Late Pleistocene fauna from Zesch Cave, Mason County, Texas

Quaternary International 217 (2010) 159–174

Contents lists available at ScienceDirect

Quaternary International journal homepage: www.elsevier.com/locate/quaint

Late Pleistocene fauna from Zesch Cave, Mason County, Texas James Christopher Sagebiel* Department of Geological Sciences, University of Texas at Austin, 1 University Station C1100, Austin, TX 78712, USA

a r t i c l e i n f o

a b s t r a c t

Article history: Available online 28 December 2009

The Zesch Cave local fauna is one of the most diverse fossil vertebrate localities from central Texas, and one of the only three sites on the Edwards Plateau juxtaposed to the Llano Uplift. At least 70 vertebrate taxa are identified in this local fauna including fish, four lissamphibians, six sauropsids, eight birds, and fifty-one mammal species. A largely granitic structural dome, the Llano uplift differs from the rest of the predominantly carbonate Edwards Plateau in geology, soils and ecology. This is reflected in the Zesch Cave local fauna as well, which has greater similarity to high plains faunas than those recorded 80 km or more to the south. Notably, this local fauna contains the first record of Sorex hoyi (pygmy shrew) and Pica pica (magpie) from central Texas, which indicates similarity or connection with a Rocky Mountain fauna. The Zesch Cave vertebrates provide a more complete picture of faunal zones as they existed in the Rancholabrean. Ó 2010 Elsevier Ltd and INQUA. All rights reserved.

1. Introduction Zesch Cave, located on the Edwards Plateau near Mason, Texas, juxtaposed to the granitic Llano Uplift of Texas is one of the three described Pleistocene mammal localities within this structural uplift region, and none is as diverse as the Zesch Cave local fauna. At least seven extinct and thirteen extralimital taxa occur in Zesch Cave. This local fauna includes fish, lissamphibian, sauropsid, avian and mammalian taxa, but is biased towards cavernicolous vertebrates because of the mode of accumulation – bats account for 31% of the fauna as measured by MNI. The Zesch Cave local fauna probably accumulated through pitfall entrapment and as a result of carnivoran and raptor activity. Carnivore utilization of the cave is evinced by the relative abundance of fossils of carnivorans (33% NISP, 9.4% MNI) compared to the paucity of similar sized herbivorous mammals (2.5% NISP, 3% MNI). Sylvilagus fossils are heavily represented in the fauna (19.2% NISP, 6.8% MNI), most likely as a result of prey selection by carnivorans and raptors. The diversity of taxa allows a relatively complete paleoenvironmental interpretation and an opportunity to compare the environmental signals provided by the mammalian and avian faunas. 2. Regional setting Zesch Cave is located 4 km west of Mason, Texas (30 450 N, W, 470 m elev.), in the Llano uplift region of the Edwards

99150

* Corresponding author at: Division of Geological Sciences, San Bernardino County Museum, 2024 Orange Tree Lane, Redlands, CA 92373, USA. Tel.: þ1 909 307 2669x237; fax: þ1 909 307 0537. E-mail address: [email protected] 1040-6182/$ – see front matter Ó 2010 Elsevier Ltd and INQUA. All rights reserved. doi:10.1016/j.quaint.2009.11.029

Plateau. It contains the northwest-most Pleistocene fauna described from the Edwards Plateau (Fig. 1). Zesch Cave, Mason County and Miller’s Cave, Llano County (Patton, 1962) are the only Late Pleistocene sites described from the Llano uplift region of central Texas (Toomey, 1994). This area is significant for its geographic location, which bridges the Llano Estacado-High Plains Region to the north with the Balcones Escarpment (Fig. 1, sites 7– 12) and ultimately the Gulf of Mexico Coastal Plain (Fig. 1, sites 13 and 14). Zesch Cave lies within the Pennsylvanian Smithwick Formation, which crops out on the southern edge of the Llano Uplift structural dome. Soils in this region vary from well-drained sandy soils adjacent to granite uplifts, to alkaline soils on limestone formations and thin, rocky soils on the uplands of the dissected plateau. The geological complexity of the region creates an ecological mosaic that roughly mimics soil distribution (Barnes, 1981; Riskind and Diamond, 1988). 3. Geology The cave is currently a dome-shaped room with a single entrance situated roughly central to the cavern and 6 m above a Holocene debris cone. A fossiliferous breccia, the source of the Zesch Cave local fauna, crops out in the eastern corner of Zesch Cave. This sediment encroaches into Zesch Cave from an adjacent passage that is now inaccessible. The Pleistocene entrance to the cavern clearly possessed an opening sufficient to accommodate an adult American black bear (Ursus americanus), but its location is not visible today. The cave sediment allows a reconstruction of the Pleistocene entrance. It is a karst collapse breccia with grain sizes

160

J.C. Sagebiel / Quaternary International 217 (2010) 159–174

heavily indurated with carbonate cement, Cabaniss collected blocks of fossiliferous rock. The cementing carbonate was dissolved in a 10% solution of glacial acetic acid. The collection methods and preparation were not sensitive to the internal stratigraphy of these deposits. 5. Results The presence of Bison at a site indicates a fauna no older than Rancholabrean (Bell et al., 2004). An undoubtedly Rancholabrean mammalian assemblage is also indicated by the extinct species Platygonus compressus (flat-headed peccary), Camelops hesternus (yesterday’s camel) and Canis dirus (dire wolf), known only from Rancholabrean sites (Kurte´n and Anderson, 1980; Lundelius et al., 1987). The extant species Myotis velifer (cave bat), Sorex hoyi (pygmy shrew) and Baiomys taylori (northern pygmy mouse) first appear elsewhere in North American faunas in the Rancholabrean as well (Kurte´n and Anderson, 1980). 5.1. Abbreviations

Fig. 1. Localities cited in the text and important Texas Quaternary vertebrate localities. 1. Schultze Cave Dalquest et al., 1969, 2. Cave Without a Name Lundelius, 1967, 3. Hall’s Cave Toomey, 1993, 4. Zesch Cave Lundelius, 1967, This Study, 5. Miller’s Cave Patton, 1963, 6. Longhorn Cavern Semken, 1961, 7. Wilson-Leonard Site Winkler, 1990, 8. Laubach Cave Lundelius, 1985, 9. The Avenue Site Lundelius, 1992, 10. Barton Road Site Lundelius, 1967, 11. Friesenhahn Cave Graham, 1976, 12. Natural Bridge Caverns Werdelin, 1985, 13. Sabine River Site Eddleman and Akersten, 1966, 14. Ingleside Site Lundelius, 1972.

ranging from mud (less than 10%) to small boulders (76 cm diameter). A well-indurated surface 10–20 cm thick caps the deposit. The larger clasts are autochthonous limestone pebbles and cobbles derived from the surrounding Ellenburger Limestone and Smithwick Formation. Frank (1965) used point counting to determine that the sediment fraction smaller than gravel is composed of 64% vertebrate fossils, with the remaining fraction being composed of internal sediment from host rock (12%) and externally derived sand-size fragments of quartz (15%), feldspar (4%), and other rock and mineral grains (5%). The combination of large autochthonous clasts and paucity of fine sediment coarsens the internal stratigraphy and, therefore, increases time averaging of the sediments. As an example, a heavily weathered Equus humerus bridged a 10 cm crevice between large limestone blocks. Microvertebrate fossils had not only accumulated beneath the bone as well as on top of the limestone clasts, but also atop and within the heavily weathered humerus. Because of the complex internal stratification of the Zesch Cave sediment as well as the collection methods (Section 4), the fauna was treated as a single unit. 4. Collection history and methods Fossils were first discovered in Zesch Cave in 1951 by cave explorers Bob Hudson, Laban Walton, and George Danz. Later that year, Glen Evans (then with the Texas Memorial Museum) recognized that the fossils from the Zesch Cave conglomeratic deposits were Pleistocene in age. In the 1960s, Ruben (Bud) Frank and Ernest L. Lundelius, Jr. visited Zesch Cave to investigate its paleontology and sediments (Frank, 1965). Lundelius (1967) published a preliminary faunal list for Zesch Cave as a result of these early investigations. Boyce Cabaniss collected most of the fossils that are the basis of the present study in the summer of 1982. Because the debris cone is

Institutional – TCWC, Texas Cooperative Wildlife Collection, Texas A and M University; TMM, Texas Memorial Museum Statistical – CV: coefficient of variation; N: number of specimens examined; OR: observed range; SD: standard deviation Measurement – DB: distal breadth; E: ear length; FHB: femoral head breadth; HF: hindfoot length; HHB: humeral head breadth; L: length; MSD: minimum shaft diameter; PB: proximal breadth; T: tail length Chronological – cal. BP: calendar years before present; 14C BP: radiocarbon years before present; NALMA: North American land mammal age Dental terminology – I1: first upper incisor i1: first lower incisor C1: first upper canine c1: first lower canine P1: first upper premolar p1: first lower premolar M1: first upper molar m1: first lower molar 5.2. Systematic paleontology The Zesch Cave local fauna is Texas Memorial Museum locality TMM 40685. Complete catalog numbers for these specimens are TMM 40685-#, but for brevity are listed here as TMM #. 5.2.1. Perciformes Referred material: operculum right partial (TMM 500), Perciformes operculum fragment (TMM 507) These opercula are readily identifiable in general morphology and size as Perciformes, but more specific identification was not made. In addition to these opercula, Teleostei vertebrae are not uncommon in this fauna. 5.2.2. Ambystoma tigrinum Referred material: atlas vertebra (TMM 680), dorsal vertebra (TMM 681, TMM 686, TMM 691), caudal vertebra (TMM 684), dentary right (TMM 682), dentary left (TMM 683) Specimens of A. tigrinum (tiger salamander) are identical in size and morphology to Recent specimens of A. tigrinum. These fossils represent a large member of Caudata. Ambystoma, Necturus and Siren are the only taxa as large as the Zesch Cave salamander

J.C. Sagebiel / Quaternary International 217 (2010) 159–174

specimens that could reasonably be expected to have occurred in the Zesch Cave area. The Zesch Cave salamander vertebrae are more similar in their morphology to A. tigrinum than Necturus or Siren. A. tigrinum trunk vertebrae have a relatively broad, flat neural arch that is upswept caudally, with a robust spinous process and a large, round, persistent notochordal canal (Holman, 2006). Diapophyses and parapophyses are dorsoventrally paired at the midline constriction of the vertebral centrum. The caudal vertebrae are distinctive, each having a keeled hemal arch and a fenestrated neural arch with a neural spine. The ontogeny of the vertebrae of Ambystoma opacum is described by Worthington (1971). Assuming that osteological changes are similar in A. tigrinum, the Ambystoma vertebrae identified from Zesch Cave appear to represent adult (post-metamorphic) individuals. The Zesch Cave Ambystoma fossil vertebrae have bifurcate transverse processes. The transverse processes of A. opacum do not bifurcate until after metamorphism (Worthington, 1971). This suggests that the Zesch Cave Ambystoma were terrestrial adults. 5.2.3. Scaphiopodidae – ?Scaphiopus couchii Referred material: urostyle and sacral vertebra (fused) (TMM 510), calcaneum and astragalus (fused) (TMM 677). The fused sacral vertebra and urostyle are characteristic for this large anuran (Holman, 1995). The Scaphopodidae have a robust calcaneum and astragalus with a mediolateral breadth nearly equal to the proximodistal length. Specimens were indistinguishable for modern specimens of S. couchii from the Texas Memorial Museum Vertebrate Paleontology Laboratory Recent collections. 5.2.4. Anaxyrus sp. Referred material: ilium left (TMM 513, TMM 707, TMM 708, TMM 755), ilium right (TMM 678, TMM 703, TMM 753), scapula right (TMM 704, TMM 709), scapula left (TMM 706), sphenethmoid (TMM 710), occipital (TMM 713), ischia (TMM 757). Tihen (1962) identified the morphologically distinct Anaxyrus americanus group, which includes the species: A. americanus, Anaxyrus cognatus, Anaxyrus hemiophrys, Anaxyrus houstonensis, Anaxyrus microscaphus, Anaxyrus terrestris and Anaxyrus woodhousei. The A. americanus group is identifiable by having a very high ilial prominence that is relatively broad at the prominence base compared to similar species (Holman, 2003). The sphenethmoid is anteroposteriorly shortened – described by Tihen (1962) as an ‘‘elevated braincase’’. 5.2.5. Lithobates sp. Referred material: sphenethmoid (TMM 761, TMM 768), ilium right (TMM 763, TMM 764), scapula right (TMM 767), calcaneum and astragalus (fused) (TMM 769). Its keeled and rounded iliac blade distinguishes Lithobates. Its large size range also distinguishes this anuran from many others. Several species of Lithobates occur in Texas today including: Lithobates areolata, Lithobates berlandieri, Lithobates blairi, Lithobates catesbeiana, Lithobates clamitans, Lithobates grylio, Lithobates palustrus, Lithobates pipiens and Lithobates sphenocephala (Stebbins, 1985; Dixon, 1987). Today, the latter three species are the most geographically proximal to Zesch Cave. The Lithobates ilium is readily identified by relatively large size and expansive iliac crest. The sacrum has a bicondylar articulation with the urostyle, while the urostyle lacks transverse processes (Holman, 2003). There are no known reliable criteria for identifying the Lithobates material from Zesch Cave to the species level. Although some specimens of Lithobates in this local fauna are relatively large, none is large enough to definitely identify as L. catesbeiana. However, this does not exclude L. catesbeiana from the list of possible Lithobates species.

161

5.2.6. Terrapene sp. Referred material: occipital region with opisthotic and quadrate left (TMM 354). This partial skull is identical in size and morphology to Recent specimens of Terrapene ornata. However, no reliable synapomorphies could be found to distinguish among species of Terrapene. 5.2.7. Phrynosoma cornutum Referred material: parietal left (TMM 366), parietal and squamosal right (TMM 367), parietals (fused) (TMM 373). Projecting spines on the cranial material made Phrynosoma readily identifiable. Phrynosoma douglassi has short cranial horns, which distinguishes this species from P. cornutum and P. douglassi. The single midline horn on the fused parietal is useful for distinguishing P. cornutum from Phyrynosoma modestum, for the latter has no median horn (Presch, 1969). Squamosal and frontal bones were identified as P. cornutum by comparison with Recent specimens of P. modestum, P. cornutum and P. douglassi. 5.2.8. Crotaphytus sp. cf. Crotaphytus collaris Referred material: maxilla left (TMM 523, TMM 525), maxilla right (TMM 528, TMM 529), dentary left (TMM 522, TMM 524). Fossil lower jaws of C. collaris were indistinguishable from Recent specimens examined. The toothrow of Crotaphytus is identified by wide, robust and mostly tricuspid teeth that show little or no recurvature (Hollenshead and Mead, 2006). 5.2.9. Colubridae – ?Rhinocheilus sp. Referred material: partial skull with stapes left and right (TMM 363). This small colubrid basicranium is very similar to those of Rhinocheilus specimens from the Texas Memorial Museum Vertebrate Paleontology Laboratory Recent collections (TMM M5077, M6944, M4466). However, this identification is tentative. 5.2.10. Crotalus sp. Referred material: shaker (TMM 362). The shaker, or fused terminal caudal vertebrae, of Crotalus is readily identifiable. Fossil rattlesnake material from the Edwards Plateau is frequently identified as Crotalus atrox. However, there are no reliable criteria upon which to base a specific identification. 5.2.11. Alligator mississippiensis Referred material: tooth (TMM 509). This specimen is an isolated crocodilian tooth that is worn in a manner consistent with either transport or digestion. This tooth may have been transported or scavenged from a carcass. This tooth is identical in morphology to modern A. mississippiensis specimens. 5.2.12. Anas platyrhyncos Referred material: tarsometatarsus right (TMM 43). Anatidae tarsometatarsi are identifiable by the shallow anterior metatarsal groove and an elongate and narrow tubercle for tibialis anticus (Gilbert et al., 1996). This specimen is indistinguishable from modern specimens of A. platyrhyncos both in relatively large size and gracile build relative to other anatids of similar size (Fig. 2A). 5.2.13. Meleagris gallopavo Referred material: premaxilla (TMM 332). It is identified by relatively large size and overall morphological similarity to modern specimens of M. gallopavo. 5.2.14. Coragyps sp. Referred material: tarsometatarsus right distal (TMM 304), tarsometatarsus right (TMM 327).

162

J.C. Sagebiel / Quaternary International 217 (2010) 159–174

Fig. 2. (a) Anas platyrhyncos tarsometatarsus (b) Coragyps sp. tarsometatarsus (c) Colaptes sp. cf. C. auratus partial skull (d) Pica pica humerus (e) Pica pica carpometacarpus.

The tarsometatarsus is identified as a cathartid by large, deeply recessed proximal foramina and a triangular hypotarsus with three low calcaneal ridges. The tarsometatarsus is morphologically more similar to Coragyps based on relatively vertically oriented digital trochlea and larger size compared to Cathartes (Fig. 2B). The material is relatively incomplete, preventing positive discrimination as Coragyps occidentalis, which is 10–15% larger than Coragpus atratus (Howard, 1968). However, the Zesch Cave specimens appear to be larger than modern C. atratus. 5.2.15. Zenaida sp. Referred material: humerus left proximal (TMM 280), humerus left (TMM 315). Zesch Cave Zenaida was identified by comparison with Recent specimens of Zenaida (TMM M2439, M7228, M808). Zenaida humeri are identified as being relatively short and proximally broad, with an indistinct bicipital furrow (Gilbert et al., 1996). No characters distinguish these specimens to the species level. 5.2.16. Colaptes sp. cf. Colaptes auratus Referred material: partial skull (TMM 277), carpometacarpus right (TMM 495), carpometacarpus right (TMM 322). Two characters allow the identification of a Picidae carpometacarpus: the presence of a deep groove between the facets for digits II and III and the intercarpal process forms a bridge across the intercarpal space (Fig. 2C). These specimens were identical in size and morphology to modern specimens of C. auratus from Texas and match the dimensions published by Gilbert et al. (1996) for C. auratus (Table 1). 5.2.17. Picidae –? Dryocopus pileatus Referred material: partial skull (TMM 323). A partial skull consisting of basicranium, partial sphenoid region and partial occipital region is tentatively referred to D. pileatus. D.

pileatus is one of the largest of the North American woodpeckers and is only smaller than Campephilus principalis (ivory-billed woodpecker) (Pearson et al., 1936; DeGraaf et al., 1991). The partial skull compares favorably with modern specimens of D. pileatus and the specimen is distinguished by having a relatively small occipital condyle and rostrocaudally long sphenoid region. This identification is tentative. 5.2.18. Pica pica Referred material: premaxilla (TMM 55, TMM 310), squamosal (TMM 294), quadrate right (TMM 330), basicranium (TMM 313), scapula right (TMM 316), coracoid right (TMM 290), humerus left (TMM 45, TMM 319, TMM 295, TMM 296, TMM 297, TMM 326), humerus right (TMM 298, TMM 299, TMM 293, TMM 49), ulna left (TMM 50), ulna right (TMM 47, TMM 291, TMM 57), carpometacarpus left (TMM 278), synsacrum (TMM 56), femur left (TMM 329, TMM 281, TMM 53), femur right (TMM 325), tibiotarsus right partial (TMM 54, TMM 58), tarsometatarsus right proximal (TMM 46, TMM 289). The passerine humerus is identified by the presence of a round tuberosity proximal to the entepicondyle (Fig. 2D). Corvids are identifiable by several characters of the carpometacarpus (Fig. 2E). The intercarpal process of the carpometacarpus bridges the intercarpal space, metacarpal III and the facet for digit III extend far distal to the facet for digit II, the facet for digit II is small and the pisiform process is large, overlapping metacarpal I (Gilbert et al.,

Table 1 Measurements from Colaptes sp. cf. C. auratus (northern flicker). See Section 5.1 for an explanation of abbreviations. Colaptes sp. cf. C. auratus measurements (mm) TMM 495 Right carpometacarpus L ¼ 24.47 PB ¼ 7.81 TMM 322 Right carpometacarpus L ¼ 24.40 PB ¼ 7.35 Gilbert et al. (1996) OR (N ¼ 12) Carpometacarpus L ¼ 22–25 PB ¼ 6–8

J.C. Sagebiel / Quaternary International 217 (2010) 159–174 Table 2 Measurements and descriptive statistics from the humeri of Pica pica (black-billed magpie). See Section 5.1 for an explanation of abbreviations. Pica pica humerus measurements (mm) L

HHB

DB

MSD

TMM TMM TMM TMM TMM TMM TMM TMM TMM

44.35 48.05 43.91

>9.75a 12.56 11.22

44.11

>11.28a 14.21 11.94 14.37 12.75 12.79

a

a

a

a

3.34 3.63 3.35 3.77 3.36 3.33 3.75 3.65

a

a

L (N ¼ 4) 45.11 2.33 43.91–48.05 41–47

HHB (N ¼ 5) 13.21 1.04 11.94–14.37 11–14

DB (N ¼ 6) 11.82 0.82 10.61–12.56 No data

MSD (N ¼ 8) 3.52 0.20 3.33–3.77 No data

43.7

12.3

11.2

3.7

41.9–47.9

11.8–13.4

10.6–12.1

3.5–4.3

Variable Zesch Cave mean Zesch Cave SD Zesch Cave OR Gilbert et al. (1996) OR (N ¼ 11) Ashley (1941) mean (N ¼ 17) Ashley (1941) OR (N ¼ 17) a

a a

a a

11.51 12.55 12.50 10.61

a

TMM 48 TMM 288 Gilbert et al. (1996) OR (N ¼ 8) TMM 285

Specimen broken on measurement dimension.

5.2.19. Corvus corax Referred material: quadrate right (TMM 287), coracoid right (TMM 285), sternum anterior (TMM 320), humerus left (TMM 314), ulna right distal (TMM 286), femur left (TMM 288), femur right (TMM 48). The corvid sternum is readily identifiable by the mediolaterally bifurcate manubrium (Gilbert et al., 1996). C. corax is distinguished from the Corvus brachyrhynchos (American crow) and Corvus cryptoleucus (Chihuahuan raven) by its relatively larger size (Table 4). 5.2.20. Megalonychidae – cf. yMegalonyx jeffersoni Referred material: thoracic vertebra (subadult) (TMM 182).

Table 3 Measurements from Pica pica (black-billed magpie). See Section 5.1 for an explanation of abbreviations. Pica pica measurements (mm) TMM 53 TMM 325 TMM 329 Gilbert et al. (1996) OR (N ¼ 11) TMM 278 TMM 290 TMM 292 Gilbert et al. (1996) OR (N ¼ 11) TMM 47 TMM 50 TMM 57 TMM 291 Gilbert et al. (1996) OR (N ¼ 11)

Right femur Right femur Left femur Femur Right carpometacarpus Right carpometacarpus Left carpometacarpus Carpometacarpus Right ulna Left ulna Right ulna Right ulna Ulna

Specimen broken on measurement dimension.

L¼a L ¼ 41.46 L ¼ 40.18 L ¼ 36–42 L ¼ 30.31 L ¼ 31.84 L ¼ 32.09 L ¼ 28–33 L ¼ 53.49 L ¼ 51.63 L¼a L ¼ 55.67 L ¼ 48–56

DB ¼ 8.45 DB ¼ 7.60 DB ¼ 7.66 DB ¼ 6–8 PB ¼ 8.38 PB ¼ 7.18 PB ¼ 8.72 PB ¼ 6–8 PB ¼ 7.33 PB ¼ 7.15 PB ¼ 8.15 PB ¼ 7.78 PB ¼ 6–8

Right femur L ¼ a Left femur L ¼ 70.38 Femur L ¼ 61–78

Anterior L ¼ 46.00 3/4 coracoid Gilbert et al. (1996) Coracoid L ¼ 53–70 OR (N ¼ 8) TMM 314 Humerus L ¼ 86.08a est. L 87 Gilbert et al. (1996) Humerus L ¼ 83–108 OR (N ¼ 8) Ashley (1941) Humerus L ¼ 82.1– OR (N ¼ 6) 101.7 Ashley (1941) Humerus L ¼ 89.0 mean (N ¼ 6) a

1996). Pica is a medium-size corvid, larger than any jay and smaller than the genus Corvus. The material referred to Pica pica is identical in size and morphology to modern specimens examined and matches the reported size variation within the species as reported by Ashley (1941) and Gilbert et al. (1996) (Tables 2 and 3). Zesch Cave represents the most southerly North American occurrence of the genus Pica known, and is the first from central Texas.

a

Table 4 Measurements and descriptive statistics from Corvus corax (common raven). See Section 5.1 for an explanation of abbreviations. Corvus corax measurements (mm)

Variable 45 299 298 297 296 295 326 319 293

163

FHB ¼ a FHB ¼ 15.38 No data

DB ¼ 14.84 DB ¼ 14.56 DB ¼ 13–17

Not applicable Not applicable MSD ¼ 6.44

DB ¼ a DB ¼ 13–20

No data

No data

MSD ¼ 6.7– 8.9 MSD ¼ 7.8

DB ¼ 19.0– 24.7 DB ¼ 21.2

DB ¼ 22.48

Specimen broken along measurement dimension.

This specimen compares favorably with the thoracic vertebra of M. jeffersoni from Laubach 3 (TMM 41343-43) – a specimen similar in size and ontogenetic stage to the Zesch Cave sloth. This vertebra is similar to both Nothrotheriops and Megalonyx in having a relatively large neural canal, pre- and postzygapophyses that are laterally elongate (versus round in Paramylodon) and neural spines that thicken terminally (Stock, 1925). These characters and the intermediate size of this specimen suggest identification as M. jeffersoni, but the immaturity of this individual limits the certainty of taxonomic assignment. 5.2.21. Sylvilagus floridanus Referred material: temporal bulla right (TMM 339), partial skull (TMM 345). The smoother surface and smaller size of the temporal bullae in S. floridanus distinguish it from Sylvilagus audubonii (Chapman et al., 1982; Davis and Schmidly, 1994). All specimens referred to S. floridanus are indistinguishable from Recent specimens of S. floridanus. 5.2.22. Lepus sp. ?Lepus californicus Referred material: parietals and squamosal right (TMM 357). The absence of an interparietal bone distinguishes Lepus from Sylvilagus (Dunn et al., 1982). Although TMM 357 is indistinguishable from modern specimens of L. californicus, it is not identifiable to the species level. There is a notable paucity of jackrabbit material from Zesch Cave relative to Sylvilagus (11 Lepus or Lepus-sized specimens versus over 260 Sylvilagus or Sylvilagus-sized elements among all identified leporid elements). 5.2.23. Spermophilus sp. Referred material: dentary with p4-m3 left (TMM 839), dentary with p4-m3 left (TMM 267), dentary left edentulous (TMM 269), m3 left (TMM 841), dentary with p4-m3 right (TMM 266), m1 right (TMM 270), m1 right (TMM 837), m1 right (TMM 838), humerus left (TMM 511), ilium right (TMM 512). These squirrels are similar in size and dentary morphology to Tamias, but can be discriminated from Tamias by the greater size of the p4 in Spermophilus. The p4 of Tamias is also squarer in outline than the p4 of Spermophilus. The humerus (TMM 511) is identical to Recent specimens of Spermophilus spilosoma (TMM M7270, M2441) and differs from Tamias in having a broader, better-developed deltoid crest and lateral epicondylar crest. The Spermophilus ilium (TMM 512) is also identical to that of S. spilosoma and is larger and

164

J.C. Sagebiel / Quaternary International 217 (2010) 159–174

flatter mediolaterally than the iliac blade of Tamias. Specimens from Zesch Cave compare favorably with Recent specimens of S. spilosoma. Although S. spilosoma may be discriminated from the species Spermophilus. tridecemlineatus and Spermophilus mexicanus by its smaller size, there is considerable overlap among S. spilosoma, S. mexicanus and S. tridecemlineatus (Toomey, 1993). Hall’s Cave specimens of Spermophilus demonstrated a progressive decrease in size with increasing depth in the deposit (Toomey, 1993). This calls into question the use of size as a diagnostic criterion for the undated Zesch Cave deposits. Considering the problems with identifying Spermophilus to the species level, the Zesch Cave fossils are identified as Spermophilus sp. 5.2.24. cf. Tamias – ?Tamias striatus Referred material: M3 left (TMM 271). The teeth of Tamias are smaller than those of Spermophilus, but larger than those of Eutamias. The posterolingual edge of the M3 is emarginated in all examined specimens of Tamias. The same area of the M3 in all Spermophilus examined appeared convex in occlusal aspect. Distinguishing these isolated teeth from teeth of Ammospermophilus is difficult, as the two genera are approximately the same size. 5.2.25. Cynomys ludovicianus Referred material: partial skull with P4-M2 right and P4-M2 left (TMM 572), M1? left (TMM 573), dentary with m3 left (TMM 575, TMM 577), dentary with p4-m3 right (TMM 574), p4 right (TMM 571), ulna right (TMM 579), ulna right (TMM 580), tibia left (TMM 576). This large ground squirrel is easily identified by comparison with Recent specimens from Texas. Prairie dog fossils are uncommon in Zesch Cave, but their low abundance is probably a taphonomic effect, as was noted by Dalquest and Stangl (1986) and Toomey (1993). ‘‘The prairie dog is diurnal, too large for a barn owl to overcome’’ (Dalquest and Stangl, 1986, p. 13). 5.2.26. Thomomys bottae Referred material: P4 right (TMM 567), dentary with p4-m3 left (TMM 566). At Hall’s Cave, Thomomys does not appear until 10,500 14C BP (Toomey, 1993). Today, Zesch Cave and Hall’s Cave have very similar geographic locations and biotic settings. Both cave sites are at the eastern edge of the range of Thomomys (Dalquest and Kilpatrick, 1973; Davis and Schmidly, 1994). Thomomys are found east of their present range in the Pleistocene of north-central Texas and the Texas Panhandle (Toomey, 1993). Why Thomomys did not occur further to the east on the southern Edwards Plateau is not certain, but Toomey (1993) suggests that conditions may have been too moist. 5.2.27. Geomys bursarius Referred material: m1 or m2 left (TMM 570). Pleistocene fossils of Geomys have been traditionally assigned to the species G. bursarius. Recently, this taxon has been separated into five cryptic species: G. bursarius, Geomys attwateri, Geomys breviceps, Geomys knoxjonesi and Geomys texensis. These species are only identifiable by karyotypic, electrophoretic and mitochondrial DNA analyses (Davis and Schmidly, 1994). It has been hypothesized that Holocene warming and drying of the Texas climate has resulted in a reduction of soil depth, causing the Recent geographic isolation and karyotypic speciation of Geomys (Davis and Schmidly, 1994). Extralimital fossil occurrences of Geomys across the Edwards Plateau indicate that the range of this genus has become increasingly restricted as upland soils have

thinned throughout the Holocene (Dalquest and Kilpatrick, 1973; Toomey, 1993). The cryptic nature of speciation in Geomys and the broader distribution suggested by the fossil record may indicate a recent speciation. Geomys may have occurred across the state as a single species in the Pleistocene. If this is the case, Pleistocene Geomys from central Texas should be given a single specific designation. Because a single morphotype of Geomys occurs in the Pleistocene of Texas, any cryptic species that may have been present in the Pleistocene cannot be recognized. One possible solution to the matter is to identify the Pleistocene Geomys from Texas as a morphotypic group that may include several cryptic species. The name G. bursarius has precedence for Geomys from Texas, and the Zesch Cave fossils are placed into the morphotypic group G. bursarius, recognizing the possibility that this name may include several biological species. 5.2.28. Perognathus sp. Referred material: dentary right (TMM 185). This small, adult Perognathus specimen compares favorably with Recent specimens of Perognathus merriami, but cannot be identified to species. 5.2.29. Chaetodipus hispidus Referred material: temporal bulla left (TMM 188), dentary with p4 left (TMM 187), dentary left edentulous (TMM 186), p4 left (TMM 193), m3 left (TMM 202), dentary with i1–m3 right (TMM 206), m3 right (TMM 194). C. hispidus is readily identifiable by the presence of transverse rows of small cusps on the molars and large size relative to other species of Chaetodipus and Perognathus. 5.2.30. Dipodomys sp. Referred material: premaxilla with I1 left (TMM 639), temporal bulla right (TMM 641), dentary with i1–m3 left (TMM 634), dentary with i1–m1 left (TMM 31), dentary with p4 left (TMM 635), dentary left edentulous (TMM 637), tibia left (TMM 632). Although similar to geomyids, the maxillary and mandibular material can be distinguished from that of geomyids by their smaller size. Dipodomys premolars and molars are rootless and distinctive with mesial and distal enamel plates on each molar (Toomey, 1993). Identification of Dipodomys to the species level presents more difficulty. Of the numerous recognized species that occur within the United States, five occur in the state of Texas today (Dipodomys elator, Dipodomys spectabilis, Dipodomys ordii, Dipodomys compactus and Dipodomys merriami) (Hall, 1981). Criteria presented by Toomey (1993) were followed to identify species of Dipodomys. D. spectabilis can be removed from consideration in the Zesch Cave local fauna on the basis of size. None of the Zesch Cave specimens are as large as D. spectabilis. The remaining four species can be distinguished from one another based on the morphology of the dentary. Dentaries of the species D. elator are identifiable by the poor development of a retromolar fossa. This fossa is moderately developed in D. compactus and D. merriami and well developed in D. ordii and D. spectabilis (Toomey, 1993). The Zesch Cave Dipodomys show only moderate development of the retromolar fossa and are therefore assignable to either the species D. merriami or D. compactus. Size may further discriminate species of Dipodomys. Of the three Dipodomys dentaries, one is not as small as Recent specimens of D. merriami and shows a moderately developed retromolar fossa. Another specimen is as small as D. merriami and has a moderately developed retromolar fossa. Unfortunately, this specimen is edentulous. The third specimen is incomplete and cannot be identified beyond the genus level.

J.C. Sagebiel / Quaternary International 217 (2010) 159–174

5.2.31. Reithrodontomys sp. cf. Reithrodontomys fulvescens Referred material: maxilla with M1–M3 left (TMM 263), dentary with i1–m2 left (TMM 621), dentary with m1–m2 right (TMM 623), dentary with m2 right (TMM 629). Many of the fossil specimens from Zesch Cave are identical to Recent specimens of R. fulvescens, but many of the specimens cannot be distinguished from among the following species: R. fulvescens, Reithrodontomys montanus, Reithrodontomys megalotis and Reithrodontomys humulis, all of which occur in Texas today. These sigmodontines are smaller than most species of Peromyscus and usually larger than most B. taylori. Some size overlap does occur with Peromyscus and Reithrodontomys. As a result, it is not always possible to separate these genera. Although some size overlap occurs with Baiomys, these genera can be distinguished by tooth morphology (see B. taylori description in 5.2. Systematic Description). 5.2.32. Peromyscus spp. Referred material: dentary with i1–m3 left (TMM 219), dentary with m2 left (TMM 210), dentary with i1–m2 right (TMM 200), dentary with i1, m1–m2 right (TMM 201), dentary with m1 right (TMM 203), dentary with i1–m3 right (TMM 204), dentary with i1 to m1 right (TMM 217), dentary with i1 m2 right (TMM 218). Of the numerous North American species of Peromyscus, nine occur in Texas today. Characters that are used to discriminate among these species often vary as greatly intraspecifically as they do interspecifically. Dalquest and Stangl (1983) established criteria for discriminating among seven Trans-Pecos species of Peromyscus based on characters of the dentary, and their criteria were followed in an attempt to make an assessment of the number of Peromyscus species occurring in the Zesch Cave fauna. The criteria of Dalquest and Stangl (1983) were established for a limited geographic area and do not include most of the species of Peromyscus. Moreover, the success rate for identification using these criteria is typically less than 90% for each of the species involved in their study. Dentary TMM 200 exhibited character states that matched those given by Dalquest and Stangl (1983) for Peromyscus difficilus: m1 anteroconid well divided, no incisor capsule bulge, lophids and stylids present and large size (m1–m3 length 4.10–4.70, ave. 4.36; m1 length 1.85–2.05, ave. 1.94). Dentaries TMM 203, TMM 204, and TMM 858 exhibited character states that matched those given for Peromyscus leucopus by Dalquest and Stangl (1983): undivided m1 anteroconid and welldeveloped incisor capsule bulge. Dentary TMM 219 exhibited character states that matched those given for Peromyscus maniculatus by Dalquest and Stangl (1983): m1 anteroconid moderately divided and robust incisor capsule bulge. Other specimens from Zesch Cave were not identifiable to any of the species categories described by Dalquest and Stangl (1983). It is possible that more than three species of Peromyscus occur in the Zesch Cave fauna. Because only seven Peromyscus species from a limited geographic and temporal sample were considered in the Dalquest and Stangl (1983) study, these criteria are not strictly applied to the Pleistocene Zesch Cave Peromyscus. The purpose is to demonstrate the presence of multiple Peromyscus species in the Zesch Cave local fauna by following their criteria. 5.2.33. B. taylori Referred material: maxilla with M1 right (TMM 620), M1 right (TMM 624), dentary with i1–m2 left (TMM 618, TMM 628), dentary with i1–m3 left (TMM 622), dentary with i1 m1–m2 right (TMM 625), dentary with i1–m2 right (TMM 630). B. taylori is smaller than all other species of sigmodontine rodents except small specimens of Reithrodontomys. These rodents can be distinguished by the better-developed, posteriorly directed

165

coronoid process of B. taylori. B. taylori also has relatively simple teeth with no accessory cuspules and high anteriorly directed cusps (Toomey, 1993). 5.2.34. Onychomys leucogaster Referred material: dentary with m1 left (TMM 647, TMM 648, TMM 649), maxilla with M1 right (TMM 650, associated with TMM 649). Fossils of Onychomys can be identified by the high, alternating molar cusps and the presence of a prominent valley between the procingulum and the protocone and metacone on the m1 (Toomey, 1993). Onychomys also has a long, well-developed, posteriorly directed coronoid process that is not seen in Peromyscus (Toomey, 1993). The tooth-bearing Zesch Cave specimens were all of the size range given by Carleton and Eshelman (1979) for O. leucogaster, and all tooth-bearing elements have been identified to this species. 5.2.35. Neotoma sp. Referred material: maxilla with M1–M2 left (TMM 214), M1 left (TMM 236), M1 right (TMM 208), dentary with m1–m2 left (TMM 215). Five species of Neotoma occur in Texas today (Neotoma cinerea, Neotoma micropus, Neotoma floridana, Neotoma mexicana, Neotoma albigula); and there are a number of problems with identification of Neotoma to the species level, which are outlined in Toomey (1993). None of the Zesch Cave specimens appear to represent N. cinerea or N. mexicana, which have a well developed dentine tract on the m1 that is not seen in N. micropus, N. floridana or N. albigula. Each of the Zesch Cave specimens had dental morphology that was reproduced by modern specimens of N. micropus, N. floridana and N. albigula from the Texas Cooperative Wildlife Collection at Texas AandM. The Zesch Cave specimens cannot be identified confidently to any of the three species. 5.2.36. Microtus ochrogaster or Microtus pinetorum Specimens referred to M. ochrogaster or M. pinetorum: maxilla with M1–M2 left (TMM 738), M1 right (TMM 716, TMM 718, TMM 749), M2 right (TMM 742, TMM 743), M3 right (TMM 744), m2 left (TMM 717), m3 left (TMM 730), dentary with i1, m3 right (TMM 747), m1 right (TMM 734), m2 right (TMM 728). Specimens referred to M. ochrogaster: dentary with i1–m2 left (TMM 227), m1 left (TMM 732, TMM 733), m1 left (TMM 745, TMM 746), dentary with i1 m2 right (TMM 228, TMM 229, TMM 736), m1 right (TMM 735). Specimens referred to M. pinetorum: m1 left (TMM 729), dentary with i1 m2 right (TMM 750). M. ochrogaster and M. pinetorum are discriminated from other species of Microtus by their molar morphology. Both species have m1 and m2 with three closed and two confluent triangles. The species M. pinetorum can be separated from M. ochrogaster on the basis of m1 morphology. Specifically, M. pinetorum has a more posteriorly directed fourth triangle and a more anteriorly inflected third labial re-entrant angle (Toomey, 1993). Based on this morphology, both species appear to be represented by fossils from Zesch Cave. 5.2.37. Microtus sp. (5 m1 triangles) Referred material: dentary with i1–m3 left (TMM 207), dentary with m1–m2 left (TMM 725). Specimens of Microtus with five closed triangles on the m1 were assigned to the species Microtus pennsylvanicus in a number of earlier studies on the Pleistocene of Texas. However, there are fifteen North American species of Microtus with five closed triangles on the m1. Of these fifteen species, Microtus longicaudus, Microtus montanus and Microtus mexicanus have Recent distributions that are geographically closer to Zesch Cave than the range of

166

J.C. Sagebiel / Quaternary International 217 (2010) 159–174

M. pennsylvanicus (C.J. Bell, personal communication, 1998; Toomey, 1993). There are no characters of the dentary that discriminate among these species. 5.2.38. ySynaptomys australis Referred material: skull with M1 (TMM 272), M1 left (TMM 275), M2 left (TMM 276), M2 left (TMM 273), maxilla with M1–M2 right (TMM 274). The species S. australis is morphologically identical to Synaptomys cooperi, but is 35% larger (Simpson, 1928; Martin et al., 2003). The Zesch Cave specimens agree in size and morphology with the austral bog lemming, S. australis. With an average M1 length of 3.22 mm (OR: 3.18–3.25), the Zesch Cave specimens are larger than S. australis reported from the Carrol Creek local fauna of north Texas (Kasper, 1992). 5.2.39. Zapus hudsonius Referred material: dentary with m1 m3 right (TMM 205). The Zesch Cave Zapus has a wide m1 with an anteromedian fold of the anteroconid and broad re-entrants, similar to Zapus adamsi (sensu Hibbard, 1955). Hibbard (1955) identified Z. adamsi on the basis of m2 characters and in the breadth of re-entrant folds. Klingener (1963) considered Z. adamsi a subspecies of Z. hudsonius. Klingener (1963) found that Z. hudsonius reproduced the Z. adamsi m2 characters and that the difference in the breadths of the reentrant folds was minor. There are no characters that differed between the Zesch Cave Zapus and Recent specimens of Z. hudsonius from Kansas. Because the Zesch Cave Zapus cannot be separated from either Z. adamsi (sensu Hibbard) or Recent specimens of Z. hudsonius, identification follows Klingener (1963) in assigning this fossil specimen to the species Z. hudsonius (Fig. 3B). 5.2.40. S. hoyi Referred material: dentary with i1–m3 left (TMM 216) (Fig. 3A). The genus Sorex contains three subgenera: Sorex, Otiosorex and Microsorex. Because species of Microsorex have extremely reduced third and fifth upper unicuspids, the subgenus Microsorex was considered a separate genus until 1980 (Diersing, 1980; Jones and Birney, 1988). Microsorex is now considered a subgenus of Sorex, with close affinities to the subgenus Otiosorex (Diersing, 1980; Junge and Hoffman, 1981). The subgenus Sorex is distinguished from other subgenera by the presence of both a mandibular and a postmandibular canal (Junge and Hoffman, 1981). The subgenera Microsorex and Otiosorex, and the Zesch Cave Sorex have only a mandibular canal. Unicuspid pigmentation also distinguishes the subgenera and can be useful for species-level taxonomy (Diersing, 1980; Junge and Hoffman, 1981; Carraway, 1995). Unfortunately, the Zesch Cave fossils do not retain any original pigments and are stained a deep red–brown color which is similar to the original pigmentation color seen on soricid teeth, rendering this suite of characters useless for the Zesch Cave soricids.

The subgenus Microsorex contains one extant and two extinct species. The species S. hoyi is identifiable by its small size (dentary length 6.1 mm, length of c1–m3 4.2 mm) (Carraway, 1995). Only the species S. nanus (dwarf shrew) is small enough to mistake for S. hoyi. Work by Carraway (1995) describes several characters that discriminate the dentary of S. hoyi from that of Sorex nanus. The Zesch Cave Sorex dimensions agree with mensural data for both S. nanus and S. hoyi presented by Carraway (1995) (Table 5). One distinguishing character for S. nanus is a coronoid process with a height of 3.1 mm. S. hoyi coronoid heights range from 3.1 to 3.4 mm, and the Zesch Cave specimen has a coronoid height of 3.1 mm. Unfortunately, this character is not discriminatory in this instance. The position of the lower incisor (i1) alveolus relative to the p4 paraconid is also informative. The Zesch Cave Sorex and S. hoyi have an alveolus that extends beneath the paraconid of p4, whereas this alveolus is located proximal to the paraconid in S. nanus. On the basis of this character, the Zesch Cave Sorex is identified as S. hoyi. The occlusal surface of the Zesch Cave Sorex p4 is more similar to that illustrated by Carraway (1995) for S. hoyi than to the more robust p4 illustrated for S. nanus. Zesch Cave Sorex has a p4 occlusal pattern that is somewhat J-shaped as described and figured by Repenning (1967) for Microsorex hoyi. The articular condyle morphology is ‘‘unspecialized’’ (primitive for the Soricinae, sensu Repenning [1967]) with a slight lingual emargination-similar to that figured and described briefly by Repenning (1967). The Zesch Cave specimen has two characters that are more similar to the S. nanus descriptions in Carraway (1995). The Zesch Cave specimen has a coronoid spicule, which is not indicated as a diagnostic character for any of the soricids, but is shown in the S. nanus illustration and not shown on the S. hoyi illustration. The i1–p4 distance of the Zesch Cave Sorex (0.19 mm) was more similar to the range given for S. nanus (OR 0.15–0.3 mm) than S. hoyi (OR 0.07–0.17 mm). However, the i1–p4 distance was the most variable among all measurements taken by Carraway (1995) with the coefficient of variation ranging from CV ¼ 0.0 to CV ¼ 1.28 (CV ¼ 0.18 for S. nanus and CV ¼ 0.34 for S. hoyi) versus CV  0.12 for all other measurements. The i1–p4 distance was not considered diagnostic by Carraway (1995). Another peculiar character for the Zesch Cave Sorex is the position of the mental foramen, which is anterior to the mesial m1 root. This is atypical for any of the Soricinae, which generally have the mental foramen located below the middle of the m1. However, some individuals within modern Sorex populations do have anteriorly positioned mental foramina (Repenning, 1967). The Zesch Cave specimen also has a prominent ridge on the labial edge of the dentary ramus. This feature may be a fracture in the ramus, or it may be a peculiarity of this individual. The subgenus Microsorex contains two fossil species in addition to the modern species S. hoyi (see Microsorex discussion in 5.2. Systematic Paleontology). These species are Sorex pratensis (Hibbard) and Sorex minutus (Brown) (Brown, 1908; Hibbard, 1944). Because he could find few characters to separate these species,

Fig. 3. (a) Sorex hoyi dentary (b) Zapus hudsonius dentary. Bar is one mm.

J.C. Sagebiel / Quaternary International 217 (2010) 159–174

167

Table 5 Measurements from Zesch Cave Sorex hoyi (pygmy shrew). See Section 5.1 for an explanation of abbreviations. Sorex hoyi dental measurements (mm) Measurement

Repenning, 1967 Sorex hoyi

Carraway, 1995 OR Sorex hoyi

Carraway, 1995 mean Sorex hoyi

Zesch Cave Sorex hoyi

Number of specimens c1-m3 Length m1 Length m2 Length m1 Height at protocone i1–p4 Distance Dentary depth at m1 talonid Dentary length Coronoid height Coronoid-condyle length C1 Width P4 Width M1 Width M2 Width p4–m3 Length m1–m3 Length

13 No data No data No data No data No data No data 6.1–6.2 2.7–2.9 No data No data No data No data No data 3.4–3.6 2.7–3.0

30 3.7–4.2 1.2–1.3 1.0–1.2 0.8–1.2 0.07–0.17 0.7–1.0 5.3–6.1 3.1–3.4 2.6–3.1 0.4–0.6 0.5–0.6 0.6–0.8 0.6–0.8 No data No data

30 3.95 1.26 1.06 1.00 0.09 0.87 5.63 3.24 2.87 0.51 0.56 0.70 0.69 No data No data

1 4.06 1.29 1.10 0.89 0.20 0.80 5.85 3.10 2.65 0.54 0.60 0.71 0.73 3.61 2.96

Graham (1972) suggested that these fossils might represent the same species. Both S. minutus and S. pratensis have heavier cingula, teeth and rami than modern specimens, which is not the case for the Zesch Cave Sorex. The species S. minutus is identifiable by the parallel arrangement of the occlusal surfaces of the p4 and i2 (Brown, 1908; Graham, 1972). The Zesch Cave Sorex does not have a parallel arrangement of these occlusal surfaces. S. hoyi has been identified from a number of localities dating from the Pleistocene to Recent. Mason, Texas is 1050 km from the closest occurrence of S. hoyi today – the Rocky Mountains of Colorado (Junge and Hoffman, 1981; Jones and Birney, 1988). S. hoyi at Zesch Cave demonstrates the southern-most fossil occurrence of this species. The closest known fossil occurrence to Zesch Cave is Peccary Cave, Newton County, Arkansas (FAUNMAP Working Group, 1996). 5.2.41. Blarina carolinensis Referred material: maxilla with I1–M3 right (TMM 597), dentary with c1–m3 (TMM 209), dentary with i1–m1, m3 left (TMM 211), dentary with i1–m2 left (TMM 212), dentary with m1–m2 right (TMM 213). The large size relative to other soricids distinguishes the genus Blarina. B. carolinensis is slightly smaller than other species of the genus and is also discriminated from Blarina hylophaga by the relatively greater angle of the incisor to the rest of the dentary and smaller P4 (Schmidly, 1983; Carraway, 1995). Zesch Cave specimens all match the size range and morphology of the smaller southern species, Blarina carolinensis. The southern short-tailed shrew is found in east Texas as far west as Bastrop County (which holds a relict coniferous forest), south to Victoria County and north to Cooke County. Zesch Cave demonstrates a 290 km reduction in this animal’s range since the Pleistocene (Davis and Schmidly, 1994). 5.2.42. Cryptotis parva Referred material: dentary with i1–m3 left (TMM 333). Both C. parva (least shrew) and Notiosorex crawfordi (desert shrew) have a robust articular process of the dentary and a reduced m3 talonid relative to Blarina and Sorex. The dentary of N. crawfordi has a noticeable emargination of the lingual portion of the interarticular area that is not seen in C. parva (Carraway, 1995). The reduced m3 and relatively small size distinguishes C. parva from other species of Cryptotis (Hall, 1981). The presence of a single postmandibular canal and double internal temporal fossa also identifies this specimen as C. parva.

C. parva is extralimital to Mason County. C. parva generally skirts the Edwards Plateau to the east, north and south, occurring as near to Mason County as Burnet and Blanco counties (Davis and Schmidly, 1994). Zesch Cave demonstrates a 75 km eastward reduction in this animal’s range since the late Pleistocene. 5.2.43. N. crawfordi Referred material: dentary with m1 left (TMM 374). This shrew has a lingually emarginated interarticular area, which is characteristic for N. crawfordi (Carraway, 1995). The Zesch Cave Notiosorex also falls within the size range published by Carraway (1995) (Table 6). 5.2.44. Scalopus aquaticus Referred material: maxilla with M1 right (TMM 593), dentary ramus with m2-m3 left (TMM 594), scapula and humerus left (TMM 591), humerus and ulna left (TMM 592), femur left (TMM 331). Nearly every skeletal element of S. aquaticus (eastern mole) is adapted for subterranean life and is therefore easily identifiable. 5.2.45. M. velifer Referred material: skull with P4, M2-M3 (TMM 4), skull with P4M3 (TMM 11), skull with I1–M3 left and I1–M1 right (TMM 34), dentary with i1–m3 left (TMM 5), dentary with p4-m3 left (TMM 6), dentary with c1–p2 m2–m3 right (TMM 7), dentary with i2-i3 p2-m3 right (TMM 9), dentary with m2-m3 right (TMM 10).

Table 6 Measurements from Zesch Cave Notiosorex crawfordi (desert shrew). See Section 5.1 for an explanation of abbreviations. Notiosorex crawfordi dental measurements (mm) Measurement

TMM 374

Carraway, 1995 mean

Carraway, 1995 OR

M1 Length m2 Lengtha

1.60 12.5 Alveolar 9.5 Alveolar 1.05 1.20 3.97 3.49 0.90 3.80

1.45 1.33

0.90–1.70 0.80–1.50

No data 1.19 1.14 4.00 3.47 0.98 No data

No data 0.90–1.30 0.90–1.40 3.30–4.70 3.00–3.90 0.80–1.10 No data

m3 Lengtha m1 Height at protocone Dentary depth at m1 talonid Coronoid height Coronoid-condyle length m1 Width m1–m3 Length a

Alveolar length was measured for Zesch Cave Notiosorex m2 and m3.

168

J.C. Sagebiel / Quaternary International 217 (2010) 159–174

M. velifer is identified by a forearm length of 37–47 mm, the presence of 6 post-canine teeth in the upper jaw, greatest length of the skull greater than 15.5 mm, width across the canines greater than 4.3 mm, a relatively massive rostrum and a well-defined sagittal crest (Schmidly, 1991). Postcranial fossils of M. velifer are commonly found in association with the cranial material, and complete cranial material is also common from Zesch Cave. Much of the material can be identified as juvenile by unfused epiphyses, unerupted teeth in the jaws (e.g. TMM 515, 516) and the unfinished texture of cortical bone on many specimens. 5.2.46. Eptesicus fuscus Referred material: dentary with i1–p4 m2–m3 left (TMM 517), dentary with p4 m1 m3 left (TMM 616), dentary with p4 left (TMM 518), dentary with c1 p4 m2–m3 right (TMM 32), dentary with c1– m3 right (TMM 519). E. fuscus is identified by forearm length (42–51 mm), tooth count (I 2/3, C 1/1, P 1/2, M 3/3) and relatively large size (120 mm average total length, skull length >18 mm) (Jones and Birney, 1988). Eptesicus fuscus grandis was described by Brown (1908) from the Pleistocene deposit at Conard Fissure, Arkansas. Gidley and Gazin (1938) elevated this taxon to the species E. grandis. However, more recent work has shown that these specimens are not distinct from Recent specimens of E. fuscus (Guilday et al., 1967). Guilday et al. (1967) stated that E. fuscus exhibited a positive Bergman’s response in California. Further, they concluded that because females are generally larger than males, and because hibernacula populations do not contain a balanced number of males and females, cave populations and the resultant fossil cave faunas do not accurately represent the size structure of the natural population of E. fuscus. A total of 47 specimens of E. fuscus from the Texas Cooperative Wildlife Collection were measured, which represented populations from Texas, Mexico and Central America. These specimens exhibited a negative Bergman’s response, with the Central American specimens being the largest. Following Guilday et al. (1967), because E. fuscus grandis does not exceed the size range of modern E. fuscus populations and has no other distinct characteristics, it should not be considered a separate species. The Zesch Cave E. fuscus are as large as E. fuscus grandis described by Brown (1908) and Gidley and Gazin (1938). However, large size is an artifact of the population structure of E. fuscus in the cave. Males are usually smaller than females, and they typically avoid maternity colonies until the young mature (Altringham, 1996). As Guilday et al. (1967) observed, a largely female hibernaculum population would result in a fossil fauna that is biased towards a larger size than the natural size range of the whole population. E. fuscus is extralimital to Mason County – today E. f. fuscus occurs 75 km east and E. f. pallidus occurs 240 km northwest (Davis and Schmidly, 1994). 5.2.47. Canis latrans Referred material: skull with P4-M2 left and M1–M2 right (TMM 382), skull with P4-M2 left (TMM 383), P4 left (TMM 381), frontal right (TMM 590), dentary with c1 p3–m2 left (TMM 279), dentary with p4 right (TMM 380), humerus left (TMM 775), radius right proximal (TMM 183), ulna right proximal (TMM 588), ulna left proximal (TMM 589), innominate left and sacrum (TMM 778). C. latrans specimens were identified by comparison with Recent specimens of C. latrans and other canids. 5.2.48. Canis sp. cf. yC. dirus Referred material: p3 right (TMM 384). This premolar is within the size range of C. dirus published by Merriam (1912) (Table 7). The mesial and distal edges of the

Table 7 Measurements from Zesch Cave Canis sp. cf. C. dirus. See Section 5.1 for an explanation of abbreviations. Canis dirus m3 dimensions (cm) Measurement

TMM 384

Merriam, 1912 mean ‘‘large’’ Canis dirus

Merriam, 1912 mean ‘‘medium’’ Canis dirus

m3 Mesial-distal length

16.41

16.7

15.8

premolar are broad perpendicular to the tooth length, as found in all C. dirus premolars. Canis lupus premolars are not inflated mesially and distally. 5.2.49. Canis sp. (large) Material referred to Canis sp. cf. C. lupus: M1 right (TMM 646), humerus right (TMM 386). Material referred to Canis sp. cf. Canis rufus: m1 right (TMM 385) Fossil Canis material may represent both or either species of wolf. A humerus (TMM 386) from a large Canis may represent C. lupus, but it is relatively short and may also represent C. rufus. Dental material referred to Canis sp. cf. C. rufus is greater in size than any Canis latrans subspecies, but small for C. lupus. However, because of the broad overlap in size and morphology between these species, it is not possible to identify this material to the species level. 5.2.50. Urocyon cinereoargenteus Referred material: skull with P4 M2 left (TMM 827), premaxilla with I3 right (TMM 673), maxilla right edentulous (TMM 584), scapula right (TMM 675). The strong hourglass pattern of the parasagittal crests of Urocyon makes the skull of this animal easy to identify. Urocyon dentition is also distinctive, with taller, less robust premolars and a reduced P4 paraconid relative to any species of Vulpes. U. cinereoargenteus has a deeper depression above the postorbital process of the skull and a notch at the lower edge of the dentary below the coronoid process and immediately in front of the angular process. Because U. cinereoargenteus has more robust limbs that are relatively shorter than the limbs of any comparably sized Vulpes, most postcranial material is distinguishable from species of Vulpes by direct comparison with Recent specimens. 5.2.51. Vulpes velox or Vulpes macrotis Referred material: premaxilla with I3 right (TMM 790), occipital parietal and frontal (TMM 829), mandible with p3-m2 right, c1 p1– m1 m3 left (TMM 828), humerus left proximal (TMM 256), ulna left proximal (TMM 257), metacarpal IV (TMM 250), metacarpal V (TMM 251), femur left distal (TMM 247), tibia (TMM 249), tibia right proximal (TMM 258), vertebra lumbar (TMM 248). The taxonomic status of V. velox (swift fox) and V. macrotis (kit fox) has been a contentious issue (Mercure et al., 1993). The species differ morphologically with V. macrotis having inflated temporal bullae relative to V. velox. This character can be used reliably, even in areas where the two species are parapatric (Thornton and Creel, 1975; Dragoo et al., 1990). However, controversy has arisen over the significance of genetic similarity between the species V. velox and V. macrotis. Recent work has shown that these two foxes may be conspecific with significant gene flow between the two groups (Hall, 1981; Davis and Schmidly, 1994). Genetic differences are slight enough that Dragoo et al. (1990) decided to place V. velox and V. macrotis as subspecies within V. velox, and subsequent workers have followed suit (Wozencraft, 1993). No temporal bullae are found among the Zesch Cave V. velox fossils, and no other morphological traits separate the swift and kit

J.C. Sagebiel / Quaternary International 217 (2010) 159–174

foxes. These species (or subspecies) can be readily distinguished from other canids by size, being smaller than all other North American canids except Urocyon. Urocyon has a distinct cranial morphology (see discussion of U. cinereoargenteus in 5.2. Systematic Description) and shorter, more robust limbs than V. velox. 5.2.52. Vulpes vulpes Referred material: m1 left (TMM 830), Vulpes sp. cf. V. vulpes: tibia left (TMM 184). V. vulpes is easily distinguished from other canids by its intermediate size range. It is larger than other foxes, but much smaller than coyotes. Fossils from Zesch Cave are identical in size and morphology to specimens of V. vulpes from the Recent collection at the Texas Memorial Museum Vertebrate Paleontology Laboratory. 5.2.53. U. americanus Referred material: partial skull with I3 C1 M1–M2 right and I3 C1 P4–M2 left and mandible with c1 p4–m1 right and i3 c1 p4– m3 left (TMM 2), M1 left (TMM 99), mandible with c1 p4–m1 right and c1 left (TMM 39), dentary with i1–c1 p4–m3 right (TMM 100), m2 right (TMM 98), innominate with sacrum (TMM 284), femur left (TMM 103, TMM 105, TMM 106), femur right (TMM 102, TMM 104, TMM 107, TMM 108, TMM 114), tibia left (TMM 59, TMM 94, TMM 97, TMM 140, TMM 141), tibia right (TMM 63, TMM 142), metatarsal IV (juvenile) (TMM 128), metatarsal III (juvenile) (TMM 128). U. americanus (black bear) is distinguished from Ursus arctos (brown bear) by smaller size and the lack of a medial accessory cusp and median anteroposterior sulcus on the mesial p4 (Graham, 1991). 5.2.54. Mephitis mephitis or Mephitis macroura Referred material: frontals, maxillae with P3-M1 right (TMM 796), frontals, parietals, nasals (TMM 794), frontals, parietals (TMM 797), occipital (TMM 806), m1 left (TMM 799), m2 left (TMM 798), dentary with i3–m1 right (TMM 801), dentary with m1 right (TMM 802), m1 and m2 right (TMM 807), dentary right articular and angular processes (TMM 586), ulna left proximal (TMM 400), manus (TMM 795), innominate left (TMM 809), axis vertebra (TMM 805), vertebra sacral (TMM 225). Zesch Cave Mephitis fossils are identical to Recent M. mephitis specimens. Unfortunately, specific identification of the Zesch Cave Mephitis specimens is not possible. 5.2.55. Mustela frenata Referred material: atlas vertebra (TMM 581). M. frenata is identifiable by size, being the largest of the American weasels (Hall, 1936, 1981) and comparison with modern specimens. The atlas of M. frenata is also characterized by a pattern of foramina unlike any other similar sized carnivoran. 5.2.56. Taxidea taxus Referred material: parietals and occipital (TMM 674). This broad, relatively flat skull with prominent nuchal and lambdoidal ridges is easily identified as T. taxus. 5.2.57. Leopardus wiedii or yLeopardus amnicola or Herpailurus yaguarondi Referred material: dp4 left (TMM 583). This specimen may represent the extralimital occurrence of Herpailurus yaguarondi or L. wiedii, or the occurrence of the extinct species L. amnicola. Both H. yaguarondi and L. wiedii have been recorded from the Rio Grande Valley of south Texas in historical times (Nowak and Paradiso, 1983; Davis and Schmidly, 1994). Neither species has a very good fossil record, nor are the geological ranges of either species well established. L. amnicola is an extinct

169

species from the Gulf of Mexico coastal plain, identified from deposits of Sangamonian to Wisconsinan age (Werdelin, 1985; Hulbert and Pratt, 1998). This tooth fragment is indistinguishable from specimens of H. yaguarondi and L. wiedii from Mexico in the Texas Cooperative Wildlife Collection. Although L. amnicola is somewhat larger than H. yaguarondi and L. wiedii, there is size overlap among these species (Werdelin, 1985). This deciduous tooth cannot be positively identified to the species level. 5.2.58. Lynx rufus Referred material: skull edentulous (TMM 784), frontal left (TMM 785), maxilla right edentulous (TMM 793), humerus left distal (TMM 582), navicular left (TMM 334), phalanx terminal (TMM 779), ischium left (TMM 788), axis vertebra (TMM 780, TMM 813), sacrum (TMM 789). L. rufus is easily identified by comparison with modern specimens, and the Zesch Cave specimens are identical in all respects to modern L. rufus. 5.2.59. Equus (yEquus niobrarensis) sp. Referred material: metatarsal (TMM 818), phalanx (TMM 819), Equus sp.: petrosal right (TMM 237), I2 left (TMM 224), humerus left (TMM 824), innominate left (TMM 822), innominate right (TMM 823), femur right (TMM 825), tibia right (TMM 826), vertebra cervical (TMM 820), vertebra sacral I (TMM 821). Mensural data from the metacarpal (TMM 818) and first phalanx (TMM 819) were used to identify this Equus material to the species level. Using the methods of Harris and Porter (1980), this specimen is identified as E. niobrarensis. Equus excelsus Leidy, 1858, is also a name applied to middle-size horses, and the name has priority over E. niobrarensis Hay, 1913 (Dalquest, 1988). However, the type specimen of E. excelsus does not include postcranial material; and E. excelsus may be a nomen dubium (Winans and Lundelius, personal communication, 1997). Specimens of E. niobrarensis have been identified from sites ranging in age from late Irvingtonian to 11,170 BP (Kurte´n and Anderson, 1980). However, recent genetic work on Pleistocene equids suggests that only one species of stilt-legged and a second caballine species may have been present during the Rancholabrean, with regional variation among populations (Weinstock et al., 2005). Although the Zesch Cave horse is morphologically classified as E. niobrarensis, it should probably be referred to as Equus sp. considering the problems with horse taxonomy. 5.2.60. yPlatygonus sp. cf. P. compressus Referred material: vertebrae sacral first and second (fused) (TMM 714). This specimen was identified by direct comparison with known specimens of P. compressus, Tayassu and Mylohyus from the Texas Memorial Museum Vertebrate Paleontology collections (TMM 41465-231, TMM 41465-186, TMM 40673-151). 5.2.61. yC. hesternus Referred material: maxilla with P4-M2 left (TMM 814), vertebra cervical (TMM 815). Specimen TMM 814 is easily identified as Camelops by the selenodont dentition and by its large size relative to Hemiauchenia. C. hesternus is identified by its narrow, blade-like P3 and quadrate, submolariform P4 (Kurte´n and Anderson, 1980). The two Rancholabrean species Camelops huerfanensis and C. hesternus are distinguished from each by the position of the postpalatine foramen, which is opposite the P3 or P4 in C. hesternus and opposite the M1 in C. huerfanensis (Kurte´n and

170

J.C. Sagebiel / Quaternary International 217 (2010) 159–174

Anderson, 1980). The Zesch Cave Camelops has a postpalatine foramen that is located at the level of the P4 and is therefore identified as C. hesternus. 5.2.62. yHemiauchenia macrocephala Referred material: skull partial edentulous (TMM 833), maxilla with P3-M3 left (TMM 832), maxilla with M2-M3 right (TMM 831), dentary with p4-m3 left (TMM 676), dentary right edentulous ramus and symphysis (TMM 800). Hemiauchenia has antero-external and antero-internal styles on the lower molars that are weaker than in Lama (Breyer, 1977). The molars are more hypsodont and the dentary is deeper than in Paleolama. The p4 is a simple triangular tooth with a single fossetid in contrast to the complex p4 with multiple fossetids of Paleolama (Webb, 1974; Breyer, 1977). H. macrocephala possesses a caniniform c1, a caniniform p1 (when present), the p2 is lost and the p3 is rarely present, usually possessing a single root. The occlusal length of p4-m3 is shorter than in specimens of Hemiauchenia blancoensis in equivalent state of wear. The symphysial region of the dentaries is more attenuated and the diastema is longer in H. macrocephala than in H. blancoensis (Breyer, 1977). 5.2.63. Odocoileus sp. Referred material: innominate left (TMM 816). Odocoileus hemionus and Odocoileus virginianus overlap in size and no characters clearly allow specific identification of this innominate. 5.2.64. yCapromeryx sp. Referred material: P4? left (TMM 359), naviculocuboid right (TMM 231), second phalanx (TMM 360). Capromeryx is identifiable by its small size and morphological similarity to Recent specimens of Antilocapra americana. The small size of Capromeryx distinguishes it from Antilocapra, Stockoceros and Tetrameryx. These specimens are most likely from one of the late Rancholabrean species: Capromeryx furcifer, Capromeryx mexicana or Capromeryx minor (Kurte´n and Anderson, 1980). These three antilocaprid species are distinguished by horn-core morphology and characters of the upper molars (Furlong, 1925; Kurte´n and Anderson, 1980). Because Zesch Cave has yielded no pronghorn cranial material, these specimens are only identified to the genus Capromeryx. 5.2.65. Bison sp. Referred material: vertebra lumbar (TMM 836). This specimen is readily identifiable as Bison by its large size, overall morphology, and in particular, the strongly S-shaped preand postzygapophyses. Other mammals that are of comparable size to Bison do not have the strong S-curve to the zygapophyses. The first occurrence of Bison defines the Rancholabrean Land Mammal Age, its presence indicates that the Zesch Cave local fauna is Rancholabrean in age. 6. Discussion The identifications that form the basis of this research were synapomorphy-based. In cases such as Peromyscus, although species keys are available, it still may not be possible to make species-level identifications because there is not a comprehensive species-level key for all species of the genus. Clearly work towards this end still needs to be done, and would greatly improve paleoenvironmental and evolutionary research on Quaternary mammals. Ideally, the genetics of these synapomorphies should be understood as well, in order to establish that the observed variation is

consistent with taxonomic differences. These connections have been made successfully for some groups of animals already, such as Thomomys (Hadley, 1997) and Canis (Carrier et al., 2005). Clearly, without such well-defined synapomorphies for guidance, researchers can be significantly misled, as appears to be the case with Quaternary species of Equus (Weinstock et al., 2005).

6.1. Taphonomy Caves accumulate fossils from four general sources: (1) avian and carnivore waste, (2) transport as sediment, (3) death of cavernicol and (4) accidental entrapment. Only the large ungulate (equid and camelid) and canid bones at Zesch Cave show evidence of pre-depositional exposure (i.e., desiccation and soil acid etching) that suggests transport from outside the cave. Most of the small mammal material probably came to this cave in the jaws or beak of a predator. Clear puncture marks are present on at least one leporid bone fragment (TMM 672). These puncture marks are paired and a stabbing puncture is visible directly above rasping tooth marks-presumably caused by occluding teeth of a coyote or bobcat-size animal. Coprolites (TMM 791) also evince denning by small carnivorans in Zesch Cave. Bear, coyote, skunk and fox fossils are commonly found semi-articulated and unbroken, suggesting these animals resided within the cave. Fossils of teleost vertebrae also argue for carnivorans using Zesch Cave as a den. Fish bones typically occur as isolated elements in the deposit (35 specimens representing a minimum of one individual), which contrasts sharply with the mammalian fossils, most of which are partial skeletons. The large number of isolated fish fossils argues against their representing troglobytic teleosts. It is most likely that the fish were carried to Zesch Cave by trogloxenic birds or carnivorans. The taphonomy of the Zesch Cave local fauna is interpreted using NISP (number of identified specimens) and MNI (minimum number of individuals) for mammalian taxa because these are the most common quantitative terms applied to taphonomic analyses (White, 1953; Grayson, 1984; Klein and Cruz-Uribe, 1984; Lyman, 1985). Values for rodents, bats and eulipotyphlans were based on cranial and dental material; values for larger mammals were based on cranial and post-cranial fossils (Table 8). Caves provide refuge from the elements that might otherwise destroy fossil material and thus caves have a high preservation potential. However, by their nature, caves provide a biased record. Mammals that frequent caves (e.g., Myotis, Ursus and Urocyon) will be over-represented and other taxa under-represented with respect to relative abundance on the surface. Bats undoubtedly colonized Zesch Cave (16.7% NISP, 31% MNI). The wealth of U. americanus bone (17.5% NISP, 1.9% MNI), much of it in articulation, attests to its use of the cave, possibly as a den. Metatarsals (TMM 128, 129) are metapodials from a neonatal black bear. These specimens lack the distal epicondyles and the cortical bone is not finished. This speaks to the possibility of U. americanus using Zesch Cave as a maternal den. Den selection by U. americanus is a factor critical to their reproductive success (Madan et al., 1997; Weaver and Pelton, 1994). Urocyon (4.4% NISP, 1.1% MNI), Mephitis (2.2% NISP, 1.1% MNI), and C. latrans (3.4% NISP, 0.75% MNI) are also overrepresented compared to raptor sites (Guilday, 1978) The Zesch Cave faunal assemblage clearly does not represent a true cross-section of the paleofauna, and may have been a carnivore trap. It has a definite bias towards trogloxenic carnivorans – carnivorans comprise 33% NISP and 9.4% MNI to the total fauna. Bones collected by carnivorans should show evidence of digestion such as surface pitting and a low frequency of whole bone material (Andrews, 1990). However, these signals are rare in Zesch Cave.

J.C. Sagebiel / Quaternary International 217 (2010) 159–174 Table 8 Absolute and relative abundances of Zesch Cave local fauna mammals. Abbreviations: NISP, number of identified specimens; MNI, minimum number of individuals. Mammalian specimen quantities Taxon

% Total

MNI

% Total

1

0.07

1

0.38

11 262

0.81 19.24

1 18

0.38 6.79

Rodentia Spermophilus Spermophilus or Tamias Cynomys ludovicianus Thomomys bottae Geomys Chaetodipus hispidus Chaetodipus/Perognathus Dipodomys Reithrodontomys sp. cf. R. fulvescens Peromyscus sp. cf. P. difficilus Peromyscus sp. cf. P. leucopus Peromyscus sp. cf. P. maniculatus Peromyscus sp. indeterminate Baiomys taylori Onychomys leucogaster Sigmodontinae (Peromyscus-size) Neotoma Microtus ochrogaster/pinetorum Microtus sp. cf. M. ochrogaster Microtus sp. cf. M. pinetorum Microtus sp. (five closed triangles) Synaptomys australis Zapus hudsoniu

14 3 11 5 31 13 4 13 33 3 11 1 45 19 22 10 39 27 15 4 3 8 1

1.03 0.22 0.81 0.37 2.28 0.95 0.29 0.95 2.42 0.22 0.81 0.07 3.30 1.40 1.62 0.73 2.86 1.98 1.10 0.29 0.22 0.59 0.07

3 2 2 2 4 2 2 4 12 2 6 1 17 11 7 5 7 6 10 2 2 3 1

1.13 0.75 0.75 0.75 1.51 0.75 0.75 1.51 4.53 0.75 2.26 0.38 6.42 4.15 2.64 1.89 2.64 2.26 3.77 0.75 0.75 1.13 0.38

Eulipotyphla Sorex hoyi Blarina carolinensis Cryptotis parva Notiosorex crawfordi Scalopus aquaticus

1 31 1 1 7

0.07 2.28 0.07 0.07 0.51

1 9 1 1 3

0.38 3.40 0.38 0.38 1.13

Microchiroptera Eptesicus fuscus Myotis sp. (medium size) Myotis velifer Microchiroptera (juvenile)

15 60 135 18

1.10 4.41 9.91 1.32

3 22 48 9

1.13 8.30 18.11 3.40

Carnivora Canis latrans Canis sp. cf. C. dirus Canis lupus/rufus Urocyon cinereoargenteus Vulpes macrotis/velox Vulpes vulpes Ursus americanus Mephitis mephitis or M. macroura Mustela frenata Taxidea taxus Leopardus or Herpailurus Lynx rufus

46 1 4 60 31 14 238 30 1 1 2 22

3.38 0.07 0.29 4.41 2.28 1.03 17.47 2.20 0.07 0.07 0.15 1.62

2 1 1 3 2 2 5 3 1 1 2 2

0.75 0.38 0.38 1.13 0.75 0.75 1.89 1.13 0.38 0.38 0.75 0.75

15

1.10

1

0.38

1 3 9 2 3 1

0.07 0.22 0.66 0.15 0.22 0.07

1 1 2 1 1 1

0.38 0.38 0.75 0.38 0.38 0.38

Xenarthra Megalonyx jeffersoni Lagomorpha Lepus californicus Sylvilagus floridanus

Perissodactyla Equus Artiodactyla Platygonus sp. cf. P. compressus Camelops hesternus Hemiauchenia macrocephala Odocoileus Capromeryx Bison

NISP

Owls contribute significantly to cave collections of small vertebrates (Andrews, 1990; Dalquest and Baskin, 1991; Guilday, 1978). Owls typically swallow their prey whole after biting the back of the skull and pulling off the head. As a result, most (89–99% of long

171

bones) of the bones swallowed by large owls and raptors are unbroken. In contrast, carnivorans masticate bone and digest the large majority of it. No owl fossils have been identified from Zesch Cave. However, much of the small vertebrate fossil material is relatively complete and pristine. Owls clearly were major contributors to this local fauna, and bone could also have been contributed by cathartids or corvids, which did leave fossils in the cave. The distribution of Sylvilagus bone from Zesch Cave is similar in profile to those presented by Andrews (1990) for owls/raptors and not similar to the distribution typical of carnivorans (Fig. 4). In summary, the Zesch Cave local fauna probably is the result of raptor accumulation. However, there is good evidence that Zesch Cave was also a carnivore trap. Both corvids and cathartids regurgitate indigestible material and probably brought considerable amounts of bone to Zesch Cave as a consequence of their scavenging activities. 6.2. Paleoecology Calaby (1978) recognized that vertebrates expand their ranges rapidly into suitable habitat. Because more offspring are produced each year than the habitat can carry, animals that disperse into newly available habitat will increase their species range. Unsuitable habitat is a barrier to immigration, and species ranges essentially map suitable species habitat. Rapid expansion into newly available habitat is demonstrated by the recent invasions of Oryctolagus cuniculus and Felis catus across Australia, as well as the expansion of the B. taylori and Dasypus novemcinctus across Texas. One should expect that a taxon would quickly occupy any suitable and available habitat. Conversely, the past occurrence of an animal in an area where it no longer occurs indicates that conditions were suitable for habitation by that species in the past. By examining the environmental conditions found across the modern ranges of extralimital species, one can predict the conditions that were present to support an ancient vertebrate community. Examination of the community that was present in the late Pleistocene of Mason County can be used to reconstruct the environmental conditions needed to support all members of that community. Considering that at least four species have deciduous and mixed forest affinities, fairly continuous strands of forested habitat clearly were present near Zesch Cave. B. carolinensis is a deciduous forest species, suggesting deciduous forest was present in the area (Schmidly, 1983). T. striatus is scansorial and typically associated with wooded environments. If it is present in the Zesch Cave environment, it indicates the presence of mature forest (Graham, 1984). Avian species such as the picids (most notably Dryocopus) and Pica pica suggest woodland habitats were present near Zesch Cave, at least in the riparian areas (Linsdale, 1937; Birkhead, 1991; DeGraaf et al., 1991). Five species in the Zesch Cave local fauna are usually associated with open grasslands. Bison, Spermophilus and especially C. ludovicianus typically inhabit open grasslands, as do the species that prey on them, such as Taxidea taxus and Vulpes velox/macrotis. Camelops and Hemiauchenia probably browsed in shrubby or broken forest environs while Odocoileus prefers broken forest environments (Davis and Schmidly, 1994; Dompierre and Churcher, 1996; MacFadden and Cerling, 1996). Five of the small mammals are burrowing taxa or animals that have specific soil requirements, totaling a combined 4.9% NISP, 5.7% MNI. Dipodomys is most likely extirpated from this area because of the loss of sandy loam in the uplands. Burrowing taxa such as Scalopus aquaticus, Cynomys and geomyids still occur near Zesch Cave, but are now relegated to marginal environments with deeper soil adjacent to granitic rocks of the Llano uplift (Schmidly, 1983).

172

J.C. Sagebiel / Quaternary International 217 (2010) 159–174

Fig. 4. Skeletal proportions of Sylvilagus from Zesch Cave.

The presence of burrowing rodents that require sandy loam soils suggest a broader distribution of relatively deep soil in the Mason County area during Rancholabrean time. The paleoenvironmental interpretations applied to some species from Zesch Cave appear to contradict the interpretations of others. C. ludovicianus, Chaetodipus hispidus and Lepus californicus, for example, are open grassland species; and one does not expect to find them associated with animals that either inhabit woodlands, such as the picids (woodpeckers and flickers) or prefer dense vegetation (Z. hudsonius and Synaptomys) (DeGraaf et al., 1991; Davis and Schmidly, 1994; Zwank et al., 1997). Such a mosaic of animals was most likely supported by a patchy environment with interfingering strands of wooded areas and open grassland (Guthrie, 1984). This habitat mosaic must have been controlled by soil types that in turn mirror the complexity of the underlying geologic formations of the Llano uplift. The fact that such a variety of habitats are demonstrated by their vertebrate denizens is the result of the taphonomic pathway of the bone in Zesch Cave-carnivoran and avian accumulation. With a hunting radius of tens of kilometers, these carnivores, scavengers and raptors have sampled a large enough area to provide a regional picture of the Llano uplift that surrounds Zesch Cave. This local fauna is very similar to others from the Edwards Plateau, and the interpretation of the paleoenvironment largely corroborates the findings of previous studies from this area (Patton, 1962; Lundelius, 1967; Graham, 1984; Toomey, 1993). The Zesch Cave local fauna does contain two northern boreal species that have not previously been reported from the Edwards Plateau (S. hoyi and Pica pica). These animals probably demonstrate a closer association of the northern Edwards Plateau with the high plains during the Pleistocene.

 Zesch Cave local fauna provides unique insight into the Rancholabrean paleoenvironment of the Llano uplift region of central Texas. The paleoecology is interpreted as a mosaic of woodland and open grassland.  Zesch Cave local fauna records the first record of Pica pica (black-billed magpie) from central Texas.  The Zesch Cave local fauna records the first record of S. hoyi (pygmy shrew) from central Texas.  Burrowing taxa suggest deeper, better-developed soils in this region during the Rancholabrean.  Zesch Cave local fauna is an unusual taphonomic situation, having evidence of fossils being contributed by both raptors and carnivorans. Acknowledgements I am grateful to Gene Zesch, Kurt Zesch and his family for providing access to Zesch Cave. Ernest L. Lundelius, Jr., Timothy Rowe and Robert Folk supervised this work as my thesis committee. Martin Lagoe provided material and guidance for acetic acid preparation. I received assistance with identifications from Wann Langston, Pamela Owen, and David Froehlich. Thor Holmes and George Baumgardner provided advice and access to their Recent mammal collections at the University of Kansas and the Texas Cooperative Wildlife Collection at Texas A and M, respectively. Walter Dalquest and Fred Stangl also provided comparative specimens, advice and reprints in support of my efforts. This work was supported by grants from the University of Texas Geology Foundation and the Austin Paleontological Society. References

7. Conclusions Analysis of the Zesch Cave local fauna demonstrates a Rancholabrean age for the fauna. This local fauna appears more similar to northern faunas than do other Edwards Plateau faunas, with the presence of S. hoyi and Pica pica at the Zesch Cave. Although biased by its use as a carnivoran den site, Zesch Cave nevertheless contributes significantly to the knowledge of the Pleistocene of central Texas. Important contributions from the Zesch Cave local fauna include:

Altringham, J.D., 1996. Bats: Biology and Behaviour. Oxford University Press, New York, pp. 1–262. Andrews, P., 1990. Owls, Caves and Fossils. University of Chicago Press, Chicago, pp. 1–231. Ashley, J.F., 1941. A study of the structure of the humerus in the Corvidae. The Condor 43 (4), 184–195. Barnes, V.E., 1981. Geologic Atlas of Texas: Llano Sheet. The University of Texas at Austin, Bureau of Economic Geology, Austin. scale 1:250,000. Bell, C.J., Lundelius Jr., E.L., Barnosky, A.D., Graham, R.W., Lindsay, E.H., Ruez Jr., D.R., Semken Jr., H.A., Webb, S.D., Zakrzewski, R.J., 2004. The Blancan, Irvingtonian, and Rancholabrean mammal ages. In: Woodburne, M.O. (Ed.), Late Cretaceous

J.C. Sagebiel / Quaternary International 217 (2010) 159–174 and Cenozoic Mammals of North America: Biostratigraphy and Geochronology. Columbia University Press, New York, pp. 232–314. Birkhead, T.R., 1991. The Magpies: The Ecology and Behaviour of Black-Billed and Yellow-Billed Magpies. T. and A.D. Poyser, London, pp. 270. Breyer, J., 1977. Intra- and interspecific variation in the lower jaw of Hemiauchenia. Journal of Paleontology 51 (3), 527–535. Brown, B., 1908. The Conard Fissure, a Pleistocene bone deposit in Northern Arkansas with description of two new genera and twenty new species of mammals. Memoirs of the American Museum of Natural History 9, 157–208. Calaby, J.H., 1978. Dispersal and establishment of animals. In: Walker, D., Guppy, J.C. (Eds.), Biology and Quaternary Environments. Australian Academy of Sciences, Canberra City, Australia, pp. 1–264. Carleton, M.D., Eshelman, R.E., 1979. A Synopsis of fossil grasshopper mice, genus Onychomys, and their relationships to Recent species: Claude W. Hibbard Memorial, Vol. 7. Museum of Paleontology, The University of Michigan, Papers on Paleontology 21, pp. 1–63. Carraway, L.N., 1995. A key to recent Soricidae of the western United States and Canada based primarily on dentaries. In: Occasional Papers of the Natural History Museum, vol. 175. The University of Kansas. 49. Carrier, D.R., Chase, K., Lark1, K.G., 2005. Genetics of canid skeletal variation: size and shape of the pelvis. Genome Research 15, 1825–1830. Chapman, J.A., Gregory, J.G., Edwards, W.R., 1982. Cottontails. In: Chapman, J.A., Feldhamer, G.A. (Eds.), Wild Mammals of North America: Biology, Management, Economics. The Johns Hopkins University Press, Baltimore, Maryland, pp. 1–1147, pp. 83–123. Dalquest, W.W., 1988. Astrohippus and the origin of Blancan and Pleistocene horses. In: Occasional Papers, vol. 116. The Museum, Texas Tech University. 1–23. Dalquest, W.W., Baskin, J.A., 1991. Local abundance of prairie voles in Beaver County, Oklahoma. The Texas Journal of Science 43 (1), 104–105. Dalquest, W.W., Kilpatrick, W., 1973. Dynamics of pocket gopher distribution on the Edwards plateau of Texas. The Southwestern Naturalist 18 (1), 1–9. Dalquest, W.W., Roth, E., Judd, F., 1969. The mammalian fauna of Schulze Cave, Edwards County, Texas. Bulletin of the Florida State Museum 13, 205–276. Dalquest, W.W., Stangl Jr., F.B., 1983. Identification of seven species of Peromyscus from Trans-Pecos Texas by characters of the lower jaws. The Museum, Texas Tech University, Occasional Papers 90, 1–12. Dalquest, W.W., Stangl Jr., F.B., 1986. Post-pleistocene mammals of the Apache mountains, Culberson county, Texas, with comments on zoogeography of the trans-pecos front range. The Museum, Texas Tech University, Occasional Papers 104, 1–35. Davis, W.B., Schmidly, D.J., 1994. The Mammals of Texas. Texas Parks and Wildlife, Austin, Texas, pp. 1–338. DeGraaf, R.M., Scott, V.E., Hamre, R.H., Ernst, L., Anderson, S.H., 1991. Forest and Rangeland Birds of the United States: Natural History and Habitat Use. In: Agriculture Handbook, vol. 688. U.S. Department of Agriculture, Forest Service, pp. 1–625. Diersing, V.E., 1980. Systematics and evolution of the pygmy shrews (subgenus Microsorex) of North America. Journal of Mammalogy 61 (1), 76–101. Dixon, J.R., 1987. Amphibians and Reptiles of Texas. Texas A&M University Press, College Station, pp. 434. Dompierre, H., Churcher, C.S., 1996. Premaxillary shape as an indicator of the diet of seven extinct late Cenozoic New World camels. Journal of Vertebrate Paleontology 16 (1), 141–148. Dragoo, J.W., Choate, J.R., Yates, T.L., O’Farrell, T.P., 1990. Evolutionary and taxonomic relationships among North American arid-land foxes. Journal of Mammalogy 71 (3), 318–332. Dunn, J.P., Chapman, J.A., Marsh, R.E., 1982. Jackrabbits. In: Chapman, J.A., Feldhamer, G.A. (Eds.), Wild Mammals of North America: Biology, Management, Economics. The Johns Hopkins University Press, Baltimore, Maryland, pp. 124–145. Eddleman, C.D., Akersten, W.A., 1966. Margay from the post-Wisconsin of Southeast Texas. Texas Journal of Science 18 (4), 378–385. FAUNMAP Working Group, 1996. Spatial response of mammals to Late Quaternary environmental fluctuations. Science 272, 1601–1606. Frank, R.M., 1965. Petrology Study of Sediments from Selected Central Texas Caves. Unpublished M.A. Thesis, University of Texas at Austin. Furlong, E.L., 1925. Notes on the occurrence of mammalian remains in the Pleistocene of Mexico, with a description of a new species Capromeryx mexicana. University of California Publications in Geological Sciences 15 (5), 137–152. Gidley, J.W., Gazin, C.L., 1938. The Pleistocene Vertebrate Fauna from Cumberland Cave, Maryland. In: United States National Museum Bulletin, vol. 171. Smithsonian Institution, Washington, D.C., pp. 1–99. Gilbert, B.M., Martin, L.D., Savage, H.G., 1996. Avian Osteology. Missouri Archaeological Society, Columbia, Missouri, pp. 1–252. Graham, R.W., 1972. Biostratigraphy and Paleoecological Significance of the Conard Fissure Local Fauna with Emphasis on the Genus Blarina. Unpublished Master of Science thesis, University of Iowa. Graham, R.W., 1976. Pleistocene and Holocene Mammals, Taphonomy, and Paleoecology of the Friesenhahn Cave Local Fauna, Bexar County, Texas. Unpublished Ph.D. Dissertation, University of Texas at Austin. Graham, R.W., 1984. Paleoenvironmental implications of the Quaternary distribution of the eastern chipmunk (Tamias striatus) in central Texas. Quaternary Research 21, 111–114. Graham, R.W., 1991. Variability in the size of North American Quaternary black bears (Ursus americanus) with the description of a fossil black bear from Bill

173

Neff Cave, Virginia. In: Purdue, J.R., Klippel, W.E., Styles, B.W. (Eds.), Beamers, Bobwhites and Bluepoints: Tributes to the Career of Paul W. Parmalee. Illinois State Museum Scientific Papers 23, 237–250. Grayson, D.K., 1984. Quantitative Zooarchaeology: Topics in the Analysis of Archaeological Faunas. Academic Press, New York, pp. 202. Guilday, J.E., 1978. The Baker Bluff cave deposit, Tennessee, and the Late Pleistocene faunal gradient. Bulletin of Carnegie Museum of Natural History 11, 1–68. Guilday, J.E., Hamilton, H.W., Anderson, E., Parmalee, P.W., 1967. Notes on the Pleistocene big brown bat. Annals of Carnegie Museum 39 (7), 105–114. Guthrie, R.D., 1984. Mosaics, allelochemics and nutrients d an ecological theory of late Pleistocene megafaunal extinctions. In: Martin, P.S., Klein, R.G. (Eds.), Quaternary Extinctions: A Prehistoric Revolution. University of Arizona Press, Tuscon, p. 264. Hadley, E.A., 1997. Evolutionary and ecological response of pocket gopher (Thomomys talpoides) to late-Holocene climatic change. Biological Journal of the Linnean Society 60, 277–296. Hall, E.R., 1936. Mustelid mammals from the Pleistocene of North America, (with systematic notes on some Recent members of the genera Mustela, Taxidea and Mephitis). In: Contributions to Paleontology IV, vol. 473. Carnegie Institute of Washington Publication. 41–119. Hall, E.R., 1981. The Mammals of North America, vol. 2. John Wiley and Sons, New York, pp. 1–1265. Harris, A.H., Porter, L.S.W., 1980. Late Pleistocene horses of dry cave, Eddy County, New Mexico. Journal of Mammalogy 61 (1), 46–65. Hibbard, C.W., 1944. Stratigraphy and vertebrate paleontology of Pleistocene deposits of southwestern Kansas. Bulletin of the Geological Society of America 55, 707–754. Hibbard, C.W., 1955. The Jinglebob interglacial (Sangamon?) fauna from Kansas and its climatic significance. University of Michigan, Contributions from the Museum of Paleontology. vol. 12(10), 179–228. Hollenshead, M.G., Mead, J.I., 2006. Early Pliocene Crotaphytus and Gambelia (Squamata: Crotaphytidae) from the Panaca Formation of Southeastern Nevada. Journal of Herpetology 40 (4), 566–569. Holman, J.A., 1995. Pleistocene Amphibians and Reptiles in North America. Oxford University Press, New York, pp. 1–243. Holman, J.A., 2003. Fossil Frogs and Toads of North America. Indiana University Press, Indianapolis, pp. 1–246. Holman, J.A., 2006. Fossil Salamanders of North America. Indiana University Press, Indianapolis, pp. 1–232. Howard, H., 1968. Limb Measurements of the Extinct Vulture, Coragyps occidentalis. In: Papers of the Archaeological Society of New Mexico 1 115–127. Hulbert Jr., R.C., Pratt, A.E., 1998. New Pleistocene (Rancholabrean) vertebrate faunas from coastal Georgia. Journal of Vertebrate Paleontology 18 (2), 412–429. Jones Jr., J.K., Birney, E.C., 1988. Handbook of Mammals of the North-Central States. University of Minnesota Press, Minneapolis, pp. 1–346. Junge, J.A., Hoffman, R.S., 1981. An annotated key to the long-tailed shrews (genus Sorex) of the United States and Canada, with Notes on Middle American Sorex. In: Occasional Papers of the Museum of Natural History, vol. 94. The University of Kansas. 1–48. Kasper, S., 1992. Mammals from the Late Pleistocene Carrol Creek local fauna, Donley County, Texas. The Southwest Naturalist 37 (1), 54–65. Klein, R.G., Cruz-Uribe, K., 1984. The Analysis of Animal Bones from Archeological Sites. University of Chicago Press, Chicago, pp. 266. Klingener, D.,1963. Dental evolution of Zapus. Journal of Mammalogy 44 (2), 248–260. Kurte´n, B., Anderson, E., 1980. Pleistocene Mammals of North America. Columbia University Press, New York, pp. 1–422. Linsdale, J.M., 1937. Pacific Coast Avifauna: the natural history of magpies. In: Contributions from the University of California Museum of Vertebrate Zoology, 25 1–234. Lundelius Jr., E.L., 1967. Late Pleistocene and Holocene faunal history of central Texas. In: Martin, P.S., Wright, H.E. (Eds.), Pleistocene Extinctions. Yale University Press, New Haven, pp. 287–319. Lundelius Jr., E.L., 1972. Report of Investigations. Fossil Vertebrates from the Late Pleistocene Ingleside Fauna, San Patricio County, Texas, vol. 77. Bureau of Economic Geology, University of Texas at Austin, pp. 1–74. Lundelius Jr., E.L., 1985. Pleistocene vertebrates from Laubach Cave. In: Woodruff Jr., C.M., Snyder, F., De La Garza, L., Slade Jr., R.M. (Eds.), Edwards Aquifer-Northern Segment. Austin Geological Society Guidebook 8, 41–45. Lundelius Jr., E.L., 1992. The avenue local fauna, Late Pleistocene vertebrates from terrace deposits at Austin, Texas. Annales Zoologici Fennici 28, 329–340. Lundelius Jr., E.L., Downs, T., Lindsay, E.H., Semken, H.A., Zakrzewski, R.J., Churcher, C.S., Harington, C.R., Schultz, G.E., Webb, S.D., 1987. The North American Quaternary sequence. In: Woodburne, M.O. (Ed.), Cenozoic Mammals of North America: Geochronology and Biostratigraphy. University of California Press, Berkeley, pp. 211–235. Lyman, R.L., 1985. Bone frequencies: differential transport, in situ destruction, and the MGUI. Journal of Archaeological Science 12, 221–236. MacFadden, B.J., Cerling, T.E., 1996. Mammalian herbivore communities, ancient feeding ecology, and carbon isotopes: a 10 million-year sequence from the Neogene of Florida. Journal of Vertebrate Paleontology 16 (1), 103–115. Madan, K.O., Jacobson, H.A., Leopold, B.D., 1997. Denning ecology of black bears in the White River National wildlife refuge, Arkansas. Journal of Wildlife Management 61 (3), 700–706. Martin, R.A., Duobinis-Gray, L., Crockett, C.P., 2003. A new species of early Pleistocene Synaptomys (Mammalia, Rodentia) from Florida and its relevance to southern bog lemming origins. Journal of Vertebrate Paleontology 23 (4), 917–936.

174

J.C. Sagebiel / Quaternary International 217 (2010) 159–174

Mercure, A., Ralls, K., Koepflik, P., Wayne, R.K., 1993. Genetic subdivisions among small canids – mitochondrial-DNA differentiation of swift, kit, and arctic foxes. Evolution 47, 1313–1328. Merriam, J.C., 1912. The Fauna of Rancho La Brea. Part II. Canidae. In: Memoirs of the University of California, 1 (2), pp. 217–273. Nowak, R.M., Paradiso, J.L., 1983. Walker’s Mammals of the World, fourth ed., vol. 2. Johns Hopkins University Press, Baltimore, pp. 1–1362. Patton, T.H., 1962. Fossil Vertebrates from Miller’s Cave, Llano County, Texas. Unpublished M.A. thesis, University of Texas at Austin. Patton, T.H., 1963. Fossil vertebrates from Miller’s Cave Llano County, Texas. Bulletin of the Texas Memorial Museum 7, 1–41. Pearson, T.G., Burroughs, J., Forbush, E.H., Job, H.K., Finley, W.L., Nichols, L.N., Gladden, G., Burdick, J.E., 1936. Birds of America. Garden City Publishing Company, Garden City, New York, pp. 1–289. Presch, W., 1969. Evolutionary osteology and relationships of the horned lizard genus Phrynosoma (Family Iguanidae). Copeia 1969 (2), 250–275. Repenning, C.A., 1967. Subfamilies and genera of the Soricidae. Geological Survey Professional Paper 565, 1–74. Riskind, D.H., Diamond, D.D., 1988. An introduction to environments and vegetation. In: Amos, B.B., Gehlbach, F.R. (Eds.), Edwards Plateau VegetationPlant Ecological Studies in Central Texas. Baylor University Press, Waco, Texas, pp. 1–16. Schmidly, D.J., 1983. Texas Mammals East of the Balcones Fault Zone. Texas A and M University Press, College Station, Texas, pp. 1–400. Schmidly, D.J., 1991. The Bats of Texas. Texas A and M University Press, College Station, Texas, pp. 1–188. Semken Jr., H.A., 1961. Fossil vertebrates from Longhorn Cavern Burnet County, Texas. The Texas Journal of Science 13, 290–310. Simpson, G.G., 1928. Pleistocene Mammals from a Cave in Citrus County, Florida. American Museum Novitates 328, 1–16. Stebbins, R.C., 1985. Western Reptiles and Amphibians, second ed. Houghton Mifflin, Baltimore, Maryland, pp. 1–336. Stock, C., 1925. Cenozoic gravigrade edentates of western North America with special reference to the Pleistocene Megalonychidae and Mylodontidae of Rancho La Brea, vol. 331. Carnegie Institute of Washington Publication. 1–206.

Thornton, W.A., Creel, G.C., 1975. The taxonomic status of kit foxes. The Texas Journal of Science 26 (1 and 2), 127–136. Tihen, J.A., 1962. Osteological observations on New World Bufo. The American Midland Naturalist 67 (1), 157–183. Toomey, R.S., III, 1993. Late Pleistocene and Holocene Faunal and Environmental Changes at Hall’s Cave, Kerr County, Texas. Unpublished Ph.D. Dissertation, University of Texas at Austin. Toomey III, R.S., 1994. Vertebrate paleontology of Texas Caves. In: Elliott, W.R., Veni, G. (Eds.), The Caves and Karst of Texas. National Speleological Society, Huntsville, Texas, pp. 50–68. Weaver, K.M., Pelton, M.R., 1994. Denning ecology of black bears in the Tensas River Basin of Louisiana. International Conference on Bear Resources and Management 9 (1), 427–433. Webb, S.D., 1974. Pleistocene llamas of Florida, with a brief review of the Lamini. In: Webb, S.D. (Ed.), Pleistocene Mammals of Florida. The University Presses of Florida, Gainesville, pp. 170–213. Weinstock, J., Willerslev, E., Sher, A., Tong, W., Ho, S.Y.W., Rubenstein, D., Storer, J., Burns, J., Martin, L., Bravi, C., Prieto, A., Froese, D., Scott, E., Xulong, L., Cooper, A., 2005. Evolution, systematics, and phylogeography of Pleistocene horses in the New World: a molecular perspective. PLoS Biology 3 (8), e241. Werdelin, L., 1985. Small Pleistocene felines of North America. Journal of Vertebrate Paleontology 5 (3), 194–210. White, T.E., 1953. A method of calculating the dietary percentage of various food animals utilized by aboriginal peoples. American Antiquity 19, 396–398. Winkler, E.J., 1990. Small mammals from a Holocene sequence in central Texas and their paleoenvironmental implications. The Southwestern Naturalist 35, 199–205. Worthington, R.D., 1971. Postmetamorphic Changes in the Vertebrae of the Marbled Salamander Ambystoma opacum Gravenhorst (Amphibia, Caudata). In: Science Series, vol. 4. The University of Texas, El Paso, pp. 1–74. Wozencraft, W.C., 1993. Order carnivora. In: Wilson, D.E., Reeder, D.M. (Eds.), Mammal Species of the World: A Taxonomic and Geographic Reference, second ed. Smithsonian Institution Press, Washington, DC, pp. 279–348. Zwank, P.J., Najera, S.R., Cardenas, M., 1997. Life history and habitat affinities of meadow jumping mice (Zapus hudsonius) in the middle Rio Grande Valley of New Mexico. The Southwestern Naturalist 42 (3), 318–322.