MAMMALIAN PALEONTOLOGY

Warren Local Fauna

Since the early 1900s, a moderately large assemblage of fossil mammals has been collected from the Horned Toad Formation. C.L. Baker (U.C. Berkeley) first reported fossils from this area in 1911 (Reynolds et al. 1991). A. Alexander and L. Kellogg, also from U.C. Berkeley, collected additional specimens in 1925, and R. A. Stirton recovered more fossils in 1938 (Figure 25.1). The collections were significantly expanded by W. Daily, G. Gustely, and others from U.C. Riverside from the 1960s through the early 1980s (Figure 25.2). May (1981a) described the mammalian fossils from the Horned Toad Hills in a Master's thesis at U.C. Riverside under the direction of M.O. Woodburne. The U.C. Riverside specimens are now housed at the University of California Museum of Paleontology at U.C. Berkeley. When the collection was transferred to Berkeley, specimen numbers were modified by replacing the prefix of UCR with UCMP and adding the number 3 to the original numeric designation. Locality numbers were unchanged.

This collection of stratigraphically associated fossils is referred to as the Warren Local Fauna and includes 24 identified mammalian taxa:

shrew
Cryptotis sp.

mole
cf. Scapanus

rabbits
Hypolagus vetus, Hypolagus edensis

ground squirrel
?Spermophilus sp.

gopher
Prothomomys warrenensis n. gen., n. sp.

pocket mouse
Perognathus sp.

mice
Repomys gustelyi, Postcopemys valensis, Peromyscus sp. A, Peromyscus sp. B, Jacobsomys dailyi, n. sp.,

dog
Borophagus cf. B. secundus

bear
cf. Agriotherium

saber-tooth cat
Machairodus sp. cf. M. coloradensis

proboscideans
Rhynchotherium sp. cf. R. edensis, Pliomastodon vexillarius

horse
Dinohippus edensis

rhino
Teleoceras sp. cf. T. fossiger

peccary
cf. Prosthennops sp.

camels
Megatylopus sp. cf. M. matthewi, Hemiauchenia vera, Camelidae gen. et. sp. indet.

antelope
cf. Sphenophalos

We have chosen to follow McKenna and Bell (1997) for classification of mammals at the ordinal level.