Dinosaurs May Have Been Neither Warm-blooded Nor Cold-Blooded

An anonymous reader writes An article published in Science (abstract) points to the possibility that dinosaurs were mesotherms more akin to modern Tuna. Their internal temperature would have been warmer than their surrounding environment, conferring on them the ability to move more quickly than any ectotherm ("cold blooded" animal), but wouldn't have been constant or as warm as any endoderm ("warm blooded" animal). Their energy use and thus their necessary food intake would have been greater than an ectotherm, but much less than an endotherm. In order to arrive at this possibility, bone growth rings in fossilized bone were used to establish growth rates and then compared to modern ectotherms and endotherms.

Comments

Relation of birds to dinosaurs

[jphamlore]

So did the dinosaurs become birds or were they parallel evolved species after some earlier branching point?

Re:Relation of birds to dinosaurs

[wisnoskij]

Obviously Dinosaurs became Tuna.

Re:Relation of birds to dinosaurs

[Anonymous Coward]

"Dinosaurs" werent just a single species. There were quite a lot of them. Some of them developed feathers and went on to become birds, some stayed in the water and went on to become Nessies, but most of them just plain died and their descendants didnt evolve into anything.

Re:Relation of birds to dinosaurs

[NatasRevol]

Impossible. There's nothing in between! They couldn't have just made that jump! I'm not a monkey's uncle!!

(sarcasm, for the humor impaired)

Re:Relation of birds to dinosaurs

[mrchaotica]

Ichthyosaurs, Plesiosaurs and Mosasaurs are Lepidosaurs (the group containing lizards and snakes), which is a different branch off Diapsids from Archosaurs (the group containing dinosaurs and birds and crocodiles). Megalodon is a shark, which is a kind of fish and therefore not even a Diapsid.

New theory?

[Anonymous Coward]

TFA makes this sound like a new theory, but the first time I read an article proposing this (with supporting evidence) was at least 20 years ago, and may well have been longer ago than that.

It's nice that they've come up with more evidence for it, but it would also be nice if every time someone tested an idea out they didn't feel compelled to pretend they were the first to have it.

Re:New theory?

[Oligonicella]

Yep. Paleontology is a field rife with one-upmanship. Cold blooded, warm blooded, hot blooded and meso. All had their day multiple times. My personal belief is that the theropods were most likely hot-blooded like the birds and the sauropods were meso-blooded. Their respective activity levels make this likely to me.

Re:New theory?

[Anonymous Coward]

It's nice that they've come up with more evidence for it, but it would also be nice if every time someone tested an idea out they didn't feel compelled to pretend they were the first to have it.

I think this is a very unfair attack. The authors of this paper did not make the claim you've attributed to them. They start the actual article with this.

Over the past few decades, the original characterization of dinosaurs by early paleontologists as lumbering, slow-metabolizing ectotherms has been challenged.

There are 397 references given in this paper. I think they're clear about what previous science existed. Even the lay article doesn't pretend this is new research it talks about compiling existing research.

Re:New theory?

[Princeofcups]

After several false starts during which she repeatedly and noisily attempts to clear her throat, Ms. Elk spends most of the interview circuitously leading up to the "theory of dinosaurs by Anne Elk bracket Miss brackets", making assertions like "My theory, which belongs to me, is mine." It turns out that in the end Miss Elk's new theory on brontosauruses is rather shallow: "All brontosauruses are thin at one end, much, much thicker in the middle, and then thin again at the far end." Her true concern is that she receive full credit for devising this new theory: "That is the theory that I have, and which is mine, and what it is too."