Paleontologists say the fossil is a very complete, 12-inch lizard with more than a dozen embryos in its body that was probably just days from giving birth when it died and was buried during the Cretaceous period, the BBC reported Thursday.
The fossil is of a reptile that produced live young rather than laying eggs, something found in only 20 percent of living species of lizards and snakes.
"I didn't think much of the fossil when I first saw it," University College London Professor Susan Evans said.
But when a colleague from the Chinese Academy of Sciences examined it, the tiny remains of at least 15 almost fully developed embryos were found inside it.
"Sure enough, when I examined it under the microscope, I could see all these little babies," Evans recalled.
The lizard has been identified as a Yabeinosaurus, a large, slow-growing and relatively primitive lizard.