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Pleistocene Environments


Early Wisconsin or Early Mid Wisconsin // Mid Wisconsin // Mid Wisconsin to Pleniglacial // Full-glacial Wisconsin


A caution is necessary. Until late in the Pleistocene, fine chronologic control is the exception (and rather crude even in later Pleistocene times). Any faunas in the early and mid Pleistocene (and to considerable degree in the late Pleistocene) may be separated by expanses of time long enough to create confusion between different spans of similar environments, much as the early interpretation of four Pleistocene glaciations left us lumping together faunas from different glacial or interglacial ages. Marine isotope data, among other sources of information, make it clear that alternations of cooler and warmer climates extend back into the Blancan, thus rendering useless any broad characterizations of Blancan climate. To some degree, an individual fauna may characterized as indicating warm or cool conditions (for example, presence of glyptodont usually is taken as indicating relative warmth), but seldom allows for generalizations except of the broadest form.


There is little environmental information specifically applicable to our region from the early Pleistocene. This largely is because published faunal material from the Irvingtonian Land Mammal Age of the region consists almost entirely of megafaunal elements. The widespread presence of horses, camels, and antilocaprids indicates at least moderate presence of open areas with grasses and forbs, but such habitat is available in almost every region except, possibly, those with heavy forest cover. Sloths and gomphotheres such as Stegomastodon indicate presence of browse, but there are few data to indicate relative proportions of grassland and wooded habitats, especially since most of the fossil deposits likely were in riparian situations not necessarily representative of habitats in the uplands.

The early Irvingtonian Mesilla C fauna (Morgan and Lucas 2003) suggests mild temperatures, with glyptodonts and ground sloths likely unable to withstand severe freezing winter conditions. Likewise, the large tortoises recorded indicate a temperate climate. Relatively mild climatic conditions apparently extended northward, with Glyptotherium recorded in the Tijeras Arroyo fauna in north-central New Mexico (Morgan and Lucas 2005).

The major exception to a paucity of microfaunal fossils is San Antonio Cave, where medial Irvingtonian faunas were present and interpreted by Rogers et al. (2000). However, the high elevation (2737 m) and position in the extreme northern part of our region (about 2.5 mi south of the New Mexico/Colorado border) leaves little applicability to the areas to the south and at lower altitudes. Rogers et al. (2000) indicated that the oldest faunas (dating from between ca. 1 mya and 0.85 mya) from the cave indicate mild, warm climatic conditions with moisture varying from rather dry to relatively wet. The somewhat later, but still medial Irvingtonian, deposits were said to suggest growth and regression of glacial conditions, probably with times of severe drought and other times forested, with much more effective moisture than in the area today.

? Early Wisconsin or Early Mid Wisconsin

The Dry Cave sites of Lost Valley, Room of the Vanishing Floor, Sabertooth Camel Maze, and Balcony on Lost Valley, along with possibly some sites within Anthony Cave, appear to be earlier than other late Pleistocene cave localities. Although generally recorded in the site and taxonomic accounts as "Early or Early Mid Wisconsin", there is the possibility that some or all predate the Wisconsin.

The dates associated with the Dry Cave sites are 29,290 ± 1060 for Lost Valley, 25,160 ± 1730 for the Sabertooth Camel Maze, and 33,590 ± 1500 for the Room of the Vanishing Floor. All dates are radiocarbon dates on bone carbonates, collagen being absent for all practical purposes. I consider all of these dates as too recent based on the generally untrustworthiness of carbonate dates and that the faunas (Tables 1-3) seem too different from similarly dated faunas (Pendejo Cave, U-Bar Cave). The relative commonness of Corvus neomexicanus and Neotoma pygmaea, the appearance of Hesperotestudo wilsoni, and the extreme eastern occurrence of Gopherus agassizii are notable. Only the latter is known from elsewhere in the region, and it is absent from all other Guadalupe Mountains sites. A large tortoise, probably Gopherus, does occur in disturbed deposits in Sierra Diablo Cave; however, presence of Desmodus stocki and Aztlanolagus agilis suggests that at least some of those fossils represent a time well before the late Wisconsin.

Climatically sensitive taxa indicate warm winter temperatures, at least lacking the severe cold fronts that would be expected to bar the tortoises from the region. The Greater Roadrunner appears to be the smaller form characteristic of the warm post-Pleistocene climate rather than the larger Conkling's Roadrunner more characteristic of glacial climates (Harris and Crews 1982). The Texas and Round-tailed horned lizards suggest summer temperatures warm enough to allow successful egg development, whereas glacial faunas of the area supported only the live-bearing Mountain Short-horned Lizard that is able to breed successfully where the summer growing season is too short for the other species.

On the other hand, several taxa are indicative of temperatures slightly cooler than currently characteristic of Dry Cave. The Mountain Short-horned Lizard currently occurs at slightly higher elevations than Dry Cave. Merriam's Shrew is the Southwestern species of Sorex most adapted to arid conditions, but doesn't currently occur in southern New Mexico at the elevation of Dry Cave. The Prairie Vole, currently occurring in extreme northeastern New Mexico and out into the Great Plains, is present in these site and of a size fitting better the northeastern New Mexican modern specimens than members of the Nebraskan/Kansan populations characterized by smaller sized individuals (Harris 1988). Presence of the Mountain Cottontail (see the Sylvilagus account for taxonomic problems) suggests woodland habitat nearby.

Overall, the record indicates relatively warm winter temperatures and moderately warm summers that were cooler than today and/or with more effective precipitation. Absence in a rather large faunal sample of marmot, mesic-adapted shrews, and voles other than the Prairie Vole seemingly places an upper limit to the amount of precipitation and cooling. A mixture of woodland and grasslands with a climate similar to that of today's northeastern New Mexico appears reasonable.

Mid Wisconsin

The Wisconsin Age commenced with the resurgence of continental glaciation following the Sangamon Interglacial. The early Wisconsin glacial advances paused and retreated to a degree, though climatic conditions in general remained cooler than during either the Sangamon Interglacial or the current Holocene Interglacial. This somewhat less severe climate, here considered to be the Mid Wisconsin, lasted from about 60,000 B.P. to the major renewal of glacial activity in the Late Wisconsin that commenced around 32,000 to 27,000 B.P. By about 25,000 radiocarbon years ago, the regional climate was such as to have more in common with late glacial conditions than with the somewhat milder Mid Wisconsin. The 25,000 B.P. date is used here as the division between Mid and Late Wisconsin. It should be kept in mind that throughout the Wisconsin, climatic fluctuation with major facies changes was the rule.

In hindsight, a comparison of the older Dry Cave sites with two major sites west of the Guadalupe Mountains under the intent to compare Mid-Wisconsin climates (Harris 1987) may have been comparing sites of two different ages, and some of the differences between the eastern and western sites may be due to this. The Pit North & West Animal Fair site, judging from stratigraphic relationships, is more certainly comparable to the western sites, but unfortunately has a relatively restricted fauna.

The differences between the early Dry Cave sites and U-Bar Cave were summarized as follows (Harris 1987:150-151):

Although both the Dry Cave and U-Bar Cave faunas indicate more equable conditions than today, there were significant differences between the sites. At Dry Cave, there was greater seasonality of precipitation, particularly in the form of winter-early spring drought, and summer temperatures probably were depressed less than at U-Bar Cave. Thus animals that require continuous availability of green fodder through the warm season, and forms stressed by hot temperatures, were barred from the area. Somewhat cooler temperatures than today enhanced effective moisture, allowing the occurrence of woodland plants and animals now found mostly in the nearby highlands, but with the presence of a few more-northern animals.

At U-Bar Cave, absence of high temperatures together with greater effective moisture during the spring allowed occurrence of now-distant plants and animals favored by cool summers and moderate year-round moisture. As a result, the U-Bar Cave fauna differed more from the present fauna of southwestern New Mexico than did the Dry Cave fauna from the present fauna of southeastern New Mexico. This may record primarily geographic differences in climatic regimes or, conversely, temporal differences between the faunas. The broad overlap in radiocarbon dates from the two sites suggests the former, but uncertainty is sufficient to prevent ruling out the latter.

My tentative conclusion is that the older Dry Cave sites likely are older than the relatively well dated sites west of the Guadalupe Mountains. Speculatively, they may represent an early stage of post-Sangamon cooling or an exceptionally warm period of the Mid Wisconsin. On the other hand, of course, they may merely reflect differences similar to those seen today between the extreme climatic conditions at the edge of the Great Plains compared to the more protected interior Southwest.

Table 1. Fish and herptile taxa recorded from the Dry Cave "old" sites and Mid Wisconsin sites in New Mexico. U-Bar = U-Bar Cave Mid Wisconsin; Pendejo = Pendejo Cave Mid Wisconsin; Pit = Pit N & W Animal Fair; BLV = Balcony on Lost Valley; LV = Lost Valley; RVF = Room of the Vanishing floor; SCM = Sabertooth Camel Maze. ? gen = ? genus and species; cf gen = cf genus and species.

Taxon U-Bar Pendejo Pit BLV LV RVF SCM
Osteichthyes—Bony Fish         X X  
Ambystoma mavortium—Barred Tiger Salamander X X          
Anura—Frogs and Toads         X    
Scaphiopus/Spea—Spadefoot X            
Spea multiplicata—New Mexico Spadefoot   X          
Anaxyrus/Ollotis sp.—True Toad X            
Cophosaurus texanus—Greater Earless Lizard         ? gen    
Crotaphytus collaris—Eastern Collared Lizard X X     X X  
Phrynosoma cornutum—Texas Horned Lizard X       X    
Phrynosoma hernandesi—Mountain Short-horned Lizard X     X X  
Phrynosoma modestum—Round-tailed Horned Lizard       X    
Sceloporus (small)—Spiny Lizard (small) X       X X  
Sceloporus (large)—Spiny Lizard (large) X            
Sceloporus cowlesi—Southern Plateau Lizard   cf gen          
Urosaurus ornatus—Tree Lizard cf            
Cnemidophorus (large)—Whiptail (large) X            
Serpentes—Snakes         X    
Bogertophis subocularis—Trans-Pecos Rat Snake   X          
Coluber/Masticophis—Racer/Whipsnake   X          
Elaphe emoryi—Great Plains Rat Snake   X          
Pituophis sp.—Gopher Snake ?            
Pituophis catenifer—Gopher Snake   X          
Rhinocheilus lecontei—Long-nosed Snake   X          
Salvadora sp.—Patchnose Snake ?            
Salvadora grahamiae—Mountain Patchnose Snake   ? gen          
Sonora semiannulata—Ground Snake   ? gen          
Trimorphodon biscutatus—Lyre Snake   ? gen          
Crotalus sp.—Rattlesnake X         X  
Diadophis punctatus—Ringneck Snake   X          
Hypsiglena torquata—Night Snake   cf gen          
Thamnophis sp.—Garter Snake   X          
Chelonia—Turtles X            
Gopherus agassizii—Desert Tortoise   X       X X
Hesperotestudo wilsoni—Wilson's Tortoise             X

Table 2. Bird taxa recorded from the Dry Cave "old" sites and Mid Wisconsin sites in New Mexico. U-Bar = U-Bar Cave Mid Wisconsin; Pendejo = Pendejo Cave Mid Wisconsin; Pit = Pit N & W Animal Fair; BLV = Balcony on Lost Valley; LV = Lost Valley; RVF = Room of the Vanishing floor; SCM = Sabertooth Camel Maze. ? gen = ? genus and species; cf gen = cf genus and species.

Taxon U-Bar Pendejo Pit BLV LV RVF SCM
Anabernicula sp.—Sheldgoose cf            
Anas sp.—Duck   ?          
Anas americana—American Wigeon
Anas platyrhynchos—Mallard cf            
Callipepla squamata—Scaled Quail 
  cf          cf
Colinus virginianus—Northern Bobwhite ? gen            
Cyrtonyx montezumae—Montezuma Quail           ? gen  
Meleagris sp.—Turkey   X          
Meleagris crassipes—Big-foot Turkey             X
Breagyps clarkii—Clark's Condor
        X   X
Cathartes aura—Turkey Vulture cf gen            
†Coragyps occidentalis—Western Vulture   X X X X X
Accipiter cooperi—Copper's Hawk     X        
Accipiter striatus—Sharp-shinned Hawk   X       cf  
Aquila chrysaetos—Golden Eagle X       cf ?  
Buteo sp.—Buteo Hawk           X  
Buteo swainsoni—Swainson's Hawk   cf X        
Circus cyaneus—Harrier   cf gen          
Caracara cheriway—Crested Caracara     X        
Falco mexicanus—Prairie Falcon   X          
Falco peregrinus—Peregrine Falcon           ?  
Falco sparverius—American Kestrel cf gen X          
Fulica americana—American Coot           X  
Zenaida sp.—Zenaida Dove             cf
Zenaida macroura—Mourning Dove X X     cf X  
Geococcyx californianus californianus—Greater Roadrunner
  X       X  
Geococcyx californianus conklingi—Conkling's Roadrunner X          
Asio flammeus—Long-eared Owl   X          
Bubo virginianus—Great Horned Owl   X     X X  
Megascops kennicottii—Western Screech-owl           cf gen  
Otus flammeolus—Flammulated Owl   X          
Strix occidentalis—Spotted Owl cf            
Colaptes auratus—Northern Flicker X X     X cf  
Melanerpes lewis—Lewis Woodpecker   cf gen           
Aphelocoma californica—Western Scrub-jay   X       X  
Corvus corax—Common Raven     X   X    
Corvus cryptoleucus—Chihuahua Raven   X          
†Corvus neomexicanus—New Mexican Raven         X X X
Cyanocitta—Blue Jays         ? X  
Cyanocitta stelleri—Steller's Jay   X          
Gymnorhinus cyanocephalus—Pinyon Jay   cf gen          
Pica hudsonia—Black-billed Magpie   X          
Sitta pygmaea—Pygmy Nuthatch   cf gen          
Salpinctes sp.—Rock Wren   cf          
Salpinctes obsoletus—Rock Wren  cf gen            
Sialia sp.—Bluebird   cf          
Turdus migratorius—American Robin   cf gen       cf gen   
Mimus polyglottis—Mockingbird   ? gen       cf gen  
Aimophila sp.—Aimophila Sparrows           X  
Amphispiza bilineata—Desert Sparrow   ? gen          
Calamospiza melanocorys—Lark Bunting   cf gen          
Pipilo sp.—Towhee   cf          
Euphagus cyanocephalus—Brewer's Blackbird   cf gen          
Quiscalus quiscala—Common Grackle   cf gen          
Sturnella sp.—Meadow Lark   X          
Xanthocephalus xanthocephalus—Yellow-headed Blackbird ? gen            
Carpodacus sp.—Purple Finches   ?          

Table 3. Mammalian taxa recorded from the Dry Cave "old" sites and Mid Wisconsin sites in New Mexico. U-Bar = U-Bar Cave Mid Wisconsin; Pendejo = Pendejo Cave Mid Wisconsin; Pit = Pit N & W Animal Fair; BLV = Balcony on Lost Valley; LV = Lost Valley; RVF = Room of the Vanishing floor; SCM = Sabertooth Camel Maze. ? gen = ? genus and species; cf gen = cf genus and species.

Taxon U-Bar Pendejo Pit BLV LV RVF SCM
†Nothrotheriops shastensis—Shasta Ground Sloth X         X  
Ammospermophilus sp.—Antelope Squirrel
Ammospermophilus interpres—Texas Antelope Squirrel   X          
Cynomys sp.—Prairie Dog X         X  
Cynomys gunnisoni—Gunnison's Prairie Dog   X          
Cynomys ludovicianus—Black-tailed Prairie Dog     X        
Cynomys mexicanus—Mexican Prairie Dog         cf    
Marmota flaviventris—Yellow-bellied Marmot X X          
Spermophilus (Ictidomys)—Ground Squirrel (subgenus Ictidomys) X X     X X  
Spermophilus sp., S. elegans size—Wyoming Ground Squirrel size   X          
Spermophilus spilosoma—Spotted Ground Squirrel     cf        
Spermophilus variegatus—Rock Squirrel X         X  
Tamias sp.—Chipmunk         X    
Tamias canipes/quadrivittatus—Gray-footed or Colorado Chipmunk   X          
Tamias dorsalis—Cliff Chipmunk ?            
Tamias minimus—Least Chipmunk   X          
Dipodomys sp. (small)—Small Kangaroo Rat           X X
Dipodomys ordii—Ord's Kangaroo Rat   X     X    
Dipodomys spectabilis—Banner-tailed Kangaroo Rat  cf X     X    
Chaetodipus sp.—Spiny Pocket Mouse  X         X  
Perognathus sp.—Silky Pocket Mouse         X X  
Perognathus flavus/flavescens—Silky Pocket Mice cf X          
Cratogeomys castanops—Yellow-faced Pocket Gopher   X X   X X X
Geomys arenarius/bursarius—Desert/Great Plains Pocket Gopher   X          
Thomomys bottae—Botta's Pocket Gopher  X X  X   X X X
Thomomys talpoides—Northern Pocket Gopher   X          
Lemmiscus curtatus—Sagebrush Vole X X          
Microtus mogollonensis—Mogollon Vole X X X        
Microtus ochrogaster—Prairie Vole     X   X    
Microtus pennsylvanicus—Meadow Vole X            
Neotoma albigula—White-throated Woodrat X            
Neotoma cinerea—Bushy-tailed Woodrat X X X        
Neotoma findleyi—Findley's Woodrat X       X X  
Neotoma leucodon—White-toothed Woodrat   X cf   X X X
Neotoma mexicana—Mexican Woodrat X            
Neotoma micropus—Southern Plains Woodrat         X    
Neotoma pygmaea—Pygmy Woodrat         X X cf
Neotoma stephensi—Stephen's Woodrat X            
Onychomys leucogaster—Northern Grasshopper Mouse   X X   cf    
Peromyscus sp.—White-footed Mouse   X X     X  
Peromyscus boylii—Brush Mouse  ?       X    
Peromyscus difficilis—Rock Mouse X            
Peromyscus eremicus—Cactus Mouse X            
Peromyscus maniculatus—Deer Mouse X            
Peromyscus truei—Pinyon Mouse X            
Reithrodontomys sp.—Harvest Mouse   X       X  
Reithrodontomys megalotis—Western Harvest Mouse cf            
Sigmodon sp.—Cotton Rat X X     X    
Erethizon dorsata—American Porcupine           ? gen  
Aztlanolagus agilis—Aztlán Rabbit X X     X X X
Lepus sp.—Jackrabbit X            
Lepus californicus—Black-tailed Jackrabbit   X X X X X X
Lepus townsendii—White-tailed Jackrabbit   X          
Sylvilagus sp.—Cottontail       X      
Sylvilagus audubonii/floridanus—Desert or Eastern Cottontail X            
Sylvilagus audubonii—Desert Cottontail   X   X X
Sylvilagus floridanus—Eastern Cottontail   X     cf    
Sylvilagus nuttallii—Mountain Cottontail) X X X X cf
Notiosorex crawfordi—Desert Shrew   X          
Sorex merriami—Merriam's Shrew X X     X    
Sorex preblei—Preble's Shrew X       X    
? Nyctinomops sp.—Large Free-tailed Bat         ?   X
Tadarida brasiliensis—Mexican Free-tailed Bat       cf    
Desmodus stockii—Stock's Vampire Bat X            
Antrozous pallidus—Pallid Bat X     X    
Corynorhinus sp.—Big-eared Bat X       X X  
Eptesicus fuscus—Big Brown Bat X            
Lasiurus cinereus—Hoary Bat   X          
Myotis sp.—Myotis Bats     X      
Myotis lucifugus—Little Brown Bat ?            
Myotis thysanodes—Fringe-tailed Myotis           ?  
Myotis velifer—Cave Myotis X       X X  
Lynx sp.—Bobcat             ?
Lynx rufus—Bobcat X     X X  
Panthera atrox—American Lion     X     X  
Panthera atrox/Arctodus simus—American Lion or Giant Short-faced Bear   X          
Panthera onca—Jaguar           Xa  
Puma concolor—Mountain Lion         cf cf X
Canis latrans—Coyote   X     X X  
Canis dirus—Dire Wolf             X
Canis lupus—Gray Wolf   ? gen X     X X
Urocyon sp.—Gray Foxes       cf      
Urocyon cinereoargenteus—Gray Fox X     X X  
Vulpes velox/macrotis—Swift or Kit Fox   X          
Vulpes velox—Swift Fox     X       cf
Arctodus simus—Giant Short-faced Bear X            
Ursus sp.—Bear           cf ?
Ursus americanus—American Black Bear cf X          
Mustela frenata—Long-tailed Weasel   X          
Taxidea sp.—Badger           cf  
Taxidea taxus—Badger X X          
Brachyprotoma sp.—Short-faced Skunk         ?    
Conepatus leuconotus—Hognosed Skunk     X        
Mephitis mephitis—Striped Skunk X X          
Spilogale sp.—Spotted Skunk X   X    
Bassariscus astutus—Ringtail             X
Tapirus sp.—Tapir         X    
Equus sp.—Horse         X    
Equus conversidens—Mexican Horse X X X        
Equus niobrarensis—Niobrara Horse cf X X        
Equus occidentalis—Western Horse cf         X  
Platygonus sp.—Flat-headed Peccary           X  
Camelops sp.—American Camel cf        X  
Camelops hesternus—Yesterday's Camel          cf   cf
Hemiauchenia macrocephala—Big-headed Llama           X
Navahoceros fricki—Mountain Deer ?            
Odocoileus sp.—Deer         ? cf
Odocoileus hemionus—Mule Deer   cf          
Antilocapra americana—Pronghorn       X    
Capromeryx sp.—Miniature Pronghorn   X X X
Stockoceros conklingi—Conkling's Pronghorn X X          
Bison antiquus—Ancient Bison   cf          
Euceratherium collinum—Shrub-ox cf            
Oreamnos harringtoni—Harrington's Mountain Goat cf            

a Also South Chimney, likely about the same age

Literature. Harris 1987, 1988; Harris and Crews 1982; Morgan and Lucas 2003, 2005; Rogers et al. 2000.


Last Update: 4 Jan 2010