Eggs with embryos belonging to the southern African dinosaur Massospondylus were discovered in 1978 from a road cut-away in the Golden Gate National Park in the Free State. These dinosaurs lived in the early Jurassic, between 200 and 183 million years ago. A clutch of six eggs was removed but this was surrounded by rock and scientists believed that it would damage the eggs and embryos if this and the egg shells were removed, and the appearance of the embryos remained hidden until 2005. Once the detail of the structure of the embryos was revealed, scientists were able to improve understanding about reproduction of this remarkable dinosaur. The embryos are in the Bernard Price Institute collection of the University of the Witwatersrand.
Image: Massospondylus eggs showing the structure of the embryo. Image provided by Bernhard Zipfel, Evolutionary Studies Institute, WITS.