Avimaia

Avimaia is a genus of fossil birds of the Enantiornithes clade that lived about 115 million years ago in Northwest China. The only known species is A. schweitzerae. The holotype fossil of the bird was found in the Xiagou Formation, and is noted as the first discovered fossil bird with an unlaid egg. Abnormalities, including egg binding in which the egg becomes stuck within the body of the bird causing death, were found in the egg suggesting that the preserved egg may have caused this bird's demise. Egg binding is a serious and lethal condition that is fairly common in small birds undergoing stress.

According to paleontologist Jasmina Wiemann of Yale University, “This is a spectacular fossil with a lot of potential for future paleobiological investigations." Further, "This new specimen is arguably one of the most interesting Cretaceous fossil birds yet discovered, providing more reproductive information than any other Mesozoic fossil bird," according to a paleontology researcher at the Chinese Academy of Sciences.