Paleontologists have discovered the oldest belly button known to science on a 125 million-year-old fossil of a dinosaur in the genus Psittacosaurus. Oh, the fossil also had the first dinosaur butthole ever found.
As reported by Live Science, the Psittacosaurus lived during the Cretaceous period, which was between 145 million to 66 million years ago, and the scientists discovered this belly button after they exposed the fossil to a concentrated beam of laser light.
Artist rendering of the Psittacosaurus. Image Credit: Jagged Fang Designs
These scientists reported their findings in the journal BMC Biology on June 7 and say they spotted a “thin trace of an umbilical scar” that is a “slight misalignment in the pattern of skin and scaled over the dinosaur’s abdomen and is the reptile equivalent of a mammalian belly button.”
While fetal mammals get their nutrients from a placenta, birds and reptiles get what they need from a yolk sac that is connected to their abdomens via blood vessels. When these types of creatures hatch, the yolk is absorbed into the body and an abdominal scar is all that remains.
For most birds and reptiles, the scar heals in a few days or weeks, but some reptiles, including alligators, can have the scar “beyond sexual maturity.” This fossil has shed new light on dinosaurs and gives an indication that some dinosaurs did have these scars that didn’t heal early on.
The fossil, which is known as SMF R 4970, was an early type of ceratopsian called Psittacosaurus mongoliensis that fell into a group of beaked herbivores that include Triceratops. It was discovered roughly 20 years ago, and it was so well preserved because the dinosaur was “fossillized while lying on its back.” This also led to scientists discovering the previously mentioned “perfect” and “unique” butthole.
“Using LSF imaging, we identified distinctive scales that surrounded a long umbilical scar in the Psittacosaurus specimen, similar to [scars in] certain living lizards and crocodiles,” paleontologist Michael Pittman, an assistant professor in the School of Life Sciences at the Chinese University of Hong Kong, said in the statement. “We call this kind of scar a belly button, and it is smaller in humans. This specimen is the first dinosaur fossil to preserve a belly button, which is due to its exceptional state of preservation.”
Aside from its importance to science, this fossil has also been the subject of a “fierce repatriation controversy.” The fossil was discovered in an unknown region of China in the 80s or 90s and was “allegedly smuggled out of the country and into underground European markets before being purchased and put on display in 2001 at the Senckenberg Museum in Frankfurt, Germany.”
“There is ongoing debate regarding the legal ownership of this specimen and efforts to repatriate it to China have not been successful. Our international team of Australian, Belgian, British, Chinese and American members all hope for and support an amicable solution to this ongoing debate,” the researchers wrote in their paper. “We think it is important to note that the specimen was acquired by the Senckenberg Museum to prevent its sale into private hands and to ensure its availability for scientific study.”
For more on dinosaurs, check out how the Tyrannosaurus Rex may have actually been three separate dinosaurs and the recently discovered dinos in England that were dubbed “Hell Heron” and “Riverbank Hunter.”
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Adam Bankhurst is a news writer for IGN. You can follow him on Twitter @AdamBankhurst and on Twitch.