Modeling nasal airflow in the pachycephalosaurid dinosaur Stegoceras bit.ly/1tksIgs. 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 (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. For more on this project, visit bit.ly/1tksIgs. Visit our Facebook page for more content like this: facebook/witmerlab . - Radiator-nosed dinosaur? news.sciencemag.org/brain-behavior/2014/10/radiator-nosed-dinosaur A bipedal, German shepherd–sized dinosaur may have had soft tissues in its nasal cavity that cooled the blood flowing to its brain, a new study suggests. The plant-eating Stegoceras validum belongs to a group called pachycephalosaurs (which in Greek means “thick-headed lizards”). CT scans of one particularly well preserved skull revealed delicate scrolls of bones in a chamber at the rear of the creature’s nasal cavity—bones that would have been covered with soft tissue containing smell receptors (purplish pink in reconstruction at lower right), researchers say. A new study modeling fluid dynamics suggested something strange: that air breathed in through Stegoceras’s nasal cavity would have largely bypassed its smell receptors. The mystery was solved after the researchers noticed a small bony ridge in the front part of the creature’s nasal cavity. When the team added soft tissues to that bony ridge—structures called turbinates (in green), similar to those in many modern creatures—they found that inhaled air was diverted back to the olfactory chamber, allowing the dinosaur to better exercise its sense of smell, the researchers reported online this week in The Anatomical Record. The turbinates might have offered other benefits as well. As in today’s ostriches and alligators, hot blood flowing through the soft tissues of Stegoceras’s turbinates would have been cooled before streaming onward to the dinosaur’s brain—possibly helping prevent excess body heat absorbed from a warm environment or generated by vigorous activity from frying the creature’s gray matter. - Dinosaur breathing study shows that noses enhanced smelling and cooled brain Researchers discover preserved nasal features in bony-headed dinosaur fossils eurekalert.org/pub_releases/2014-10/ou-dbs101414.php Its 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 whats going on in their complicated snouts is challenging because noses have so many different functions. And it doesnt 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. Well do whatever it takes, said Lawrence Witmer, professor in the Ohio University Heritage College of Osteopathic Medicine and principal investigator on the National Science Foundations 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 didnt 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 werent 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 dont 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 dont 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. - Breathing life into dinosaurs — modeling nasal airflow in pachycephalosaurid dinosaurs oucom.ohiou.edu/dbms-witmer/pachy_airflow.htm 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. News Dinosaur breathing study shows that noses enhanced smelling and cooled brain Researchers discover preserved nasal features in bony-headed dinosaur fossils oucom.ohiou.edu/dbms-witmer/pachy_airflow.htm Reference Breathing Life Into Dinosaurs: Tackling Challenges of Soft-Tissue Restoration and Nasal Airflow in Extinct Species The Anatomical Record Special Issue - The Vertebrate Nose: Evolution, Structure, and Function Volume 297, Issue 11, pages 2148–2186, November 2014, 14 OCT 2014, DOI: 10.1002/ar.23046 onlinelibrary.wiley/doi/10.1002/ar.23046/abstract Facts, images, & animations for dinosaur breathing story PDF: oucom.ohiou.edu/dbms-witmer/Downloads/dinosaur_breathing_facts_and_graphics.pdf Abstract The nasal region plays a key role in sensory, thermal, and respiratory physiology, but exploring its evolution is hampered by a lack of preservation of soft-tissue structures in extinct vertebrates. As a test case, we investigated members of the “bony-headed” ornithischian dinosaur clade Pachycephalosauridae (particularly Stegoceras validum) because of their small body size (which mitigated allometric concerns) and their tendency to preserve nasal soft tissues within their hypermineralized skulls. Hypermineralization directly preserved portions of the olfactory turbinates along with an internal nasal ridge that we regard as potentially an osteological correlate for respiratory conchae. Fossil specimens were CT-scanned, and nasal cavities were segmented and restored. Soft-tissue reconstruction of the nasal capsule was functionally tested in a virtual environment using computational fluid dynamics by running air through multiple models differing in nasal soft-tissue conformation: a bony-bounded model (i.e., skull without soft tissue) and then models with soft tissues added, such as a paranasal septum, a scrolled concha, a branched concha, and a model combining the paranasal septum with a concha. Deviations in fluid flow in comparison to a phylogenetically constrained sample of extant diapsids were used as indicators of missing soft tissue. Models that restored aspects of airflow found in extant diapsids, such as appreciable airflow in the olfactory chamber, were judged as more likely. The model with a branched concha produced airflow patterns closest to those of extant diapsids. These results from both paleontological observation and airflow modeling indicate that S. validum and other pachycephalosaurids could have had both olfactory and respiratory conchae. Although respiratory conchae have been linked to endothermy, such conclusions require caution in that our re-evaluation of the reptilian nasal apparatus indicates that respiratory conchae may be more widespread than originally thought, and other functions, such as selective brain temperature regulation, could be important. Anat Rec, 297:2148–2186, 2014. © 2014 Wiley Periodicals, Inc.
Posted on: Thu, 23 Oct 2014 17:46:44 +0000
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