In an article published by Current Biology on January 19th, 2021 scientists describe the first ever preserved cloaca (more commonly described as a butthole) of a dinosaur. The fossil with the intact hiney is from a Psittacosaurus, a labrador-sized dinosaur with horns on its face like a small triceratops. They discovered from the color patterns and pigmentation preserved in its skin that it was camouflaged to live in a shady jungle around where it was found in the Liaoning province of China. It lived during the Cretaceous period, probably hunted by early ancestors of the velociraptor.
The cloaca was found to resemble that of a crocodile or a bird. Both are very similar, however a crocodile has a vertical opening, while a bird has a horizontal opening. The dinosaur’s was shaped more like a V and it was determined that dinosaurs have a ‘unique’ and ‘perfect’ butthole. Scientists found that the dark pigment in scales around the opening of the cloaca meant that these were a dark color against the light skin of the animal, probably used for mating. Modern day birds also use colorful cloaca as a sexual display.
The scientists also found that much like crocodiles, this dinosaur had glands on either side of the opening, probably used to leave a musky scent, much like most tetrapods or four legged animals. This is confirmation of a theory believed to be true by paleontologists and science fiction writers alike. In the 1995 novel “The Lost World” by Michael Crichton, he describes a scene where the protagonists are hiding from a T-rex in a jeep. The rex doesn’t see them as it lumbers by, but does notice the car. It goes over to investigate and ends up turning around and sitting on the car, smearing a brown smelly substance all over the hood of the vehicle. It was scenting the vehicle, marking this new thing in its territory.
The same year, Dr. Robert Bakker, one of the world’s leading paleontologists, wrote a book called “Raptor Red”. It is told from the point of view of a few different velociraptors during the cretaceous period. The dinosaurs would not only leave scent with their droppings, but would mark trees and such with their musk as an identifier to other raptors.
Aside from scenting and pooping, the dinosaur cloaca was also used for urinating and laying eggs. Most dinosaurs are believed to have laid eggs, as is the case with most other reptiles. Evidence has been discovered however, that some dinosaurs may have given birth to live offspring. This same anomaly is present in modern reptiles as well. Jackson’s chameleon is the only species of chameleon to give live birth.
As scientists examined the cloaca of the Psittacosaurus, they discovered a cream colored substance just inside the opening of the cloaca that they determined was coprolite, or dinosaur poop. It seems that this dinosaur was in the process of pooping itself as it died. The incredible preservation of its body leads this author to believe that it was probably killed by a large, fast, and possibly violent event, probably something like a mudslide that would quickly kill the dinosaur and then preserve its body.
The scientists also found that much like crocodiles, this dinosaur had glands on either side of the opening, probably used to leave a musky scent, much like most tetrapods or four legged animals. This is confirmation of a theory believed to be true by paleontologists and science fiction writers alike. In the 1995 novel “The Lost World” by Michael Crichton, he describes a scene where the protagonists are hiding from a T-rex in a jeep. The rex doesn’t see them as it lumbers by, but does notice the car. It goes over to investigate and ends up turning around and sitting on the car, smearing a brown smelly substance all over the hood of the vehicle. It was scenting the vehicle, marking this new thing in its territory.
The same year, Dr. Robert Bakker, one of the world’s leading paleontologists, wrote a book called “Raptor Red”. It is told from the point of view of a few different velociraptors during the cretaceous period. The dinosaurs would not only leave scent with their droppings, but would mark trees and such with their musk as an identifier to other raptors.
Aside from scenting and pooping, the dinosaur cloaca was also used for urinating and laying eggs. Most dinosaurs are believed to have laid eggs, as is the case with most other reptiles. Evidence has been discovered however, that some dinosaurs may have given birth to live offspring. This same anomaly is present in modern reptiles as well. Jackson’s chameleon is the only species of chameleon to give live birth.
As scientists examined the cloaca of the Psittacosaurus, they discovered a cream colored substance just inside the opening of the cloaca that they determined was coprolite, or dinosaur poop. It seems that this dinosaur was in the process of pooping itself as it died. The incredible preservation of its body leads this author to believe that it was probably killed by a large, fast, and possibly violent event, probably something like a mudslide that would quickly kill the dinosaur and then preserve its body.