Posted on 12/19/2018 11:52:43 AM PST by ETL
Being a gigantic dinosaur presented some challenges, such as overheating in the Cretaceous sun and frying your brain. Researchers from Ohio University and NYITCOM at Arkansas State show in a new article in PLOS ONE that the heavily armored, club-tailed ankylosaurs had a built-in air conditioner in their snouts.
"The huge bodies that we see in most dinosaurs must have gotten really hot in warm Mesozoic climates," said Jason Bourke, Assistant Professor at the New York Institute of Technology College of Osteopathic Medicine at Arkansas State and lead author of the study. "Brains don't like that, so we wanted to see if there were ways to protect the brain from cooking. It turns out the nose may be the key."
Bourke and the team used CT scanning and a powerful engineering approach called computational fluid dynamics to simulate how air moved through the nasal passages of two different ankylosaur species, the hippo-sized Panoplosaurus and larger rhino-sized Euoplocephalus, to test how well ankylosaur noses transferred heat from the body to the inhaled air.
"A decade ago, my colleague Ryan Ridgely and I published the discovery that ankylosaurs had insanely long nasal passages coiled up in their snouts," said study co-author Lawrence Witmer, professor at the Ohio University Heritage College of Osteopathic Medicine. "These convoluted airways looked like a kid's 'crazy-straw!' It was completely unexpected and cried out for explanation. I was thrilled when Jason took up the problem as part of his doctoral research in our lab."
"This project is an excellent example of how advances in CT scanning, 3-D reconstruction, imaging, and computational fluid dynamics modeling can be used in biological research to test long-standing hypotheses," said Kathy Dickson, a program officer at the National Science Foundation that funded the research. "From these new images and models, fossils can provide further insight into extinct organisms like the ankylosaur—in this case, offering an explanation of how unusual features actually function physiologically."
Smell may be a primary function of the nose, but noses are also heat exchangers, making sure that air is warmed and humidified before it reaches our delicate lungs. To accomplish this effective air conditioning, birds and mammals, including humans, rely on thin curls of bone and cartilage within their nasal cavities called turbinates, which increase the surface area, allowing for air to come into contact with more of the nasal walls. "Ankylosaurs didn't have turbinates, but instead made their noses very long and twisty," said Bourke.
When the researchers compared their findings to data from living animals, they discovered that the dinosaurs' noses were just as efficient at warming and cooling respired air. "This was a case of nature finding a different solution to the same problem," said Bourke.
Just how long were these nasal passages? In Panoplosaurus, they were a bit longer than the skull itself and in Euoplocephalus they were almost twice as long as the skull, which is why they're coiled up in the snout. To see if nasal passage length was the reason for this efficiency, Bourke ran alternative models with shorter, simpler nasal passages that ran directly from the nostril to the throat, as in most other animals. The results clearly showed that nose length was indeed the key to their air-conditioning ability. "When we stuck a short, simple nose in their snouts, heat-transfer rates dropped over 50 percent in both dinosaurs. They were less efficient and didn't work very well," said Bourke.
Another line of evidence that these noses were air conditioners that helped cool the brain came from analyses of blood flow.
"When we reconstructed the blood vessels, based on bony grooves and canals, we found a rich blood supply running right next to these convoluted nasal passages," said Ruger Porter, lecturer at the Ohio University Heritage College of Osteopathic Medicine and one of the study's co-authors. "Hot blood from the body core would travel through these blood vessels and transfer their heat to the incoming air. Simultaneously, evaporation of moisture in the long nasal passages cooled the venous blood destined for the brain."
So why the need for such effective heat exchangers? The large bodies of Panoplosaurus and Euoplocephalus were really good at retaining heat, which is good for staying warm, but bad when the animals need to cool off. This heat-shedding problem would have put them at risk of overheating even on cloudy days. In the absence of some protective mechanism, the delicate neural tissue of the brain could be damaged by the hot blood from the body core.
The complicated nasal airways of these dinosaurs were acting as radiators to cool down the brain with a constant flow of cooled venous blood, allowing them to keep a cool head at all times. This natural engineering feat also may have allowed the evolution of the great sizes of so many dinosaurs.
"When we look at the nasal cavity and airway in dinosaurs, we find that the most elaborate noses are found in the large dinosaur species, which suggests that the physiological stresses of large body size may have spurred some of these anatomical novelties to help regulate brain temperatures," Witmer said.
The next step for the researchers is to examine other dinosaurs to determine when this nasal enlargement happened.
"We know that large dinosaurs had these crazy airways, but at exactly what size did this happen?" Bourke said. "Was this elaboration gradual as body size increased, or is there a threshold size where a run-of-the-mill nose can no longer do the job? We just don't know yet."
Explore further: Dinosaurs used nasal passages to keep brains cool
More information: PLOS ONE (2018). journals.plos.org/plosone/arti … journal.pone.0207381
Journal reference: PLoS ONE 
Provided by: Ohio University
"....so what you're saying is these gigantic walking air conditioners were the start of global warming?"
achoo! bkmk
So the warm blooded vs cold blooded debate is over?
Ankylosaurs were cool, right? They didn’t bother you guys (Sauropods), did they?
Or maybe they were snuffing whole coca leaves.
Anyone given any thought to the so-called “Dinosaur and Gravity Problem”?
I’m not sure Saturn is the answer, but would like to know if there’s something more widely accepted.
https://www.bibliotecapleyades.net/ciencia/ciencia_dinosaurs01.htm
If they did, we just stepped on ‘em. ;-D
That must have hurt!
Hmm, this might suggest that Saturn’s rings are “young”...
https://earthsky.org/space/saturns-rings-disappearing-ring-rain-video
FWIW, likely my last post on the subject in this thread, I’m really liking this explanation....
https://www.dinosaurtheory.com/big_dinosaur.html
Ankylosaurs
dinosaur version of ankle biters? :)
Thanks ETL.
arctic dinosaur site:freerepublic.com -- Google
antarctic dinosaur site:freerepublic.com -- Google
The Ankylosaurs tried to replace the Kylosaurs, but both lost out to the StatuteMilosaurs.
Sorry for the slow reply - have mostly been away the last couple days.
This entire topic of how to explain the larger dinosaurs’ size is VERY interesting to me. I tend to dismiss the Jupiter / Saturn / much different planetary System explanation because virtually all the available evidence flies against it. For one thing, even Jupiter is not big enough to actually become even a weak star. Even if that is incorrect, then you have the paradox of Earth being so close to Jupiter as to cause drastically lower gravity on the Jupiter-facing side of Earth (relatively a greater effect than what Mercury sees from the much more massive Sun), and the “star” Jupiter is producing sufficient light to grow plants on Earth (like crazy), yet this practically “right on top of us” white-hot oven is not roasting the Earth.
Maybe some non-fusion source of the light “works” in this “design”, but none such has ever been observed, that I know of.
Then there is the problem of how you get from that old Jupiter - Saturn System to what we have today. The orbital mechanics just don’t work out...
The “very dense atmosphere Earth” hypothesis seems a bit more likely. However, there were plenty of “2018-size” flying insects (as well as larger versions) in the era of the dinosaurs, and I’ve never heard or read that those insects were adapted to a very dense atmosphere.
The author at that last link also proposes a FAIRLY dense atmosphere until rather recently, and the core samples simply don’t back that up.
We are left with some fascinating mysteries!
Sorry, you lost me when you threw Saturn in the mix.
Thanks, it wasn’t my idea, had found an odd theory that reminded me of an early James P. Hogan novel, and provided a link to it, but I didn’t especially like it.
I like the denser atmosphere idea I later posted, but haven’t seriously analyzed the math supporting it.
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