News Paleontology

These mammal ancestors birthed live young far earlier than thought

New fossil pushes a shift from egg laying to live birth back by 90 million years

Artist's depiction of a pregnant mammal ancestor Chiniquodon theotonicus and another nursing two young.

A life reconstruction of the cynodont Chiniquodon theotonicus, which lived about 236 million years ago, portraying a pregnant female (illustrated, left) and a female nursing a few relatively large newborns (right).

María de los Ángeles Miceli Baro

By Carolyn Gramling

Mammal ancestors may have made the evolutionary leap from egg-laying to live birth at least 90 million years earlier than thought.