COAST RANGE CORRIDOR IN CALIFORNIA 161 



are rare, isolated fragments. Cave and asphaltic deposits of the late 

 Pleistocene produce more remains, but nearly all are disarticulated 

 and easy to overlook in the quest for larger and more durable re- 

 mains of mammals and birds. 



Current interests of paleontologists in the washing and sifting of 

 sediments for microfossils are greatly increasing the recovery of 

 herpetological remains. For example, students of the University of 

 California, Berkeley, have made large collections of small lizard 

 remains from Eocene and Cretaceous strata of Colorado and Wyo- 

 ming (Malcolm McKenna and Robert Estes, personal communica- 

 tion). However, a fossil amphibian, particularly a fossil urodele, will 

 continue to be a rare find for the paleontologist because of the an- 

 cient trend toward deossification in their skeleton and because bone 

 is a prime prerequisite for preservation. Fortunately, the fossil 

 record of amphibians is enhanced significantly by the discovery of 

 numerous, clear, and distinctive trackways of urodeles in Mio- 

 Pliocene sediments of the Sierra Nevada Mountains in California 

 (Peabody, 1940, 1954). 



A general conclusion from a survey of the paleontology of the far 

 western herpetofauna is that considerable progress is to be expected 

 in the future as a result of new techniques and of heightened interest 

 in paleoherpetology. However, we cannot ever expect to approach 

 the relative completeness of the mammalian record, and discoveries 

 in the far west will continue to be infrequent. Also a necessary ad- 

 junct to paleontological studies will continue to be more detailed 

 osteological studies of living species. 



The fossil record of the herpetofauna, admittedly deficient, is 

 complete enough to establish firmly some general considerations of 

 historical importance. Fossils from the Cenozoic of Europe and 

 North America clearly indicate great antiquity for most living 

 genera of salamanders. By the dawn of the Cenozoic the three 

 families of terrestrial salamanders, Salamandridae, Ambystomidae, 

 Plethodontidae, were evolved, and by the Miocene epoch living 

 genera of all urodeles were probably in existence. The most dramatic 

 and unusual evidence of modern families and genera comes from the 

 Mio-Pliocene trackways of the Sierra Nevada (Peabody, 1940) where 

 the genera Taricha, Batrachoseps, and a Dicamptodon-l'ike form 

 coexisted in association with a fossil flora described by Condit 

 (1944). These trackways and the Oligocene skeleton of Paleotaricha 



