Dinosaur Eggs

Photograph by Sinclair Stammers/Science Photo Library

Paleontologists in China's Henan Basin discovered this nest of fossilized eggs laid by the Jurassic duck-billed herbivore Hadrosaurus. Current evidence suggests all dinosaurs laid eggs of a wide variety of shapes and sizes—from 3 inches (8 centimeters) to 21 inches (53 centimeters), round or elliptical. Dinosaur eggs were perforated with tiny holes, which allowed life-giving oxygen to enter.