Lawrence M. Witmer, PhD
Professor of Anatomy
Chang Professor of Paleontology

Dept. of Biomedical Sciences
Heritage College of Osteopathic Medicine
Life Science Building, Rm 123
Ohio University
Athens, Ohio 45701 USA

Email: witmerL@ohio.edu

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Breathing life into dinosaurs — modeling nasal airflow in pachycephalosaurid dinosaurs

Common Language Summary
3D modeling of airflow sheds new light on dinosaur smelling and physiology. Technology, engineering, and anatomy provide the first ever glimpse into how air moves through the head of a breathing dinosaur. A team of researchers lead by an Ohio University doctoral student capitalized on the discovery of extraordinary preservation of soft tissues within the nasal cavities of dinosaurs, leading to new findings about not just breathing, but also brain cooling and the sense of smell. The Cretaceous “bone-headed” pachycephalosaurid dinosaurs were small herbivores known for thick bony skulls. Building all that bone had the by-product of ossifying delicate nasal tissues that usually don’t fossilize. CT scanning the fossils of a Canadian “pachy” called Stegoceras revealed these internal structures in unprecedented detail, including scrolled olfactory “turbinates” in the back of the nose and a long bony ridge in the front. By adapting techniques from a branch of engineering called computational fluid dynamics, the team was able to simulate airflow during breathing and test different turbinate shapes. The simulations revealed that for realistic airflow to take place, the bony ridge must have supported a respiratory turbinate in the front of the nasal cavity that helped to direct inspired air to the olfactory region in the back, directly adjacent to the part of the brain that processes odor information. The idea of respiratory turbinates as baffles to direct air around the nasal cavity had never been suggested for dinosaurs. Moreover, the team discovered patterns of blood flow in the nasal region of Stegoceras that indicate that the turbinates also likely functioned to cool blood destined for the brain, allowing these animals to moderate brain temperatures in times of heat stress. Armed with these new techniques, the team will now tackle other more complicated dinosaur noses, such as those of ankylosaurs and hadrosaurs.

Graphics & Animations

Airflow modeled through the nasal cavity of the Cretaceous pachycephalosaur Stegoceras based on restoration of nasal soft tissues and Computation Fluid Dynamics of nasal airflow. This is the first study to analytically model nasal airflow in any extinct animal. A very general key finding was that comparative anatomy can be combined with engineering to restore the nasal physiology of extinct species. Courtesy of WitmerLab at Ohio University.

Airflow modeled through the nasal cavity of the Cretaceous pachycephalosaur Stegoceras based on restoration of a respiratory turbinate onto a long bony ridge preserved in the fossil. Simulations using computational fluid dynamics software revealed that a turbinate of at least broadly similar shape must have been present to act as a baffle to allow realistic airflow to the olfactory region. Courtesy of WitmerLab at Ohio University.

Restoration of blood flow through the nasal cavity of the Cretaceous pachycephalosaur Stegoceras . The restored respiratory turbinate increased the surface area of the nasal tissues. Hot arterial blood coming from the body core would have been cooled by evaporation on the respiratory turbinate, and the cooled venous blood would have then flowed to the brain region to moderate brain temperatures. Courtesy of WitmerLab at Ohio University.


A irflow modeled through the nasal cavity of the Cretaceous pachycephalosaur Stegoceras in the absence of restoration of a respiratory turbinate. The fossil itself only preserves a bony ridge, not the respiratory turbinate itself. Simulations using computational fluid dynamics software revealed that, taking the fossil at “face value,” absence of the turbinate produces unrealistic airflow patterns in that almost no inspired air reaches the olfactory region. Courtesy of WitmerLab at Ohio University.


Skeleton of the Cretaceous pachycephalosaur Stegoceras with the silhouette of a human for scale. The original skull of Stegoceras is shown at top right. Skeleton and silhouette provided by C. Brown, Royal Tyrrell Museum of Palaeontology; photo of skull provided by P. Currie, University of Alberta. Courtesy of WitmerLab at Ohio University.


Silhouettes of the Cretaceous pachycephalosaur Stegoceras in head-butting posture and of a human, for scale. The original skull of Stegoceras is shown at top left. Silhouettes provided by C. Brown, Royal Tyrrell Museum of Palaeontology; photo of skull provided by P. Currie, University of Alberta. Courtesy of WitmerLab at Ohio University.

Mounted skeletons two Stegoceras in the gallery at the Royal Tyrrell Museum of Palaeontology in Drumheller, Alberta. Photo by S. Bergmann, Wikipedia.

Animation of simulated airflow in the Cretaceous pachycephalosaurid dinosaur Stegoceras (UALVP 2) based on different models of restored nasal soft tissues. In the absence of any restored soft tissues, modeled airflow bypasses the olfactory region, which is not realistic. By modeling a respiratory turbinate (in this case, an ostrich-like branched concha) attaching to the preserved bony ridge, realistic olfactory airflow is modeled. It's also likely that the nasal structures functioned to cool blood that was destined for the brain region. This is largely the work of Jason Bourke (Ohio University) to accompany an article published in the Anatomical Record (2014) by Bourke, Porter, Ridgely, Lyson, Schachner, Bell, and Witmer. Research supported in part by the NSF-funded Visible Interactive Dinosaur project, WitmerLab at Ohio University. Download a 43 MB QuickTime version (HD: 1920x1080)
Download a 24 MB QuickTime version (1280x720)
Download a 14 MB QuickTime version (853x480)
Download a 10 MB QuickTime version (640x360)

Animation of simulated airflow in the Cretaceous pachycephalosaurid dinosaur Stegoceras (UALVP 2) based on different models of restored nasal soft tissues. This video is largely the work of Jason Bourke (Ohio University) and is an AR WOW video ( http://bcove.me/k1si0ck1 )  to accompany an article published in the Anatomical Record (2014) by Bourke, Porter, Ridgely, Lyson, Schachner, Bell, and Witmer. Research supported in part by the NSF-funded Visible Interactive Dinosaur project, WitmerLab at Ohio University. Download a 102 MB QuickTime version (HD: 1920x1080)
Download a 58 MB QuickTime version (1280x720)
Download a 28 MB QuickTime version (853x480)
Download a 19 MB QuickTime version (640x360)


Skulls of pachycephalosaurid dinosaurs discussed in the scientific article, based on volume-rendered CT scan data. The three Sphaerotholus specimens are missing the facial part of the skull. Scale bar is 3 cm. Courtesy of WitmerLab at Ohio University.


The original skull of Stegoceras . Photo of skull provided by P. Currie, University of Alberta. Courtesy of WitmerLab at Ohio University.

Animated GIF: A irflow modeled through the nasal cavity of the Cretaceous pachycephalosaur Stegoceras in the absence of restoration of a respiratory turbinate. Courtesy of WitmerLab at Ohio University.

Animated GIF: Restored respiratory turbinate moving into place to attach to the long internal nasal ridge preserved in the fossil. Courtesy of WitmerLab at Ohio University.

Animated GIF: Airflow modeled through the nasal cavity of the Cretaceous pachycephalosaur Stegoceras based on restoration of nasal soft tissues and Computation Fluid Dynamics of nasal airflow. Courtesy of WitmerLab at Ohio University.


Animated GIF: Restoration of blood flow through the nasal cavity of the Cretaceous pachycephalosaur Stegoceras . Courtesy of WitmerLab at Ohio University.

Ohio University News Release

EMBARGOED FOR RELEASE TUESDAY, 14 OCT 2014, 4:00 PM EDT

Dinosaur breathing study shows that noses enhanced smelling and cooled brain
Researchers discover preserved nasal features in bony-headed dinosaur fossils

ATHENS, Ohio (Oct. 14, 2014)—It’s been millions of years since T. rex took its last breath, but a team led by Ohio University scientists is breathing life back into dinosaurs using high-powered computer simulations to model airflow through dinosaur snouts. The research has important implications for how dinosaurs used their noses to not only breathe but to enhance the sense of smell and cool their brains.

“Dinosaurs were pretty ‘nosy’ animals,” said Ohio University doctoral student Jason Bourke, lead author of the new study published today in the Anatomical Record . “Figuring out what’s going on in their complicated snouts is challenging because noses have so many different functions. And it doesn’t help that all the delicate soft tissues rotted away millions of years ago.”

To restore what time had stripped away, the team turned to the modern-day relatives of dinosaurs—birds, crocodiles and lizards—to provide clues. “We’ll do whatever it takes,” said Lawrence Witmer, professor in the Ohio University Heritage College of Osteopathic Medicine and principal investigator on the National Science Foundation’s Visible Interactive Dinosaur Project, which funded much of the research. “We did lots of dissections, blood-vessel injections and CT scanning, but a major new tool was 3D computer simulation of airflow.”

Bourke drew from a branch of engineering called computational fluid dynamics, an approach commonly used in the aerospace industry and medicine, to model how air flowed through the noses of modern-day dinosaur relatives such as ostriches and alligators. “Once we got a handle on how animals today breathe,” Bourke said, “the tricky part was finding a good candidate among dinosaurs to test our methods.”

The dinosaurs that best fit the bill were the pachycephalosaurs, or “pachys,” a group of plant-eating dinosaurs best known for the several-inch-thick bone on the tops of their skulls which is thought to have served both as a visual display and as protection for head-butting behaviors like those of modern-day rams. It turns out that building all that extra skull bone resulted in ossifying soft tissues in other areas of the body—such as the nose.

“When we cleaned up the fossil skull of Sphaerotholus , a pachy from North Dakota, we didn’t expect to see these delicate scrolls of bone in the nasal region. We knew they must be nasal turbinates,” said Emma Schachner, a co-author on the study from Louisiana State University who, along with Tyler Lyson of the Denver Museum of Nature and Science, studied some of the fossil specimens used in the study. Similar structures were found in a different pachy species from Canada called Stegoceras by co-author Phil Bell from the University of New England in Australia.

The first nasal turbinates to be discovered were in the back part of the nasal cavity, called the olfactory chamber, where smelling takes place. Work by Witmer and Ohio University researcher Ryan Ridgely on CT scans of Stegoceras showed that the olfactory region of the brain was quite large, which, along with the large olfactory turbinates, suggested that Stegoceras had a good sense of smell.

But when Bourke ran his airflow simulation analyses, the inspired air bypassed the olfactory chamber. “It made no sense,” Bourke said. “ Stegoceras obviously had a pretty decent sense of smell, but the odors weren’t reaching where they needed to go. We obviously were missing a piece of the puzzle.”

That missing puzzle piece was hinted at by a long bony ridge on the wall of the front of the nasal cavity. In the modern-day relatives of dinosaurs, cartilaginous nasal turbinates often attach to such ridges, suggesting to the team that pachys may have had turbinates in the front, respiratory part of the nasal cavity.

When Bourke digitally inserted respiratory turbinates of different shapes—whether it was the scrolled turbinate of a turkey or the branched turbinate of an ostrich—the computer airflow simulations started to make more sense.

“Some of the restored airflow patterns now carried odors to the olfactory region,” said Bourke. “We don’t really know what the exact shape of the respiratory turbinate was in Stegoceras , but we know some kind of baffle had to be there. We have the smoking gun of the bony ridge on the fossil, and the airflow analyses show that attaching some kind of turbinate produced the only airflow that made any real biological sense.”

Why have turbinates at all? Some scientists had previously suggested that warm-blooded animals such as birds and mammals have turbinates to act like condensers to save water that might have been lost during exhalation. That may be true in some cases, but this new research suggests that turbinates also have important functions as baffles to direct air to the olfactory region. But they might also play another critical role—cooling the brain.

Study co-author Ruger Porter, another Ohio University doctoral student, has been studying the pattern of blood flow in pachycephalosaurs and other dinosaurs, as well as their modern-day relatives. “The fossil evidence suggests that Stegoceras was basically similar to an ostrich or an alligator,” Porter said. “Hot arterial blood from the body was cooled as it passed over the respiratory turbinates, and then that cooled venous blood returned to the brain. It may not have been much of a brain, but you don’t want it cooked!”

Now that Bourke and his team have worked out nasal airflow in the “easy case” of Stegoceras , the team is turning its attention to trickier dinosaur cases, such the crazy-straw airways of armored ankylosaurs and duckbilled hadrosaurs.

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

Editors:
• Related images and animations can be downloaded from the WitmerLab site: pachy_airflow.htm
• A fact sheet can be accessed here: Downloads/dinosaur_breathing_facts_and_graphics.pdf

Contacts (all Eastern Daylight Time):
1. Jason Bourke, 740-818-7503, jb513009@ohio.edu   [lead author]
2. Lawrence Witmer, 740-591-7712, witmerL@ohio.edu   [co-author]
3. Andrea Gibson, 740-597-2166, gibsona@ohio.edu   [Director of Research Communications]

This website provides supplementary information as an adjunct to the published paper. Witmer, with the skilled assistance of Ryan Ridgely , is responsible for the content of the website. Content provided here is for educational and research purposes only, and may not be used for any commercial purpose without the permission of L. M. Witmer and other relevant parties.

This project was funded by grants from the National Science Foundation .

Ohio University
Heritage College of Osteopathic Medicine
Irvine Hall, Athens, Ohio 45701
740-593-2530 740-597-2778 fax

Last updated:11/23/2015

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