Artist's reconstruction of Sonselasuchus cedrus in its environment in what is now Petrified Forest National Park, 215 million years ago. Credit: Gabriel Ugueto A newly described prehistoric reptile is giving scientists a surprising look at how some ancient animals may have changed the way they moved as they grew. Researchers say this "peculiar" crocodile relative likely began life walking on four legs, only to adopt a two-legged stance as it reached adulthood. The species, called Sonselasuchus