RESEARCH· ·1970·

Bl34
PALEONTOLOGY
a b c d e
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D
EXPLANATION
Enamel Dentine Cement
FIGURE 3.-Enamel patterns of the cheek teeth of the various genera an'd species of lagomorphs from the OurtiSI Ranch local
fauna. a, Lepus near L. ca»i/01"nicl!,S, LPa, Univers~ty of Arizona. specimen UA 1375; b, A.luralagus virginiae, LPa, type
•specimen, UA 1382; c, A.ltwalagus virginiae, LPa, UA 1372, enamel pattern at base of tooth; fl, A.luralagus 'li i1·ginliae, LPa,
UA 1378; c, Lept!,S near L. calif01'nicus, RP", UA 1374; /, L epus near L. calij01·nicl~S, RPa, UA 1379, juvenile; u, L epuS' near
L. calijornict!,S, RP', UA 1374; and h A.lura"lagus ? 'li'irginiae, RP', RP 3 , RP', UA 1376, Enamel patterns are approximately
X 10.
line of descent (Downey, 1968; Hibbard, 1963),
namely, the joining of the posterior external enamel
reentrant on lower P 3 with an internal enamel lake
or fold, thus forming a deep enamel reentrant that
crosses nearly the entire occlusal surface of the tooth.
The lower P 3 of A. vi1·giniae appears to display features
indicating the continued development of this
process through time.
FIGURE 4.-Lower left jaw of A.luralagus virginiae from the
Curtis Ranch local fauna. Type specimen, UniYersity of
Arizona UA 1382. a, mental foramen; and b, secondary mental
foramen described in text. Approximately X 3.9.
In A. vi1·giniae the posterior enamel wall of the posterior
external reentrant of the lower P 3 has become
less complex when compared with the same feature of
A . bensonensis, and the anterior enamel wall of the
posterior reentrant of lower P 3 developed two broad
folds into the anterior column of the tooth.
Genus ALURALAGUS?
Aluralagus? virginiae
Figure 3h
One specimen, an upper right jaw fragment with
P 2 , P 3 , and P 4 , UA 1376, from the Curtis Ranch local
fauna is tentatively assigned to the genus Alittralagtts.
This assignment is based on the enamel pattern of the
upper P 2 , which displays one well-developed anterior
enamel reentrant and a shallow anterior enamel groove
on the occlusal surface. The upper P 2 from the Curtis
Ranch fauna resembles in general shape the upper
P 2 of Pratilepus vagus from the Hagerman local fauna
of Idaho (Hibbard, 1969, fig. 3e) .
'Vhen first described the genus Pmtileptts was
thought to display three anterior enamel folds on the