Looking at fossil eggshells from China, researchers have found evidence that an omnivorous, ostrich-like dinosaur laid clutches of blue-green eggs, potentially helping to camouflage them in open nests dug into the ground.

The discovery overturns a common assumption: “Everyone thought dinosaur eggs were white,” says study coauthor Jasmina Wiemann at Yale University.

Many birds lay white, unpigmented eggs—as do all lizards, turtles, crocodiles, and the only known egg-laying mammals, the platypus and the echidna. For this reason, ornithologists had long assumed that colored eggshells evolved solely in some groups of birds after nonavian dinosaurs had died out. (Also find out the surprising link between eggs shape and flight in birds.)

“Once the idea that colored eggs evolved in birds