Has anyone read "Citadel of Fear" by Gertrude Barrows Bennett? It's a decent pulp sci-fi/fantasy novel, similar to the works of Edgar Rice Burroughs, Robert E. Howard, et al. To the lizardmen/seraphon flavor specifically; The first part of the book is about two lost adventurers in Mexico who stumble upon the hidden city of Tlapallan, devoted to the Aztec gods. That part of the book is unfortunately too short, but has some good ideas and a couple of neat scenes. The rest of the book is more sci-fi and a fun read/listen (at least I enjoyed it). I think you can find it on YouTube, or on Libirvox.org.