T Rex: mighty forebear of the ... chook

[Drooling Iguana]

Insert obligatory dinosaurs taste like chicken joke here

Thats ok, If his brain was large enough the T-Rex would probably think the same of you. ;-)

More likely it would think we tasted like pork.

[Akhlut]

Most Theropods have air sacs and a bird-like pulmonary system.

Ah. Well, as I said, dinosaurs and birds are not my strong point.

Does taxonomy only concern skeletal issues? Surely this is necesary in the fossile record, but I though a main trait that places one within Mammalia is hair/fur and lactation? Correct me if I'm wrong. Of course, we have no way of knowing when the Synapsids developed lactation and hair due to the lack of trace of such features in fossils. In any case, some later Therapsids had the D-S Joint.

As it is, we are arguing semantics, taxonomy is not precise, particularly in the fossil record, but also overall, as so-called "transitory species" that have traits from two different clades are difficult to place on a cladogram.

For modern mammals, I'd assume it's mainly lactation (as evidenced by cetaceans, who lack fur, basically), though fur and heterodonty probably play a fairly large role, too, as nothing else alive has those features.


Also, I'm not saying I necessarily disagree with you on the way that the taxonomic arrangement should be, just that I'd imagine taxonomists would find some reason to differentiate between bird-like dinosaurs and birds.

[Vehrec]

It's pretty much a given that ALL dinosaurs- not just theropods- were endothermic. Pterosaurs HAD to be, they're impossible otherwise. And pterosaurs diverged earlier than theropods. So either the archosaurs have developed warm-bloodedness twice or the cutoff is anything more advanced than a crocodile. Interestingly, crocodiles already have most of the necessary hardware (an advanced heart that distinguishes them from lizards).

Interesting. What are some ideas on how Sauropods coped with being endothermic, the issue being radiating heat despite their great mass and food consumption?

Well, I think that there are really only two ways to go about this. first, increasse surface area by wrinkling up that skin a lot. Second, drop the core temperature a few degrees anyways. Thirdly, and prehaps most importantly, run the arteries close to the surface of the skin in the neck, legs and tail. This will serve as an adaquete counter-current cooling system, at least it does in most animals.

[Johonebesus]

Interesting. What are some ideas on how Sauropods coped with being endothermic, the issue being radiating heat despite their great mass and food consumption?

Well, I think that there are really only two ways to go about this. first, increasse surface area by wrinkling up that skin a lot. Second, drop the core temperature a few degrees anyways. Thirdly, and prehaps most importantly, run the arteries close to the surface of the skin in the neck, legs and tail. This will serve as an adaquete counter-current cooling system, at least it does in most animals.

One documentary on the Discovery Channel (not the best source, I know) stated that exothermic creatures are not perfectly cold blooded. They still produce heat, they just can't regulate it and will cool off too quickly in the wrong conditions. However, the greater the mass, the less heat is lost, and, assuming they were similar to crocodiles, the scientists calculated that exothermic sauropods would still have high body temperatures comparable to mammals and birds.

Is there any reason in this at all? Disc.'s documentaries are often grossly oversimplified and inaccurate, but they usually aren't that far off.

[Akhlut]

One documentary on the Discovery Channel (not the best source, I know) stated that exothermic creatures are not perfectly cold blooded. They still produce heat, they just can't regulate it and will cool off too quickly in the wrong conditions. However, the greater the mass, the less heat is lost, and, assuming they were similar to crocodiles, the scientists calculated that exothermic sauropods would still have high body temperatures comparable to mammals and birds.

Is there any reason in this at all? Disc.'s documentaries are often grossly oversimplified and inaccurate, but they usually aren't that far off.

This is an anecdote from my mammalogy prof., but I have no reason to believe that the incident didn't occur back in the 60s or whatever. Anyway, a scientist was on a whaling boat, if I'm not mistaken, and he measured the body temperature of a freshly dead whale in relatively cold ocean water. After a few days of being dead and still being in the water, the whale's body temperature was taken again and it remained the same.

So, yeah, I wouldn't be surprised if the ambient body temperature produced by sauropods' cells, however little it was, would be conserved by their enormous masses and comparitively smaller surface area.

[The Original Nex]

Also, I'm not saying I necessarily disagree with you on the way that the taxonomic arrangement should be, just that I'd imagine taxonomists would find some reason to differentiate between bird-like dinosaurs and birds.

Aye, I agree with you there. I would think they'd be slow to change with the ammount of reorganization we're talking about.

Well, I think that there are really only two ways to go about this. first, increasse surface area by wrinkling up that skin a lot. Second, drop the core temperature a few degrees anyways. Thirdly, and prehaps most importantly, run the arteries close to the surface of the skin in the neck, legs and tail. This will serve as an adaquete counter-current cooling system, at least it does in most animals.

I see. I wonder if radiative dewlaps or similar structure would have been utilized. Though that goes along with increased surface area as you said.

One documentary on the Discovery Channel (not the best source, I know) stated that exothermic creatures are not perfectly cold blooded. They still produce heat, they just can't regulate it and will cool off too quickly in the wrong conditions. However, the greater the mass, the less heat is lost, and, assuming they were similar to crocodiles, the scientists calculated that exothermic sauropods would still have high body temperatures comparable to mammals and birds.

Yes, I'm aware of exothermic theories on Sauropods, I was wondering about endothermic Sauropods regulating temperature, because, as Darth Raptor said, it is likely all dinosaurs were endothermic.

[Broomstick]

This new study leads me to a question:

If dinosaurs are found to not only close relatives of birds, but ancestors as well, doesn't that actually make them birds? For example, bats are descended from insectivores like shrews, but they aren't given a new class. They are mammals. Under the Linnaean system the older name takes precedence. Wouldn't the dinosaurs be "retconned" as Aves?

No.

Go back far enough and mammals have fish ancestors, but they aren't fish. Reptiles have amphibians in the family tree way back, but they aren't amphibians.

If the differences are great enough you get a new category. With dinos and birds you may have quibbles over where to draw the line, but feathers and warm blood distinguish birds from reptiles. You might get some dinos classified as reptiles and some as birds, and maybe "dinosaur" might pass away or be redefined (possibly as "warm blooded reptile without feathers" or some such). But "reptile" and "bird" were categories before "dinosaur", which was considered a subset of "reptile" anyhow.

[Broomstick]

like that for mammals and reptiles (wherein the only thing that separates mammals from reptiles, taxonomically speaking, is the fact that mammals have dentary-squamosal joints for their jaws and reptiles don't).

And hair, and lactation.

Hair is seldom preserved in rock and lactation not at all - seemed to me, from the context, the poster was referring to the fossil record here and not living animals. The jaw-joint distinction is one that can be seen in a skeleton.

[hongi]

Does taxonomy only concern skeletal issues? Surely this is necesary in the fossile record, but I though a main trait that places one within Mammalia is hair/fur and lactation?

Cladistics too. If you are a descendant of mammals, you are a mammal.

[Shogoki]

Why aren't we injecting this protein into frog eggs? I want a God Damned baby T-Rex for a pet!

And then you'll flush it down the toilet and we'll end up with giant reptiles rampaging beneath the streets, eating the crocodiles and alligators.

...Actually, that sounds like a cheesy, but enjoyable Sci-Fi movie.

I would pay to see that.

[Ritterin Sophia]

And then you'll flush it down the toilet and we'll end up with giant reptiles rampaging beneath the streets, eating the crocodiles and alligators.

This is a lie, I've never flushed a live animal down the sink, as my pet alligators Fluffy (Female) and Cuddles (Male) can attest, so the only rampaging dinosaurs will either be zombie baby T-Rex's or the T-Rex I have trained as a mount that attacks on command.