First Preserved Fossil of Psittacosaurus Dinosaur With Umbilical Scar Equivalent to Belly Button Discovered in China

Paleontologists from The Chinese University of Hong Kong (CUHK) may have found the oldest belly button known to science in an exquisitely preserved fossil of a horned dinosaur, Science Alert reported.

Although drawings or renderings of dinosaurs do not generally depict belly buttons on them, reptiles have something equivalent to a navel in mammals. They have a slit-like scar from the egg's yolk sac, unlike mammals that get their belly button from an umbilical cord. The researchers found the fossilized umbilical from 130 million years ago and it was the first example of its kind.

Umbilical Scar Identified in Non-Avian Dinosaur

Scientists have identified an umbilical scar on a non-avian dinosaur for the first time. The rare and exciting discovery was particularly found in the well-preserved fossil of Psittacosaurus in China, according to Gizmodo. Besides that, they also found a cloaca and countershading camouflage from this same specimen.

Reptiles and birds do not have umbilical cords, so they also do not have belly buttons, which are a product of a detached umbilical cord from birth. Instead, embryo reptiles and birds are connected to a yolk sac and other members. Once they are detached from them after hatching from the egg, it forms a scar that is the non-mammalian equivalent of a belly button.

The umbilical scar they found is approximately 130 million years old and was first publicly announced in 2002. It came from the bipedal, meat-eating Psittacosaurus dinosaur that lived during the early Cretaceous period and is said to be an early form of the beaked herbivore ceratopsian.

Other than its umbilical scar, paleontologists found its complete skin and tail bristles most remarkable for laying on its back when it died and preserving most of it. Until today, it breaks new and unique ground.

Paleontologists Used Laser Imaging to Identify Umbilical Scar

The study's joint-corresponding author Dr. Michael Pittman, an assistant professor at CUHK's School of Life Sciences, has been studying this particular fossil in detail and applied the Laser-Stimulated Fluorescence (LSF) invented by Pittman and co-author Thomas G. Kaye to reveal details in fossils that might have been unseen for many years.

A new non-destructive imaging technique identified distinctive scales that surrounded a long umbilical scar similar to certain living lizards and crocodiles, Phys.org reported.

Dr. Pittman said that the beautiful specimen may have been a sensation since it was publicly shared in 2002, but it was only now that they shed new light on it using a novel laser fluorescence imaging that helped them reveal the scales in such incredible detail.

Study lead and joint-corresponding author Dr. Phil R. Bell from the University of New England in Armidale, Australia, commented that the Psittacosaurus specimen is perhaps one of the most important fossils they have for studying dinosaur skin.

More so, it is remarkable that new laser technology has enabled them to bring it to life and learn more about them. The specimen is now held on display at the Senckenberg Museum in Frankfurt, Germany.

They detailed in full the results of their study in the paper titled "Oldest Preserved Umbilical Scar Reveals Dinosaurs Had 'Belly Buttons,'" published in BMC Biology.

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