Feathers, huh? I have my doubts

[HD-man]

That's where phylogenetic bracketing comes into play.

In reference to what?

[CarnegieCollector]

That's where phylogenetic bracketing comes into play.

In reference to what?

I believe he means that things such as Yutyrannus also have those kind of feathers, therefore, because of phylogenetic bracketing, all other members of the family (tyrannosauridae) also had feathers.


I don't like phylogenetic bracketing.......

[Silvanusaurus]

There's nothing wrong with phylogenetic bracketing in itself, but I don't think it should be used as a substitute for conclusive knowledge, one way or another. Like countless other scientific methods in the past, it's a system that provides us (humans) with a sense of certainty and control over things we don't really know very much about at all. A lot of people seem to think the 'science' of their time is static and solid, and if it makes sense at that time then it must be definitive, but that simply isn't the case, and the way we understand prehistoric animals in 200 years time could make us today look foolish and naive.

I think we need to remain open to the potential of 'maybes', rather than black and white 'feathers or no feathers' presumptions. There is a potentially infinite wealth of fossilised specimens that have yet to be discovered that could reveal new 'truths' at which we would never have guessed. Discoveries have been made in the last few decades that already make our very recent predecessors' view of dinosaurs appear totally ridiculous. Ultimately we have to draw the most thorough conclusion possible from the things we do know, and that can be discerned in reality rather than the imagination (and indeed phylogenetic bracketing, as with any theory, is based around imagination). But nonetheless, one need only watch a chicken roaming around a bit of farm-land to behold, with only a vague sense of scientific knowledge, how undeniably close it's anatomy is to what we have discovered of theropod dinosaurs, and it makes a lot more sense for them to look like chickens than lizards.

But just as there have been numerous undeniably feathered dinosaur remains discovered, there are equally numerous specimens which undeniably possess scales and apparently no feathers at all. The fact is, it is possible to suggest and presume that a Tyrannasaurus rex (that old chestnut) was covered in feathers of some kind, but the only tangible fact we would seem to have is that small patch of rounded scales, and until anything more is found, we do not know either way (even a significant liklihood of feathers is nowhere near a certainty). Thus there is nothing scientifically wrong with supposing that said dinosaur had no feathers, or vice versa, but it is wrong, in my opinion, to state that it did or did not without being open to alternatives. There is nothing wrong with just accepting the 'maybe' of a situation, that is what I strive to do, as it honours the mystery and infinite strangeness of the natural world.

[stargatedalek]

One also needs to take into account reasons why an animal would be a certain way. IE if there was no reason for Tyrannosaurus to ever loose feathers than it probably didn't loose them, but if it was descended from semi-aquatic animals that existed between feathered Tyrannosauroids and Tyrannosaurus (which it wasn't) that could present reason.

[Postosuchus84]

There's nothing wrong with phylogenetic bracketing in itself, but I don't think it should be used as a substitute for conclusive knowledge, one way or another. Like countless other scientific methods in the past, it's a system that provides us (humans) with a sense of certainty and control over things we don't really know very much about at all. A lot of people seem to think the 'science' of their time is static and solid, and if it makes sense at that time then it must be definitive, but that simply isn't the case, and the way we understand prehistoric animals in 200 years time could make us today look foolish and naive.

I think we need to remain open to the potential of 'maybes', rather than black and white 'feathers or no feathers' presumptions. There is a potentially infinite wealth of fossilised specimens that have yet to be discovered that could reveal new 'truths' at which we would never have guessed. Discoveries have been made in the last few decades that already make our very recent predecessors' view of dinosaurs appear totally ridiculous. Ultimately we have to draw the most thorough conclusion possible from the things we do know, and that can be discerned in reality rather than the imagination (and indeed phylogenetic bracketing, as with any theory, is based around imagination). But nonetheless, one need only watch a chicken roaming around a bit of farm-land to behold, with only a vague sense of scientific knowledge, how undeniably close it's anatomy is to what we have discovered of theropod dinosaurs, and it makes a lot more sense for them to look like chickens than lizards.

But just as there have been numerous undeniably feathered dinosaur remains discovered, there are equally numerous specimens which undeniably possess scales and apparently no feathers at all. The fact is, it is possible to suggest and presume that a Tyrannasaurus rex (that old chestnut) was covered in feathers of some kind, but the only tangible fact we would seem to have is that small patch of rounded scales, and until anything more is found, we do not know either way (even a significant liklihood of feathers is nowhere near a certainty). Thus there is nothing scientifically wrong with supposing that said dinosaur had no feathers, or vice versa, but it is wrong, in my opinion, to state that it did or did not without being open to alternatives. There is nothing wrong with just accepting the 'maybe' of a situation, that is what I strive to do, as it honours the mystery and infinite strangeness of the natural world.

Quoting this for posterity and because I feel it summarizes the point that I was trying to make earlier rather wonderfully. Not only that, but this is actually a good and healthy thought pattern to have about the subject (or any subject) I feel. Thanks for wording this so nicely! I agree 100% here with it. It is one thing to be open about the possibility of it, it's another thing to attach a static value to something in saying that it is/is not especially when there's no firm evidence specifically showing that fact. Phylogenetic bracketing is an assumption of sorts, but it's like an educated assumption. Closer to an inference from what is known. It is assuredly, not a confirmation for it though.

[Sim]

Hi CarnegieCollector.  Others have made a lot of great points already.  There's just a few things I want to add.  Pterosaurs didn't have fur, their pycnofibers are structurally different from fur.  I think I remember reading that even the single filament type feathers are structurally different from fur.  Different types of feathers, and a diagram showing which types of feathers have been found in which dinosaur group can be seen on the Wikipedia Feather page, under the "Evolutionary stages" section.  Evolution of feathers can be seen within Coelurosauria, with the complexity of feathers generally increasing as more derived groups appear.

I think it's good to not just accept something in palaeontology as true without thinking about it, especially with initial very impressive claims (which often get shown to be less impressive soon after).  However, I wouldn't be confident in views that contradict scientific consensus, especially if they contradict quite a few things, if I wasn't a palaeontologist (which I'm not).  There are some things that one probably won't be able to see without specific knowledge and experience, and without seeing the fossils in person.

The more bird-like dinosaurs with DEFINATE, TRUE, WITHOUT A SHADOW OF A DOUBT feathers, seem to resemble birds. Not dinosaurs.....but true birds. Archaeopteryx is now considered a true bird, as well as confusiosornis. Many of the features found on these two birds are shared with other extinct birds. Hesporornis had teeth, some of the giant "terror birds" had claws on their wings (some modern day birds such as emus, ostriches, and hoatzin chicks also have claws), and birds such as roadrunners are only capable of gliding and flying short distances, something that archaeopteryx seems capable of doing. Microraptor, protoavis, and other "dinosaurs" seem to resemble these true birds more than they do dinosaurs. Who's to say these feathered critters aren't true birds either? As for other feathered bird-like dinosaurs......I don't know....
Zhenyaunlong, caudipteryx, and protarcheopteryx could vary well be feathered dinosaurs, but caudipteryx and protarcheopteryx (in my opinion) are more likely flightless birds. I don't know what to think of zhenyaunlong.


Some dinosaurs such as apatoraptor, struthiomimus, velociraptor, dakotaraptor, and concavenator, have all been found with small bumps on their fore-arms. These are always interpreted as quil knobs, something birds possess, to hold the primary feathers on the arms. But these could also simply be the result of deterioration, erosion, or anchor points for muscles. I'm not saying they're NOT quil knobs, but they could be a number of other things.

I usually don't have a problem with people using "dinosaur" to mean "non-bird dinosaur" but in this context I think it's important it's clear not all dinosaurs are birds, but all birds are dinosaurs.  Bird is an arbitrary classification, and there are different views on what should be considered a bird.  Microraptor, Zhenyuanlong and Velociraptor have many features that show they are very closely related, one being the long bony rods found in the dorsal and ventral area in most of their tail which is a feature of dromaeosaurids excluding the Unenlagiinae.  No other dinosaurs are known to have tail anatomy like this, not even closely related animals like troodontids or Archaeopteryx.  Microraptor and Zhenyuanlong both preserve feather impressions and the part of the world they are from is known for being good at preserving feather impressions.  I can't think of any reason why the bumps on the ulna of Velociraptor and Dakotaraptor wouldn't be quill knobs.  They are where the secondary feathers attach in birds and in dromaeosaurids which have had feathers preserved, and they look like quill knobs.  A comparison of the quill knobs of Velociraptor to that of an extant bird can be seen here.  How could these uniformly positioned bumps be result of deterioration or erosion?  The ulnar bumps of Concavenator have only been found to most likely be quill knobs by some palaeontologists.  Other palaeontologists have found things that contradict this interpretation, finding that the ulnar bumps of Concavenator are most likely not quill knobs but muscle attachment points.  More on this below.

Quill knobs are quill knobs, the fossils you mention are clear enough to identify these are not preservation artifacts, nor would the region of the arm have any other purpose to possess such muscle attachments. The shafts themselves don't reach the bone, rather the quill knobs support a specialized muscle that supports the shafts. The idea of it being another muscle attachment has already been tested to death with Concavenator*, and in the end the result was the same as Velociraptor and Dakotaraptor. Feathers make a hell of a lot more sense than a literally pointless (and rather large) muscle.

* It was still considered another muscle until fairly recently. And some people argue that Concavenators quill knobs represent literal "quills" like a lionfish, but I think it's far more reasonable to stick with the most likely explanation than to invent an entirely new theoretical integument just to isolate feathers within coelurosauria.

As far as I've seen, quill knobs support ligaments as opposed to muscle.  I agree with Mickey Mortimer and Andrea Cau about why the ulnar bumps of Concavenator most likely aren't quill knobs.  What they've said about this is summarised on the Concavenator Wikipedia page, in the "Feathers and scales" section.  Andrea Cau really thoroughly refuted the Concavenator quill knob hypothesis!  In the past, you said you thought Mickey Mortimer saying a crocodilian being a better reference than a bird for reconstructing the musculature of Concavenator appeared to be arbitrary.  The reason why a crocodilian is better is that non-maniraptoran theropods have been found to have these muscles configured in a crocodilian-like way, this is explained in full in this comment: http://theropoddatabase.blogspot.co.uk/2010/09/concavenator-part-ii-becklespinax.html?showComment=1284187382791#c1854585565985159621

[Derek.McManus]

Very interesting comments I have learned something new here! Thank you!

[Halichoeres]

There's nothing wrong with phylogenetic bracketing in itself, but I don't think it should be used as a substitute for conclusive knowledge, one way or another. Like countless other scientific methods in the past, it's a system that provides us (humans) with a sense of certainty and control over things we don't really know very much about at all. A lot of people seem to think the 'science' of their time is static and solid, and if it makes sense at that time then it must be definitive, but that simply isn't the case, and the way we understand prehistoric animals in 200 years time could make us today look foolish and naive.

I think we need to remain open to the potential of 'maybes', rather than black and white 'feathers or no feathers' presumptions. There is a potentially infinite wealth of fossilised specimens that have yet to be discovered that could reveal new 'truths' at which we would never have guessed. Discoveries have been made in the last few decades that already make our very recent predecessors' view of dinosaurs appear totally ridiculous. Ultimately we have to draw the most thorough conclusion possible from the things we do know, and that can be discerned in reality rather than the imagination (and indeed phylogenetic bracketing, as with any theory, is based around imagination). But nonetheless, one need only watch a chicken roaming around a bit of farm-land to behold, with only a vague sense of scientific knowledge, how undeniably close it's anatomy is to what we have discovered of theropod dinosaurs, and it makes a lot more sense for them to look like chickens than lizards.

But just as there have been numerous undeniably feathered dinosaur remains discovered, there are equally numerous specimens which undeniably possess scales and apparently no feathers at all. The fact is, it is possible to suggest and presume that a Tyrannasaurus rex (that old chestnut) was covered in feathers of some kind, but the only tangible fact we would seem to have is that small patch of rounded scales, and until anything more is found, we do not know either way (even a significant liklihood of feathers is nowhere near a certainty). Thus there is nothing scientifically wrong with supposing that said dinosaur had no feathers, or vice versa, but it is wrong, in my opinion, to state that it did or did not without being open to alternatives. There is nothing wrong with just accepting the 'maybe' of a situation, that is what I strive to do, as it honours the mystery and infinite strangeness of the natural world.

Yeah, that's a good point. Any inference from character optimization is a prediction, not a datum. A piece of skin that should preserve feathers if they are present, but does not, is a datum falsifying the prediction. The available skin impressions from Tyrannosaurus in particular are maddeningly ambiguous, but there is definitely a plausible physiological mechanism by which something that large would have skimpier integument than its relatives. Unfortunately, there is also a plausible taphonomic mechanism by which fuzzy integument would fail to be preserved. I can't get too exercised about presence/absence of feathers on T rex for that reason, but I do think it's special pleading to assume smaller relatives were merely scaly.

[Dinoguy2]

"That may be stretching the degree of what we can call a "feather""

Richard Prum, who's an expert on feather evolution and development, has recently published a paper (can't remember the citation off hand, but I'd check his recent output) basically arguing that "feather" should be defined as any hollow epidermal filament. The reason being that the structures many people erroneously called "protofeathers" are identical to other structures that we can currently find in modern birds. People who call these "protofeathers", according to Prum, seem to be ignorant of the vast diversity of feathers in modern birds and the term presumes to know more than we do about their various stages of evolution, when we have genetic evidence that seemingly "simpler" structures have evolved from more complex feathers numerous times in birds alone, let alone the kinds of evolution that might have been happening in non-avian dinosaurs.

So if you have a filament that can be shown to be hollow, it should be called a feather, whether it is a precursor to, or derived from, something that looks like a "Classic" bird feather. If it's not hollow, it's something else.

Of course, given the kind of crushing and poor preservation often found in many fossils, proving some fossil structure is hollow can be a challenge. For example, some papers studying pycnofibers have stated they are not hollow. Therefore they would not be considered features (though that's not to say they couldn't be some ancestral structure to feathers). However, there are other sources that claim to show that they ARE hollow. Maybe some are and some aren't, or maybe somebody is interpreting the evidence wrong. Either way, needs more work.

[Sim]

@Dinoguy2:  So does that mean hair isn't hollow?  I can't find where I read about differences between hair and single filament type feathers at the moment, and I'm not remembering much about their differences.

[stargatedalek]

"That may be stretching the degree of what we can call a "feather""

I was referring to the idea of pycnofibres and Kulindadromeus being synonymous, since they potentially share a common ancestor yet aren't directly related to modern feathers.

[Lanthanotus]

Richard Prum, who's an expert on feather evolution and development, has recently published a paper (can't remember the citation off hand, but I'd check his recent output) basically arguing that "feather" should be defined as any hollow epidermal filament.

Wouldn't that mean, that polar bears are feathered? Sure, reptilian/avian feathers and mammalian hair developed independently, but both are keratineous structures growing from invagination of the epidermis....

A point within all that discussion about feathers in dinosaurs is, imho, "Does it make sense?"

.... for example, an gigantic animal like Tyrannosaurus would have a hard time in tropical or even moderatly temperatured environment, if it would be covered in a coat of insulating feathers (of whatever type these are). As cooling is way harder to achieve than heating in a terraneous environment, an active, several ton weighing predator would be in severe danger of overheating its system. If Tyrannosaurus had feathers, I deem it likely that this was a feature of young animals that was lost during adolescence.

Another point is...

... feathers (or even fur) needs a lot of maintenance and grooming. Modern birds and (fur coated) mammals (maybe with the exception of sloths) dedicate a considerably time of their day for grooming and care for their coat, may its function be insulation, sexual display or whatever. A lot of these animals have special adaptations to make the best of it and even big and "clumsy" ones (giraffes, cow or such) do so a more or lesser degree. So now imagine a full grown Tyrannosaurus with its arms that can't even scratch its throat or turn in their wrists.... well, there's the possibility of social grooming (with steakknives).... This may sound jestingly, but seriously, it's a point I deem valid.

[CarnegieCollector]

"there's the possibility of social grooming (with steakknives)...."

sounds painful! 

[stargatedalek]

A few problems with that idea.

Firstly Tyrannosaurus didn't live in a sun baked tropical environment, warmer than modern North America yes, but it still had seasonal fluctuation and even probably got small amounts of snow for parts of the year.

Secondly no animal known to science looses substantial amounts of integument as it ages, birds grow new integument to replace damaged integument or to aid in new functions they have available to them as they age, but that's still a far cry from loosing it.

Lastly there is no reason that Tyrannosaurus would need the use of it's forelimbs to groom itself, birds don't exactly have the use of their forearms and they manage just fine. Nor does Tyrannosaurus particularly lack locomotion in its neck that could potentially prevent it from grooming itself. And as you said yourself there's no reason they couldn't have groomed socially or perhaps symbiotically with smaller animals as many large carnivores do today.

[CarnegieCollector]

I never picture T. rex (or any large carnivorous dinosaur) having more than just a little brush-over with feathers or fluff.
This is how I personally picture a feathered T. rex (if they had any feathers at all)

http://fc02.deviantart.net/fs70/i/2012/164/1/0/__the_soul_of_gentleness___by_himmapaan-d53e81t.jpg


Not so much this:

https://i.kinja-img.com/gawker-media/image/upload/s--GXDXDYUD--/813266302148042132.jpg


The one that I don't exactly agree with seems to have too much feathers. No, that's not me hating on the feathered T. rex, it just seems illogical. As lanthanotus said, T. rex, being an enormous animal, would have a hard time in a warm climate with that much plumage.

The one with less feathers seems more plausible. It has less feathers so the over heating thing wouldn't be a problem for it, nor would grooming, and it keeps in tune with phylogenetic bracketing.

I could be wrong, and I most likely am, but it just seems more plausible for such a huge animal that lives in a hot climate to have less feathers.

Quite honestly, I couldn't agree more with lanthanotus on this. He makes some great points.

Now I can't get the image of a feathered polar bear out of my mind though

RAWR 

[Rain]

Secondly no animal known to science looses substantial amounts of integument as it ages, birds grow new integument to replace damaged integument or to aid in new functions they have available to them as they age, but that's still a far cry from loosing it.

A bit off topic, but wouldn't the amount Ostritch(es?) lose as they age be enough to be considered "substantial"

[CarnegieCollector]

Secondly no animal known to science looses substantial amounts of integument as it ages, birds grow new integument to replace damaged integument or to aid in new functions they have available to them as they age, but that's still a far cry from loosing it.

A bit off topic, but wouldn't the amount Ostritch(es?) lose as they age be enough to be considered "substantial"

I would think so. I believe the same thing goes for cassowaries and some vultures.

[HD-man]

That's where phylogenetic bracketing comes into play.

In reference to what?

I believe he means that things such as Yutyrannus also have those kind of feathers, therefore, because of phylogenetic bracketing, all other members of the family (tyrannosauridae) also had feathers.

Just to clarify, "things such as Yutyrannus" aren't tyrannosaurids, but earlier tyrannosauroids. "Things such as Yutyrannus" + tyrannosauridae = tyrannosauroidea. In any case, I'm familiar w/phylogenetic bracketing & get what your saying. If we didn't have any tyrannosaurid skin impressions, then earlier tyrannosauroids would give us the best idea of what tyrannosaurids looked like. However, we do have a few tyrannosaurid skin impressions (including some from T.rex: https://books.google.com/books?id=5WH9RnfKco4C&pg=PA46&dq=%221.26.+wyrex%22&hl=en&sa=X&ved=0ahUKEwjm2InPhIvOAhXEZCYKHbAfBzEQ6AEIHjAA#v=onepage&q=%221.26.%20wyrex%22&f=false ) & they suggest that tyrannosaurids were secondarily scaled ("Thomas Carr, a palaeontologist at Carthage College in Kenosha, Wisconsin, argues, for example, that unpublished fossils with skin impressions from close relatives of T. rex show scaly skin. These findings suggest that even though some earlier tyrannosauroids had feathers, the subgroup called tyrannosauridae...seems to have undergone an evolutionary reversal from fuzz to scales": http://www.nature.com/news/palaeontology-the-truth-about-t-rex-1.13988 ).

I never picture T. rex (or any large carnivorous dinosaur) having more than just a little brush-over with feathers or fluff.
This is how I personally picture a feathered T. rex (if they had any feathers at all)

http://fc02.deviantart.net/fs70/i/2012/164/1/0/__the_soul_of_gentleness___by_himmapaan-d53e81t.jpg

I was thinking more like in T. rex Autopsy ( http://channel.nationalgeographic.com/t-rex-autopsy/ ) or Stewart's Why Did T. rex Have Short Arms?: And Other Questions about Dinosaurs ( http://csotonyi.com/wp-content/uploads/2014/07/WhyDidTrexHaveShortArms_Cover.jpg ).

[CarnegieCollector]

That's where phylogenetic bracketing comes into play.

In reference to what?

I believe he means that things such as Yutyrannus also have those kind of feathers, therefore, because of phylogenetic bracketing, all other members of the family (tyrannosauridae) also had feathers.

Just to clarify, "things such as Yutyrannus" aren't tyrannosaurids, but earlier tyrannosauroids. "Things such as Yutyrannus" + tyrannosauridae = tyrannosauroidea. In any case, I'm familiar w/phylogenetic bracketing & get what your saying. If we didn't have any tyrannosaurid skin impressions, then earlier tyrannosauroids would give us the best idea of what tyrannosaurids looked like. However, we do have a few tyrannosaurid skin impressions (including some from T.rex: https://books.google.com/books?id=5WH9RnfKco4C&pg=PA46&dq=%221.26.+wyrex%22&hl=en&sa=X&ved=0ahUKEwjm2InPhIvOAhXEZCYKHbAfBzEQ6AEIHjAA#v=onepage&q=%221.26.%20wyrex%22&f=false ) & they suggest that tyrannosaurids were secondarily scaled ("Thomas Carr, a palaeontologist at Carthage College in Kenosha, Wisconsin, argues, for example, that unpublished fossils with skin impressions from close relatives of T. rex show scaly skin. These findings suggest that even though some earlier tyrannosauroids had feathers, the subgroup called tyrannosauridae...seems to have undergone an evolutionary reversal from fuzz to scales": http://www.nature.com/news/palaeontology-the-truth-about-t-rex-1.13988 ).

I never picture T. rex (or any large carnivorous dinosaur) having more than just a little brush-over with feathers or fluff.
This is how I personally picture a feathered T. rex (if they had any feathers at all)

http://fc02.deviantart.net/fs70/i/2012/164/1/0/__the_soul_of_gentleness___by_himmapaan-d53e81t.jpg

I was thinking more like in T. rex Autopsy ( http://channel.nationalgeographic.com/t-rex-autopsy/ ) or Stewart's Why Did T. rex Have Short Arms?: And Other Questions about Dinosaurs ( http://csotonyi.com/wp-content/uploads/2014/07/WhyDidTrexHaveShortArms_Cover.jpg ).

Oh wow! I had never heard of T. rex autopsy. looks awesome! The "why did T. rex have short arms?" Interpretation is amazing! I love that artists work. Yeah, that's by far, my favorite feathered T. rex interpretation as of now. Looks awesome and plausible. Thanks for sharing!
As far as Yutyrannus goes, I couldn't remember the exact classification for its family. It makes since that more primitive rexes were more densely feathered. Also, wasn't China where Mr. Yutyrannus lived cold for the Mesozoic? That would make since of its denser coat. I think I can remember reading somewhere that China woulda been rather cold and snowy

[Dinoguy2]

Please note "insulating" does NOT mean heating. It means "preventing heat transfer".

Insulation works like a thermos. Thermos does not make your liquid hot. It keeps you liquid at the same temperature it started. If you put in hot soup, it will stay hot. If you put in cold juice, it will stay cold. That's what insulation means.

If a T. rex wakes up on a cool morning, it would prefer to stay cool by keeping heat out when it warms up.

That's not to say this is evidence T. rex had insulation. Countless animals use behavioral strategies to regulate their temperature, often in addition to some kind of insulation. But neither is it evidence that rex didn't have insulation. Because insulation works both ways, the evidence goes both ways. Which means it's useless as an argument either way.

People need to live with the answer "we have no idea." This is a fundamental principle of science. We don't know if T. rex is feathered and it's not possible for us to know unless we discover a patch of its skin larger than 4 square inches in surface area

If you draw a feathered T. rex - Congratulation! You're just as right as everybody else.

If you draw a scaly T. rex - Congratulations! You're just as right as everybody else. Reversals happen. (Though it's rare for total and complete reversals happen, which is why the consensus of modern scientists would lean towards at least sparse, elephant-like covering).

Also, wasn't China where Mr. Yutyrannus lived cold for the Mesozoic?

It's average temperature was slightly colder than the average temperature of the Hell Creek Formation. The Yixian formation of Yutyrannus would have been similar to modern North Carolina in terms of temperature extremes. The Hell Creek of T. rex would have been closer to modern Florida. Not a huge difference.

(Artists tend to draw Yutyrannus like a polar bear inhabiting a winter snowscape, which is utterly ridiculous and proves they have no conception of how averages work when it comes to climate...)

That would make since of its denser coat

I'm not sure I'd call the coat of Yutyrannus particularly dense. The individual filaments average something like 18 cm long, which is pretty darn short for a 30ft animal. Not exactly shaggy.