Ascaphus is the only living representative of a basal lineage of anurans, and may retain some relatively primitive traits of early frogs (e.g. Ford and Cannatella 1992).
See another account at californiaherps.com.
- Stebbins, R. C. (1985). A Field Guide to Western Reptiles and Amphibians. Houghton Mifflin, Boston.
- Ford, L.S., and Cannatella, D.C. (1993). ''The major clades of frogs.'' Herpetological Monographs, 7, 94-117.
- Nussbaum, R. A., Brodie, E. D., Jr., and Storm, R. M. (1983). Amphibians and Reptiles of the Pacific Northwest. University of Idaho Press, Moscow, Idaho.
- Stebbins, R.C. (1951). Amphibians of Western North America. University of California Press, Berkeley.
- Bull, E. L. and Carter, B. E. (1996). ''Tailed Frogs: Distribution, ecology, and association with timber harvest in Northeastern Oregon.'' United States Forest Service Research Paper, (497), 1-12.
- Orchard, S.A. (1992). ''Amphibian population declines in British Columbia.'' Declines in Canadian amphibian populations: designing a national monitoring strategy. C. A. Bishop nd K.E. Petit, eds., Canadian Wildlife Service, 10-13.
- Wallace, R. L. and Diller, L. V. (1998). ''Length of the larval cycle of Ascaphus truei in coastal streams of the redwood region, northern California.'' Journal of Herpetology, 32(3), 404-409.