Now in 3D — Dinosaur Cloaca, the World’s Oldest All-Purpose Orifice
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Birthing, defacating, urinating, copulating— according to a research team that includes biologist Diane Kelly, a single orifice might have been used by the Psittacosaurus to do all four. Using 3-D technology, the researchers reconstructed the unique hole using rare soft-tissues found on the remains of this herbivorous dinosaur that roamed the earth millions of years ago, allowing them to draw new conclusions about the utility of the cloaca.
From “Finally in 3-D: A Dinosaur’s All-Purpose Orifice:”
Dr. Diane Kelly spent a long afternoon in her institution’s natural history collections photographing preserved animal rear ends, from amphibians to reptiles to birds, then turned her lens on the back ends of a friend’s live chickens. What she couldn’t find in person, she and her colleagues scavenged online, until the team had amassed a hefty survey of the known cloacal landscape.
Most vents look like nondescript slits — some horizontal, others vertical — or rounded holes, sometimes shrouded by a wrinkly wreath of skin or a smattering of scales, Dr. Kelly said. The Psittacosaurus variety might have been a bit more adorned.
Perhaps the closest analog is that of the crocodile, whose vent is ornamented with lips that pinch together at both ends, instead of fanning out tailward, Dr. Kelly said. The similarities were striking enough that the researchers proposed that, like crocodiles, the Psittacosaurus might have sported odor-rich musk glands on either side of its vent, wafting out a pungent perfume to attract mates.
The researchers couldn’t draw firm conclusions about the cloaca’s interior. But if Psittacosaurus plumbing was more crocodilian than not, it might be reasonable to think that the animal’s cloaca also harbored a penis or clitoris, as most contemporary cloacas do.
The researchers also found a fossilized lump of feces fixed in the Psittacosaurus’s fanny, a gratifying reminder of the cloaca’s versatility, Dr. Jakob Vinther [of the University of Bristol in England] said: “It’s quite nice to find it, right near where it’s supposed to come out.”
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