Scientists have uncovered the fossilized skull of a 270-million-year-old ancient amphibian ancestor in the collection of the Smithsonian's National Museum of Natural History. In a paper published today, March 21, in the Zoological Journal of the Linnean Society, the team of researchers described the fossil as a new species of proto-amphibian, which they named Kermitops gratus in honor of the iconic muppet, Kermit the Frog.