Scientists have discovered the oldest belly button ever found in a dinosaur fossil dating back 125 million years. This fossil also contains the first dinosaur butthole ever discovered.

Live Science reported that this belly button was found after a concentrated beam of laser light was directed at a fossil of the Psittacosaurus from the Cretaceous period, which spanned between 145 million years and 66 million years ago.

The researchers describe how they spotted a 'thin trace of an umbilical scar' on a dinosaur's abdomen, which is the reptile equivalent of a mammalian belly button.'

Fetal mammals get their nutrients from the placenta. Birds and reptiles get their nutrients from yolk sacs that are connected to their abdomens via blood vessels. An abdominal scar is all that remains after a creature of this type hatches, the yolk is absorbed into the body.

Most birds and reptiles heal their scars within a few days or weeks, but some reptiles, such as alligators, can have them 'beyond sexual maturity.' This fossil sheds new light on dinosaurs and indicates that some dinosaurs did have scars that didn't heal within the first few months.

This fossil, known as SMF R 4970, is a type of ceratopsian called Psittacosaurus mongoliensis that belongs to a group of beaked herbivores that includes Triceratops.

The fossil was discovered roughly twenty years ago, and it was well preserved since the dinosaur was fossilized while lying on its back. This also led to scientists discovering the previously mentioned 'perfect' and 'unique' butthole.

According to the statement, 'Using LSF imaging, we identified distinctive scales that surrounded an umbilical scar on the specimen of Psittacosaurus, similar to scars on certain living crocodiles and lizards,' said paleontologist Michael Pittman, an assistant professor in the School of Life Sciences at the Chinese University of Hong Kong.

This type of scar is called a belly button in humans, and this specimen, due to its exceptional state of preservation, is the first dinosaur fossil to preserve a belly button.'

As well as being of 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 sold on underground European markets before being purchased and put on display at the Senckenberg Museum in Frankfurt, Germany, in 2001.'

It is unclear who owns the specimen, and attempts to repatriate it to China have not succeeded.

Our team of Australians, Belgians, British, Chinese, and American researchers hope for and support an amicable resolution to this issue,' they wrote in their paper.

We note that the specimen was acquired by the Senckenberg Museum to prevent its sale to a private individual and to ensure its availability for scientific study.'