BULLETIN FLORIDA STATE MUSEUM


was apparently Neotropical in distribution (although Blancan faunas
are not known in Central America). In the well-sampled more northern
Hagerman L. F. and Grand View L. F. of equivalent age in Idaho, N.
phlegon is not represented (Gazin 1936, Shotwell 1970). Its presence in
Florida seems to be another example of the Neotropical influence of
late Cenozoic faunas of the Gulf Coastal region.
 Fossil horses, because of their rapid evolution and wide distribu-
tion both geologically and geographically, are among the best in-
dicators of time in terrestrial Cenozoic sequences. The occurrence of
Nannippus phlegon is also consistent with this generally held view. In
organizing the biochronology of the North American continental Ter-
tiary, the Wood Committee (1941) presented a synthesis of the stages
of mammalian evolution. The Blancan North American Land Mammal
Age was proposed in that report. This time term is a faunal
characterization that includes a combination of first appearances, last
appearances, index fossils, and characteristic fossils. As a result of the
recent advent of precise geochronological tools such as radiometric
and paleomagnetic dating, it is now known that the Blancan spans a
period of time from about 4.5 to 2 million years ago (although not in
total agreement, see Berggren and Van Couvering 1974, Johnson, Op-
dyke, and Lindsay 1975, Lindsay, Opdyke, and Johnson 1975, Tedford
et al., in press).
 With regard to horses, "primitive" Equus (Dolichohippus) is con-
sidered an index fossil of Blancan time. Nannippus is stated to last ap-
pear during this time (Wood et al. 1941). Besides the last occurrence of
this genus, the species N. phlegon is taken as an index of Blancan time,
with its presence in characteristic faunal assemblages (based on other
constituent taxa) such as the type Blancan of the Texas Panhandle,
Arizona, Kansas, and Nebraska. Similarly, Webb (1974) stated that
the presence of Nannippus phlegon in Florida, again based on
associated characteristic faunal elements, is consistent with an inter-
pretation of Blancan time for the Santa Fe River and Haile localities.
 The two additional localities reported here also appear to be of
Blancan age. Besides Nannippus phlegon, the Sarasota TRO localities
include the following taxa collected in situ: Equus (Dolichohippus) cf
simplicidens, Kraglievichia cf floridanus, Megalonyx, leptostomus,
Hemiauchenia macrocephala, Tapirus cf veroensis, Cuvieronius sp.,
primitive capybara, and Chrysemys platymarginata. This assemblage
is taxonomically similar to the Santa Fe River and Haile Blancan
localities (Webb 1974, Robertson 1976). The field associations and
small faunal assemblages of the Port Charlotte localities are of doubt-
ful significance; besides Nannippus phlegon, only primitive Equus and
Chrysemys platymarginata have been collected from spoil piles.


Vol. 25, No. 1