Avimaia

Avimaia is the only fossil bird ever found with an unlaid egg still inside its body.1

The eggshell of Avimaia was very thin and had multiple layers. Scientists think this happened because the egg stayed too long inside the mother.1

Avimaia's leg bones contain medullary bone. This is a special tissue that only female birds make when they are ready to lay eggs.1

The egg of Avimaia was flattened and measured about 5.2 square centimeters.1

Avimaia lived during the Early Cretaceous period, about 121 to 113 million years ago.2

The name Avimaia means 'bird mother' in Latin, because the fossil is a female with an egg.1