Chilean-born evolutionary biologist Damien Esquerre has made a discovery that challenges the "golden rule of evolution", the broadcaster ABC reported.
"We have strong evidence that suggests that they re-evolved laying eggs when they re-colonised warmer areas", he said, stressing that such a backflip is an extremely rare thing, as it contradicts Dollo's law of irreversibility.
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The principle, proposed by Belgian-French palaeontologist Louis Dollo around 1890 says that a structure or organ lost during the course of evolution will not reappear in that organism.
According to Esquerre, it would be "a very significant evolutionary event" if further research confirms the current data on the issue.