Frog evolution mystery
‘The origins of the modern Amphibia, such as frogs, has been the subject of considerable debate, a fact indicating the difficulty involved in tracing their ancestry back to the early Amphibia that roamed the earth, and also to the fish stocks from which they, in turn, had evolved.
‘ Just when and how the first frogs evolved remains unknown.’
Michael J. Tyler, Australian Frogs, Viking O’Neil, South Yarra (Victoria, Australia), 1989, pp. 1–2.