Dinosaurs are hot & sexy... but mostly hot.

In celebration of this being my last blog, I step out of bounds (but only one, teeny, tiny little step) and discuss physiology, a slight divergence from communication. I poured over the sites we have linked and nothing really tickled my fancy as far as communication was concerned.

I'm going to write about dinosaurs. Come on. Who doesn't like them?

If you are at all interested in Dinosaurs... hell, even if you aren't THAT interested, you're in a 500 level bio class about animals, so you may know this anyway... Dinosaurs have been the subject of the hottest debate ever known to man: were they cold blooded or warm blooded?... or, simply creations of some higher power...

Seriously, dinosaurs have been under the scope for a long time. The debate has raged as to whether or not their massive size was fueled by the suns warmth, as in lizards, snakes, and other cold blooded creatures, or by their own ability to regulate body temperature via their own metabolism (warm blooded).

Herman Pontzer, an avid sandal enthusiast and assistant professor of Anthropology at some school called Harvard, did a pretty awesome study that showed Dinosaurs must be warm-blooded. He used a biomechanical model that used the size of animals leg bones based on fossil findings to predict the energy cost of walking and running. And by model, I mean some incredibly awesome math equations that look a little bit like these:

COT (mlO2 kg−1 m−1)
Vmusc (cm3 kg−1 m−1)

In fact, they look EXACTLY like those, because those are the EXACT equations he used. The first is the cost of transport (measured in milliliters of oxygen) and the second is the volume of muscle activated based on the estimated mass of the animal.

The basic idea is that the size of the muscle can reliably relate to the amount of energy that is needed to use it. Since warm blooded animals have a greater aerobic capacity (i.e. their ability to use oxygen as energy) than cold blooded animals, the fact that dinosaurs had larger muscles and thus larger energy requirements would favor the idea that they must have been warm blooded.

The paper cites an awesome study done previously, way back in the day, in 2000, that found a dinosaur fossil that contained a fossilized heart:

Those researchers did a CT scan of the fossilized heart and found a four-chambered, double-pump heart with one aorta:

In case you don't know, or are are a little foggy or something, those heart structures exactly coincide with like... almost every single warm blooded creature on Earth, including us:




















There are few inconsistencies, of course, that keep the debate far from being over. The dinosaur nose lacks a certain structure called the turbinate, which protects against water loss in rapid breathing. This structure is only found in something like 99% of warm blooded animals though, so who really cares, dinosaurs are sweet. They probably had some way cooler method of protecting against water loss anyway. Finally, I guess this paper implies that the cost of walking and running is directly correlated to the dinosaurs size, which a bunch of paleontologists disagree with.

Article

Welp, that's all folks... until I reply to whatever comments I get, which will hopefully be myriad in nature... at which time, THAT will be all, unless you read my blog, which is totally cool and has less rambling.

Alex out.

Comment Replies:

Bethany: That's awesome, and it would have been even funnier if you got shushed by someone. Thank you for the compliments. The reason that some paleontologists disagree with the idea that energy cost and size are related is that, apparently, the two can also be related in cold blooded animals. Some guy that the article mentions says that net cost is "roughly similar" in all vertebrates, cold blooded AND warm blooded, so they still could have been cold blooded.

Jess: Thanks, I think that this is one of the vaguest things to try and answer. I read some discussions online and the whole quarrel is that we haven't found EVERY fossil EVER, so it's impossible to say definitely that all dinosaurs didn't have something similar to a turbinate. Apparently some bird AND dinosaur fossils they found in the Mesozoic have similar structures to the turbinate. Also, there are some warm blooded animals now that do not have the turbinate and manage just fine.

Christine: Thanks, I'm really glad you liked the post. According to what I found, I don't think the four chamber heart would necessarily make them less reptilian. Some reptiles like Crocodiles have four chamber hearts, so I think it just makes them different in that maybe it helped them be better evolved to maintain such large sizes.

Deysha: Right?! When I found out that that asshole Spielberg's representation of a Velociraptor was wrong (and unfortunately way cooler than the Raptors that really existed) I was pretty pissed off. Then the feather thing happened, and I was like... Eh, that kind of sucks... it's still not certain as far as I know that they had feathers, I think it's just an idea and excuse to make different drawings in dinosaur books (if you can prove me wrong here, and evidence has shown that some dinos did have feathers, I'll cry). And THEN, when I found out the Brontosauruses really didn't exist I was even more pissed. Brontosauruses were supposedly another species of dinosaur but really weren't different enough to get labeled as an independent species, so they're really called Apatosauruses, but supposedly they're synonymous out of sympathy for all the Bronty fans.

Crystal: Thanks for the compliments. As for your question, I know what you mean-- tons of birds are descended from dinosaurs, and it's pretty difficult to get the proper discrimination between all of them and their history. Like I said in an earlier reply, not all dinosaur fossils have been found, and especially not with preserved hearts like the one mentioned in my post. This leaves room for a lot of guess work and theorizing as to warm or cold bloodedness and heart anatomy. So I don't think anyone is really able to say that one thing applies to all dinosaurs, but they're just going with what they find.

Alyson: Thanks for the props! I think that what muscles that the flying dinosaurs lacked for running, they probably made up for with their flying muscles. The dinosaurs that flew back then were considerably larger than most birds we know today, so I think their muscle mass and energy demands must have been pretty huge. I couldn't find anything in regards to what animals in present day don't have a turbinate, but I'm on your side. I would guess that they probably are at least more closely related to dinosaurs than other evolved animals today with the turbinate.