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Late Pleistocene faunas from caves in the eastern Grand Canyon, Arizona
... Czaplewski et al. (this volume) identified a partial radius as Miracinonyx trumani from Pyeatt Cave, which is probably based on the same specimen as Harris' (1985) Puma record. The most recent description of late Pleistocene Puma concolor from Arizona is by Mead et al. (2003) from Next Door Cave in the eastern Grand Canyon, based on a well preserved calcaneum. ...
... Next Door Cave-the locality (CB: 8:1) represents a small overhang adjacent to and most likely connected to Kaetan Cave (Mead, 1981). The cave in the Redwall Limestone is in the more open central region of the Grand Canyon at 1,431 m elevation and well above the Inner Gorge with the Colorado River (Mead et al., 2003). The region is steep, with many cliffs and talus slopes reaching up to the South Rim. ...
... Sub-Adult Referred Material-GRCA 21734, partial skull rostrum with premaxilla, maxilla, left and right I1-I3, right P2, left and right P3-M1; GRCA 21743, temporal fragment; GRCA 21739, frontal and parietal fragment; GRCA 21736/21738, right lower jaw with i1-i3, alveolus for c1, p3-p4, fragmentary m1; GRCA 21725/21726, thoracic vertebrae 6-13 and lumbar vertebra 1; GRCA 21579/21580, lumbar vertebrae 3 and 4; GRCA 21729, Rancholabrean age assignment for the felid specimens during the Last Glacial Maximum (~25,000 to 15,000 BP) (Carpenter 2003;Mead et al., 2003). ...
A new record of Miracinonyx trumani has been recognized from the Grand Canyon of northern Arizona. Three sites along the length of the canyon contain fossils of M. trumani; Rampart Cave, Next Door Cave, and Stanton's Cave. Rampart Cave contains partial skeletons of a juvenile and a sub-adult cat. Cranial materials from Rampart Cave are distinct from Puma in the presence of a heavy dentition, a reduced protocone of the P4, short robust canine, and a reduced diastema between the c1 and p3. Next Door Cave has a single record of an adult calcaneum of M. trumani that is morphologically distinct from Puma by its large size and presence of a well-developed navicular facet. Stanton's Cave contains phalanges that are similar to Puma but are proportionately gracile in comparison to the modern Puma. The presence of Miracinonyx within the Grand Canyon raises questions about the ecology of this large cat. Previously, Miracinonyx was proposed as a cheetah (Acinonyx jubatus) ancestor or an unrelated felid which co-evolved a cheetah-like ecology hunting prey in open savanna-like habitats.
... Probably the most significant locality is Sandblast Cave (Figure 11-5) which is a grouping of crevices and tunnels (Emslie 1988). Excavations produced important data about the condor (Gymnogyps californianus, including a preserved nest; Figure 11-1) in addition to specimens of the extinct mountain goat, bison, camel, and horse, along with the only reported mammoth remains from the GC; these large mammal remains are thought to be remnants of food items brought in by condors (Emslie 1987(Emslie , 1988Mead et al. 2003). Other caves with fossils in the corridor stretch include Skylight (Figure 11-4) and Hummingbird caves, among others (Emslie 1987). ...
... Crescendo (CC:5:1), Rebound (CC:5:5), Left and Right Eye, Five-Windows (CC:5:2), Shrine (CC:5:3), and Stevens (CC:5:4; Figure 11-6) caves have been the most intensely studied and described, but many chambers and passageways in these caves still contain numerous areas and deposits that remain to be fully analyzed. Besides data on condors (Emslie 1987(Emslie , 1988, a series of packrat middens produced copious plant macrofossils (Coats et al. 2008) and faunal remains (Carpenter and Mead 2000;Mead et al. 2003). The entrances to most of these caves are on the sheer cliff face of the Redwall Limestone well out of the main river corridor. ...
... Lindsay and Tessman 1974 Rodentia Erethizon dorsatum , Mead and Phillips 1981 Rodentia Eutamias sp. Lindsay and Tessman 1974, Cole and Mead 1981 Rodentia Lemmiscus curtatus Mead et al. 2003 Rodentia Marmota flaviventris Lange 1956 Rodentia Marmota flaviventris cf. M. f. engelhardti Wilson 1942 ...
Full citation:
Mead, J.I., J.S. Tweet, V.L. Santucci, B. Tobin, C.L. Chambers, S.C. Thomas, and M.C. Carpenter, 2020. Pleistocene/Holocene Cave Fossils from Grand Canyon National Park: Ice Age (Pleistocene) Flora, Fauna, Environments, And Climate Of The Grand Canyon, Arizona. in Santucci, V.L. and J.S. Tweet, (editors), Grand Canyon National Park: Centennial paleontological resource inventory (non-sensitive version). Natural Resource Report NPS/GRCA/NRR—2020/2103. National Park Service, Fort Collins, Colorado, p. 403-463.
... Archaeological and fossil plant records from the Quaternary CP, in contrast, have been more-extensively studied and provide an important context for new vertebrate fossil data presented here. Holocene rockshelter deposits are common across the CP (Mead et al., 2003;Tweet et al., 2012) and contain abundant small mammal remains that can be used to track the communities through long time spans. To this end, I excavated and quantified mammal diversity change in two fossil-bearing alcoves located in San Juan County, Utah. ...
... In contrast, the sagebrush vole, Lemmiscus curtatus, is found in more arid brushy environments -usually sagebrush or rabbit brush (Carroll and Genoways, 1980). L. curtatus is restricted to the Great Basin today but is found in late Pleistocene records from across the CP (Mead et al., 2003;Murray et al., 2005). Teeth of L. curtatus are present in ECR2 level 4 (time bin E, 1054-735 cal. ...
... BP) and RBA level 4 (time bin C, estimated 2700-2350 ybp). To my knowledge, these are the youngest records of L. curtatus on the CP (Bell and Glennon, 2003;Carrasco et al., 2005;FAUN-MAP Working Group, 1994Mead et al., 2003;Neotoma Paleoecological Database, 2013): other occurrences of this species on the CP in the last 40 kyr are Sheep Camp Shelter (late Glacial/Holocene; Gillespie, 1985), Screaming Neotoma Cave (29-25 kyr; Bell and Glennon, 2003;Mead et al., 2003), and Isleta Cave No. 2 (late Glacial/Holocene; Harris and Findley, 1964). ...
Biological conservation depends on understanding and disentangling the effects of decadal- to centennial-scale dynamics from the millennial-scale dynamics documented in the fossil record. The American Southwest is expected to become increasingly arid over the next few decades and will continue to experience large-scale human land use in various forms. A primary question is whether the ecological fluctuations recorded over the past few decades fall outside the range of variation expected in the absence of recent land use and management. I excavated and quantified mammal diversity change in two fossil-bearing alcoves, East Canyon Rims 2 and Rone Bailey Alcove, located in San Juan County, Utah. AMS radiocarbon dates on 33 bone samples from these sites span ~4.4–0.5 kyr and shed light on pre-industrial faunal dynamics in the region over the course of environmental change. Localities with comparable small mammal diversity have not been reported from this region previously, so these deposits provide novel insight into Holocene mammal diversity in southeastern Utah. Taxa recorded in these sites include leporids, sciurids, perognathines, arvicolines, Onychomys, Cynomys, Dipodomys, Peromyscus, Neotoma, and Thomomys. Using temporal cross-correlation, I tested for a relationship between regional temperature and species richness, evenness, relative abundance, and rank abundance. I also tested for changes in the overall taxon abundance distribution and visualized faunal relationships among time bins using non-metric multidimensional scaling of relative abundance data. None of the measures of diversity tested here were correlated with temperature change through time except for relative abundance of leporids. Overall, these results suggest that climatic fluctuations of the magnitude preserved in these deposits did not significantly alter the small mammal community, nor is there evidence that the presence, then exodus, of Native Americans from the region significantly affected small mammals.
... Arizona has some of the most extensive cave assemblages of Rancholabrean (late Pleistocene) fossil mammals in the United States (Kurtén and Anderson, 1980;Harris, 1985;Santucci et al., 2001;Mead et al., 2003). Many of these same caves yield diverse faunas of late Pleistocene amphibians and reptiles, summarized elsewhere in the volume by Mead (2005). ...
... This and other caves yield late Pleistocene mammal remains, including some soft tissue and dung preservation possible because of the arid climate. Packrat middens within the caves are a considerable focus of ongoing research and yield fossil mammal bones that date back more than 30,000 years (e.g., Mead, 1981Mead, , 2005Mead et al., 2003). In addition, the ringtail Bassariscus forms refuse deposits of small animal bones and feces in some caves, though these are mostly of Holocene age (Mead and Van Devender, 1981). ...
... Dung and a horn sheath of O. harringtoni from Tse'an Bida Cave yielded radiocarbon dates ranging from 11,850-24,190 yrBP, while dates on O. harringtoni dung from Tse'an Kaetan Cave range from 14,220-30,600 yrBP (Mead et al., 1986b;Mead and Agenbroad, 1992). Mead et al. (2003) reported late Pleistocene vertebrate faunas from eight caves in the eastern Grand Canyon region. Following the policy of Grand Canyon National Park, the names and specific locations of these caves were not disclosed. ...
Arizona's fossil record of Pleistocene mammals is distributed across the state in both sur-ficial, stratified sites and in caves. Only two Irvingtonian faunas are known, Taylor gravel pit from northeastern Arizona and Prospect from the San Pedro Valley in the southeastern corner of the state. Rancholabrean sites from surficial settings are mostly records of large mammals, especially Mammuthus (more than 80 published accounts), although a diverse (but largely undescribed) mammal assemblage comes from the Shonto site in the Navajo Nation. There are a few significant Paleoindian sites associated with Clovis artifacts in southeastern Arizona, including Murray Springs, Lehner Ranch, and Naco. Rancholabrean cave sites are the bulk of Arizona's Pleistocene mammal record, and feature Clovis sites as well as the famous caves in the Grand Canyon, including Rampart Cave and Stanton's Cave, which include preserved soft tissues and dung that have allowed unique insights into the paleobiology of large mammals such as the Shasta ground sloth, Nothrotheriops shastensis and Harrington's extinct mountain goat, Oreamnos harringtoni. Diverse mammalian faunas are also known from several caves in southern Arizona, including Papago Springs Cave, Ventana Cave, and Deadman Cave. Research on the packrat midden record in Arizona's caves is a burgeoning field that continues to amplify the late Pleistocene (and Holocene) record of mammals from Arizona.
... Thus, Konzentrat-Lagerstätten are distinguished primarily by quantity, whereas Konservat-Lagerstätten are distinguished by the quality of preservation (Seilacher, 1990). Mead et al., 2003). These dung represent rodents (?Peromyscus), packrats (Neotoma spp.) carnivore (Bassariscus astutus), Shasta Ground Sloth (Nothrotheriops shastensis), Harrington's Mountain Goat (Oreamus harringtoni), Bighorn Sheep (Ovis canadensis) and raptors Mead et al., 2003). ...
... Mead et al., 2003). These dung represent rodents (?Peromyscus), packrats (Neotoma spp.) carnivore (Bassariscus astutus), Shasta Ground Sloth (Nothrotheriops shastensis), Harrington's Mountain Goat (Oreamus harringtoni), Bighorn Sheep (Ovis canadensis) and raptors Mead et al., 2003). The dung occurs in a variety of contexts, from isolated pellets through matted dung to stratified dung deposits . ...
... However, middens are present in other caves in Arizona (e. g., Bell and Glennon, 2003) and we believe that they may be the most numerous vertebrate trace fossils in Arizona. There is evidence of other late Pleistocene vertebrate nests in Arizona such as raptors including the condor (Gymnogyps) (Mead et al., 2003;Mead, 2005). ...
Arizona has significant tetrapod ichnofaunas, many of which are from National Park Service units, including traces from the Pennsylvanian Wescogame Formation, Permian Coconino and DeChelly sandstones and Hermit Formation, Triassic Moenkopi Formation and Blue Mesa and Sonsela Members of the Petrified Forest Formation, Jurassic Navajo Sandstone, Cretaceous Toreva Formation, Miocene Bidahochi Formation and the Pliocene Verde Formation. Arizona ichnofaunas are significant for several reasons as they include the first large Paleozoic ichnofaunas described, westernmost Pennsylvanian tetra-pod tracks in North America, largest collected and described sample sizes of trace fossils from eolianites, the most significant Early-Middle Triassic tetrapod ichnofaunas in the New World, and a Cretaceous dinosaur tracksite with multiple tail drags. Other vertebrate trace fossils from Arizona include coprolites from the Moenkopi Formation and Chinle Group and late Cenozoic cave deposits, putative nests from the Chinle Group and numerous middens from the late Pleistocene. There are four temporal phases in the taphonomy of tetrapod tracks: Devonian, Carboniferous-Triassic, Jurassic-Cretaceous and Cenozoic.
... These paleontological deposits are the result of a unique set of circumstances : (1) long and deep canyons; (2) exposure of a sequence of marine limestones; (3) development of hundreds of caves in these limestones; (4) dry, hot climate, which provides exceptional conditions for preservation; and (5) inaccessible location of many of these caves, which has limited disturbance. Because the Grand Can-yon caves provide exceptional preservation and an abundance of fossils, providing a window into an ancient world, (Santucci et al., 2001;Mead et al., 2003;. The coprolites represent rodents (?Peromyscus, Neotoma spp.), carnivorans (Bassariscus astutus), Shasta Ground Sloth (Nothrotheriops shastensis), Harrington's Mountain Goat (Oreamnos harringtoni), Bighorn Sheep (Ovis canadensis) and raptors (Santucci et al., 2001;Mead et al., 2003). ...
... Because the Grand Can-yon caves provide exceptional preservation and an abundance of fossils, providing a window into an ancient world, (Santucci et al., 2001;Mead et al., 2003;. The coprolites represent rodents (?Peromyscus, Neotoma spp.), carnivorans (Bassariscus astutus), Shasta Ground Sloth (Nothrotheriops shastensis), Harrington's Mountain Goat (Oreamnos harringtoni), Bighorn Sheep (Ovis canadensis) and raptors (Santucci et al., 2001;Mead et al., 2003). The coprolites occur in a variety of contexts, from isolated pellets to stratified latrinites (Santucci et al., 2001). ...
... Midden Cave contains multiple paleomiddens, as its name suggests. Mead et al. (2003) reported on coprolites from caves in eastern GRCA. Cave CC:5:1 contains some packrat paleomiddens (neotomalites) and small deposits of O. harringtoni coprolites. ...
... Many of the caves in Grand Canyon National Park preserve fossil dung, including Vulture Cave, Rampart Cave, Muav Caves, Stanton's Cave, Tse'an Bida Cave, Tse'an Kaetan Cave, Steven's Cave, Sandblast Cave, Shrine's Cave, Hummingbird Cave, Crescendo Cave, Rebound Cave, Left Eye Cave, Five Windows Cave, White Cave, Disappearing Cave, CC:5:1 cave, CC:5:3 cave, CC:5:4 cave and CC:5:6 cave (Santucci et al., 2001;Mead et al., 2003;Hunt et al., 2005). These dung deposits represent rodents (?Peromyscus), packrats (Neotoma spp.) carnivore (Bassariscus astutus), Shasta Ground Sloth (Nothrotheriops shastensis), Harrington's Mountain Goat (Oreamnos harringtoni), Bighorn Sheep (Ovis canadensis) and raptors (Santucci et al., 2001;Mead et al., 2003). ...
... Many of the caves in Grand Canyon National Park preserve fossil dung, including Vulture Cave, Rampart Cave, Muav Caves, Stanton's Cave, Tse'an Bida Cave, Tse'an Kaetan Cave, Steven's Cave, Sandblast Cave, Shrine's Cave, Hummingbird Cave, Crescendo Cave, Rebound Cave, Left Eye Cave, Five Windows Cave, White Cave, Disappearing Cave, CC:5:1 cave, CC:5:3 cave, CC:5:4 cave and CC:5:6 cave (Santucci et al., 2001;Mead et al., 2003;Hunt et al., 2005). These dung deposits represent rodents (?Peromyscus), packrats (Neotoma spp.) carnivore (Bassariscus astutus), Shasta Ground Sloth (Nothrotheriops shastensis), Harrington's Mountain Goat (Oreamnos harringtoni), Bighorn Sheep (Ovis canadensis) and raptors (Santucci et al., 2001;Mead et al., 2003). The dung occurs in a variety of contexts, from isolated pellets through matted dung to stratified dung deposits (Santucci et al., 2001). ...
North America preserves an unparalleled record of Cenozoic nonmarine tetrapod trace fossils. Tracks are the most studied, followed by coprolites, and most of the other kinds of trace fossils have received little attention. Paleogene tracks are relatively uncommon in North America, but they increase in number up through the Paleogene with an acme zone in the Eocene. Tracks are much more common in the Neogene than in the Paleogene. Tracks have two Neogene acmes, one in the Miocene (late Hemingfordian-Clarendonian) and the other in the Plio-Pleistocene. Paleocene tracks are mainly restricted to fluvial strata in Laramide basins. These ichnofaunas are rare because of taphonomic factors. With the advent of more pervasive lacustrine environments in the Eocene, vertebrate ichnofaunas become more widespread, although through the Oligocene they are still mainly restricted to the intermontane West. Most Neogene ichnofaunas are from lacustrine margin strata of the desert West and Southwest, notably California. Tracks are rare in the eastern United States because of past environments and present climate. Pre-Pleistocene coprolites mainly occur in fluvial strata in basins of the western United States. Fish coprolites are very common, but under-studied in the Eocene Green River Formation basins. There is an acme for tetrapod coprolites in the Eocene-Oligocene White River Group. Pleistocene tetrapod coprolites are principally known from caves in the arid Southwest. The distribution of human coprolites is comparable. The North American track record can be divided into six biostratigraphic intervals, and there appears to be a strong distinction between Paleogene and Neogene ichnofaunas. There is a distinct difference between Pleistocene and younger coprolites, but this is heavily biased by taphonomic factors. The arid Southwest preserves abundant herbivore coprolites, which are rare in pre-Pleistocene ichnofaunas. Late Pleistocene ichnofaunas, principally in caves of the arid West and Southwest, preserve human coprolites. All five archetypal ichnofacies are present in the Cenozoic-Chelichnus, Grallator, Brontopodus, Batrachichnus and Characichnos ichnofacies. There is a distinct coprolite ichnofacies in North American caves as opposed to those in Europe, Asia and Africa. Old World caves are dominated by hyena coprolites, whereas those in North America are dominated by diverse herbivore coprolites.
... Lindsay and Tessman (1974) and Harris (1985) summarized the Pleistocene vertebrate fauna of Arizona, Saunders (1970) reviewed the distribution of Mammuthus throughout the state, and Agenbroad and Mead (1989) discussed the occurrence of Mammuthus on the Colorado Plateau. Pleistocene sites are found throughout Arizona, with the largest concentration of open sites in the southeastern portion of the state, which may reflect a collecting bias (Lindsay and Tessman, 1974), and the largest concentration of caves is in the Grand Canyon area in northwestern Arizona (Mead, 1981;Emslie, 1988;Mead et al., 2003). The Pleistocene sites from Arizona discussed by Saunders (1970), Lindsay and Tessman (1974), Harris (1985), and Agenbroad and Mead (1989) total slightly over 100, with 82 open sites and at least 20 caves, although there are certainly more than 20 caves based on work by Emslie (1988), Mead et al. (2003), and Nick Czaplewski (pers. ...
... Pleistocene sites are found throughout Arizona, with the largest concentration of open sites in the southeastern portion of the state, which may reflect a collecting bias (Lindsay and Tessman, 1974), and the largest concentration of caves is in the Grand Canyon area in northwestern Arizona (Mead, 1981;Emslie, 1988;Mead et al., 2003). The Pleistocene sites from Arizona discussed by Saunders (1970), Lindsay and Tessman (1974), Harris (1985), and Agenbroad and Mead (1989) total slightly over 100, with 82 open sites and at least 20 caves, although there are certainly more than 20 caves based on work by Emslie (1988), Mead et al. (2003), and Nick Czaplewski (pers. comm.). ...
... Finally, there are the exquisite individual chronologies available for Harrington's mountain goat (Oreamnos harringtoni; because the genus still occurs in North America, this extinct species does not appear on Table 1) and Shasta ground sloth. Radiocarbon dates on O. harringtoni horn sheaths and dung pellets show this animal to have become extinct in the Grand Canyon (Arizona) area very close to 11,000 years ago (Mead and Agenbroad 1992;Mead et al. , 2003. Detailed analysis of the plant remains found in goat dung pellets from this same area, coupled with strong knowledge of the nature of Pleistocene vegetational change here, provides no support for the argument that the local extinction of this animal was due to such change (Mead and Lawler 1994;). ...
... As with Harrington's mountain goat, analyses of plants found in Shasta ground sloth dung do not support vegetational change as the cause of extinction in these areas (e.g., Hansen 1978;Martin et al. 1961;Thompson et al. 1980;see Kropf et al. 2007 for a similar situation with the shrub ox Euceratherium). What we do not know, however, is whether these late populations refl ect the last fl icker in the fading history of this species or instead one part of a discrete and synchronous extinction event (Mead et al. 2003). ...
The debate over the cause of North American Pleistocene extinctions may be further from resolution than it has ever been in its 200-year history and is certainly more heated than it has ever been before. Here, I suggest that the reason for this may lie in the fact that paleontologists have not heeded one of the key biogeographic concepts that they themselves helped to establish: that histories of assemblages of species can be understood only be deciphering the history of each individual species within that assemblage. This failure seems to result from assumptions fi rst made about the nature of the North American extinctions during the 1960s. THERE IS PROBABLY NO ARCHAEOLOGIST, PALEONTOLOGIST, OR ECOLOGIST who is not aware of the debate that rages over the causes of the massive extinctions that occurred in North America toward the end of the Pleistocene. Were they, as some claim, caused entirely by human predation? Or were they, as others argue, caused entirely by climate change or, as still others suspect, by some combination of these and/or other factors? This debate has its roots in the late eighteenth century but appears further from resolution than it did more than a century ago (Grayson 1983, 1984).
... The coprolite-bearing caves are clustered in two geographic regions ( Fig. 1): (1) northern realm -(southern Nevada, northern Arizona, southeastern Utah) on the Colorado Plateau plus Nevada; and (2) southern realm -southern New Mexico and southwestern Texas. Many other caves occur in intermediate areas such as eastern and southern Arizona or central or northern New Mexico, including several with important archeological records or/and Pleistocene vertebrate fossils (Harris, 1985a(Harris, , 2005Mead et al., 2003;Morgan and Harris, 2015). There are no described vertebrate coprolites from caves in these intermediate areas. ...
An extensive record of desiccated coprolites of diverse Late Pleistocene taxa is preserved in caves of the American Southwest. These include 21 caves in Arizona, 12 in Utah, six in Texas, four in New Mexico and one in Nevada. The majority of the coprolites represent herbivores, which is extremely rare for coprofaunas. There are two distinct regions characterized by cave coprolites – a northern realm (northern Arizona and southeastern Utah) is characterized by diverse morphologies of coprolites, and a southern realm (southern New Mexico and West Texas) where caves usually yield only coprolites of ground sloths (Castrocopros martini) and coprolites of the packrat or woodrat Neotoma. The geographic distribution of the localities is governed by precipitation patterns and by the availability suitable cave-producing rock types. Desiccated coprolites can yield some of the highest quality radiocarbon dates, and these demonstrate extinctions of the megafauna between 11 and 12,000 yr B.P. in the terminal Pleistocene. Macro-botanical specimens and pollen provide important evidence of individual diet and the local ecosystem. Castrocopros martini and coprolites of Neotoma are widespread, whereas coprolites of bighorn sheep Ovis canadensis and the extinct mountain goat Oreamnos harringtoni are common in caves in Arizona and Utah, but they are absent from Nevada and New Mexico. Coprolites of a large ruminant (Suaviocopros harrisi igen. et isp. nov.) and mammoths (Mammuthocopros allenorum) are restricted to Utah, which likely relates to topography. We advocate the discontinuation of the term “dung” for the cave coprolites and the use of binomial ichnotaxonomy for Pleistocene coprolites.
... Between 1970 and 2010, most of the paleontology related activities undertaken at GRCA were primarily related to research and collecting by outside academic paleontologists and geologists working in the park. Jim Mead and students from the Quaternary Studies Program at Northern Arizona University coordinated paleontological research and collecting at Rampart Cave and other caves in GRCA (Mead 1981;Mead and Van Devender 1981;Mead and Phillips 1982;Mead et al. 2003;Carpenter 2003). In 2001, an inventory of paleontological resources associated with NPS caves, including those in GRCA, was undertaken by the NPS Geologic Resources Division (Santucci et al. 2001). ...
... The most extensive late Pleistocene dung deposits are preserved in some of the hundreds of caves in Grand Canyon National Park in Arizona (Mead, 1981;Mead et al., 1986a;Santucci et al., 2001;Hunt et al., 2005). These dung deposits represent rodents (?Peromyscus), packrats (Neotoma spp.) carnivore (Bassariscus astutus), Shasta Ground Sloth (Nothrotheriops shastensis), Harrington's Mountain Goat (Oreamnos harringtoni), Bighorn Sheep (Ovis canadensis) and raptors (Santucci et al., 2001;Mead et al., 2003). The dung occurs in a variety of contexts, from isolated pellets through matted dung to stratified dung deposits (Santucci et al., 2001). ...
The New Mexico Museum of Natural History and Science has been involved in major advances in Paleozoic, Mesozoic and Cenozoic tetrapod ichnology. The Cenozoic track record is relatively depauperate and it is also in need of much more study. Most Cenozoic tracks are from North America; significant Paleogene tracksites are known in Europe, and Neogene tracksites in South America. Most Paleogene mammal tracks represent primitive perissodactyls, with lesser numbers of carnivores (including " creodonts ") and some artiodactyls, whereas Neogene tracks are dominanated by derived ungulates (proboscideans, camelids and equids) and large carnivores (canids and felids). Bird tracks are also common in the Cenozoic. Reptile and amphibian tracks are rare.Five archetypal vertebrate track ichnofacies for nonmarine environments (Chelichnus, Grallator, Batrachichnus, Brontopodus, Characichnos) have recently been defined; we infer that all of which are present in the Cenozoic. Pre-Pleistocene vertebrate coprolites are common in two general environments; fluvial and lacustrine. Pleistocene coprolites are locally common, principally in caves, in both the New and Old World. Old World caves are dominated by hyena coprolites, whereas those in North America are dominated by diverse herbivore coprolites.
... Unlike other extant Sonoran Desert artiodactyls (e.g., pronghorn, and mule deer), bighorn sheep commonly use caves and rock overhangs to bed and escape the midday heat in summer [55] and their kidneys concentrate urine to conserve water [56]. As it evaporates, the viscous urine can crystallize and cement both sediment and dung on the cave floor, much like the process that forms packrat and other rodent middens [57]. ...
Background/Question/Methods
The processes that led to the formation of plant and animal communities encountered in modern landscapes are often cryptic. Yet, biogeographic patterns of extant species provide clues of their origin. This is especially the case on islands where isolation and vicariance distil evolutionary and historical patterns. Tiburón Island in the Gulf of California, the largest island in North America south of Canada, was recently separated (ca. 6,000 years ago) from mainland Mexico, but contains surprising and unresolved biogeographic mysteries. A half dozen disjunct temperate plant species are restricted on the high mountaintops of this desert island, several hundred kilometers south of the next nearest populations. Does the presence of these species represent recent long distance dispersal or ancient vicariance from past Ice Ages? Bighorn sheep (Ovis canadensis) were introduced to Tiburón Island in 1975 as a conservation measure. Surprisingly, no evidence suggested their past occurrence on this land-bridge island. Did bighorn sheep once occupy Tiburón, and if so what are the implications for future management of this iconic species? Genetic analyses, modern and ancient, provide an avenue to answer these specific questions to dig beyond observed distributions.
Results/Conclusions
Analysis of modern Chloroplast DNA sequences from throughout the range of the exemplar disjunct relict on Tiburón Island, Canotia holacantha(Celastraceae), has revealed significant genetic variation between island and northern populations. The results support the ancient vicariance origin hypothesis of the Tiburón population, suggesting the same for the other half-dozen disjunct temperate species on the island. Tiburón Island and the coast of the Gulf of California was likely not a refuge for desert environments in the Ice Ages, and the elevation shifts in vegetation known to occur further north in the Sonoran Desert extended to the shores of the Gulf.
Fossil dung morphologically similar to that of bighorn sheep was discovered in a dung mat deposit in the mountains of Tiburón Island. The fossil dung was 14C-dated to 1476–1632 calendar years before present and was confirmed as bighorn sheep by morphological and ancient DNA analysis of the 12S ribosomal RNA and control regions. Native desert bighorn sheep were extirpated from the island sometime in the last ~1500 years. This discovery refutes conventional wisdom that bighorn sheep are not native to Tiburón Island, and establishes its recent introduction as an example of unintentional rewilding – the introduction of a species without knowledge that it was once native and has since gone locally extinct.
... Unlike other extant Sonoran Desert artiodactyls (e.g., pronghorn, and mule deer), bighorn sheep commonly use caves and rock overhangs to bed and escape the midday heat in summer [55] and their kidneys concentrate urine to conserve water [56]. As it evaporates, the viscous urine can crystallize and cement both sediment and dung on the cave floor, much like the process that forms packrat and other rodent middens [57]. ...
Bighorn sheep (Ovis canadensis) were not known to live on Tiburón Island, the largest island in the Gulf of California and Mexico, prior to the surprisingly successful introduction of 20 individuals as a conservation measure in 1975. Today, a stable island population of ∼500 sheep supports limited big game hunting and restocking of depleted areas on the Mexican mainland. We discovered fossil dung morphologically similar to that of bighorn sheep in a dung mat deposit from Mojet Cave, in the mountains of Tiburón Island. To determine the origin of this cave deposit we compared pellet shape to fecal pellets of other large mammals, and extracted DNA to sequence mitochondrial DNA fragments at the 12S ribosomal RNA and control regions. The fossil dung was 14C-dated to 1476-1632 calendar years before present and was confirmed as bighorn sheep by morphological and ancient DNA (aDNA) analysis. 12S sequences closely or exactly matched known bighorn sheep sequences; control region sequences exactly matched a haplotype described in desert bighorn sheep populations in southwest Arizona and southern California and showed subtle differentiation from the extant Tiburón population. Native desert bighorn sheep previously colonized this land-bridge island, most likely during the Pleistocene, when lower sea levels connected Tiburón to the mainland. They were extirpated sometime in the last ∼1500 years, probably due to inherent dynamics of isolated populations, prolonged drought, and (or) human overkill. The reintroduced population is vulnerable to similar extinction risks. The discovery presented here refutes conventional wisdom that bighorn sheep are not native to Tiburón Island, and establishes its recent introduction as an example of unintentional rewilding, defined here as the introduction of a species without knowledge that it was once native and has since gone locally extinct.
... There may also have been a consequent decline in tytonid owl populations. (1) Baynes and Baird (1992) and Bilney et al. (2010) suggest that the potential age of similar Australian subfossil bone accumulations may be measured in thousands of years; Mead et al. (2003) report unconsolidated accumulations dating back 18 000 years in the Grand Canyon, Arizona. O'Connor et al. (2008), whose site at Windjana Gorge was stratified, reported calibrated ages from 90 (AE30) to 6337 (AE208) years ago and, apart from the recent loss of some species, found no evidence of substantial change in the composition of the mammalian fauna over that time span. ...
To assess the current status of mammals in relation to mean annual rainfall and to improve knowledge of the original mammalian assemblages in tropical Western Australia, extant terrestrial mammals and subfossil mammalian remains were sought along a rainfall gradient in two parallel ranges in the Kimberley, Western Australia. As expected, extant mammal species richness decreased with decreasing rainfall. Data from other studies in higher-rainfall areas complemented this conclusion and a parallel decline in trap success implied an overall decline in abundance, although numbers of two rodents (Rattus tunneyi and Zyzomys argurus) were highly variable. Small rodents were rare. Subfossil deposits were biased by accumulation processes, with most attributable to tytonid owls. They largely consisted of rodent and, to a lesser extent, small dasyurid bones and there was a high level of consistency in the proportional composition of many common species across the rainfall gradient. Most deposits appear to predate the introduction of stock in the 1880s and some may be much older. All species persist in the study area except two Notomys spp. and three Pseudomys spp. Both the Notomys and one Pseudomys are apparently undescribed, extinct species. However, there were marked ratio differences between subfossil and modern assemblages. Although specimens of species larger than those taken by tytonid owls were scarce, their occurrences were broadly consistent with the modern understanding of distributions.
... Lava tube caves occurring in parts of the northwestern United States are well known for Pleistocene paleontological remains (e.g., White et al., 1984). Areas such as the Great Basin and Grand Canyon have late Pleistocene vertebrate records built almost entirely upon excavated cave deposits (Grayson, 1993;Mead et al., 2003). This suggests that wherever caves are present, they may act as valuable repositories of paleontological data, particularly when the complexities of conducting paleontological research in cave deposits can be overcome or minimized through careful excavation. ...
Mammal-bearing cave deposits are an important part of the Quaternary fossil record, but the exact nature of the contribution that caves make to the fossil record is a research area that is largely unexplored. To explore this issue, late Pleistocene species representation in cave versuses non-cave deposits was examined. Additionally, this study examined how fossiliferous cave deposits influence perceptions of past biogeographic distributions, and evaluated factors that impact the distribution of cave deposits. Across the United States, cave deposits account for a high proportion of the individual species records known from the late Pleistocene and caves provide the only late Pleistocene records of 14 individual taxa. Calculated ratios of individual taxonomic records from caves relative to the total number of individual taxonomic records resulted in a value of 0.62. The impact of cave data on understanding of late Pleistocene biogeographic distribution patterns vary among individual species of sciurid rodents. Geographic analyses comparing the distribution of cave and non-cave sites in Texas suggest a strong relationship between site distribution and specific geologic and hydrologic features. Ultimately, understanding potential biases recorded in distinct depositional settings provides improved frameworks for interpreting the adequacy of the fossil record.
... Samples were hand picked for floral and faunal remains, and sub-samples of Neotoma fecal pellets were removed for radiocarbon analysis. Each packrat midden unit was radiocarbon dated at least once using a bulk sample of pellets to establish a chronology (Table 2), with the exceptions of WF 1, dated on a specimen of Zea mays (maize); FWC 2, accelerator mass spectrometry (AMS) dated on a single feather of Gymnogyps californianus (California Mead et al., 2003. condor); and SHR 1, which was AMS-dated on a single coprolite of Oreamnos harringtoni (Harrington's mountain goat). ...
Sixty packrat middens were collected in Canyonlands and Grand Canyon National Parks, and these series include sites north of areas that produced previous detailed series from the Colorado Plateau. The exceptionally long time series obtained from each of three sites (> 48,000 14C yr BP to present) include some of the oldest middens yet discovered. Most middens contain a typical late-Wisconsinan glaciation mixture of mesic and xeric taxa, evidence that plant species responded to climate change by range adjustments of elevational distribution based on individual criteria. Differences in elevational range from today for trees and shrubs ranged from no apparent change to as much as 1200 m difference. The oldest middens from Canyonlands NP, however, differ in containing strictly xeric assemblages, including middens incorporating needles of Arizona single-leaf pinyon, far north of its current distribution. Similar-aged middens from the eastern end of Grand Canyon NP contain plants more typical of glacial climates, but also contain fossils of one-seed juniper near its current northern limit in Arizona. Holocene middens reveal the development of modern vegetation assemblages on the Colorado Plateau, recording departures of mesic taxa from low elevation sites, and the arrival of modern dominant components much later.
... One of the most remarkable finds in the American Southwest has been the preservation of dung remains from Pleistocene animals such as Mammuthus (mammoth; Mead et al., 1986a), Nothrotheriops (ground sloth; Martin et al., 1961), and various pellet-producing artiodactyls, including Oreamnos harringtoni (Harrington's mountain goat; Mead et al., 1986c) in dry caves (Davis et al., 1984;Mead et al., 1984;Agenbroad et al., 1989;Mead and Agenbroad, 1992;Mead et al., 2003). Large distinctively shaped dung pellets (HK pellets), with an average cylindrical diameter of 14.5 mm and length of 19.3 mm, tapered on one end only, with a flat to concave shape on the opposite end (giving them their distinctive 'Hershey's Kiss' morphology), are located in numerous alcoves and caves within the Escalante River Basin, southern Colorado Plateau (Table 1; Mead and Agenbroad, 1992). ...
Fossil remains of Euceratherium collinum (extinct shrub-ox) have been found throughout North America, including the Grand Canyon. Recent finds from the Escalante River Basin in southern Utah further extend the animal's range into the heart of the Colorado Plateau. E. collinum teeth and a metapodial condyle (foot bone) have been recovered in association with large distinctively shaped dung pellets, a morphology similar to a ‘Hershey's Kiss’ (HK), from a late Pleistocene dung layer in Bechan Cave. HK dung pellets have also been recovered from other alcoves in the Escalante River Basin including Willow and Fortymile canyons. Detailed analyses of the HK pellets confirmed them to be E. collinum and indicate a browser-type diet dominated (> 95%) by trees and shrubs: Artemisia tridentata (big sagebrush), Acacia sp. (acacia), Quercus (oak), and Chrysothamnus (rabbit brush). The retrieval of spring and fall pollen suggests E. collinum was a year-round resident in the Escalante River Basin.
We present the Late Pleistocene extinct shrub-ox, Euceratherium collinum (Bovidae), dung pellets recovered from Pontatoc Ridge Shelter, a dry alcove in the Santa Catalina Mountains of southern Arizona. The shelter is at the current upper edge of the Arizona Upland subdivision (the highest and coldest part) of the Sonoran Desert. Packrat (Neotoma) middens with macrobotanical fossils and a floor deposit consisting of midden debris and dung pellets were sampled and are described here. Six packrat middens radiocarbon date to 15,69022,874 cal yr B.P. (calibrated years before present); dung pellets from the floor deposit date to 14,990 cal yr B.P. Macrobotanical fossils primarily from the middens but also from the floor deposit indicate that a woodland composed of Arizona cypress (Hesperocyparis [Cupressus] arizonica), Douglas fir (Pseudotsuga menziesii), ponderosa pine (Pinus ponderosa), a hybrid singleleaf pinyon pine (Pinus monophylla var. fallax), border pinyon (Pinus discolor), juniper (Juniperus), manzanita (Arctostaphylos pungens), and canyon live oak (Quercus chrysolepis) grew outside the shelter. Dung pellets were measured, compared with other extant and extinct species, and sampled for phytoliths and pollen. Based on size, morphology, DNA, and physiographic setting (cliff face), our assumption is that only a single taxon of slickrock-climbing ruminant used the small, extremely inaccessible Pontatoc Ridge Shelter and that all large pellets belong to the extinct shrub-ox. The distribution of Late Pleistocene shrub-ox is reviewed; the stocky, rather short ruminant is recovered mainly in mountainous and canyon-county terrains of western United States and northern Mexico. Presentamos los coprolitos del buey arbustivo Euceratherium collinum (Bovidae) extinto del Pleistoceno tardo recuperados del refugio Pontatoc Ridge, un nicho seco en las montaas de Santa Catalina en el sur de Arizona. El refugio se encuentra en el borde ms alto actual de la subdivisin de las tierras altas de Arizona (la parte ms alta y fra) del desierto de Sonora. Se tomaron muestras de basureros de la rata de campo (Neotoma) con fsiles macrobotnicos y de un depsito en el suelo compuesto por coprolitos y escombros de los basureros de ratas del campo, que se describen aqu. Seis basureros de ratas de campo tienen fechas de radiocarbono 15,69028,874 aos cal A.P. (calibrado aos antes del presente); los coprolitos tomados del piso del refugio tienen una fecha de 14,990 aos cal A.P. Los fsiles macrobotnicos principalmente de los basureros de ratas del campo, pero tambin de los depsitos del piso, indican que un bosque compuesto de ciprs de Arizona (Hesperocyparis [Cupressus] arizonica), abeto de Douglas (Pseudotsuga menziesii), pino ponderosa (Pinus ponderosa), un hbrido de pino pin de una sola hoja (Pinus monophylla var. fallax), pin de borde (Pinus discolor), enebro (Juniperus), manzanita (Arctostaphylos pungens) y encino de can (Quercus chrysolepis) crecan fuera del refugio. Se midieron los coprolitos, se compararon con otras especies existentes y extintas, y se tomaron muestras de fitolitos y polen. Con base en el tamao, la morfologa, el ADN y el entorno fisiogrfico (cara del acantilado), nuestra suposicin es que solo un taxn de rumiantes trepadores de rocas resbaladizas us el pequeo y extremadamente inaccesible refugio Pontatoc Ridge y que todos los coprolitos grandes pertenecen al buey arbustivo extinto. Se revisa la distribucin del buey arbustivo del Pleistoceno tardo; este rumiante bastante bajo y de porte robusto se recupera principalmente en terrenos montaosos y de caones del oeste de EE. UU. y el norte de Mxico.
Natural analogues are defined for this report as naturally occurring or anthropogenic systems in which processes similar to those expected to occur in a nuclear waste repository are thought to have taken place over time periods of decades to millennia and on spatial scales as much as tens of kilometers. Analogues provide an important temporal and spatial dimension that cannot be tested by laboratory or field-scale experiments. Analogues can be used in a qualitative mode to provide a means of understanding complex or abstract processes or in a quantitative mode to test models. Analogues provide one of the multiple lines of evidence intended to increase confidence in the safe geologic disposal of high-level radioactive waste. Although the work in this report was completed specifically for Yucca Mountain, Nevada, as the proposed geologic repository for high-level radioactive waste under the U.S. Nuclear Waste Policy Act (and it is referred to as such throughout this report), the U.S. Geological Survey believes that the applicability of the science, analyses, and interpretations is not limited to a specific site. The work is important as a contribution not only to investigations of future waste-disposal options, such as the assessment of alternative sites or solutions, but also as a contribution to scientific investigations unrelated to waste disposal. Isolation of radioactive waste at a mined geologic repository would be through a combination of natural features and engineered barriers. In this report we examine analogues to many of the various components of the Yucca Mountain system, including the preservation of materials in unsaturated environments, flow of water through unsaturated volcanic tuff, seepage into repository drifts, repository drift stability, stability and alteration of waste forms and components of the engineered barrier system, and transport of radionuclides through unsaturated and saturated rock zones. Hundreds of delicate and easily destroyed artifacts and biological materials have been well preserved both in natural (for example, caves and rock shelters) and in manmade (for example, tombs and mines) underground openings. The maintenance of a stable microclimate is a critical feature in making caves suitable for long-term preservation. The survival of metal artifacts over prolonged periods of time is related to the corrosion-resistant properties of metals and metal alloys, the development of protective passive film coatings with the onset of corrosion, and sequestering artifacts with water, which is enhanced by the location of artifacts in arid to semiarid environments. Numerous examples demonstrate that both natural and manmade underground openings can exist for thousands of years in a wide variety of geologic settings, even with minimal or no engineered supports. Examination of these openings also leads to the conclusion that seismic events at or near a mined repository are not likely to cause significant damage to the emplacement tunnels. As a consequence, the tunnels should be expected to be a long-term hydrologic feature. Analogues add valuable insight to understanding long-term waste-form degradation processes through the record left behind in secondary minerals and groundwater chemistry. In addition, measurement of the concentration of fission products as tracers in rock and groundwater surrounding uraninite provides a satisfactory approach to estimating natural dissolution rates, as was tested at a number of sites that demonstrated a more rapid dissolution rate under oxidizing conditions. Models predict that much of the water percolating through the unsaturated zone will be held in the wall rock of tunnels by capillary forces rather than entering the tunnels as seepage. Analogues in natural and manmade underground openings demonstrate the tendency for water that does become seepage to run down the walls of underground openings rather than drip from the ceiling; thus, not all seepage would affect stored waste. In the event of waste mobilization and migration away from the emplacement drifts, the rate of radionuclide transport through the unsaturated zone is determined by the percolation flux and by the hydrologic properties and sorptive properties of the tuff units. Fractures act both as transport pathways and as places of retardation at a number of unsaturated analogue sites, including the Idaho National Laboratory, near Idaho Falls; Peña Blanca, Mexico; Akrotiri, Greece; and volcanic tuff-hosted uranium deposits in northern Nevada. In the saturated zone, advective transport along fractures has been identified as a more significant transport mechanism than matrix diffusion in all the analogue sites studied, although matrix diffusion may account for loss of lead in uraninites at Oklo, in Gabon. The Poços de Caldas site in Brazil highlighted the importance of amorphous phases in suspension or as coatings on rock as the principal sorptive surfaces for many trace elements in solution. Some of the fixing processes appeared to be irreversible over long time scales. Sorption onto fracture coatings, particularly calcite, also efficiently retards uranium transport in fractures at Palmottu, Finland, and El Berrocal, Spain. Matrix diffusion in crystalline rock is generally limited to only a small volume of rock close to fractures, but even a small volume can make a significant difference in radionuclide retardation. In most studies of natural systems, a proportion of the total uranium, thorium, and rare earth elements (REE) in the groundwater was associated with colloids. Colloid transport appears to be an important factor for migration of thorium in one open unsaturated system, Steenkampskraal, in South Africa, but not in another, Nopal I, in Mexico. Colloidal transport of uranium was shown to be minimal at the analogue site in Koongarra, Australia, where filtration of colloids appears to be effective. Observations from the Nevada Test Site lend support to the concept that radionuclide transport in the saturated zone can be facilitated by colloids; but so far, no natural analogue studies have quantified the importance of this process. The emplacement of heat-generating waste in a geologic repository located in the unsaturated zone will cause perturbations to the natural environment through heat transfer, as well as by associated geochemical and geomechanical changes taking place in the repository near-field and altered-rock zones. The unsaturated conditions, lower temperatures, and much lower fluid-flow rates predicted for the Yucca Mountain system should result in less extensive water/rock interaction than is observed in geothermal systems. Evidence from fossil hydrothermal systems indicates that mineral alteration resulting from flow of hot fluids through fractures extends only a few centimeters from the fracture wall into the matrix. Simulations indicate that only small reductions in fracture porosity (4-7 percent) and permeability (less than 1 order of magnitude) will occur in the near field as a result of amorphous silica and calcite precipitation. Changes in permeability, porosity, and sorptive capacity are expected to be relatively minor at the mountain scale, where thermal perturbations will be reduced. The Yucca Mountain Project has applied analogues for testing and building confidence in conceptual and numerical process models and has less frequently used analogues to provide specific parameters in total system performance assessment (TSPA) models. Analogues have been widely used as model validation of aspects of Yucca Mountain characterization. In conclusion, natural and anthropogenic analogues have provided and can continue to provide value in understanding features and processes of importance across a wide variety of topics in addressing the challenges of geologic isolation of radioactive waste.
Descubrimos una mandíbula de la javelina Platygonus compressus en una cantera de arena y grava (Pit Stop Quarry) entre Taylor y Show Low, condado de Navajo en Arizona. Encontramos también elementos esqueléticos aislados de una salamandra (Ambystomatidae), del conejo pigmeo (Brachylagus idahoensis), del campañol (Lemmiscus curtatus,) y varios otros mamíferos pequeños en sedimentos alrededor de la mandíbula de la javelina. La presencia de P. compressus indica que el depósito es del Pleistoceno tardío. Los especimenes también representan el primer registro del Pleistoceno de Ambystomatidae en el Colorado Plateau, un importante registro adicional de P. compressus en el Colorado Plateau, y 1 de 2 registros de B. idahoensis en Arizona.
Eight postcranial elements (humerus, radius, metacarpal, femur, tibia, metatarsal, astragalus, calcaneum) of late Pleistocene (Rancholabrean Land Mammal Age) bighom sheep Ovis canadensis from Natural Trap Cave, north-central Wyoming were measured. The sample ranges in age from 110,000 to 12,000 yr B.P., encompassing nearly 100,000 years of faunal history. Variation observed in the postcranial skeleton is discussed and compared with samples of modem bighorn sheep from Wyoming and Montana The bighorn sheep from Natural Trap Cave are well within the size range of living bighorn sheep found in the same area today. There is overlap in all measurements taken except the minimum depth of the diaphysis of the metatarsal, suggesting that modem bighorn sheep have at least the genetic potential to reach the overall size of the fossil form. The data are in agreement with previous work and suggest that the Natural Trap Cave bighorn sheep should be considered a temporal subspecies of modem Ovis canadensis.
Fifteen packrat middens and a ringtail refuse area were recovered and analyzed from Vulture Cave, western Grand Canyon, Arizona. Nineteen radiocarbon dates indicate that packrats inhabited the cave as early as 30,000 B.P. and persisted there throughout the Wisconsinan full and late glacial. No deposits were found which indicate that Neotoma lived in the cave from 11,000 to 2,000 B.P. Only one Holocene age (1,000 B.P.) packrat midden was dated from the cave. Forty-seven plant taxa were identified from the cave deposits. Extralocal species accounted for 28% of the total fossil flora while species still present in the local community accounted for 57%. Thirty-seven animal taxa (19 reptiles, 3 birds, and 15 mammals) were identified from the cave deposits. The long temporal depth of the Vulture Cave deposits has provided the only late Wisconsinan maximum and pre-maximum plant and animal community assemblage so far reported from the Grand Canyon.
A minimum of 27 species of amphibians and reptiles were identified in 22 early Holocene and late Pleistocene packrat middens from the Sonoran Desert in Arizona and California. A total of 31 radiocarbon dates ranges from 5,020 ± 80 to more than 30,000 years ago. Plant macrofossils associated with the bones in the middens record juniper or pinyon-juniper woodland communities near the sites prior to 8,000 years ago. The herpetofauna has been stable in these areas for the last 15,000 years and several species now restricted to desertscrub habitats formerly lived in woodland. Biogeographical scenarios calling for the desert faunas to be restricted to Mexican refugia during glacial periods are not supported. Equable climates with mild winters, cool summers and increased winter precipitation are inferred.
Twenty-one taxa and 130 identifiable specimens of reptiles and small mammals preserved in late Pleistocene packrat middens from the lower Grand Canyon of Arizona were identified. Samples range in age from 8540 ± 180 to 16,330 ± 270 radiocarbon years. Plant macrofossils of approximately 75 species are associated with the fauna. The plants are a mixture of present desert forms and woodland species (Juniperus sp., Fraxinus anomala, Ribes montigenum) now restricted to higher elevations on the rims of the Grand Canyon. The fauna also represents a mixture of present desert species (Gopherus agassizi, Sauromalus obesus, Coleonyx variegatus) and higher woodland species (Sceloporus undulatus or occidental is Neotoma mexicana, Erethizon dorsatum, Marmota flaviventris). Mixed biotic communities in the Pleistocene may reflect a more moderate climate which had mild winters, cool summers, and slightly increased winter rainfall.
San Josecito Cave is located on a steep western flank of the Sierra Madre Oriental, Nuevo Leon, Mexico, at 2250 m elevation. A total of 1115 skeletal remains of lizards are known from the deposit; only two specimens were from previous excavations. In greater than 100,000 vertebrate remains, only four species of lizards have been recovered: one anguid (Barisia cf. B. imbricata, n = 1088 fossils) and three phrynosomatids (Phrynosoma josecitensis, n = 1; P. orbiculare, n = 1; P. cf. P orbiculare, n = 12; and Sceloporus sp., n = 13). The cave has produced the type and only known specimen of the extinct species Phrynosoma josecitensis, described from an earlier excavation. The presence of, or the validity of, this extinct species cannot be verified on the basis of remains recovered from the current excavation, and the taxon may be a variant of the locally living P. orbiculare. The first fossil record of Barisia imbricata is presented.
Large numbers of Late Pleistocene bighorn sheep (total counts of identifiable elements: 4,497) Ovis canadensis. are described from the Natural Trap Cave, northern Wyoming. The specimens consist of nearly-intact skulls and enough post-cranial materials to assemble several complete sheep skeletons. Most of the fossils yield radiocarbon dates from 12,000 to 21,000 BP, while the oldest are more than 110,000 years old as dated by the fission-track method on the volcanic ash. The specimens resemble modern bighorn sheep (Ovis canadensis) in having shallow lachrymal fossae and relatively wide rostra. in contrast to the Asian argali (Ovis ammon), which exhibit deep fossae and narrow rostra. The sheep also have a proportionally large body size. A direct ancestor-descendent relationship between modern and the fossil sheep in North America seems probable. Reduction of body size seems likely to have occurred at the end of Pleistocene or the beginning of Holocene time. Young males predominated among the fossil sheep found in the Natural Trap Cave.
The carbon isotope analyses reported here include all radiocarbon dates run on packrat middens in the United States and Mexico by the Arizona radiocarbon laboratory through October 1977. All samples described below report dates by CO 2 (0.5 or 2.0L) counting. Age calculations are based on a 14 C half-life of 5568 years, using 0.949 NBS oxalic acid as the modern value. Errors, based on counting statistics, are quoted to ± 1δ; infinite ages quoted to — 2δ.
Chester Stock (1936) described a late Rancholabrean species of extinct mountain goat (Oreamnos harringtoni) based on scant remains from a cave in the Great Basin, Nevada. We present a review using cranial, mandibular, and metapodial remains of O. harringtoni from 13 localities in the southwest. The extinct mountain goat is not just a smaller form of the living species, O. americanus. O. harringtoni has metapodials 25% smaller than those of the living species, indicating that the mountain goat is shorter; however, its feet are relatively robust. Its masticatory region is robust but is situated on a narrower face; the apparently longer, narrower face is accentuated by the presence of thinner and smaller horns.
Oreamnos harringtoni remains are relatively uncommon in the fossil record. Pleistocene-age skeletal remains from Muskox Cave, Guadalupe Mountains, New Mexico, are referred to O. harringtoni. Qualitative and quantitative characters of recovered skeletal elements fit previous descriptions for Harrington's extinct mountain goat. This specimen extends the known range of the species eastward
We surveyed mitochondrial DNA (mtDNA) sequence variation in short-horned lizards (Phrynosoma douglasi) from throughout western North America and used these data to estimate an intraspecific phylogeny and to assess biogeographic scenarios underlying the geographic structure of lineages in this species. We sequenced 783 base pairs from 38 populations of P. douglasi and three putative outgroups (P. ditmarsi, P. orbiculare, P. platyrhinos). We detected high levels of nucleotide variation among populations and a spatial distribution of mtDNA lineages compatible with major geographic regions. The phylogenetic hypotheses best supported by the data suggest that P. douglasi, as currently described, is paraphyletic with respect to P. ditmarsi. Populations of P. douglasi from the Pacific Northwest (ID, CA, OR, WA) form a monophyletic group that is sister to the subsequent radiation of P. ditmarsi and other P. douglasi clades. These results suggest that divergences within this widespread species are fairly old. We focused on the genetic structure of populations of P. douglasi from a geographic perspective and interpreted the intraspecific phylogeny in light of geologic and climatic changes in western North America during the last 20 million years. The generally high levels of genetic variation found in these population comparisons are in accord with high levels of morphological variation in this species group; however, only in the Pacific Northwest region is there spatial congruence between these phylogenetic results and subspecific ranges based on previous morphological studies. We compared the evolutionary units delineated in this study with previously described subspecies of P. douglasi and evaluated the support (from morphology and mtDNA) for each population lineage in the phylogeny and the implications for the taxonomy of this group.
Gives carbon 14 dates on Shasta ground sloth dung from caves in the arid SW USA. The youngest samples from Rampart Cave date close to 11 000 yr BP, and this is the most common youngest date from other sites. Extinction coincides with Clovis Point mammoth kill dates, and is interpreted as the result of the arrival of man in N America at that time. K.Clayton
Identified dung and keratinous remains of large mammals are considered the most reliable materials to 14C date, when the initial question includes the application of the date to the time of local extirpation and extinction. The Colorado Plateau provides a unique preservation habitat (desiccation), found in greater abundance of deposits than anywhere else in North America. Twenty localities from the Colorado Plateau that contain dung of megaherbivores are reviewed. Seven species of herbivores were identified utilizing dung: Bison (bison), Equus (horse), "Euceratherium' (shrubox), Mammuthus (mammoth), Nothrotheriops (ground sloth), Oreamnos (mountain goat) and Ovis (bighorn), and 79 14C dates were measured from the sites. Most sites contain additional associated 14C and U/Th dates on skeletal and botanical remains. -Authors
Late Pleistocene fossils of the extinct Harrington's mountain goat, Oreamnos harringtoni, have been analyzed from eight localities in Grand Canyon National Park, Arizona. Unique finds of this species are the remains of hair, muscle and ligament, keratinous horn sheaths, and dung. Large, cuboid to sub-rectangular dung pellets are referable to the adult of the species. Pollen in dung indicates that the mountain goat frequented the caves during early to late spring and possibly portions of late winter and early summer. Plant material in the dung indicated that the major dietary components (33% to 47%) were grasses (Sporobolus, Festuca, Oryzopsis, and Agropyron); conifers (Picea and Pseudotsuga) also were important.
A total of 395 microtine rodent specimens recovered from Snake Creek Burial Cave (SCBC) are referred to Microtus sp. and Lemmiscus curtatus. Radiocarbon and Uranium series dates indicate an age for these fossils of between 9460 ± 160 yr. B.P. and 15,1000 ± 700 yr. B.P The sample of lower first molars of Lemmiscus includes 4-, 5-, and 6-closed triangle morphotypes. Earlier reports of the 4-closed triangle morphotype are from Irvingtonian deposits in Colorado, Nevada, and New Mexico and from early Rancholabrean deposits in Washington. The morphotype is not known in living populations of Lemmiscus. SCBC specimens constitute the youngest record of the 4-closed triangle morphotype and are the only specimens reported from the late Rancholabrean. The time of disappearance of Lemmiscus with this molar morphology is unknown, but populations with this morphotype possibly became extinct at or near the end of the Pleistocene.
Two new species of Neotoma are described from New Mexican cave deposits older than late Wisconsinan full-stadial time. One of these species, morphologically similar to N. cinerea, N. fuscipes, and N. mexicana, is tentatively hypothesized to be a descendent of Neotoma cinerea populations isolated in the southeastern New Mexican highlands since early Wisconsinan stadial events; the other is most similar to the living Neotoma goldmani of north-central Mexico, and likely is ancestral to that species.
The vertebrate fauna of the last 30,000 radiocarbon years in the Grand Canyon is reviewed. Faunas accompanied with 92 14C dates have been analyzed from nine cave sites (four systematically excavated) and 50 packrat middens. Reasonably precise chronological and environmental data of late Pleistocene and Holocene age were obtained through dung studies in Rampart, Muav, and Stanton's Caves; from the numerous packrat middens; and from a ringtail refuse deposit in Vulture Cave. The desert tortoise, 8 species of lizards, 12 species of snakes, 68 species of birds, and 33 species of mammals are identified. Extinct animals include the avian carrion feeder, Teratornis merriami, and the mammalian herbivores, Oreamnos harringtoni, Camelops cf. hesternus, Equus sp., and Nothrotheriops shastense. There is no apparent abrupt end to the late Pleistocene as observed in the Grand Canyon fossil faunal or floral record. Animal and plant taxa of the Grand Canyon responded individually to the changes in climate of the last 30,000 yr. Both animal and plant fossil assemblages indicate that a pre-full glacial, a full glacial, and a late glacial woodland community with many less dominant desert taxa were slowly replaced by a Holocene desert community. All woodland taxa were absent from the lower elevations of the Grand Canyon by 8500 yr B.P.
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