Discoveries

June 22, 2022

Jurassic Belly Buttons

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All mammal species, including humans, have belly buttons. one dinosaur species had them as well, according to Smithsonian Magazine.

In a new study, scientists studied the remains of a Psittacosaurus, a non-avian dino species that lived more than 100 million years ago in what is now China and Mongolia.

A member of the horned Ceratopsia group, the extinct creature measured nearly seven feet in length and was known for its high and narrow skull with a parrot-like beak.

Using special lasers and imaging techniques, researchers saw that the Psittacosaurus had a peculiar belly button that had faded over time.

The team explained that this belly button – scientifically known as an umbilical scar – was not similar to those in mammals because Psittacosaurus were egg-hatchers.

Unlike mammals, egg-hatcher embryos are connected to the yolk sac in the egg, providing them with the nutrients to grow and develop. Modern egg-hatchers, such as snakes and birds, lose their belly button within days or weeks but that wasn’t the case with the Psittacosaurus.

Scientists had long speculated that egg-laying dinosaurs had belly buttons but the findings offer the first evidence of such a feature.

Even so, the authors added that the discovery doesn’t mean that umbilical scars were present in all non-avian dinosaurs.

This story originally appeared in the June 22, 2022 newsletter, Drawing in Pencil.