The Palaeobiology Thread:

[Xemina]

This thread is just an idea I came up with after seeing @ProtoJeb21's "The Biology/Wildlife Thread" but in my more favourite topic, palaeobiology. So, in this thread, you can say if you think that Tyrannosaurus had feathers, or that Meganura were red. I want to start off with the Did Tyrannosaurus Have Feathers topic.

With everything that we know about Tyrannosauridae, we know a lot of them had a plumose appearance, not necessarily contour feathers, but bristles instead. The only skin fossils we have are of regions that probably wouldn't have feathers anyway. If it did have feathers, they would probably be brown, to camouflage with the environment; most likely redwood forests. Baby Tyrannosaurus probably had a thick white coating, like a chick, and shed them as it grew. I can't think of anything else to say, so, what do you think?

[Green Baron]

T-Rex was covered in scales. Sorry :-)

http://rsbl.royalsocietypublishing.org/content/13/6/20170092

Feathers were apparently sorted out at the base of the genus.

Edited August 31, 2017 by Green Baron

[YNM]

- We never found remains of nerves

- Brain anatomy may not have anything to do with mind

∴ Mind evolution might not have happened.

How did we went from apes, again ?

 

 

Not really palaeobiology, but I just realize how shallow we have any idea about ideas and mind.

Edited August 31, 2017 by YNM

[kerbiloid]

T-Rex

Spoiler

This?

 

NO!

 

[tater]

T. rex

(sorry, I get pedantic about these things)

[p1t1o]

@tater noice

***

Question: How do we know they, dinosaurs, T. rexes (T. reges?), were cold-blooded?

Edited August 31, 2017 by p1t1o

[Green Baron]

We don't. Because they most probably weren't. They weren't really warm-blooded like mammals either.

But of course able to regulate their body temperature. A hunter has to and their occupied too many niches to be just like today's lazy lizards.

I don't find the references and have spent more than enough time here today. Kindly ask to search yourselves :-)

Dinosaurs, body temperature, regulation, warm-blooded ...

[tater]

Yeah, many now think they were mesotherms.

http://www.nature.com/news/dinosaurs-neither-warm-blooded-nor-cold-blooded-1.15399

Edited September 1, 2017 by tater

[NSEP]

4 hours ago, Green Baron said:

T-Rex was covered in scales. Sorry :-)

http://rsbl.royalsocietypublishing.org/content/13/6/20170092

Feathers were apparently sorted out at the base of the genus.

 

[BigFatStupidHead]

4 hours ago, tater said:

Yeah, many now think they were mesoderms.

http://www.nature.com/news/dinosaurs-neither-warm-blooded-nor-cold-blooded-1.15399

I think you might mean mesotherms. Being the other might be a bit... messy.

[YNM]

5 hours ago, tater said:

Yeah, many now think they were mesoderms.

http://www.nature.com/news/dinosaurs-neither-warm-blooded-nor-cold-blooded-1.15399

 

1 hour ago, BigFatStupidHead said:

I think you might mean mesotherms. Being the other might be a bit... messy.

I could only imagine... gaah nooo

[tater]

Stupid autocorrect wrecked it the first time and I didn't check.

[Scotius]

The bigger the animal, the less need it has for dermal isolating layer (fur, feathers etc.) - its sheer size serves as a decent heat retardant.

[kerbiloid]

8 hours ago, p1t1o said:

How do we know they, dinosaurs, T. rexes (T. reges?), were cold-blooded?

Inertial homeothermy.
They were enough big ("bigger than cow") and lived in warm climate when average daily temperature is not less than the desired body temperature.
This allows to warm up under sun in the daytime and stay more or less warm in the night, when smaller reptiles are usually inactive, and didn't spend much energy.
Huge body = low area/volume ratio = low cooling surface/heat capacity ratio = longer freezing time.

So, they were enough big to keep the heat just because of their heat capacity and didn't need special measures like tremor, skin pores, so on.

So, by touch they should be warm, but by design they should be "cold".

Edited September 1, 2017 by kerbiloid

[Green Baron]

Not quite up to date The classical view but interesting in this context:

http://www.ucmp.berkeley.edu/diapsids/endothermy.html

http://www.ucmp.berkeley.edu/diapsids/ectothermy.html

http://www.ucmp.berkeley.edu/diapsids/summarythermy.html

Well, nice to read :-):

https://www.nap.edu/read/11630/chapter/9

 

.... and a long list of discussion towards the one or the other.

 

So there's a conundrum of arguments for and against the one and the other, time to invent something in between, like mesod..thermy :-)

 

[Green Baron]

11 hours ago, NSEP said:

*snip*

"TREY the Explainer - YouTube

Explain Everything...and more! This is a channel of Science, Evidence, and Truth."

 

"Truth" always makes me anxious :-)

 

The guy seems not to be an insider, just someone who collects data from the internet and forms videos from it. It is of course very easy to extract points from works that interpret clues and find something that doesn't fit. But we have no living T. rex and must live with the sparse evidences at hand.

Nevertheless, the work was accepted, discussed, put together with others and the overall consensus is ... scales to the Tyrants. Reptiles rather than birds.

 

Until further notice, of course. We must stay flexible :-)

 

This page http://www.smithsonianmag.com/science-nature/five-things-we-dont-know-about-tyrannosaurus-rex-180951072/ shows the view of two years earlier.

 

If you don't want to be confused by rapidly changing data and views then this book should have a place on the shelf. It is a nice foundation and overview of what the title says.

 

[Xemina]

OK, well the truth is that question is impossible to answer.We found evidence of smaller tyrannosaurs with feathers. Most likely, it had partial bristled plumage along its upper back, tail and arms. Babies were probably covered in them though. We must stay flexible (I mean like I was shocked about the Spinosaurus news in 2014).

15 hours ago, p1t1o said:

@tater noice

***

Question: How do we know they, dinosaurs, T. rexes (T. reges?), were cold-blooded?

The plural of T. rex is T. rex.  (Genera don't have plurals).

[Iskierka]

1 hour ago, Green Baron said:

The guy seems not to be an insider, just someone who collects data from the internet and forms videos from it. It is of course very easy to extract points from works that interpret clues and find something that doesn't fit. But we have no living T. rex and must live with the sparse evidences at hand.

Nevertheless, the work was accepted, discussed, put together with others and the overall consensus is ... scales to the Tyrants. Reptiles rather than birds.

 

The point is that the evidence still points to the exact same patterns of mixed scale/feather as we've seen in more complete but smaller tyrannosaurids. And regardless of scales or feathers, they're birds, not reptiles. https://en.wikipedia.org/wiki/Avemetatarsalia contains both all dinosaurs and all of the families that are popularly thought of as dinosaurs but not actually dinosaurs. The argument of size against insulating layers also fails as feathers are not purely insulating layers, as seen from the fact birds are mostly covered in feathers regardless of the temperature of their typical habitat.
 

As for warm-blooded-ness, they have to be meaningfully warmer than reptiles, fish or amphibians. Many of them would be simply unable to possibly exist with the tiny metabolic rate of cold-blooded animals. There's also some more obscure-to-the-layman but equally telling features like microscopic bone structure, that points to rapid growth cold-blooded animals can't achieve. They possibly didn't meet modern definitions of warm-blooded from modern mammals and birds, but they definitely had elevated temperatures they were dependent on, and evolving towards modern bird's ability to regulate completely.

[Scotius]

All birds are dinosaurs. But not all dinosaurs were birds. Tyrannosaurus  from 65 millions of years ago is more closely related to a common sparrow or pigeon than to Triceratops, with which he shared living space.

[NSEP]

If you are not convinced that T-rex had feathers, here is a 40 minute video about it, enjoy.

 

[Green Baron]

 

2 hours ago, Iskierka said:

The point is that the evidence still points to the exact same patterns of mixed scale/feather as we've seen in more complete but smaller tyrannosaurids. And regardless of scales or feathers, they're birds, not reptiles. https://en.wikipedia.org/wiki/Avemetatarsalia contains both all dinosaurs and all of the families that are popularly thought of as dinosaurs but not actually dinosaurs. The argument of size against insulating layers also fails as feathers are not purely insulating layers, as seen from the fact birds are mostly covered in feathers regardless of the temperature of their typical habitat.

Overworked: Avemetatarsalia aren't birds (Aves). Dinosaur aren't Aves either, but can together with others be combined into a clade Avemetatarsalia/Ornithodira/All-Birds based on common skeletal traits. "Bird-like skin" and "reptile-like skin" has a connotation to feathers and scales and with this connotation one can name a skin "reptile-like" or "bird-like". No problem here, or ?

As to feather or scale, if you have info about feathers on T. rex then by all means don't hesitate. The article concludes that the fossil remains of these animals show "scaly, reptilian like" skin (leaving space for possible feathers on the spine) and suggests an explanation why. Climate is excluded as a cause. Because others, some of them 10s of millions of years earlier, show feathers doesn't automatically mean T. rex had them too. Clades are arbitrary, based on fossil traits and don't necessarily reflect biological relations. Similar features can have simple functional causes and so totally unrelated species can be sorted under the same clade.

I am still hesitating to spend the 25 bucks for the whole article i must admit.

Let's not forget, feathered dinosaurs are existent, but rare.

Edited September 1, 2017 by Green Baron

[kerbiloid]

Spoiler

As birds are dinos,

1. "Hot chick" is a synonym for "Warm-blooded dino".

2. "You are a chicken" means "You are big and dangerous".

For example.
Nobody calls him chicken, and he took offense.

 

 

[mikegarrison]

Birds are theropods, and theropods are dinosaurs. So all birds are dinosaurs, but not all dinosaurs are birds.

T. Rex is a theropod. Birds are theropods. But that does not mean T. Rex is a bird. It also does not mean birds are T. Rexes or descended from T. Rexes. It's like saying that you and your aunt are both descended from your grandparents, but you are not descended from your aunt (unless you live in Westeros).

[Xemina]

13 hours ago, mikegarrison said:

Birds are theropods, and theropods are dinosaurs. So all birds are dinosaurs, but not all dinosaurs are birds.

T. Rex is a theropod. Birds are theropods. But that does not mean T. Rex is a bird. It also does not mean birds are T. Rexes or descended from T. Rexes. It's like saying that you and your aunt are both descended from your grandparents, but you are not descended from your aunt (unless you live in Westeros).

T. rex not T. rexes. Anyway, everyone has a point, not all dinos are birds as some are somehow closer related to birds that others. Sauropods and other ornithischians were probably "deleted" off the evolutionary line, meaning, they didn't evolve. As raptors were "able" to evolve, for some reason.

[Green Baron]

Saurischia ("a pelvis like a reptile lizard") is the group, besides the Ornithischia ("a pelvis like a bird") under the clade of the Dinosauria that are assumed to be the ancestors of the birds. And T. rex is in the right branch that leads to the birds, guess which ? :-)

Funnily those with a pelvis like a reptile lizard, the Saurischia are the birdy ones.

Cladistic, with all it's dis- and advantages, is the classification technique. Sometimes (as in the case above) an index of a bone is used as a classification criteria. So all this is valid until it is replaced.

And, psst, Sauropods belong to the Saurischia, or am i wrogn ?

 

Edit: changed reptile to lizard to avoid action ;-)

Edited September 2, 2017 by Green Baron