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On an expedition to Greenland in 1987, this University of Cambridge paleontologist unearthed remains of a creature from the Devonian Period (408-360 million years ago) that walked around swamps on four legs. Through careful study of the anatomy, Clack determined that this creature, known as Acanthostega, nevertheless didn’t have a leg to stand on—that is, these rudimentary limbs could not support the animal’s weight. Jenny Clack, Professor of Vertebrate Palaeontology at Cambridge University, recounts how she overcame setbacks before she found and described a fossil which offered new evidence of how fish made the transition onto land.