Meade Basin, and its presence implies at least a brief episode of increased early Pliocene aridity. Three specimens from the late Pliocene (Rexroad 2, 2A,
Wendell Fox Pasture) may represent additional records of Ammospermophilus. The dp4 from Rexroad 2 differs from fossil and extant Ictidomys, but resembles Ammospermophilus in very small size, transversely narrow trigonid, and closely adjacent protoconid and metaconid. P4s from Rexroad 2A and Wendell Fox Pasture are much smaller than in coeval I. meadensis (Table 2; Fig. 5.2) and have a reduced anterior cingulum, in both features resembling Ammospermophilus, but exhibit a more developed connection between the metaloph and protocone than is typical for the genus.We tentatively assign both specimens to Ammospermophilus.
Genus Otospermophilus Brandt, 1844
Otospermophilus rexroadensis (Hibbard, 1941c) Figure 4.7
1941c Citellus rexroadensis Hibbard, p. 348, fig. 7. 1961 Citellus (Otospermophilus) rexroadensis Hazard, p. 477, figs. 1, 2.
1980 Spermophilus rexroadensis Kurtén andAnderson, p. 213.
Holotype.—KUVP 4608, left dentary with I, p4–m3 from Rexroad Loc. 3, Meade Co., KS (Hibbard, 1941c, fig. 7).
Remarks.—Assignment to Otospermophilus is supported by multiple characters, including moderately large size (Fig. 5.1, 5.2), low relative trigonid width of p4 (Figs. 5.3, 6.1), low tooth crown height, and incomplete metaloph on M1 andM2(constricted at contact with the base of the protocone). Otospermophilus rexroadensis (Hibbard, 1941c) from the type locality (Rexroad Loc. 3; Hibbard, 1941c) and other late Pliocene localities display significantly larger teeth (and presumably body mass) than fossils from FoxCanyon and other early Pliocene localities (Table 2; length of p4: t = 2.93, df = 20, p<0.01; length of P4: t = 6.26, df = 20, p<0.001), a difference previously noted by Hazard (1961) that we attribute to phyletic evolution.
Otospermophilus spp.
Remarks.—Both SawRock Canyonand FoxCanyoninclude O. rexroadensis and probably a second, larger species of Otospermophilus (UMMP 117762, P4, from Saw Rock Canyon in Fig. 5.2) that we cannot presently identify to species. Otospermophilus was not observed in early Pleistocene or the Middle Pleistocene Cudahy assemblages, but a single p4 from the Adams local fauna(UMMP34735; Fig. 5.1) is clearly assignable to the genus.We are unable to confidently assign this tooth to species, but it plausibly represents a temporary northeastern range expansion of the extant rock squirrel, Otospermophilus variegatus (Erxleben, 1777), a species that ranges today from northern Utah to southern Mexico and from far southeastern California to the panhandle of Oklahoma, ~60km SW of Meade County (Helgen et al., 2009).
Genus Ictidomys Allen, 1877
Ictidomys meadensis (Hibbard, 1941a) Figures 4.3–4.5, 7.1
Table 1. Sciurid species recovered from selected assemblages in the Meade Basin, Kansas. Assemblage abbreviations listed in approximate stratigraphic sequence from oldest (left) to youngest (right): HB = High Banks; SRC = Saw Rock Canyon; FC = Fox Canyon; RipB = Ripley B; XIT1B = XIT 1B; Rap1C = Raptor 1C; WnsB–D = Wiens B, C, D; Vas = Vasquez; Nwt = Newt; Hor = Hornet; R3A-C = Rexroad 3A-C;Wb = Wheelbarrow; WFP = Wendell Fox Pasture; R2A = Rexroad Loc. 2A; R2 = Rexroad Loc. 2; DP = Deer Park A; HD = Hart Draw; Pal = Paloma; Mar = Margaret; Bor = Borchers; SH = Short Haul; ArA = Aries A; ArNE = Aries northeast; RF = Rick Forester; Na72 = Nash 72; Cud = Cudahy; Sun = Sunbrite; RR = Robin’s Roost; AD = Adams; BS = Butler Spring; MS = Mt. Scott; Kapp = Kapp Horizon; CQ = Cragin Quarry; Jin = Jinglebob; Jon = Jones; Tay = Taylor; GolB, C = Golliher B-C; Rob = Robert; Mod = Modern. * = exact stratigraphic placement uncertain.
Ammospermophilus sp.
Otospermophilus rexroadensis
Otospermophilus sp. tridecemlineatus
Xerospermophilus spilosoma
Poliocitellus franklini Urocitellus cragini
Urocitellus richardsonii Urocitellus “morph A” Cynomys hibbardi
Cynomys ludovicianus Cynomys niobrarius Cynomys?n. sp. (small) Cynomys sp.
Paenemarmota sawrockensis
Paenemarmota barbouri
x xx x cf xx cf x x
xx x
x xx x x x x
?x x x x
x x x x cf x x x x
HB SRC FC RipB XIT1B Rap1C WnsB–D Vas/Nwt Hor R3A–C Wb* WFP* R2A R2 DP HD, Pal Mar Bor SH ArA ArNE RF Na72 Cud Sun RR AD BS MS* Kapp CQ Jin Jon Tay* GolB, C Rob Mod x
xx x x x
Ictidomys meadensis xx x Ictidomys
x x
x x
x cf x x x x x x x x x x
cf cf x
x x x x x x x x x x x x x x x x x x x xxx x x
x x x
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