Skulls of South African dinosaur embryos are recreated in 3D

According to a study, they lived 200 million years ago and developed similarly to today’s crocodiles, turtles and lizards.

A team of scientists coordinated by researchers at the University of Witwatersrand, in South Africa, reconstructed in detail the skulls of ancient dinosaur embryos. The results suggest that they developed similarly to today’s crocodiles, chickens, turtles and lizards.

Skulls of South African dinosaur embryos are recreated in 3D — The embryos of *Massospondylus carinatus* were discovered in 1976, in the Golden Gate Highlands National Park, in South Africa. (Credit: Brett Eloff).

The study, published this Thursday (9) on Scientific Reports, shows how scientists analyzed embryos belonging to the iconic South African dinosaur Massospondylus carinatus, a five-meter-long herbivore that lived 200 million years ago. They were found in 1976, and their very sensitive skull is only two centimeters long.

Paleontologists Kimi Chapelle and Jonah Choiniere took the materials to the European Synchrotron, in France, to be digitized. The site is a particle accelerator with an 844-meter electron ring capable of emitting high-power X-ray beams without damaging the fossils. With all this apparatus, the embryos could be scanned with the resolution of an individual bone cell.

African scientists digitize dinosaur embryos. (Credit: University of Witwatersrand)

With the data in hand, the researchers were able to reconstruct a 3D model of the baby dinosaur skulls. Thus, the authors found that they were much younger than previously thought and had completed only 60% of their incubation period.

The team also found that each embryo had two types of teeth preserved in its developing jaws. One was made up of very simple triangular teeth. The second set of teeth was very similar to that of adult dinosaurs and would be the one with which the embryos were born. “I was really surprised to find that these embryos not only had teeth, but had two types of teeth. The teeth are so tiny; they range from 0.4 to 0.7 mm wide. That’s smaller than the tip of a toothpick”, Explains paleontologist Kimi Chapelle.

Watercolor illustration shows embryos of Massospondylus carinatus in 17%, 60% and 100% of the incubation period. (Credit: Mélanie Saratori).

Finally, the researchers concluded that dinosaurs evolved in the egg just like their reptilian relatives, whose embryonic development pattern has not changed in 200 million years. “It is incredible that, in more than 250 million years of evolution of reptiles, the way the skull develops in the egg remains more or less the same,” concludes Jonah Choiniere, professor at the University of Witwatersrand and also co-author of the study.