NANNIPPUS PHLEGON (MAMMALIA, EQUIDAE)
 FROM THE PLIOCENE (BLANCAN) OF FLORIDA

 BRUCE J. MACFADDEN AND JOHN S. WALDROP1

SYNOPSIS: Dental and postcranial remains of the three-toed horse, Nannippus phlegon,
are described from four localities in Florida: Santa Fe River, Haile XVA, Sarasota, and
Port Charlotte. As is the case elsewhere in North America, the presence of N. phlegon
at these Florida localities appears to indicate a Blancan age, which spans a time inter-
val from about 4.5 to 2 million years ago. Specimens of N. phlegon from Florida are
similar to those found elsewhere in North America, e.g. the typotypic material from Mt.
Blanco in the Texas Panhandle. Diagnostic characters of N. phlegon include: small and
gracile stature, no preorbital facial fossa, elongate rostrum and symphysis, very hypso-
dont teeth, cement relatively thick above oval border, oval protocones, moderately
complex enamel plications, deep ectoflexids, ectoparastylid absent, metapodials tridac-
tyl and elongate, and trapezium absent. Postcranial remains demonstrate that N.
phlegon was a functionally advanced and highly cursorial "antelope-like" hipparion.
Several derived characters are presented here to support the hypothesis that a mor-
phocline, which also is interpreted to represent an ancestral-decendent sequence, pro-
ceeds from N. minor (particularly from the Bone Valley district) to N. beckensis (from
the early Blancan of Texas) to N. phlegon.




 TABLE OF CONTENTS

INTRODUCTION ................................................. ...... 2
ACKNOWLEDGMENTS ........ ....................................... 3
ABBREVIATIONS ...... .................................... .. ... 3
LOCALITIES .............................. ............. .. ......... 4
SYSTEMATIC PALEONTOLOGY .................................... ....... 4
 H OLOTYPE ...................................... .. ...... 4
 T YPE L OCA LITY ................... .............................. 4
 D ISTRIBUTION ...................................... ..... 4
 D IAGNOSIS ............................ ......... ... ..... 4
 REFERRED SPECIMENS . ..... .................................. 6
 D ESCRIPTION ................................................... . 7
 D ENTITION ...... ........ .. .................................... 7
 POSTCRANIALSKELETON ................................. ......... 16
DISCUssioN ..................... ..... ................. .......... ... 27
 Nannippusphlegon FROM FLORIDA .......... ......................... 27
 ORIGIN OF Nannipus phlegon ...................................... 29
L ITERATURE C ITED ......... .. ..................................... 35




'Bruce J. MacFadden is Assistant Curator in Vertebrate Paleontology, Department of Natural Sciences, Florida
State Museum, and Joint Assistant Professor, Departments of Zoology and Geology, University of Florida,
Gainesville 32611.
John S. Waldrop received his M.S. degree in geology at the University of Florida and is presently Director of the
Timberlane Research Organization, Rt. 2, Box 5853, Lake Wales, FL 33853. University of Florida Contribution to
Vertebrate Paleontology No. 169.

MACFADDEN, BRUCE J., and JOHN S. WALDROP. 1980. Nannippus phlegon
(Mammalia, Equidae) from the Pliocene (Blancan) of Florida. Bull. Florida State Mus.,
Biol. Sci. 25(1):1-37.