A look at the life cycle of …

Figure 6: Watercolor of Massospondylus carinatus embryos at 17% during the incubation period, 60% during the incubation period and 100% during the incubation period. Art by Mélanie Saratori.

The gift of X-ray vision has allowed scientists to take a look at the mechanics of deep evolution, which surprisingly has not changed in 200 million years.

X-ray vision, provided by the European Synchrotron Radiation Center (ESRF) in France, has allowed paleontologists at the University of the Witwatersrand to study delicate dinosaur embryos hidden within 200-million-year-old eggs.

The embryos were Massospondylus carinatus, a 5-meter-long herbivore that once roamed what is now the Free State. The egg nest was discovered in 1976 in the Golden Gate Highlands National Park and is believed to be among the oldest dinosaur embryos in the world.

But these young men were not giants like their parents; its small skulls were only 2 cm long and had teeth thinner than needles.

However, X-ray scanners were able to create 3D images of the embryos, with such resolution that the researchers were able to focus on the individual bone cells.

“No one has seen dinosaurs like this before, and the reason for this is that they need a really powerful CT scanner to be able to do this, that’s why the synchrotron is so useful,” says Dr. Kimberley Chapelle of the Institute for Evolutionary Studies at the Wits University.

The international team was chaired by Chapelle and Professor Jonah Choiniere, who is also from the Institute for Evolutionary Studies. Their findings were published Thursday in the magazine. Scientific reports.

What the scientists found was that these Massospondylus embryos seemed to have developed in the same sequence as their modern reptilian relatives.

“It’s amazing that in over 250 million years of reptile evolution, the way the skull develops in the egg stays more or less the same. It’s going to show, don’t mess with something good!” Says Choiniere .

The 3D scans also revealed other surprises.

They discovered that baby dinosaurs had two sets of teeth. One set were simple triangular teeth, which scientists believed had been reabsorbed or shed before babies were born. This is seen today in geckos and crocodiles. The second set was similar to those of their parents, which they kept.

“There are some hypotheses as to why this is so. One of them is that in order to have a complete set of teeth, you must follow a replacement pattern. And hopefully it could give us a clue as to why this still happens today, “says Chapelle.

Noting the similarities to the development of embryos from modern relatives like crocodiles, chickens, and turtles, Chapelle was also able to come to a time when the embryos died. They were originally thought to have died shortly before hatching. She believes they were much younger and only 60% during their incubation period.

Massospondylus were the impalas of their time. They were numerous, and hundreds of their fossilized remains have survived. Chapelle likes to think of Massospondylus as the “proud South African guy” that has only been found in South Africa. They are the ancestors of those famous megagiant dinosaurs like Brachiosaurus.

With so many Massospondylus fossils around, paleontologists have had a rare glimpse into this dinosaur’s entire life cycle.

They have been able to examine embryos, babies, adolescents and the elderly. A rarity in science where an entire species can be represented by a single fossil.

To understand more about the embryonic development of dinosaurs, the team plans to use the synchrotron to observe the most fossilized eggs.

“And hopefully someday we will have a large sample and be able to answer questions like if dinosaurs developed as fast as birds, or were they more like crocodiles that are slower to develop? And this may be the reason why They were so successful because they were able to figure out how to develop so quickly, “says Choiniere. DM