Unlaid egg discovered in ancient bird fossil
Unlaid egg discovered in ancient bird fossil By John Pickrell Mar. 20, 2019 , 6:00 AM For the first time, researchers have found an unlaid egg inside a fossilized bird. The find— belonging to a sparrow-size flyer that lived in northwestern China 110 million years ago—is especially remarkable because fully formed eggs typically only stay within an adult bird for about 24 hours. Researchers were initially puzzled by the discovery, as they never suspected the unusual, squashed mass within the headless fossil’s abdomen (seen as a flattened brown layer in the center of the picture) could be an egg. But a microscopic analysis of a fragment revealed it to be eggshell. Further study suggested structural abnormalities that hint that the egg may have been the cause of this bird’s demise, the paleontologists report today in Nature Communications. The fossil eggshell’s structure doesn’t have the correct proportions seen in healthy eggs and consists of multiple layers