1980 MACFADDEN & WALDROP: FLORIDA NANNIPPUS PHLEGON 33

 Many hipparions have an ectoparastylid (projection or isolation of
paralophid, also called parastylid by some workers) developed on the
anteroexternal region of P,-M3. Primitive N. minor shows a reduction
in the presence of the ectoparastylid, which is further reduced in both
advanced N. minor and N. beckensis. In N. phlegon the ectoparastylid
is normally absent (see Waldrop 1971 and Dalquest and Donovan 1973
for quantitative data). In other words, a character morphocline pro-
ceeds from primitive hipparions (ectoparastylid present) to primitive
N. minor (reduction in frequency of ectoparastylid) to advanced N.
minor-N. beckensis (further reduction in frequency of ectoparastylid)
to N. phlegon (ectoparastylid normally absent).
 N. minor, N. beckensis, and N. phlegon have numerous other dental
characters that support a hypothesis of close relationship, for exam-
ple, complexity of enamel plications and shape of dental parts. Both N.
minor and N. beckensis are smaller in maximum crown height (in both
the uppers and lowers) than N. phlegon. The maximum crown height of
N. minor is normally less than 50 mm (Waldrop 1971) whereas the
maximum crown height of N. phlegon is somewhat greater than 50 mm
(see Tables 1,4). For N. beckensis Dalquest and Donovan (1973) noted
crown heights of 56.2 mm to 60.0 mm (lowers) and 51.2 mm to 55.7 mm

TABLE 12.-MEASUREMENTS OF LEFT LOWER CHEEK TEETH OF Nannippus minor, TRO
 567, FROM PALMETTO MINE, BONE VALLEY DISTRICT, POLK COUNTY,
 FLORIDA.
 AP T
Tooth length width HT*
P, 13.3 7.5 25.2
P, 13.6 7.9 -
P, 14.0 7.6 33.5
M, 13.0 6.4 35.0
M, 13.4 6.6 -
M, 16.6 5.3 39.3
*Crown height at mesostyle.








 0 1 2 3 4 5cm

 FIGURE 16.-Left lower cheek teeth, P,-M,, of Nannippus minor, TRO 567, from Palmet-
 to Mine, Bone Valley district, Polk County, Florida.