Carissa Wong is a person.

Psittacosaurus dinosaur fossil

There is a scar on the dinosaur's body.

Phil Bell is an associate professor at the University of New England.

The herbivorous parrot-beaked dinosaur that lived in China 130 million years ago may have had a belly button.

Phil Bell is a professor at the University of New England, Australia. There aren't many fossils in existence with fossilised skin.

An abdominal scar or belly button is the result of a placenta falling off of a mammal's embryo.

The embryo is attached to a yolk sac in birds and reptiles. There is a linear abdominal scar after the animal has hatched. The scar is usually gone after a few days to weeks.

It wasn't known if dinosaurs had scars that lasted for a long time.

Bell and his colleagues used a technique called laser-stimulated fluorescence to image the scar in the dinosaur, which was 10 centimetres long and surrounded by small scales.

There are scars from injuries that show trauma. Bell says that the scales may be disrupted and lose their regular appearance and that they may not regrowth at all. The scales on both sides of the psittacosaurus are well defined. It is exactly where you would expect it to be, and it has all the characteristics of a reptilian belly button.

The team compared the length of the femur bone in the specimen with other fossils and found that the individual was about 6 years old.

If the umbilical scar remains after the first few weeks, it stays for the rest of the animal's life. It is certain that this psittacosaurus would have had it for the rest of its life and likely all individuals in that species did as well.

There is more work that needs to be done to confirm the findings. Bell said that new fossils are likely to change interpretations.

It's not known how widespread the scars may have been.

It's possible that 5 per cent of adult dinosaurs might have had them. He says the team wants to find more dinosaurbelly buttons.

The journal's title is "BMC Biology" There are 1186/s12915-022

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