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The published paper for this article appeared in PLOS ONE on 19th December 2018. You can download it here.

NYITCOM News Release

 

Embargoed for Release Wednesday, 19 December 2018, 2 PM EST

Study Finds Dinosaurs Battled Overheating with Nasal Air-Conditioning

 

Researchers used 3D computer modeling to simulate heat exchange in dinosaurs

 

Jonesboro, AR; December 19, 2018—Researchers have long wondered how huge, heavily armored dinosaurs, such as the club-tailed ankylosaurs which lived in swealtering climates, avoided overheating. While their large bodies were adept at retaining heat, their sheer  size created a heat-shedding problem that would have put them at risk of overheating, even on cloudy days. In the absence of a protective cooling mechanism, the delicate neural tissue of the brain could be damaged by the hot blood from the body’s core.

 

Now, as seen in the December 19 issue of PLOS ONE, researchers, led by a paleontologist from New York Institute of Technology College of Osteopathic Medicine at Arkansas State University (NYITCOM at A-State), have posed a new theory—the dinosaurs had an intricate cooling system in their snouts.

 

“The large bodies of many dinosaurs must have gotten very hot in warm Mesozoic climates, and we’d expect their brains to adapt poorly to these conditions. With that in mind, we wanted to see if there were ways to protect the brain from ‘cooking.’ It turns out the nose may be the key, and likely housed a ‘built-in air conditioner,’” said Jason Bourke, Ph.D., assistant professor of basic sciences, NYITCOM at A-State, and lead author of the study.

According to the researchers, smell may be a primary function of the nose, but noses are also important heat exchangers, ensuring that air is warmed and humidified before it reaches the 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 and allow for air to come into contact with more of the nasal walls.

 

The team used Computed Tomography (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. These tests examined how well ankylosaur noses transferred heat from the body to the inhaled air. The researchers found that ankylosaurs lacked turbinates, and instead evolved to have longer, coiled noses. Despite this strange anatomy, these noses were just as efficient at warming and cooling respired air.

 

“A decade ago, my colleague and I published the discovery that ankylosaurs had extremely long nasal passages coiled up in their snouts,” said study co-author Lawrence Witmer, professor of Anatomy, Ohio University Heritage College of Osteopathic Medicine. “These convoluted airways resembled a child’s ‘crazy-straw’—completely unexpected and seemingly without reason, until now.”

 

In Panoplosaurus, the nasal passages were a bit longer than the skull itself, and in Euoplocephalus they were almost twice as long as the skull, as well as coiled up 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 by over 50% 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 blood vessels were reconstructed, based on bony grooves and canals, the team found a rich blood supply running right next to these convoluted nasal passages. According to Ruger Porter, lecturer at the Ohio University Heritage College of Osteopathic Medicine and another 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.

 

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.

“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.”

 

The next step for the researchers is to examine other dinosaurs to determine when this nasal enlargement happened. For more information about NYITCOM at A-State, visit nyit.edu/Arkansas.

 

The research was funded by National Science Foundation (NSF) grants to Witmer and an NSF fellowship to Bourke, as well as by the Ohio University Heritage College of Osteopathic Medicine.

 

About NYITCOM at A-State

New York Institute of Technology College of Osteopathic Medicine at Arkansas State University (NYITCOM at A-State) is located in Jonesboro, AR, on the campus of Arkansas State University. Medical degrees are conferred by NYIT, a private, non-profit institution of higher education that established its medical school (NYITCOM) program in Jonesboro to meet the need for more physicians in this medically underserved area. Upon welcoming its inaugural class of 115 medical students in August 2016, NYITCOM at A-State began delivering on its mission to improve access to health care for the underserved and rural populations in the Mississippi Delta Region.

 

 

Editors:


Advance copy can be downloaded here:  https://people.ohio.edu/witmerl/Downloads/Bourke_et_al-Ankylosaur_MS_PLOS_ONE_Revisions-3.pdf
Related images and animations can be downloaded from the WitmerLab site: https://people.ohio.edu/witmerl/ankylosaur_brain-AC.htm
A fact sheet can be accessed here: https://people.ohio.edu/witmerl/Downloads/Dinosaur_nasal_air-conditioning_Fact_Sheet.pdf 

Contacts (all Eastern Daylight Time):


1. Jason Bourke, 740-818-7503, jbourke@nyit.edu [lead author]
2. Lawrence Witmer, 740-591-7712, witmerL@ohio.edu [co-author]
3. Jim Sabin, 740-593-0858, sabin@ohio.edu [Ohio University Communications and Marketing]
4. Kim Tucker, 516-686-4013, kimberly.tucker@nyit.edu [PR Strategist, NYIT]

 

Media

For more media options, including 3D PDFs of the two specimens studied, please visit the WitmerLab mirror for this study.

Images

Caption

Authors of the article investigate key features in the skulls of ankylosaurian dinosaurs in WitmerLab at Ohio University. From left: Jason Bourke, Ruger Porter, and Lawrence Witmer. Courtesy of WitmerLab at Ohio University.

Caption

Heat exchange through the highly convoluted nasal passages of the Cretaceous ankylosaurian dinosaur Euoplocephalus not only efficiently warmed and humidified the inspired air on its way to the lungs but also cooled the blood running through the nasal veins, much of which was destined for the brain. In this way, the brain was protected from the high temperatures of the hot arterial blood coming from the body core. Courtesy of WitmerLab at Ohio University.

(Silhouettes: Marmelad - CC-BY-SA-2.5)

Caption

This study of dinosaur thermal physiology focused on the Cretaceous ankylosaurian dinosaur Euoplocephalus (illustrated here), as well another less specialized ankylosaur called Panoplosaurus. Both dinosaurs were found in Late Cretaceous fossil deposits of Alberta, Canada. The research team used CT scanning, soft-tissue reconstruction, and engineering analyses (computational fluid dynamics) to simulate air and blood flow and calculate heat exchange in the nasal passages. Courtesy of WitmerLab at Ohio University. (Silhouettes: Marmelad - CC-BY-SA-2.5)

Caption

The Late Cretaceous armored dinosaur Euoplocephalus (center) had a long, highly convoluted nasal passage coiled up in its snout. The physiological efficiency of heat exchange was tested by computational fluid dynamics analyses that compared the (top left) “bony bounded” airway (i.e., as preserved in the fossil), (top right) the “soft tissue” airway (closer to real life due to restored nasal mucous membrane), (top middle) the “basic airway” (short and simple, as in many animals, including humans), and (bottom) the “straightened airway” (same length as bony-bounded and soft-tissue airways but without convolutions). The basic airway is the least efficient, and the long convoluted soft-tissue air is the most efficient as well as the most realistic. The long straight airway was also very efficient but less so than the convoluted airway, indicating that the twists and turns contribute significantly, probably due to the increased vorticity that slowed down the airstream and increased the chance for heat transfer. Courtesy of WitmerLab at Ohio University.

Euoplo_Skull_with_Airways.png

Caption

The skulls of the two ankylosaurian dinosaurs—Panoplosaurus and Euoplocephalus—that were the focus of the research. The skulls are rendered semitransparent, revealing the convoluted “crazy-straw” nasal passages coiled within their snouts. Colors within the nasal passages show the heat exchange modeled by the computational fluid dynamics analysis. The heat exchange allowed efficient warming and humidification of the inspired air. The more elaborately coiled nasal passages of Euoplocephalus were more efficient than the simpler ones of Panoplosaurus. Courtesy of WitmerLab at Ohio University.

Movies & Gifs

This movie is associated with an article published in PLOS ONE on 19 December 2018 (http://bit.ly/2rzFudE) by Jason Bourke, Ruger Porter, and Lawrence Witmer. Nasal airflow was modeled using Computational Fluid Dynamics analyses for two Late Cretaceous ankylosaurian dinosaurs, Panoplosaurus and Euoplocephalus. The video demonstrates how the highly convoluted nasal cavity in both species warms the inhaled air on its way to the lung and then cools the exhaled air, resulting in a highly efficient system of air conditioning that conserves both heat and water. For more in this project, visit the WitmerLab project page: http://bit.ly/2EwOzMO.

Animated GIF (640x360, 10 MB): Heat exchange of inspired air as it passes through the tortuous nasal cavity of the Late Cretaceous ankylosaur Euoplocephalus. The computational fluid dynamics analysis shows the flow of air during inhalation, with color—i.e., gray to red to orange to yellow—indicating progressively warmer temperatures. Euoplocephalus has a very efficient nasal cavity fully warming and humidifying the inspired air before it reaches the lungs; Panoplosaurus, with its simpler nose is somewhat less efficient but still impressive. Likewise, on exhalation, the long convoluted airways cool the expired air, saving heat and energy. Courtesy of WitmerLab at Ohio University.


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