NYITCOM News Release
Nasal problem plagued long-nosed crocodile relatives
Jonesboro, AR; 23-November-2021 — The endangered Indian gharial looks a lot like American alligators and crocodiles, save for their bulging eyes and extremely long snouts which contained even longer noses. Just like us, gharials split their noses down the middle using a wall of cartilage called the nasal septum. Now, new research coming out today in the Anatomical Record has found that gharials may suffer from the same septal deviations that afflict people.
Dr. Jason Bourke of the New York Institute of Technology College of Osteopathic Medicine led a team of researchers on a project to see how deviated septa effect these strange animals. Bourke and colleagues used medical imaging to view the heads of multiple gharial specimens, including a large female from the Fort Worth Zoo—nicknamed Louise—that showed an extreme cases of nasal septum deviation.
“This curvy nasal septum was an unexpected discovery” said Casey Holliday, lead researcher at University of Missouri, who scanned the specimen initially for a separate project on gharial anatomy. “I saw this wavy, snakelike shape of a septum and wondered what this might mean for respiration”
Holliday passed the information along to Bourke, a vertebrate paleontologist whose lab studies fluid dynamics in animal noses using sophisticated computer software to simulate air movement. “We know remarkably little about normal gharial anatomy, much less their pathology. I couldn’t pass up such a unique opportunity.” said Bourke who has previously modeled nasal airflow and thermoregulation in dinosaurs.
According to the Cleveland Clinic, nasal septal deviation affects up to 80% of people. Many of these deviations are only slight and don’t impact breathing. However, larger deviations can impact the airways by tightly constricting or outright blocking one side of the nose, making it harder for these individuals to breathe through their noses and requiring reconstructive surgery to fix.
Bourke and colleagues found nasal septum deviation to be similarly variable in gharials. Some specimens showed minor septal deviations whereas Louise had the most extreme case. Septal deviation in gharials comes with a twist. “When the septum is deviated in humans, a part or all of the septum bows into one of the airways.” said Nicole Fontenot, a 4th year medical student at NYITCOM and co-author of the study. “In our gharials, the septum is so long that it wiggles back and forth along the snout, creating a wavy pattern.”
As with humans, the worst case of nasal septal deviation had the greatest cost to breathing. Louise had to work harder to achieve the same breathing rate as other, larger gharials. This produced high shearing stresses along the nasal walls, which may have made the animal more prone to nose bleeds. “When your nose is this long, a nose bleed is probably really annoying because the blood has so far to drain” said Bourke.
Despite the physiological challenges produced from this nasal pathology, Louise successfully made it to adulthood and lived to the ripe old age of 50. “It’s a testament to crocodylian resiliency as well as the care of the zookeepers” said Holliday. “A human with this pathology would need surgery to fix it, but these phenomenal reptiles just keep on going.”
Nasal septal deviation has never been recorded in crocodylians before and Bourke suspects he knows why: “Other crocodilians have wider snouts with much thicker nasal septa. Thinning out the snout places a premium on space inside the nose. Gharials’ long and very thin nasal septa probably don’t need much to make them start wobbling.”
While this pathology is not found in other modern crocodilians, in the ancient past there were many other animals that showed similarly stretched-out noses, including the crested, duckbilled dinosaurs like Parasaurolophus, and strange crocodile-mimics called champsosaurs. Bourke suspects at least a few of them may have also been prone to deviated nasal septa.
Bourke’s team isn’t done with gharials just yet. The next step of their research is looking at the sound producing abilities offered by their unique noses.
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1. Jason Bourke, 740-818-7503, firstname.lastname@example.org [lead author]
2. Nicole Fontenot email@example.com [co-author]
3. Casey Holliday, firstname.lastname@example.org [co-author]
4. Kim Tucker, 516-686-4013, email@example.com [Associate Director of Media Relations]
Image of an Indian gharial (Gavialis gangeticus) with its nasal passage and associated airflow composited on it. Original gharial photo from: Soham Banerjee. Image used under a Creative Commons Attribution 2.0 Generic License
Overhead image of Louise (TNHC 110000) showing the wavy septal deviation throughout much of the nose. Inset shows areas of high resistant flow caused by the alternating compression of the airway
Image adapted from figure 18 in the paper. Gharial "Louise" shown with multiple axial cross sections to illustrate the degree of nasal septal deviation witnessed in the animal.
Image comparing the snout of an Indian gharial to that of an American Alligator. Dashed lines represent location of cross sections. Cross sections compare the thickness of the nasal septum in each animal.