SYDNEY, April 3 (Xinhua) -- In a globally first discovery, Australian researchers have observed a lizard both laying eggs and giving birth to a live baby from the same pregnancy, a study revealed on Wednesday.

The team at Australia's Sydney University (UoS) said that this bizarre occurrence can help to understand how the evolution from laying eggs to live birth occurred in vertebrates.

“It is a very unusual discovery,” Dr. Camilla Whittington, from the UoS School of Life and Environmental Sciences, said.

“We were studying the genetics of these skinks when we noticed one of the live-bearing females lay three eggs,” Whittington said.

“Several weeks later she gave birth to another baby. Seeing that baby was a very exciting moment!”

The lizard is a three-toed skink, a species which has the rare trait of being bimodally reproductive, meaning some individuals give birth to live young and some lay eggs. However, until now none have been observed doing both in the same litter.

Native to the east coast of Australia, the skinks found near coastal Sydney generally lay eggs, while those further inland birth live young.

The observation makes this particular three-toed skink, one of the “weirdest lizards in the world,” and may provide clues as to how and why species make major reproductive leaps.

“Put in the context of evolutionary biology, being able to switch between laying eggs and giving live birth could allow animals to hedge their bets according to environmental conditions,” Whittington explained.

“The earliest vertebrates were egg-layers, but over thousands of years, developing embryos in some species were held inside the body for longer, until some animals began to give live birth.”