Evidence dinosaur walked on all fours when young and switched to bipedalism as an adult
(PHYSorg.com Archaeology & Fossils)

A team of researchers affiliated with institutions in Argentina and the U.K. has found evidence of a dinosaur that walked on all fours when it was young and then switched to walking on two legs as it grew to adulthood. In their paper published in the journal Scientific Reports, the group describes their study of Mussaurus patagonicus, an early sauropod species that lived in what is now Argentina, and what they learned about it.