Dinosaurs were neither cold nor warm blooded

[tyrantqueen]

According to the Beeb:

http://www.bbc.co.uk/news/science-environment-27794723

There's also a study published here:

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0088834

They're calling it mesothermy. Any thoughts?

[Balaur]

I can see this for large dinosaurs. But what about the feathered dinosaurs? They were probably warm blooded. Also, it is one study. It is very interesting...

[Gwangi]

Well at some point dinosaurs must have evolved endothermy because birds are endothermic and we all know where they came from.

[Chad]

Well at some point dinosaurs must have evolved endothermy because birds are endothermic and we all know where they came from.

Yeah, I think I agree with you. Most likely there was a split at some point and so dinosaurs may have had multiple strategies to control internal temperature. Nothing is ever easy!

[DinoToyForum]

lukewarm blooded. 

Or, perhaps they had acid for blood. 

[tyrantqueen]

This isn't particularly new information. I've read this in other places before. I see nearly all theropods as being endothermic, whilst the others were probably mesotherms, as the article suggests.

[Balaur]

Well, wouldn't the feathered ornithischians be endothermic? If so, then the sauropods and ceratopsians, and Edmontosaurus, probably were the mesotherms.

[tyrantqueen]

Well, wouldn't the feathered ornithischians be endothermic? If so, then the sauropods and ceratopsians, and Edmontosaurus, probably were the mesotherms.

Um, no, not necessarily.

Why just Edmontosaurus and not the rest of the ornithopoda? Is there something special about it?

[HD-man]

According to the Beeb:

http://www.bbc.co.uk/news/science-environment-27794723

There's also a study published here:

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0088834

They're calling it mesothermy. Any thoughts?

For more info about mesothermy, see Chapter 11 in Sampson's Dinosaur Odyssey: Fossil Threads in the Web of Life ( http://www.amazon.com/Dinosaur-Odyssey-Fossil-Threads-Life/dp/0520269896 ) & Chapter 38 in Brett-Surman et al.'s The Complete Dinosaur ( http://www.amazon.com/Complete-Dinosaur-Life-Past/dp/0253357012 ). AFAIK, Reid's scientific paper isn't available online. However, Sampson's popular overview is (See 203-220/361: http://www.doc88.com/p-102817110518.html ) &, unlike said paper (which leaves feathered dino metabolism as an open question), explains how we know that non-bird maniraptorans were probably endothermic.

Well, wouldn't the feathered ornithischians be endothermic?

We still don't know whether ornithischian quills are homologous with bird feathers.

[Balaur]

Well, wouldn't the feathered ornithischians be endothermic? If so, then the sauropods and ceratopsians, and Edmontosaurus, probably were the mesotherms.

Um, no, not necessarily.

Why just Edmontosaurus and not the rest of the ornithopoda? Is there something special about it?

Sorry, I meant to put in hadrosaurs, but I got confused and put in Edmontosaurus.

[Dinoguy2]

Well at some point dinosaurs must have evolved endothermy because birds are endothermic and we all know where they came from.

Feathers or fur does not equal fully warm blooded, contrary to popular belief. The study talk about echidnas, for example, which are covered in a ridiculous amount of fur and are mesotherms.

It's been known for a long time that, based on growth rates, even many Mesozoic proto-birds like enantiornithes were not fully warm-blooded - these would probably fall in the mesotherm category. Warm-bloodedness must have evolved somewhere in the clade euornithes.

[Gwangi]

Well at some point dinosaurs must have evolved endothermy because birds are endothermic and we all know where they came from.

Feathers or fur does not equal fully warm blooded, contrary to popular belief. The study talk about echidnas, for example, which are covered in a ridiculous amount of fur and are mesotherms.

It's been known for a long time that, based on growth rates, even many Mesozoic proto-birds like enantiornithes were not fully warm-blooded - these would probably fall in the mesotherm category. Warm-bloodedness must have evolved somewhere in the clade euornithes.

I was not talking about feathers, I was talking about birds. Birds are warm-blooded and are dinosaurs so we know for a fact that some dinosaurs were/are warm blooded.

[Balaur]

Also, how accurately can you determine if an animal is endo or ectothermic using bone growth? I remember a study a while back where scientists took some samples from the teeth of Camarasaurus, saying they were endothermic. I don't remember how though.

[Yutyrannus]

Also, how accurately can you determine if an animal is endo or ectothermic using bone growth? I remember a study a while back where scientists took some samples from the teeth of Camarasaurus, saying they were endothermic. I don't remember how though.

Yeah, I remember that too.

[Balaur]

Well at some point dinosaurs must have evolved endothermy because birds are endothermic and we all know where they came from.

Feathers or fur does not equal fully warm blooded, contrary to popular belief. The study talk about echidnas, for example, which are covered in a ridiculous amount of fur and are mesotherms.

It's been known for a long time that, based on growth rates, even many Mesozoic proto-birds like enantiornithes were not fully warm-blooded - these would probably fall in the mesotherm category. Warm-bloodedness must have evolved somewhere in the clade euornithes.

I'll see of I can try to find this one paper. It said that the low temperatures of monotremes is actually due to harsh environmental conditions they live on, not a historical characteristic.

[tyrantqueen]

Well at some point dinosaurs must have evolved endothermy because birds are endothermic and we all know where they came from.

Feathers or fur does not equal fully warm blooded, contrary to popular belief. The study talk about echidnas, for example, which are covered in a ridiculous amount of fur and are mesotherms.

It's been known for a long time that, based on growth rates, even many Mesozoic proto-birds like enantiornithes were not fully warm-blooded - these would probably fall in the mesotherm category. Warm-bloodedness must have evolved somewhere in the clade euornithes.

I'll see of I can try to find this one paper. It said that the low temperatures of monotremes is actually due to harsh environmental conditions they live on, not a historical characteristic.

If that's true then why aren't all the other marsupials and mammals in Australia mesotherms too?

[Dinoguy2]

Well at some point dinosaurs must have evolved endothermy because birds are endothermic and we all know where they came from.

Feathers or fur does not equal fully warm blooded, contrary to popular belief. The study talk about echidnas, for example, which are covered in a ridiculous amount of fur and are mesotherms.

It's been known for a long time that, based on growth rates, even many Mesozoic proto-birds like enantiornithes were not fully warm-blooded - these would probably fall in the mesotherm category. Warm-bloodedness must have evolved somewhere in the clade euornithes.

I was not talking about feathers, I was talking about birds. Birds are warm-blooded and are dinosaurs so we know for a fact that some dinosaurs were/are warm blooded.

Yes, birds are dinosaurs, but the problem is talking about this without specifying which dinosaurs were birds. The question is where in the dinosaur to bird transition did warm bloodedness evole. The evidence suggests it was somewhere in Euornithes. Many people consider these to be "birds", therefore many early birds were NOT warm-blooded. Basically, everything more basal than Yanornis and Hongshanornis were mesotherms, while Ichthyornis may have been an endotherm, unless endothermy evolved independently in paleognaths and neognaths (though I think bone histology of Hongshanornis suggests it was a full endotherm).

(Oh, and that first paragraph was supposed to be in reply to Balaur, sorry for the confusion).

[Gwangi]

Well at some point dinosaurs must have evolved endothermy because birds are endothermic and we all know where they came from.

Feathers or fur does not equal fully warm blooded, contrary to popular belief. The study talk about echidnas, for example, which are covered in a ridiculous amount of fur and are mesotherms.

It's been known for a long time that, based on growth rates, even many Mesozoic proto-birds like enantiornithes were not fully warm-blooded - these would probably fall in the mesotherm category. Warm-bloodedness must have evolved somewhere in the clade euornithes.

I was not talking about feathers, I was talking about birds. Birds are warm-blooded and are dinosaurs so we know for a fact that some dinosaurs were/are warm blooded.

Yes, birds are dinosaurs, but the problem is talking about this without specifying which dinosaurs were birds. The question is where in the dinosaur to bird transition did warm bloodedness evole. The evidence suggests it was somewhere in Euornithes. Many people consider these to be "birds", therefore many early birds were NOT warm-blooded. Basically, everything more basal than Yanornis and Hongshanornis were mesotherms, while Ichthyornis may have been an endotherm, unless endothermy evolved independently in paleognaths and neognaths (though I think bone histology of Hongshanornis suggests it was a full endotherm).

That's the same problem I'm basically addressing. If dinosaurs were "mesotherms" and modern birds are endotherms then where was the transition made? I'm really not up to speed on the science here. I read Scott Sampson's book but that was back when it came out, I think early 2010 so my memory of it is hazy. Without knowing the different hypothesis I personally feel like the transition was made earlier on in theropods but you're clearly more well versed than me in this topic. That said, all we really know is that at some point, proper warm-blooded dinosaurs emerged and we only know this because they're alive today. That is the only certainty here.

[amargasaurus cazaui]

Mostly just watching this discussion, but I do remember a comment that Mike Everhart made, in regard to marine reptiles. I realize that marine reptiles are not dinosaurs but they also pose another question that fits around the edge of the debate.
  He was commenting about monitor lizards being placed in the water and how short of time they could stay warm, and what implications this might have for animals like Mosasaurus for instance. The inference he was making is that the larger marine reptiles had to have been warm blooded or utilize some form of that strategy.While they were not dinosaurs it does raise another interesting question.
  Perhaps Dr. Admin might have some thoughts on it.

[Balaur]

Mostly just watching this discussion, but I do remember a comment that Mike Everhart made, in regard to marine reptiles. I realize that marine reptiles are not dinosaurs but they also pose another question that fits around the edge of the debate.
  He was commenting about monitor lizards being placed in the water and how short of time they could stay warm, and what implications this might have for animals like Mosasaurus for instance. The inference he was making is that the larger marine reptiles had to have been warm blooded or utilize some form of that strategy.While they were not dinosaurs it does raise another interesting question.
  Perhaps Dr. Admin might have some thoughts on it.

There was a study (I know, again) that was published within the last three years, and it came to the conclusion that mosasaurs, ichthyosaurs, and plesiosaurs were all warm blooded. I'll see if I can find it.

Edit: Found an article on it. http://news.nationalgeographic.com/news/2010/06/100610-giant-sea-reptiles-warm-blooded-science/