D&D General Tyrannosaurs were pack hunters. Stay away from the Isle of Dread.

[Mind of tempest]

Worth noting: Scale impression fossilization (Not actual skin/scales but where the scales pressed against mud which hardened over time) show fairly clearly that T-Rex and other Tyrannosauridae did not have full-coverage feathers as adults. Whether this was because of the temperature of the world at the time, the amount of heat they generated or retained, and otherwise is kinda moot.

Though they -may- have had incomplete coverage... it's really a matter of slowly walking back the idea of feathered T-Rex inch by inch as it's much more likely they had no feathers.

Though I, for one, would still like to imagine baby T-rexes as having feathers that they slowly grow out of except for a feathered crest along their head, neck, and back, for mating displays. Just 'cause a giant murdersaur doing a wiggly little feather-tossing dance to entice a mate is hilarious and giant baby chickens with teeth are adorably terrifying.

males having a crest I could see, the females would be plane as anything.

The issue isn't genetic relation. The issue is thermodynamic similarity. The square-cube law can be a killer.

Ostriches weigh up to 320 pounds. Moas up to 550. Elephant birds weigh in around 1000 lbs. So far, nothing on the list is heavier than a bison. Rare indeed is the mammal species in this range that has gone hairless.

Cattle come in at about a ton. Rhinos come in between one and and 2.5 tons. Elephants come in between 3 and 6.5 tons. An order of magnitude more than most of those birds. At this size, some species are largely hairless (modern elephants) and some not - mastodons, mammoths, and woolly rhinos. These creatures are starting to have issues losing heat, and sometimes lose the thick hair.

The T-rex comes in at 5 to 9 tons. The heat issue will be greater. While there may be feathers, you probably no longer expect a thick coat of them in warm climates.



Yes. But "a feather impression" doesn't mean the beast was fully-feathered like a modern bird, any more than a hair impression means humans are furred like bears.



The largest oviraptor is estimated to have weighed in around 4000 lbs - this is rhino-sized, so not yet at the point where we are sure the insulation would be an issue.

I would put money on rex in colder areas being fluffier than others but in the warm land near pure scale.

 

[Whizbang Dustyboots]

Trex could not live in a jungle for the more practical reason of it not having sufficient prey and if it ran fast the fallen logs could kill it.

The island is also a base of operations for a powerful magical race. If the kopru brought the tyrannosaurs to the isle, it wouldn't be unreasonable for them to also have some sort of resources in place to make sure they stay fed (maybe a really gross large scale magical food production spell) and maybe something assigned to be their vet.

 

[Desdichado]

The issue isn't genetic relation. The issue is thermodynamic similarity. The square-cube law can be a killer.

Ostriches weigh up to 320 pounds. Moas up to 550. Elephant birds weigh in around 1000 lbs. So far, nothing on the list is heavier than a bison. Rare indeed is the mammal species in this range that has gone hairless, so you'd not expect birds that large to be featherless.

Cattle come in at about a ton. Rhinos come in between one and and 2.5 tons. Elephants come in between 3 and 6.5 tons. An order of magnitude more than most of those birds. At this size, some species are largely hairless (modern elephants) and some not - mastodons, mammoths, and woolly rhinos. These creatures are starting to have issues losing heat, and sometimes lose the thick hair.

The T-rex comes in at 5 to 9 tons. The heat issue will be greater. While there may be feathers, you probably no longer expect a thick coat of them in warm climates.

No, the issue is mostly phylogenetic bracketing, not thermodynamic similarity. Alberta and Montana certainly were warmer during the Cretaceous than today, but they weren't hot or tropical, they were similar to the American south in climate; humid, wet, marshy coastal floodplain forests. For that matter, they were very similar to the Yixian formation were fully feathered large bodied tyrannosaurs are known conclusiviely to exist. The talk about tropical animals from a completely different group has no bearing on what T. rexes would or wouldn't have done, because they didn't live in the same environment as today's tropical animals, or at least their classic ecological niche wasn't there (admittedly, it appears that very late in the Maastrichtian, they spread into the southern province to be part of the Alamosaurus NALMA. How common or successful they were there is an open question, as our fossil evidence is pretty scanty.) And, there's no good reason to assume similar metabolism, for that matter, or other variables that would have had just as significant an impact.

Plus, you can make the argument about elephants all day long, and even paleontological specialists often do. However, because they usually ignore Megatherium and the fact that it provides a directly contradictory example, the "featherless because of elephants" argument is little more than a just-so story that isn't very convincing. Plus, a lot of the "tyrannosaur" skin impressions weren't actually from T. rex anyway—the only actual T. rex skin impressions are a tiny patch on the tail, a tiny patch on the hip and a handful of small impressions of the neck. The rest of them don't come from Tyrannosaurus itself. You can't use a skin impression from a gorgosaur or daspletosaur dewlap or belly and then apply an argument that only works if you're talking about a T. rex sized creature—because gorgosaurs and albertosaurs were half the mass of T. rex, if not even smaller. The argument also tends to depend on just-so assumptions. As Phil Bell said in the most recent in depth study of the question that I know of (2017), there are real problems. Yutyrannus was not a small animal, and it didn't live in any kind of cold climate; summers, at least, would have been extremely hot in the Yixian formation. The temperatures were similar and the animal size was similar to that of Daspletosaurus, Tarbosaurus, Gorgosaurus, etc. that don't have any known feather impressions and do have small scale impressions on them. So what was driving the apparent disparity? Not thermoregulation; that's been ruled out by both the climate and the size of other animals, and Bell admits that they have no idea why some large tyrannosaurs are known for sure to have had nearly full-body feathery integuement, and others are known for sure to have at least tiny patches of unfeathered scaley skin. Which doesn't rule out feathers elsewhere on the body.

And I know that science is what the data says, not what the scientists say, but the data is inconclusive, and most practicing scientists today will tell you that the phylogenetic bracketing is a more compelling argument than the thermodynamic argument, given the counter examples that pretty much debunk the idea behind the "hairless elephants therefore hairless dinosaurs" argument. The latter might explain a more naked skin, but not a completely featherless one. In fact, feathers explain one lingering puzzle of T. rex anatomy; what the heck were the arms for? In the past, they've been discounted as a feature on its way to oblivion, like a whale's hind legs or something, but that's not actually true. T. rexes arms were fairly heavily muscled and clearly served some purpose, although for decades nobody could imagine what it would be. With the possibility—maybe even probability—of display feathers on the arms, suddenly the arms structure makes some sense.

 

[Desdichado]

Trex could not live in a jungle for the more practical reason of it not having sufficient prey and if it ran fast the fallen logs could kill it.

The Lance and Hell Creek formations (as well as the slightly earlier Judithan and Edmontonian) are interpreted has heavily forested, marshy coastal plains on the edge of the Niobrara Sea. In other words; just like jungle, except a little bit cooler.

 

[tomBitonti]

So, about range size: How much of a difference would there because the environmental conditions were quite a bit different then. I wonder what effect differences in ocean salinity, solar radiance, and atmospheric composition would have as to the amount of energy flowing through the environment. Also, how sophisticated would be the metabolism of creatures, as well as their intellect? Do we know that T-Rex (and their prey) weren't quite dumb?

There seem to be a lot of assumptions that creatures of 100 million years ago would be more or less the same as creatures now. Maybe we should cross a chicken with a crocodile and make it huge to model a T-Rex.

TomB

 

[Whizbang Dustyboots]

There seem to be a lot of assumptions that creatures of 100 million years ago would be more or less the same as creatures now. Maybe we should cross a chicken with a crocodile and make it huge to model a T-Rex.

I don't want to be around for that courtship.

 

[Umbran]

No, the issue is mostly phylogenetic bracketing, not thermodynamic similarity.

With respect. I will grant that IF they had an outer coating, a T-rex would have feathers.

However, just as elephants have largely lost body hair, large theropods may have largely lost their feathers. Feathers cost a lot of energy to produce. If the animal doesn't need them for something, there'll be a Darwinian selection against spending that energy. And the thermodynamics of that body size removes the need for an insulating coat in warm climates.

 

[Mind of tempest]

The Lance and Hell Creek formations (as well as the slightly earlier Judithan and Edmontonian) are interpreted has heavily forested, marshy coastal plains on the edge of the Niobrara Sea. In other words; just like jungle, except a little bit cooler.

how dense are its nearest modern equivalents trees are they widely spaced or super bunched up as forest elephants are much smaller than plane dwelling ones and I doubt t rexs are super good about smashing through trees?

 

[Charlaquin]

Sue the T-Rex has been given a new fleshed-out body and is on tour. It gives an even better view of what an absolute terror a T-Rex would be.
Fleshy the T-Rex

Yep, they (we use they/them pronouns for Sue now, as recent evidence has shown that what was previously thought to be indicators of sexual dimorphism probably isn’t, so we can’t really tell T.Rex sex from their bones) are currently at the museum I work at, though only for a few days more; they’ll be moving on soon. That model is incredible to see in-person.

Notably, we’re still not even sure T.Rex were hunters at all. There’s a lot to suggest they may actually have been scavengers. Though, I’m inclined to believe the truth lies somewhere in the middle - likely opportunistic hunter/scavengers.

On the subject of feathers, we really just don’t know. Young T.Rex almost certainly had down-like feathers. Whether or not they kept them into maturity is still an open question. Again, the truth is likely somewhere between the extremes. They probably weren’t covered in feathers, but it’s also not unlikely they would have retained some feathering, possibly on the head and neck.

 

[darjr]

I don't want to be around for that courtship.

Well I definitely don’t have enough bread crumbs or BBQ sauce.