Scientists have caught up with lizards about to abandon egg-laying for live births in an evolutionary leap.

The skink, snake-like with four tiny legs, has been found laying eggs along the New South Wales coast in Australia.

However, its counterpart, a three-toed lizard inhabiting the colder mountainous region of the country, is giving birth to offspring, reports the Daily Mail.

There are only two other types of reptiles which rely on both types of reproductive modes - another skink species and European lizard.

One in five snakes and lizards gives birth to live young, among the nearly 100 reptile lineages that have changed from egg-laying in the past, reports the journal National Geographic.

Study co-author James Stewart, East Tennessee State University biologist, in the US, said the discovery afforded them with an unique opportunity.

'By studying differences among populations that are in different stages of this process, you can begin to put together what looks like the transition from one [birth style] to the other,' he said.

Stewart said the transformation could be linked to how newborns get nourishment. Or it could be a way of protecting the young in harsher climates.