Pleistocene Soricidae from San Josecito Cave, Nuevo Leon, Mexico BY JAMES S. FINDLEY University of Kansas Publications Museum of Natural History Volume 5, No. 36, pp. 633-639 December 1, 1953 University of Kansas LAWRENCE 1953 UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY Editors: E. Raymond Hall, Chairman, A. Byron Leonard, Robert W. Wilson Volume 5, No. 36, pp. 633-639 December 1, 1953 UNIVERSITY OF KANSAS Lawrence, Kansas PRINTED BY FERD VOILAND, JR., STATE PRINTER TOPEKA, KANSAS 1953 25-265 Pleistocene Soricidae from San Josecito Cave, Nuevo Leon, Mexico By JAMES S. FINDLEY Bones of a large number of vertebrates of Pleistocene age have been removed from San Josecito Cave near Aramberri, Nuevo León, México. These bones have been reported upon in part by Stock (1942) and Cushing (1945). A part of this material, on loan to the University of Kansas from the California Institute of Technology, contains 26 rami and one rostrum of soricid insectivores. Nothing seems to be known of the Pleistocene Soricidae of México. The workers cited do not mention them and no shrews are listed by Maldonado-Koerdell (1948) in his catalog of the Quaternary mammals of México. Comparison of these specimens with pertinent Recent material from México, the United States, and Canada leads me to the conclusion that they represent two genera and at least three species. The material examined is described below. Sorex cinereus Kerr One right ramus, bearing all three molars but lacking the other teeth and the tip of the coronoid process, needs close comparison only with certain of the smaller North American species of _Sorex_. From _S. merriami_ of southeastern Wyoming, it differs in having a shorter, much shallower dentary, a shorter molar row, and a lower coronoid. In every particular it is identical with _Sorex cinereus_. _Sorex cinereus_ from northern British Columbia and the specimen from Nuevo León differ from _Sorex saussurei_, _S. obscurus_, and _S. vagrans_ in the ratio of the height of the coronoid to the length of the dentary. This ratio averages 49.6% in _S. cinereus_ and 53.0% or more (up to 60.0%) in the other species. _Microsorex hoyi_ differs from _S. cinereus_ and from the specimen in question in deeper and shorter dentary, more robust condyle, dentary less bowed dorsally, molars shorter in anteroposterior diameter and higher in proportion to this dimension. This record, as far as I can determine, constitutes a southward extension of the known Pleistocene or Recent range of this species of approximately 800 miles. The nearest known occurrence of _S. cinereus_ in Recent times is in the mountains of north-central New Mexico. The species now has an extensive range in boreal North America and prefers mesic and hydric communities from which it rarely wanders. I know of no instance of the occurrence of the cinereous shrew in desert areas such as there are between many of the mountain ranges of southern New Mexico, Coahuila, and Nuevo León. Therefore, unless the habitat preferences of the species have changed since Pleistocene times, this find constitutes additional evidence that more humid conditions at one time prevailed in the regions mentioned. Sorex saussurei Merriam Fragments of three other specimens of _Sorex_ occur in the collection. One of these is a right ramus, C. I. T. No. 3943, and is complete except for the canine. The other two bear no numbers and I have designated them "A" and "B." "A" is a left ramus with the dentary broken off anterior to the canine and bears p4 and the canine. "B" is a right ramus bearing m2 and the roots of m3 and is broken off at the middle of the alveolus of m1. Each specimen has certain peculiarities but they resemble one another so closely that I regard all three as of the same species. The teeth, where comparable, are of essentially the same size and configuration. The horizontal rami of the dentaries are the same. The fossils differ, however, in the configuration of the coronoid process. In No. 3943 the coronoid is robust and inclined anteriorly with respect to a line drawn perpendicular to the dentary. The posterointernal ramal fossa (see Hibbard, 1953) is deeply excavated with a distinct superior border approximately halfway between its inferior border and the top of the coronoid. In addition to the mandibular foramen there is a small foramen immediately posterior to it opening into the posterointernal ramal fossa. I shall refer to this as the post-mandibular foramen. The tip of the coronoid is broad, not tapering, and quadrate, and its entire superior border is inclined rather sharply medially. Specimen "B" differs from No. 3943 in that the posterointernal ramal fossa extends nearly to the tip of the coronoid, which is narrower toward the tip and somewhat tapered dorsally. The post-mandibular foramen is large and the opening of the mandibular canal is within the posterointernal ramal fossa. In addition the coronoid does not incline anteriorly. Specimen "A" is intermediate between No. 3943 and "B" in the characters mentioned and differs from both in that the post-mandibular foramen is widely separated from the mandibular foramen. Comparison of the Pleistocene specimens with specimens of Recent species of North American _Sorex_ reveals that the presence or absence of the post-mandibular foramen is almost constant in any one species. In possessing this foramen the fossils differ from most individuals of the species: _Sorex cinereus_, _S. pacificus_, _S. milleri_, _S. vagrans_, _S. obscurus_, _S. ornatus_, _S. fumeus_, _S. palustris_, _S. bendirii_, and _S. veraepacis_. The fossils differ from all these species in other characters as well; consequently detailed comparisons with them need not be made here. Species which possess the post-mandibular foramen include _Sorex saussurei_, _S. merriami_, _S. trowbridgii_, _S. arcticus_, _S. tundrensis_, and _S. sclateri_. _Sorex merriami_ differs in smaller size, smaller and weaker dentition, relatively higher coronoid, and relatively deeper and shorter dentary. _Sorex trowbridgii_ is similar to the fossils and to _S. saussurei_. Differences between the jaws of _S. trowbridgii_ and _S. saussurei_ seem to me to be differences of size only. _Sorex sclateri_ is larger than the fossils and m2 is longer in relation to m1, being almost the same size as m1. In the fossils m2 is noticeably shorter than m1, owing to close appression of the hypoconid and protoconid and in general to a smaller talonid area. _Sorex arcticus_ differs in larger incisor and p4. _Sorex tundrensis_ differs in relatively narrower molars. I have compared the fossils also with the Pliocene and Pleistocene _Sorex taylori_ Hibbard, and find that the fossils are larger and have larger teeth and a much wider separation of the protoconid and metaconid. I can find no significant way in which the fossils differ from _S. saussurei_. This of course implies similarity to _S. trowbridgii_. Since _S. saussurei_ is a widespread species in México today and since it occurs in the vicinity of the San Josecito area the specimens under discussion are referred to this species. Cryptotis mexicana (Coues) The San Josecito collection contains 22 rami of a species of _Cryptotis_. Many are nearly complete although none possesses the incisor. In addition there is a rostrum that on the right side bears the last two unicuspids, P4, M1, and M2. I have compared these fossils with specimens of the following species of _Cryptotis_: _C. mexicana_, _C. magna_, _C. nelsoni_, _C. thomasi_, _C. alticola_, _C. parva_, _C. orophila_, _C. pergracilis_, _C. guerrerensis_, _C. obscura_, _C. mera_, _C. soricina_, _C. fossor_, _C. goodwini_, _C. griseoventris_, _C. meridensis_, _C. mayensis_, and _C. micrura_. The four species first mentioned and the fossils seem to fall into one group. The remaining species fall into another group characterized by a smaller occlusal area of the talonid on all three molar teeth with respect to the trigonid, and especially by the smaller and weaker talonid of m3 which possesses only one bladelike cusp, the hypoconid. In the first four species the talonids are larger than in the other species when compared to the trigonids, and the talonid of m3 possesses a well developed hypoconid and entoconid with a distinct basin between them. The rami of San Josecito specimens closely resemble those of _C. mexicana_ in both size and qualitative characters. The rostrum mentioned above differs from those of _C. mexicana_ in that the unicuspids are larger, especially the posteriormost one. _Cryptotis thomasi_ and _C. magna_ are eliminated from consideration here on geographical grounds. Little difference may be seen between the rami of _C. mexicana mexicana_ from Veracruz and _C. nelsoni_. The fossils are referred to the former species since it has a rather wide distribution in México in contrast to _C. nelsoni_ which is restricted to Volcán de Tuxtla, Veracruz. The northernmost Recent occurrence of _C. mexicana_ known to me is from Las Vigas, Veracruz. As far as I know the species has not previously been recorded from the Pleistocene. Stirton (1930:225), in summarizing the group characters of Recent Soricidae, listed the bicuspid talonid of m3 as one of the characters of the "_Blarina_ group," which includes _Neomys_, _Soriculus_, _Notiosorex_, _Chimarrogale_, _Cryptotis_, and _Blarina_. That this character does not obtain universally within the group is demonstrated by the unicuspid structure of the talonid of m3 of the majority of the species of Mexican _Cryptotis_. I am grateful to Drs. David E. Johnson and Henry W. Setzer of the United States National Museum, and to Dr. John Aldrich and Miss Viola S. Schantz of the United States Fish and Wildlife Service for permitting me to examine specimens in their care. Also I am obliged to Professor E. Raymond Hall for permission to study the specimens from San Josecito Cave. The late Professor Chester Stock intrusted the specimens to Professor Hall for study and description. LITERATURE CITED CUSHING, J. E., JR. 1945. Quaternary rodents and lagomorphs of San Josecito Cave, Nuevo León, México. Jour. Mamm., 26:2, 182-186. HIBBARD, C. W. 1953. The insectivores of the Rexroad fauna, upper Pliocene of Kansas. Jour. Paleontology, 27:1, 21-32. MALDONADO-KOERDELL, M. 1948. Los vertebrados fosiles del Cuaternario en Mexico. Revista de la Soc. Mexicana de Hist. Nat., tomo 9, nos. 1-2. STIRTON, R. A. 1930. A new genus of Soricidae from the Barstow Miocene of California. Univ. California Publ., Bull. Dept. Geol. Sci., 19:217-228. STOCK, C. 1942. The cave of San Josecito, México, new discoveries of the vertebrate life of the ice age. California Inst. Tech., Balch Grad. School Geol. Sci. Contr., no. 361, 5 pp. _Museum of Natural History, University of Kansas, Lawrence, Kansas. Transmitted July 20, 1953._ 25-265