The Secret Toad-headed Agama, also called Secret Toadhead Agama, is native to the desert and steppe of Central Asia. It is one of several species of Toadhead Agama.
These photos were taken in Kazakhstan by Alexandra Makhnina (who got better photos of it than I did).
The fingers and toes are fringed to help running on sand. Neither Sasha nor I managed to photograph the "secret" -- when it opens its enormous pink mouth with frilled side wings.