeathers.  The current available impressions of pterosaur integuments are not like the "quills" found on many of the dinosaur specimens in the fossil record.They probably aren't homologous.
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:iconsmnt2000:
Smnt2000 Featured By Owner Aug 15, 2014  Hobbyist Traditional Artist
You're right noticing that and probably I should re-write that sentence. 
However, from Witton's book on pterosaurs (pg.51) : "New dinosaur discoveries reveal that feather-like or hairlike integuments may be more common to the group (Ornithodira) than previously recognized, so perhaps the idea of a completely fuzzy Ornithodira should not be ruled out just yet".
The main point I wanted to make is that 'fuzziness' might be a common trait  to all ornithodirans - some groups developed feathers (theropods and ornithischians) while others pycnofibres (pterosaurs).
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:iconlordofstamps:
LordOfstamps Featured By Owner Aug 15, 2014
Though I personally think the possibility that Ornithischians developed these structures independently can't be ruled out. I mean the structures on Psittacosaurus and Tianyulong are rigid quills, not soft protofeathers. They were probably used in display or possibly even defense (a possible forerunner to the armor of stegosaurs and ankylosaurs?) 
As for Kulindadromeus, the structures on it are unique, especially the ribbon-like stuff on it's legs.  As one guy on   Archosaur Musings pointed out

If the filamentous integument is comprised of extensions from scales, wouldn’t that suggest that these structures might not be homologous with feathers?

Maybe fuzzy integument emerged three times among ornithodirans.



Oh and there isn't really any proof of therapod feathers outside of Coelurosauria (Scirumimus was later revealed to be a Coelurosaur and the "quill knobs" on Concavenator's arms might just be  tendon attachment points because they are irregular;y spaced. Quill knobs are spaced evenly.)

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:iconsmnt2000:
Smnt2000 Featured By Owner Aug 16, 2014  Hobbyist Traditional Artist
I don't understand why they say that Psittacosaurus quills are rigid. They really aren't.
By looking at this picture for example (oficina.cienciaviva.pt/~pw011/…, we can se that they aren't even stiff, but curved, and I think that the real life appearance wouldn't be so different from a antelope's mane rather than the porcupine's quills. Beipiaosaurus, a fully feathered coelurosaur, had some real quill-like structures called EBFFs (2.bp.blogspot.com/_OVH5UC-R50w… which are the most simple feathers found, maybe even more basal than ornithischian 'quills'.
I seriously doubt that they are the tyreophorans' osteoderms forerunners since the two species you've cited aren't close relatives of that group.

Feathers may actually originate from dinosaur 'scales'. From DinoGoss.blogspot (link: dinogoss.blogspot.pt/2013/09/y…: "Reticula, often referred to as "tuberculate scales", are the bumpy structures on the plantar side of the foot. These are also, famously, the type of "scales" found in just about all non-feathered stem-bird skin impressions. And here's the kicker--these have very little to do with the "scales" of squamates or even crocodiles.
In modern birds, the reticula, unlike feathers or scutes, do not form from placodes. Unlike lizard scales, scuta, and feathers, they're made not of beta-keratin, but alpha-keratin (the same as mammalian hair and amphibian 'warts'). The reticulae do start with an overlying beta-keratin layer that is shed during development. While they don't form from placodes, they appear to be similar to the pre-placode stage of feather formation. Reticula apparently never morph into scales in nature (I suppose ptarmigans start with naked skin on their feet?), this can be induced in the lab. Dhouailly suggests that, given the weight of the developmental evidence, reticula appear to be feathers which are arrested in a very early stage of development.
You read that right--tuberculate "scales" are probably modified feathers! So, those fossilized hadrosaurid mummies covered in "scales"? It's possible or even likely that they had feathered ancestors, and evolved in such a way to stop the development of feathers early on, instead yielding a fine, pebbly skin covering derived from old feather genes."

You can find the original study here: www.ncbi.nlm.nih.gov/pmc/artic…

Kulindadromeus has feathers of the morphotype 1, 2 and 3, just like theropods. The really unique structures are the ribbon-like feathers on its legs, which are still a unique kind of feathers.
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:iconlordofstamps:
LordOfstamps Featured By Owner Aug 16, 2014
It is worth pointing out that the ones in Beipaiosaurus, the quills were flattened. The ones in Psittacosaurus and Tianyulong were round.


Actually it had a type 1 like structure, a type 3 like structure and the ribbon-like structure on it's legs (according to Wikipedia). A type 2 structure wasn't mentioned.
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:iconsmnt2000:
Smnt2000 Featured By Owner Aug 16, 2014  Hobbyist Traditional Artist
"It is worth pointing out that the ones in Beipaiosaurus, the quills were flattened. The ones in Psittacosaurus and Tianyulong were round"
What do you mean with flattened and round, precisely?

"Actually it had a type 1 like structure, a type 3 like structure and the ribbon-like structure on it's legs (according to Wikipedia). A type 2 structure wasn't mentioned"
Ops, my bad. I was sure that there was another morphotype of feathers. I should re-read the paper.
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:iconlordofstamps:
LordOfstamps Featured By Owner Aug 16, 2014
Look at the Wikipedia article on Tianyulong. It mentions that.
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:iconsmnt2000:
Smnt2000 Featured By Owner Aug 17, 2014  Hobbyist Traditional Artist
I've read it but I still don't understand. I'll read the full paper if it's available somewhere.

Citing Wikipedia once again: " Both the filaments of Tianyulong and the filaments of Beipiaosaurus were long, singular, and unbranched. In Beipiaosaurus, however, the filaments were flattened. InTianyulong, the filaments were round in cross section, and therefore closer in structure to the earliest forms of feathers predicted by developmental models".

Interesting fact, this from the supplementary information: "After the accepting of this manuscript, a new type of feather, the elongated broad
filamentous feathers (EBFFs), is reported in the therizinosaur theropod Beipiaosaurus. Both the filamentous integumentary structures in Tianyulong and the EBFFs in Beipiaosaurus are relatively long, singular and unbranched; however, the former has a circular cross-section, while the later is planar. EBFFs are more closer to the predicted most basal feather morphotype (stage I) than the composite feather structures in other nonavian theropods. Therefore, the similarities between the filamentous integumentary structures in Tianyulong and the EBFFs in Beipiaosaurus favor a homologous explanation for the filamentous integumentary structures in Tianyulong and feathers"
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(1 Reply)
:iconhellraptor:
Hellraptor Featured By Owner Apr 15, 2014  Hobbyist Digital Artist
would you say all dinosaurs exept sauropods,stegosaurs and ankylosaurs could have been featherd ? I thinks it highly possible.  i think hadrosaurs could have had feathers aswell since soem lived in colder regions like Edmontosurus so a insulation would been obvious. And also since many dinosaurs migrated from cold to warm areas, a warm insulated body would have helped them on the journey.
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:iconsmnt2000:
Smnt2000 Featured By Owner Apr 15, 2014  Hobbyist Traditional Artist
I think that feathers were the ancestral condition for all the members of Avemetatarsalia. Some species lost feathers while other kept them.
I'll have to re-write this post in a more serious way, but the main points will be the same.
The main difference is that I'll talk about dino skin with all Martyniuk and Dhouailly's considerations.
You can read more about it here: dinogoss.blogspot.pt/2013/09/y…
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:iconhellraptor:
Hellraptor Featured By Owner Apr 15, 2014  Hobbyist Digital Artist
Agreed, wonder how the first animal with feathers looked like and how old it is.

Okey, i will read it again when you have done so.
I read it, its an very intrestring article.
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:iconsmnt2000:
Smnt2000 Featured By Owner Apr 15, 2014  Hobbyist Traditional Artist
Thanks a lot ;)
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:iconhellraptor:
Hellraptor Featured By Owner Apr 16, 2014  Hobbyist Digital Artist
sure :)
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:icontheropod1:
theropod1 Featured By Owner Feb 9, 2014
Fully agreed!

Arctotherium probably wasn’t that heavy, check the description of this skeletal: blazze92.deviantart.com/art/Ar…
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:iconsmnt2000:
Smnt2000 Featured By Owner Feb 9, 2014  Hobbyist Traditional Artist
Well, this is intriguing. I'll do some research when I'll have the time ;)
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:icondynojackal19:
DYnoJackal19 Featured By Owner Dec 2, 2013

1 - Yes, you can; only theropods developed feathers. Cerapoda has quills, not feathers. And sauropods and

 ankylosaurs wouldn't need feathers (except as hatchlings).

2 - The polar theropods may have been feathered, and polar Cerapods would've had more quills covering their bodies,

 but ankylosaurs would've been blubbery and probably hunkered down. And sauropods were massive enough to not

 need feathers or blubber, for the most part.

3, 4, 5, 6 - Larger size eliminates the need for even moderate plumage.

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:iconsmnt2000:
Smnt2000 Featured By Owner Dec 3, 2013  Hobbyist Traditional Artist

1 - It is likely to consider ornithischian structures homologues to theropod feathers (and maybe even pycnofibres), and future fossils are going to confirm such a statement (Godefroit, P., Sinitsa, S., Dhouailly, D., Bolotsky, Y., Sizov, A. FEATHER-LIKE STRUCTURES AND SCALES IN A JURASSIC NEORNITHISCHIAN DINOSAUR FROM SIBERIA, 2014? ... From the abstract: simple filamentous feathers, as well as compound feather-like structures comparable to those in theropods, were widespread amongst the whole dinosaur clade). Also, I'm not saying (and I didn't even write such a thing) that adult sauropods or ankylosaurs were feathered, but instead that they most certainly evolved from a common feathered ancestor and that feathers are a common trait of Dinosauria.

2 - Okay then, give me an example of a modern terrestrial warm-blooded terapod, completely fureless or featherless in a polar environment, with just layers of blubber.

3, 4, 5, 6 - Dinosaurs had different metabolism and completely different body/surface ratios (for theropods for example, you can read this: theropoda.blogspot.it/2010/06/… . It's in italian, you may use Google translate). Also, I didn't wrote that all dinosaurs are feathered in the same way but, again, there is no reason to not consider feathers (in all their forms) a common and ancestral trait of the group.

 

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:icontheomnivore:
TheOmnivore Featured By Owner Nov 10, 2013
Why does everybody cite Yutyrannus huali as "proof" that the large maastrichtian and late campanian "super-sized" tyrannosaurs (T. rex; T. bataar; Z. magnus) were feathered? I have serious doubts about the validity of that claim:

1. Y. huali was is far older than T. rex, living in the early aptian around 125 million years ago. Zhuchengtyrannus magnus first appeared around 73.5 million years ago. This means the two genera were 51.5 megayears apart, which is about as far as Loxodonta and Elephas are from their earliest known ancestors.

2. Y. huali was nowhere near as big as T. rex, being estimated at a mere 1.4 tons, while estimates for the later vary between 6 to 9 tons, making it about 4 to 6 times as heavy as Y. huali.

3. Your metabolism argument is a serious [citation needed]. We have absolutely no idea about the metabolism of non-avian dinosaurs. You should consider, though, that grizzlies prey on far smaller creatures than T. rex did, a moose is a rather tiny meal compared to an Edmontosaurus. Predators usually grow as large as their prey allows them to.

4. Y. huali and T. rex did live in very, very different climates. The early aptian China is though of having an average temperature of about 10 C, making it a pretty cold place about as warm as modern central Europe. And there may of course be the possibility of dinosaurs changing their plummage with the season, and maybe the Y. huali discovered where "just" individuals dying during the winter months. T. rex, on the other hand, lived in a sub-tropical climate, evidenced by crocidilians in the Hell Creek fossil record. Furthermore, we should never forget that even closely related species can have very different skin covering, like the indian elephant and the woolly mammoth. So a hypothetical "Tyrannosaurus polaris" may very well be covered in dense plummage, while a more equatorial species might have little or not feathers at all.

Furthermore, I cannot really agree with the "feathers on ornithischians"-hypothesis, while saurischia and ornithischia may just as well have had a common, filament-covered ancestor, I find it highly unlikely that the filaments on both groups evolved in the same direction. The more bristle-like filaments found on some ceratopsians may be an indication for such a process.

Of course the debate will rage on in all eternity.
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:icontheropod1:
theropod1 Featured By Owner Feb 9, 2014
1. Elephas and Loxodonta still have fur. probably, by coincidence, even to a similar degree as Moeritherium or similar creatures.

2. Being 9m in lenght for the only adult specimen, 1.4t seems to be an extreme underestimate (that’s about as heavy as a 7-8m Allosaurus!). it is more likely about 2t. that is about a third the weight of a typical ("typical" beacuase I’m not referring to the particularly old and bulky sue, which is not what I think of as a representative specimen of T. rex) Tyrannosaurus, and about half the weight of Tarbosaurus or Zhuchengtyrannus. It had downright huge filaments. Do you think being a few times larger will mean being completely naked?

4. the above entry expresses that plumage would be variable, doesn’t it? The point is, that all dinosaurs were feathered, not that all looked like a chicken at all time and throughout their lifes. And T. rex had a rather big distribution, ranging from New Mexico to Canada. It is hardly likely that there would have been the same climate in that whole area.

(5) Alligators have the genetic prerequisites for filaments. The bristles on porcupines or hedgehog are homologous to the hair of mammoths. Is there any real reason why ornithischians and pterosaurs would have developed their filaments independently? Seems highly unlikely, in how many taxa comparable to ornithodira do you see independant occurrence of filamentous body covering for at least 3 times?
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:icontheomnivore:
TheOmnivore Featured By Owner Feb 24, 2014
1. Of course do Elephas and Loxodonta still have some hair. Some mammoths had lots and lots of hair. The extent of body covering can vary very widely even between closely related species.

2. Don't forget that Y. huali is a coelurosaurian, while Allosaurus is a carnosaur. The length of two not that closely related animals isn't a very good way to estimate their weight.

4. and 5. That was more a jab against some palaeo-artists out there, who started to potray tyrannosaurs with bird-like feathers soon after Y. huali showed up. The problem with the term "feather" is that the general public has a very specific image when they hear the term "feather", which is not necissarily what scientists mean when they talk about "feathered" dinosaurs. Feathers that at lest somewhat look like modern bird feathers only appeared with the maniraptorans. The few filaments found on Ornithischians show a more bristle-like appereance, and are surely nowhere near what people think of as "feathers". Wo don't call the bristles of procupines or hedgehogs fur, either. The problem there is that the original theory of the origin of the feather (as a mutation of the scales) can no longer hold up to modern research, but the terminologies haven't been updated to reflect this fact.

And I wouldn't be suprised at all if mammalian fur (and derivates) and feathers (once again, with derivates), would have a common ancestor. The Mesozoic looked very different than we thought, I see no reason why it should be any different with the Palaeozoic.
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:icontheropod1:
theropod1 Featured By Owner Feb 26, 2014
2. I’m aware of that. But it also appears to be comparable in bulk to an average Allosaurus (a specimen like Dino 2560 that would have massed about 2t). In any way, I cannot see how it could be lighter than a small one.

4/5. Yes, that’s a problem. People are not aware what the term feather means in a scientific sense and automatically envision a direved avian contour or wing feather. But look at the diversity in extant avian filaments. By that definition, I wouldn’t consider the integument of kiwis or cassowaries "feathers" either.
We currently have no clue how widespread derived feathers were in dinosaurs. Evidence suggests that at least neoornitischians and coelurosaurs had more than simple monofilaments, the rest are matters of time for further discoveries, and of terminology.

Your final paragraph is very intriguing. It’s fun to envision what implications this might have for palaeontography...
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:iconsmnt2000:
Smnt2000 Featured By Owner Nov 10, 2013  Hobbyist Traditional Artist

1. So, if your statement is correct, mammals like platypus or kangaroos can not have fur just because they've appeared much later than their ancestors? Or did I read it wrong?

 

2. See the link that follows in point 3.

 

3. Sorry, that was my fault. I thought I linked the citation (you may use Google translate since the article is in italian): theropoda.blogspot.it/2010/06/…

4. "And there may of course be the possibility of dinosaurs changing their plummage with the season, and maybe the Y. huali discovered where "just" individuals dying during the winter months."

There doesn't even exist one single animal that loses all of its plumage/fur with a seasonal changing. I've not seen so far a vertebrate completely 'naked' in summer and over-coated in winter. Also, I'm not talking about a fully feathered and fluffy Tyrannosaurus, but there is no reason to say that this theropod did not have feathers on its body like the ones seen on Old World vultures' necks. Of course it didn't need a wholly 'coat', but a thin layer of feathers for insulation doesn't seem an heresy to me.

 

"Furthermore, I cannot really agree with the "feathers on ornithischians"-hypothesis, while saurischia and ornithischia may just as well have had a common, filament-covered ancestor, I find it highly unlikely that the filaments on both groups evolved in the same direction. The more bristle-like filaments found on some ceratopsians may be an indication for such a process."

Again, maybe I wasn't clear at all in that statement (since you're not the only one who misunderstood what I wrote): when I'm speaking of 'feathers', I mean all the varieties known, including the filament-like ones.

 

"Of course the debate will rage on in all eternity."

Yep, I think it will.

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:iconthemorlock:
TheMorlock Featured By Owner Oct 10, 2013  Student General Artist
Have skin impressions been found of Ceratosaurus?
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:iconsmnt2000:
Smnt2000 Featured By Owner Oct 11, 2013  Hobbyist Traditional Artist
Apparently. Still, I've never seen any picture of them.
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:iconthemorlock:
TheMorlock Featured By Owner Oct 11, 2013  Student General Artist
Interesting. I wonder if featherless, bumpy skin was basal to all neoceratosauria. In which case, noasaurids would resemble classic depictions of "coelurosaurs" (AKA every small theropod).
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:iconsmnt2000:
Smnt2000 Featured By Owner Oct 12, 2013  Hobbyist Traditional Artist
Or maybe just some species were featherless (if they really were) so noasaurids would resemble normal depiction of coelurosaurs after all. Still, what you said it's a very intriguing possibility.
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:iconthemorlock:
TheMorlock Featured By Owner Oct 12, 2013  Student General Artist
I find it interesting how much abelisaurids resemble classic depictions of theropods with their froggy faces, stubby arms, and featherless skin.
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:iconsmnt2000:
Smnt2000 Featured By Owner Oct 14, 2013  Hobbyist Traditional Artist
Yeah, they have this kind of retro style, haven't they? I don't know how accurate is our vision of this theropods, but still it's a bit of unique.
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:iconthemorlock:
TheMorlock Featured By Owner Oct 14, 2013  Student General Artist
Yeah.
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:iconthemorlock:
TheMorlock Featured By Owner Mar 17, 2013  Student General Artist
What are EBBFs exactly?
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:iconsmnt2000:
Smnt2000 Featured By Owner Mar 18, 2013  Hobbyist Traditional Artist
Ooops, my bad. I should correct with EBFFs.
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:iconthemorlock:
TheMorlock Featured By Owner Mar 18, 2013  Student General Artist
But what are they?
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:iconsmnt2000:
Smnt2000 Featured By Owner Mar 19, 2013  Hobbyist Traditional Artist
EBFFs are the basl-most type of feather known. They're known for example in Beipiaosaurus: [link]
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:iconthemorlock:
TheMorlock Featured By Owner Mar 20, 2013  Student General Artist
ah, I see.
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:iconmaxterandkiwiking:
MaxterandKiwiKing Featured By Owner Dec 6, 2012  Hobbyist Digital Artist
That settles it,I'm drawing ALL my dinosaurs (with the exception of sauropods) with some kind of proto-feathers.The same goes for my rauisuchian crurotarsans (except for neosuchia).
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:iconsmnt2000:
Smnt2000 Featured By Owner Dec 7, 2012  Hobbyist Traditional Artist
Well done ;)
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:iconjwartwork:
JWArtwork Featured By Owner Aug 19, 2012  Hobbyist Digital Artist
So do you think (as you're saying there was never total exclusion from feathers) the biggest sauropods must have at least had some feathers as well:? And if that is the case, I what parts of the creature do you think will have been feathered:?
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:iconsmnt2000:
Smnt2000 Featured By Owner Aug 20, 2012  Hobbyist Traditional Artist
I don't know if even sauropods were feathered, but their ancestors probably had them. And, if they retained some of them, it would be like modern elephants: eyelashes and some tiny and thin filament around the body. Not an extensive coat. Polar species may had them though.
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:iconjwartwork:
JWArtwork Featured By Owner Sep 8, 2012  Hobbyist Digital Artist
Ah, thanks for explaining! :) I must compliment you for the fact that you've worked out your ideas in great detail! Bravo! :clap:
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:iconsimkoning:
SimKoning Featured By Owner Aug 13, 2012
Maybe I missed something, but it seems as though you didn't address surface area to body mass ratio. The larger an animal is, the smaller its surface area in relation to its internal volume. It's for this reason why an animal the size of T. rex wouldn't need insulation, and it's the same reason why megafauna such as elephants and rhinos lack fur as well. If we grant that a T. rex had the metabolism of a 1 ton bear (which I doubt considering they reached maturity in less than 18 years) we can infer that its body mass alone would be sufficient insulation due to the low surface area in relation to its volume. Basically, the animal's huge body acts as an insulator.
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:iconsmnt2000:
Smnt2000 Featured By Owner Aug 13, 2012  Hobbyist Traditional Artist
It's wrong. Carnivorous dinosaurs grow really fast, but they didn't need much food as you'd expect from a carnivorous mammal of the same size. And you forget that theropods, differently from mammals, had long tails. Such a feature alters the surface/volume relation. For example, Tyrannosaurs had a 5 time wider surface than a modern elephant. You can read this:[link] and this: [link] if you like. It's in italian, but there is a translator on the blog somewhere ;)
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