Pleistocene Pocket Gophers From San Josecito Cave, Nuevo Leon, MexicoRussell, Robert J.
Science
Pleistocene Pocket Gophers From San Josecito Cave, Nuevo Leon, Mexico
Russell, Robert J.
Pocket gophers, Fossil
_Remarks._--Pocket gophers do not inhabit caves; therefore gophers were
brought into the cavern probably by birds of prey, the remains of which
were common in the deposits (Miller, 1943:152-156), or conceivably by
carnivorous mammals. Since most of the raptorial predators that would
prey on pocket gophers do not have a wide hunting territory, it is
likely that the gophers were taken within a short distance of the cave.
The presence of the genus _Heterogeomys_ in the deposits strongly
suggests a tropical situation in the vicinity of the cave when these
gophers were taken, because the distribution of this genus today is
entirely within the Tropical Life-zone.
Since the presumably early time when tropical conditions, or more nearly
tropical conditions, prevailed at San Josecito Cave, climatic shifts
account for a humid boreal environment there and its associated fauna.
Findley (_lit. cit._:635-636) reports from San Josecito the remains of
the boreal shrew _Sorex cinereus_ that today occurs no nearer than 800
miles to the northward in the mountains of north-central New Mexico. As
he points out, that species requires hydric communities of cool
climates, and in the Wisconsin Glacial age such climates probably
prevailed in the high mountainous region where San Josecito is located.
Since the time when a more mesic boreal environment occurred at San
Josecito, climatic shifts have favored more xeric conditions as are
found in the vicinity of the cave today. The more arid environments
would support the occurrence of _Cratogeomys_ and _Thomomys_; however
the ecological affinities of the fragment here referred to _Cratogeomys_
sp. are unknown.
The more nearly tropical environment there could have occurred either
during a Wisconsin interglacial period or during the Sangamon
Interglacial age. _Heterogeomys onerosus_ perhaps lived near the cave
during an interglacial period; since then it became extinct or evolved
into the Recent species _Heterogeomys hispidus_. _Heterogeomys_ has not
previously been recorded from Pleistocene or earlier deposits.
LITERATURE CITED
BAKER, R. H.
1953. The pocket gophers (genus Thomomys) of Coahuila, Mexico.
Univ. Kansas Publ., Mus. Nat. Hist., 5:499-514, 1 fig. in
text, June 1.
CUSHING, J. E., JR.
1945. Quaternary rodents and lagomorphs of San Josecito Cave, Nuevo
Leon, Mexico. Jour. Mamm., 26:182-185, July 19.
FINDLEY, J. S.
1953. Pleistocene Soricidae from San Josecito Cave, Nuevo Leon,
Mexico. Univ. Kansas Publ., Mus. Nat. Hist., 5:633-639,
December 1.
HANDLEY, C. O., JR.
1955. _A new Pleistocene bat (_Corynorhinus_) from Mexico._ Jour.
Washington Acad. Sci., 45:48-49, March 14.
HOOPER, E. T.
1952. A systematic review of the harvest mice (genus
_Reithrodontomys_) of Latin America. Miscl. Publ. Mus. Zool.,
Univ. Michigan, 77:1-255, 9 pls., 24 figs., 12 maps, January
16.
JAKWAY, G. E.
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