[ad_1]
About 110 million years ago, a bird the size of a sparrow died with its egg still in its body. This egg, crushed and flattened by pressure over time, is the first uncut bird egg to be preserved in a fossil, researchers said on March 20. Nature Communications.
The fossil was discovered 11 years ago in northwestern China. In 2018, paleontologists led by Alida Bailleul of Key Laboratory for the Evolution of Vertebrates and Human Origins in Beijing took a closer look and noticed something odd: the bird had a weird tissue sheet between his pubic bones. By examining a piece of tissue under the microscope, Bailleul discovered that it was an egg.
The bird, a newly identified species, has been named Avimaia schweitzerae tribute to the work of paleontologist Mary Schweitzer on fossilized soft tissues (SN: 24/12/16, p. 15). Subsequent analyzes revealed more surprises. The skeleton of the mother bird contains traces of medullary bone, a calcium tissue that promotes the formation of the eggshell (SN: 16/04/16, p. 16). This is the strongest evidence to date that ancient birds produced this tissue during breeding.
And the cuticle of the egg, the outermost shell layer, contains tiny mineral spheres similar to the egg-cuticle spheres of modern water birds such as quail and ducks. Spheres, believed to protect embryos against microbial infections, had never been seen before in fossilized eggs.
But all was not well with this bird and its embryo. The eggshell has two layers instead of the usual one, suggesting that the egg has stayed too long in the abdomen. And the layers of the egg are extremely thin, thinner than a sheet of paper. In modern birds, especially small birds under extreme stress, these symptoms may indicate a deadly condition called egg binding, in which a bird is unable to lay. In fact, the researchers suggest, the unpeeled egg would eventually kill the mother.
[ad_2]
Source link