A revealing look

A reconstruction of Psittacosaurus showing how the cloacal vent might have been used for signaling during courtship. Photo credit: Bob Nicholls/Paleocreations.com 2020 via The New York Times.

By Keely Savoie Sexton 

Researchers have developed a 3D model of the cloaca of Psittacosaurus, a dinosaur that lived on the Earth more than 100 million years ago. The cloaca is a multifunctional orifice that exists in birds, reptiles and amphibians — and the odd mammal — for defecating, urinating and copulating. 

The team published their findings in Current Biology

On the team of scientists probing the primeval pudendal pouch was Diane Kelly, visiting professor of biological sciences at Mount Holyoke College. Using photographs of living and dead specimens, Kelly cataloged the cloacal structures in order to map the preserved Psittacosaurus specimen.

The intact specimen allowed scientists to model the structure, which they found to be unique from known cloacal topography, but they were unable to pinpoint a penis.

The mystery remains of how Psittocasaurus transmitted its sperm. Kelly believes that most dinosaurs had penises. “For the most part, if you have internal fertilization, you have some method of sticking it in,” she told The New York Times

Patricia Brennan, associate professor of biology and an expert in genital co-evolution, who also spoke to the newspaper about the research, believes that at least some dinosaurs had penises, but that Psittacosauras may not be one. 

“I am 100 percent certain that at least some dinosaurs had penises,” she said. 

Read the story.

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