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The Timing of Late Pleistocene Mammalian Extinctions in North America
Abstract
More than 375 14C dates from 150 fossil sites in North America have been analyzed to evaluate the question of extinction of Late Pleistocene megafauna. When critically evaluated, no 14C ages for any extinct Pleistocene genera are younger than 10,000 yr B.P.
... Although some consider the extinctions of most of these animals to have been coeval (e.g., Firestone et al., 2007), the last well-dated occurrences for many individual species and genera are prior to 18,000 14 C yr BP (Grayson and Meltzer, 2003; Guthrie, 2003; Barnosky et al., 2004; Stuart et al., 2004; Grayson, 2006, 2007). At least 16 genera survived into the latest glacial times (Grayson, 2006, 2007), and critical analyses of the reliability of dates associated with remains of extinct North American megafauna (Meltzer and Mead, 1983, 1985; Grayson, 1991) indicate that the extinctions of those taxa were complete by ca. 10,000 14 C yr BP, with the last appearances of some species as early as 10,500 14 C yr BP (Stuart, 1991; Grayson, 2001) or even 10,800 14 C yr BP (Meltzer and Mead, 1983, 1985). ...
... At least 16 genera survived into the latest glacial times (Grayson, 2006, 2007), and critical analyses of the reliability of dates associated with remains of extinct North American megafauna (Meltzer and Mead, 1983, 1985; Grayson, 1991) indicate that the extinctions of those taxa were complete by ca. 10,000 14 C yr BP, with the last appearances of some species as early as 10,500 14 C yr BP (Stuart, 1991; Grayson, 2001) or even 10,800 14 C yr BP (Meltzer and Mead, 1983, 1985). For more than 40 yr, controversy has surrounded many aspects of this event, including the forces driving the extinctions and its timing (Martin and Wright, 1967; Martin and Klein, 1984). ...
... C yr BP for the Rappuhn mastodon, both from Michigan (Table 1; Meltzer and Mead, 1983, 1985; Stuart, 1991). The age of the Pleasant Lake mastodon was obtained using wood fragments removed from within the pulp cavities of both tusks (Fisher, 1984), which must have been deposited sometime after the animal died. ...
The end of the Pleistocene in North America was marked by a wave of extinctions of large mammals, with the last known appearances of many species falling between ca. 11,000–10,000 14C yr BP. Temporally, this period overlaps with the Clovis Paleoindian cultural complex (11,190–10,530 14C yr BP) and with sudden climatic changes that define the beginning of the Younger Dryas chronozone (ca. 11,000–10,000 14C yr BP), both of which have been considered as potential proximal causes of this extinction event. Radiocarbon dating of enamel and filtered bone collagen from an extinct American Mastodon (Mammut americanum) from northern Indiana, USA, by accelerator mass spectrometer yielded direct dates of 10,055±40 14C yr BP and 10,032±40 14C yr BP, indicating that the animal survived beyond the Clovis time period and into the late Younger Dryas. Although the late survival of this species in mid-continental North America does not remove either humans or climatic change as contributing causes for the late Pleistocene extinctions, neither Clovis hunters nor the climatic perturbations initiating the Younger Dryas chronozone were immediately responsible for driving mastodons to extinction.
... M. columbi is thought to have interbred with the woolly mammoth (Mammuthous primigenius) (Enk et al. 2011), so it may have been a subclade rather than a separate species. Although there have been reports of more recent finds these are doubtful, an extinction date of about 12 500 bp is widely accepted and dates younger than 11 000 bp are not viewed as credible (Meltzer and Mead 1983;Haynes 1987Haynes , 1991Fisher 1996;Fiedel 1999Fiedel , 2009Barnosky et al. 2004;Martin 2005;Waters and Stafford 2007;Haynes 2008;Faith and Surovell 2009;Surovell and Grund 2012;Louguet-Lefebvre 2013). The naturalism of presumed depictions of elephantine zoomorphs in the United States varies considerably. ...
... Designations of American petroglyphs as proboscideans have appeared from the 19th, throughout the 20th century and into the present. The Columbian mammoth and American mastodon were certainly both met by the early colonisers of the continent (Meltzer and Mead 1983;Fisher 1996;Fiedel 2009;Barnosky et al. 2004;Martin 2005;Faith and Surovell 2009), but none of the proposals of their depiction could so far be credibly substantiated. The site is located in the eastern part of a long line of c. 20-m-high cliffs of Navajo Sandstone bearing several clusters of rock art, separated from the river by a flat recent floodplain or alluvial terrace postdating 1955 (Gillam and Wakeley 2013: Fig. 5c). ...
The numerous published claims concerning the depiction in North American rock art and portable palaeoart of Pleistocene animal species, and in some cases even of Mesozoic species, are examined. Such proposals have appeared since the 19th century and have involved petroglyphs, pictograms and mobiliary art. Patterns in the consideration of the evidence presented in their support are analysed and the rationales underpinning these various claims are examined in an attempt to explain their apparent foundations. This review yields no credible evidence for the depiction of extinct fauna in the United States or any other parts of the Americas.
... Their radiocarbon dates, listed in Table 1, range between 9,000 and 11,000 yBP, except for Miller's Cave (Patton, 1963), dated at 7,290 ± 260 yBP (Tamers et al., 1964). It should be noted that none of these dates are of "critical value" according to the criteria of Meltzer and Mead (1983), and are thus suspect of being too young, especially the Miller's Cave date. The presence of extinct mammals at Miller's Cave, Cave Without a Name, the Levi Site, and Schulze Cave (Layer C) indicates a probable minimum age of 10,000 yBP for each of these sites (Meltzer and Mead, 1983). ...
... It should be noted that none of these dates are of "critical value" according to the criteria of Meltzer and Mead (1983), and are thus suspect of being too young, especially the Miller's Cave date. The presence of extinct mammals at Miller's Cave, Cave Without a Name, the Levi Site, and Schulze Cave (Layer C) indicates a probable minimum age of 10,000 yBP for each of these sites (Meltzer and Mead, 1983). Zone 3 of Friesenhahn Cave contains no mammalian taxon larger than a rabbit, but does contain a micromammalian fauna consistent with either a very late Pleistocene or early Holocene age (e.g., Pitymys, Blarina, Cryptotis, Scalopus, and Cynomys; Graham, 1976). ...
The four species of Leporidae (Mammalia, Lagomorpha) present in Texas for the last 20,000 years, Sylvilagus floridanus, S. audubonii, S. aquaticus, and Lepus californicus, can be identified using discriminant analysis on maxillae, mandibles, and lower third premolars. Analysis of latest Pleistocene leporid faunas from central Texas indicates that with a moister climate the range of S. audubonii was more restricted to the west. Sometime during the early Holocene, S. aquaticus was present at Kincaid Shelter, 100 km west of its current range. Leporids from several sites indicate that the climatic record for the Holocene in western central Texas has been: 9,000-5,000 years BP, more mesic than today; 5,000-3,000 years BP, more xeric than today, 3,000-400 years BP, similar climate as today.
... Traditionally, the maximum accepted date for megafaunal extinctions has been placed at 11 ,000 yr B.P. (Martin 1967). A reevaluation of the radiocarbon evidence, however, suggests that these extinctions could have taken place as late as 10,000 yr B.P. but not more recently (Kurten and Anderson 1980;Meltzer and Mead 1983). Whalen (1971) has advanced two explanations to account for the early Holocene occurrence of extinct fauna in Whitewater Draw. ...
... The date of 10,420 yr B.P. is considered accurate and close to its true age. This radiocarbon date is the youngest date associated with articulated megafaunal remains in Whitewater Draw and falls before the maximum accepted date of 10,000 yr B.P. for extinctions in North America (Meltzer and Mead 1983). Therefore, the mammoth and camel remains appear to be in primary position within the older portion of the unit D alluvium. ...
... Additionally, two samples of S. fatalis bone from First American Bank, Tennessee, assayed in the 1970s produced dates of 9410 ± 155 B.P. (I-6125) and 10,035 ± 650 B.P (GX-2562) (Dowd, 2010, 69). While some researchers have incorporated the younger of the two dates e the one on bone collagen e in their research (e.g., Broughton and Weitzel, 2018;Meltzer and Mead, 1983), others have disregard it or both of them (e.g., Faith and Surovell, 2009). Dowd (2010, 80). ...
Outside of Rancho La Brea, southern California, United States, knowledge of the life history, ecology, and extinction of large, late Pleistocene carnivores in North America is frustrated by a scarcity of skeletal material and trustworthy radiocarbon dates. A complete Smilodon fatalis (sabertooth cat) cranium from southwestern Iowa, directly AMS radiocarbon dated to 11,685 ± 40 B.P. (13,605e13,455 cal B.P.), represents an important addition to the inventory of evidence for the taxon in the Midcontinent. Assessment of tooth eruption and wear combined with metric and nonmetric comparisons with coeval crania from Pit 61/67 at Rancho La Brea indicates the specimen belongs to a subadult male 2e3 years of age at death. Craniodental morphology falls within the range of variation in the Pit 61/67 males. Predicted live weight is 251 kg. One C 1 has an antemortem bend fracture, and the absence of use-wear on the proximal remnant suggests death ensued within days of the injury. The radiocarbon date centers the animal in the Bølling-Allerød Chronozone (14,640e12,845 cal B.P.). Whereas regional conditions were generally warmer and wetter during this period, southwestern Iowa was a cool, dry non-analog boreal grassland/ parkland that supported a diverse, large herbivore community, including Megalonyx jeffersonii (Jeffer-son's ground sloth), the taxon tentatively identified in this study as the focal prey. Bayesian modeling of 72 direct radiocarbon dates for the taxon suggests extinction of the late Quaternary Smilodon was a hemispheric and geologically synchronic phenomenon that occurred after 13,285 cal B.P. Subjects: vertebrate paleontology, paleoecology, paleozoology.
... Unsurprisingly, debates surrounding the chronology of human arrival to the Americas, founding population size, and subsequent population size fluctuations have continued with no sign of resolution. Concerning the megafauna record, it has long been known that the number of fossil finds in a given region/time to some extent corresponds with archaeological and geological research efforts aimed at dating material thought to be contemporaneous with humans in the Americas 45 . Although we attempted to correct for taphonomic and sampling biases in our analyses (see Methods section), there may still be biases that are difficult to control for at the moment and more research and data are needed. ...
The disappearance of many North American megafauna at the end of the Pleistocene is a contentious topic. While the proposed causes for megafaunal extinction are varied, most researchers fall into three broad camps emphasizing human overhunting, climate change, or some combination of the two. Understanding the cause of megafaunal extinctions requires the analysis of through-time relationships between climate change and megafauna and human population dynamics. To do so, many researchers have used summed probability density functions (SPDFs) as a proxy for through-time fluctuations in human and megafauna population sizes. SPDFs, however, conflate process variation with the chronological uncertainty inherent in radiocarbon dates. Recently, a new Bayesian regression technique was developed that overcomes this problem-Radiocarbon-dated Event-Count (REC) Modelling. Here we employ REC models to test whether declines in North American megafauna species could be best explained by climate changes, increases in human population densities, or both, using the largest available database of megafauna and human radiocarbon dates. Our results suggest that there is currently no evidence for a persistent through-time relationship between human and megafauna population levels in North America. There is, however, evidence that decreases in global temperature correlated with megafauna population declines.
... In terms of terminal age of equids in North America, Meltzer and Mead (1983) report the youngest reliable age at 10,370 ± 350 B.P. from Jaguar Cave in Idaho. Kurten and Anderson (1980) suggest that equids may have survived into the Early Holocene at 8,000 B.P. Toomey (1993) and Toomey et al. (1992) reported dates for Equus bones from Hall's Cave in Kerr County, Texas of 9200-8700 B.P. However, he further stated that additional dates are needed to confirm the Early Holocene survival of Central Texas equids. ...
... This is confirmed by the estimate of the probable age of the Glen Canyon style, of being somewhere between 2400 and 5000 BP (Cole 2009: 45). Moreover, the Columbian mammoth (Mammuthus columbi) is thought to have become extinct by 12,500 years BP, and any dates younger than 11,000 are not viewed as credible (Meltzer, Mead 1983, Haynes 1987, 1991, Fisher 1996, Fiedel 1999, Barnosky et al. 2004, Martin 2005, Waters, Stafford 2007, Haynes 2008, Faith, Surovell 2009, Surovell, Grund 2012, Louguet-Lefebvre 2013. Not only is it geologically impossible for the surface of the friable and rather porous Navajo sandstone of the site to have survived from Pleistocene times; the geological setting of the site renders such great age of the rock panel highly unlikely (Gillam, Wakeley 2013). ...
Visual pareidolia occurs when meaningful patterns representing familiar objects are seen in what are in reality random or meaningless data. It is of significance to anthropology for two reasons: as a psychological phenomenon of the human visual system; and because of its important role in rock art interpretation. Once the brain has been conditioned to anticipate specific patterns, it tends to discover them with minimal stimulation, because most of the information processed by the human visual centre derives from within the brain. The creative pattern detection that constitutes rock art "interpretation" is effectively a projection of invented meaning onto mute marks on rock. The modern beholder's perception searches the motif for details resonating with his/her visual system, in the same way as pareidolia operates. It decides arbitrarily which aspects are naturalistic and which are not, and it adjudicates which of an image's aspects are diagnostic. Yet the brain of the modern beholder of rock art differs significantly from that of its creator, and the notion that rock art connoisseurs can somehow conjure up the emic meanings of rock art motifs from their own brains' past experiences is mistaken. This paper illustrates the involvement of pareidolia in rock art appreciation through a series of examples and attempts to explain these observations.
... As such, early Clovis groups likely experienced a mosaic framework of ecological niches rich in biotic diversity but unevenly distributed across the landscape ( Guthrie 1982Guthrie , 1984. An estimated half to two-thirds of the species of North American large mammals went extinct about this time, a rather punctual ending to an otherwise slow process (Grayson 1989;2007:192;Martin and Martin 1987;Martin and Wright 1967;Meltzer and Mead 1983). Although diverse discussions have been offered as to the cause of these extinction events, it is apparent that loss of habitat played a key role (Graham 1979(Graham , 1985(Graham , 1991Graham and Lundelius 1984;Lambert and Holling 1998;Lundelius 1989;Guthrie 1982Guthrie , 1984Guthrie , 2006. ...
The terminal Pleistocene represents a dynamic period of environmental flux and resultant extirpation, extinction, and reorganization of biotic communities. Assessment of Clovis and Folsom/Midland artifacts offers an opportunity to address human response to these changing conditions. Clovis sites range in age from ca. 11,590-10,800 RCYBP (13,550-12,850 CALBP) with Folsom technology well expressed from ca. 10,800-10,200 RCYBP (12,800-11,700 CALBP). Although firm radiocarbon assessments of Midland sites are largely lacking, it is suggested Midland technology is a different expression of the same organizational system as Folsom groups. This research outlines environmental change during this dynamic period and develops models of diverse land use strategies between Clovis and Folsom/Midland groups. It is suggested that a small change in adaptive systems can result in noticeable differences in the archaeological record when compounded through redundant activity and time. This change is in part attributed to shifting ecosystems and resource availability of the terminal Pleistocene. Spatial patterning in Clovis and Folsom/Midland artifact distributions, particularly projectile points, preforms, and channel flakes is addressed at a variety of analytical scales in this research. Private artifact collections and isolated artifact discoveries from the Continental Divide of Colorado to the eastern Kansas border are used to characterize Clovis and Folsom/Midland land use and lithic procurement across the Central Great Plains. This research demonstrates that Clovis and Folsom/Midland artifact distributions are not homogenous across the study region, and are influenced by a variety of factors including ground surface visibility and geomorphic filtering, artifact collector activity and research intensity, and diverse land use and resource procurement strategies between Clovis and Folsom/Midland groups.
... A major extinction occurred in animal communities across North America during the late Pleistocene (Martin and Wright, 1967), and it is reasonable to assume that events in New England paralleled those documented elsewhere on the continent (Meltzer and Mead, 1983). The closest reliable information on the composition of Pleistocene mammal communities in the eastern United States comes from middle Appalachia. ...
Human inhabitants encountered a series of changing environments at the end of the most recent ice age in northern New England. We present our current understanding of the context of colonization of this area by a diversity of human groups some time between 13,000 B.P. and 11,000 B.P., based on archeological evidence and on geological and biological evidence synthesized by Davis and Jacobson (1985).
As the Champlain Sea separated the main body of Laurentide ice from the ice cover of northern New England and the Canadian Maritimes about 13,000 B.P., plants and animals began to invade land surfaces exposed by the dissipating ice sheet. Over a few thousand years, the vegetation changed from tundra to woodland to closed forest. There is little direct paleontological evidence for the fauna that lived in those late-glacial ecosystems, but human artifacts from several sites indicate that large mammals were probably hunted prior to the late-Pleistocene extinction of megafauna. We suggest that a shift to greater reliance on caribou hunting would have followed the extinctions. We present a speculative model of how humans adapted to the changing environments and food sources during that dynamic period.
... Several issues connected with mammoth evolution are of great scientific interest: the problem of the last mammoth; mammoth taphonomy; paleoclimate during the time of the mammoths and use of mammoth remains for the dating of host sediments. (Meltzer and Mead 1985); and from the Southwest United States, remains of Mammuthus columbi from Sandy, Utah dated to 5985 ± 210 (SI-2341b), 7200 ± 190 (RL-464) and 8815 ± 100 BP (SI-2341a) (Semken 1983;Stafford et a1.1987;Agenbroad and Mead 1989). However, contamination of samples cannot be excluded, as has been shown by Stafford et al. (1987)-for different fractions from the Domebo mammoth sample, dates from 2050 to 11,490 BP were obtained. ...
Many mammoth remains have been radiocarbon-dated. We present here more than 360 14C dates on bones, tusks, molars and soft tissues of mammoths and discuss some issues connected with the evolution of mammoths and their environment: the problem of the last mammoth; mammoth taphonomy; the plant remains and stable isotope records accompanying mammoth fossils; paleoclimate during the time of the mammoths and dating of host sediments. The temporal distribution of the 14C dates of fossils from the northern Eurasian territory is even for the entire period from 40 to 10 ka BP.
... Several issues connected with mammoth evolution are of great scientific interest: the problem of the last mammoth; mammoth taphonomy; paleoclimate during the time of the mammoths and use of mammoth remains for the dating of host sediments. (Meltzer and Mead 1985); and from the Southwest United States, remains of Mammuthus columbi from Sandy, Utah dated to 5985 ± 210 (SI-2341b), 7200 ± 190 (RL-464) and 8815 ± 100 BP (SI-2341a) (Semken 1983;Stafford et a1.1987;Agenbroad and Mead 1989). However, contamination of samples cannot be excluded, as has been shown by Stafford et al. (1987)-for different fractions from the Domebo mammoth sample, dates from 2050 to 11,490 BP were obtained. ...
... Traditionally, the maximum accepted date for megafaunal extinctions has been placed at 11,000 yr B.P. (Martin, 1967). A reevaluation of the radiocarbon evidence, however, suggests that these extinctions could have taken place as late as 10,000 yr B. P. , but not beyond (Kurten and Anderson, 1980;Meltzer and Mead, 1983). ...
... In terms of learning models, could it reflect continued guided variation? Anderson and Faught (2000;see also Anderson et al. 2011) point out that disruptions in climate and food resources associated with the Younger Dryas (12,890-11,680 calBP), coupled with the disappearance of megafauna Grayson 2007;Meltzer and Mead 1983), could have led to changes in logistic patterns (Boulanger et al. 2015). Large-distance movements may have given way to more-localized movements geared toward a wider range of small animals and plants. ...
North American fluted stone projectile points occur over a relatively short time span, ca. 13,300–11,900 calBP, referred to as the Early Paleoindian period. One long-standing topic in Paleoindian archaeology is whether variation in the points is the result of drift or adaptation to regional environments. Studies have returned apparently conflicting results, but closer inspection shows that the results are not in conflict. At one scale—the overall pattern of flake removal—there appears to have been an early continent-wide mode of point manufacture, but at another scale—projectile-point shape—there appears to have been regional adaptive differences. In terms of learning models, the Early Paleoindian period appears to have been characterized by a mix of indirect-bias learning at the continent-wide level and guided variation at the regional level, the latter a result of continued experimentation with hafting elements and other point characters to match the changing regional environments. Close examination of character-state changes allows a glimpse into how Paleoindian knappers negotiated the design landscape in terms of character-state optimality of their stone weaponry.
... Importantly, the two hypotheses are not mutually exclusive. Anderson and Faught (2000) point out that disruptions in climate and food resources associated with the Younger Dryas (12,890-11,680 calBP), coupled with the disappearance of megafauna (Boulanger and Lyman, 2014;Grayson, 2007;Meltzer and Mead, 1983), can be expected to have led to changes in logistic patterns (but see Polyak et al., 2012). Large-distance movements may have given way to more-localized movements geared toward a wider range of small animals and plants. ...
... Thus, we acknowledge that the archaeological and paleontological radiocarbon records are subject to some preservation bias and that these records are also subject to sampling bias. For instance, remains of extinct megafauna found in what are believed to be late Pleistocene sedimentsdand thus are suspected of being contemporaneous with early Americansdare more likely to be assayed by radiocarbon dating than are remains encountered in contexts clearly pre-dating the human entrance into the Americas (Meltzer and Mead, 1983). Similarly, it may be that some time periods (e.g., sites anticipated to be "the first" or "the earliest") get much dating attention (Grayson, 2011). ...
It has long been argued that specialized big-game-hunting Paleoindians were responsible for the extinction of three dozen large-bodied mammalian genera in North America. In northeastern North America, the overkill hypothesis cannot be tested on the basis of associations of Paleoindian artifacts and remains of extinct mammals because no unequivocal associations are known. The overkill hypothesis requires Paleoindians to be contemporaneous with extinct mammalian taxa and this provides a means to evaluate the hypothesis, but contemporaneity does not confirm overkill. Blitzkrieg may produce evidence of contemporaneity but it may not, rendering it difficult to test. Overkill and Blitzkrieg both require large megafaunal populations. Chronological data, Sporormiella abundance, genetics, and paleoclimatic data suggest megafauna populations declined prior to human colonization and people were only briefly contemporaneous with megafauna. Local Paleoindians may have only delivered the coup de grace to small scattered and isolated populations of megafauna.
... It is therefore important to determine how these 2 sites relate to one another chronologically . Radiocarbon dates have been published previously from specimens from PCC (Taylor 1975; Payen and Taylor 1976; Meltzer and Mead 1983), but no such analysis has been completed for Samwel Cave. It is the aim of this study to obtain 14 C dates from the fauna of Samwel Cave. ...
Although mostly excavated before 1910, the fossil deposits discovered in Samwel and Potter Creek Caves in northern California have been little studied. The deposits within the caves have yielded both extinct megafauna and archaeological remains implying that the deposits cross the Pleistocene-Holocene transition. Small mammals are abundant within these cave deposits, and many of these smaller mammals are from extant species of California, survivors of the end Pleistocene extinction. Because of the abundant fossils collected in stratigraphic context, our ultimate goal is the use these unique sites to assess community and population response of the extant mammals to the end Pleistocene event. However, our initial aim was to answer the following two questions regarding the small mammal communities: (1) What is the chronology of the small mammals in the cave deposits? (2) Are ecological changes occurring within the small mammal taxa? To determine chronology, we prepared 10 small mammal samples for radiocarbon analysis using standard techniques. The samples were analyzed and dated at the Lawrence Livermore National Laboratory. Our dates, selected from across the strata, ranged from 1,200 to 21,000 radiocarbon years before present. For a preliminary assessment of ecological changes through time, we used cranial metrics of ground squirrels ( Spermophilus sp.). Diastemal length (the distance between the first molariform tooth and incisor) is an index of body size, which is a function of the physiology of the individual. Toothrow measures the length of the molariform teeth, and does not change with the ontogeny of the individual, but can represent heritable, evolutionary changes in size or species replacement. Our preliminary results are promising, demonstrating a significant decrease in diastemal length, or ecophenotypic body size, at the top of the deposit. No significant change was observed in toothrow length. Our results confirm that the deposits of these northern California caves do span the Pleistocene-Holocene boundary. This transition is associated with our preliminary results from ground squirrels showing no species replacement and a reduction in body size. Body size reduction is an expected outcome of warming at the end Pleistocene, but future research will address mechanism directly in this and other small mammal species.
... These coincidences highlight the importance of scientific bias in what is selected for radiocarbon dating (Meltzer and Mead, 1983), but scientific bias does not explain all of the observed variability. For example, middle Holocene-age sediments capable of preserving pollen have been systematically sought (Mehringer et al., 1967), but are still under-represented in both valleys (Fig. 4). ...
The use of radiocarbon frequency distributions to reconstruct prehistoric human and animal populations must account for taphonomic loss and other factors that affect the archaeological and paleontological records. Surovell et al. (JAS, 36, 1715–1724) have recently proposed a correction for “taphonomic bias” that is based on the radiocarbon frequency of a global sample of volcanic deposits. Analysis of 717 radiocarbon dates sampled from the alluvium of the San Pedro and Santa Cruz rivers and their tributaries in southeastern Arizona shows that discovery and scientific biases also play an important role in the creation of radiocarbon frequency distributions, and that the rate of “taphonomic bias” in prehistory is not predicted by the radiocarbon frequency of volcanic deposits. The latter principle is further argued using a sample of 123 Pliocene to Clovis-age proboscideans from the San Pedro Valley. We propose an alternative model that is based on the nature of the stratigraphic record, with discovery bias, scientific bias, taphonomic loss, and the shape of the calibration curve all operating to influence the temporal frequency distribution of radiocarbon-dated prehistoric phenomena.
... The average of 11 300 yr B.P. is within the generally accepted period of extinction of Mammuthus columbi in North America, determined to be before ca. 11 000 yr B.P. (Meltzer and Mead, 1983;Agenbroad, 1984;Agenbroad andMead, 1989, 1996;Martin, 1990). Another two samples of charcoal (AA 23161 and AA 23763) collected from the upper lahar unit yielded ages of 10 220 ± 75 and 10 430 ± 75 yr B.P. This later date shows that the lahar units did not form exactly contemporaneously but formed over a period of about 1000 yr. ...
The accidental discovery in July 1996 of the Tocuila mammoth site in the eastern Valley of México was followed by intensive scientific excavation, which yielded remains of at least seven individuals of Mammuthus columbi in an area measuring only 28 m2. The high density of mostly disarticulated mammoth bones identified 3 m below the surface in a massive, 130-cm-thick lahar deposit of sandy ash and rounded pumice fragments is unusual and suggests a high-energy depositional environment. Samples of charcoal found within this deposit yielded radiocarbon ages ranging between 10 220 ± 75 and 12 615 ± 95 yr B.P. The lahar was studied in greater detail in order to establish its provenance. Determination of grain-size distribution and magnetic properties of the deposit, as well as petrographical, mineralogical, and geochemical analyses of pumice clasts, all indicate that the lahar was derived from volcanic fallout deposits that originated at Popocatépetl volcano, located 50 km south-southeast of the site. Popocatépetl underwent a major phreato-Plinian eruption, dated ca. 14 000 yr B.P., at the end of the last major glaciation. Dispersal of the fallout was mostly toward the northwest and north; deposits were found on the slopes of Tláloc mountain (4150 m), 20 km southeast of Tocuila. At the beginning of deglaciation and the onset of more humid conditions ∼3000 yr later, lahars derived from the fallout deposits picked up the bones of already dead animals and then deposited them on the shores of Lake Texcoco and/or simply covered bones without major displacement.
We need to integrate the analysis of sudden changes as well as gradual changes in Prehistory. Sudden changes in nature sometimes let to catastrophes. It depends just on the magnitude, speed of change and specially on the state of the society affected by the change.
I have chosen 10+1 example of sudden changes in the oldest prehistory to illustrate this thesis.
The terminal Pleistocene represents a dynamic period of environmental flux and resultant species extirpation, extinction, and reorganization of biotic communities. Assessment of Clovis and Folsom/Midland artifacts offers an opportunity to address human response to these changing conditions. Clovis sites range in age from ca. 11,590-10,800 RCYBP (13,550-12,850 CALBP) with Folsom technology well expressed from ca. 10,800-10,200 RCYBP (12,800-11,700 CALBP). Although firm radiocarbon assessments of Midland sites are largely lacking, it is suggested Midland technology is a different expression of the same organizational system as
Folsom groups. This research outlines environmental change during this dynamic period and develops models of diverse land use strategies between Clovis and Folsom/Midland groups. It is suggested that a small change in adaptive systems can result in noticeable differences in the archaeological record when compounded through redundant activity and time. This change is in part attributed to shifting ecosystems and resource availability of the terminal Pleistocene. Spatial patterning in Clovis and Folsom/Midland artifact distributions, particularly projectile points, preforms, and channel flakes is addressed at a variety of analytical scales in this
research. Private artifact collections and isolated artifact discoveries from the Continental Divide of Colorado to the eastern Kansas border are used to characterize Clovis and Folsom/Midland land use and lithic procurement across the Central Great Plains. This research demonstrates that Clovis and Folsom/Midland artifact distributions are not homogenous across the study region, and are influenced by a variety of factors including ground surface visibility and geomorphic filtering, artifact collector activity and research intensity, and diverse land use and resource procurement strategies between Clovis and Folsom/Midland groups.
Keys to a Unified Theory of Warfare and Arms Races1 - Volume 7 Issue 2 - R. Paul Shaw, Yuwa Wong
Geoarchaeological studies were undertaken in Whitewater Draw and around Lake Cochise in southeastern Arizona to determine the age of the Sulphur Spring stage of the Cochise culture and define its place in Southwestern prehistory. Alluvial stratigraphic studies in Whitewater Draw showed that Sulphur Spring stage artifacts occurred in deposits ranging from 8,000 to 10,000 B.P. and may even date as old as 10,400 B.P. These studies also showed that Sulphur Spring artifacts were not temporally associated with Pleistocene megafauna. Re-examination of the late Quaternary stratigraphy of Lake Cochise showed that reported Sulphur Spring stage sites were not temporally associated with the Pleistocene shoreline and were younger than first reported. The Sulphur Spring stage of the Cochise culture should be regarded as the oldest recognized Archaic manifestation in southern Arizona.
This chapter reviews the strategies for paleoenvironmental reconstruction in archaeology. Paleoenvironmental reconstruction in archaeology is the description of change in the physical and biological contexts of human existence. It is an aspect of, and an essential precursor to, paleoecology, the study of environmental relationships in the past. A productive archaeological approach to the reconstruction of paleoenvironments requires fundamentally an understanding that environmental determinism is neither the inspiration nor the goal. Once past that barrier, there need be no apology for undertaking environmental studies within a framework of ecological theory. Ecological hypotheses are not intrinsically better than other hypotheses, but they certainly are extraordinarily useful in providing the understanding of the past. It is the scientific productivity of the ecological perspective on human lives that has fascinated archaeologists and that should continue to challenge them to explore the past with imagination tempered with rigor and impartiality. The goal is knowledge of fully human responses to environmental stressors and opportunities, which cannot be achieved unless those are understood in their diversity.
For over 10,000 years, human populations have occupied the dynamic, ecologically diverse landscapes of northeastern North America. Throughout the course of the Holocene period, prehistoric and historic communities have each exhibited a wide array of behavioral, social, and technological adaptations in response to a diversity of environmental and social settings. The greater part of this period was dominated by various gathering-hunting-fishing strategies, and it was apparently only in the last 1,000 years that horticulture had a significant impact on prehistoric economy. By the sixteenth century, aboriginal lifeways were being regularly impacted by the early Basque fisheries; increasing contact with European colonists led initially to changes in land use in response to the für trade, but quickly resulted in the decimation of local native populations by a series of plagues, wars, and other adverse circumstances. The historic settlement of the region was until recently agriculturally based, with broader patterns of land use focused on coastal resources, the waterways of the interior, and the timber industries. By the mid-nineteenth century, segments of the landscape were being rapidly industrialized. The Holocene period in the Northeast is thus a period of significant social transformation, favorable and unfavorable historical circumstances, and environmental variability.
This chapter describes peopling in North America and summarizes where they were when The International Union for Quaternary Science (INQUA) was here in 1965. One element common to many models of colonization (in North America and elsewhere) is that colonizers on a landscape with few other people not only had to be able to track great distances to find mates and exchange information and resources, they also had to be able to get along with near and distantly related groups they encountered. The conventional view of fast-moving, big-game hunters exploding on to the continent as the ice-free corridor zipped opened in terminal Pleistocene times is no longer a tenable scenario for the initial peopling of North America. Yet, though it is now believed that the peopling process was far more complex––beginning much earlier, possibly involving multiple migratory pulses and involving a different entry route––fundamental questions about the antiquity, number, timing, and adaptive strategies of the Pleistocene peoples of North America remain.
Taphonomic analysis of several late Pleistocene mastodon (Mammut americanum) skeletons excavated in southern Michigan provides compelling evidence of mastodon butchery by Paleo-Indians. The occurrence of butchery and details of butchering technique are inferred primarily from patterns of bone modification. An important aspect of butchering practice was production and use of tools fashioned from bones of the animal being butchered. Evidence for butchery and bone tool use includes matching marks on the conarticular surfaces of disarticulated pairs of bones; cutmarks on bones; green bone fracturing; use wear, secondary flaking, and impact features on bone fragments; and burned bone. Interpretation of these features is facilitated by information on patterns of bone distribution and disarticulation preserved in a primary depositional context. Preliminary comparisons among nine sites indicate that putative butchering sites differ consistently and in a variety of ways from sites that appear to record no human involvement. Although based on a small sample of sites, the apparent frequency of butchered individuals relative to those that were not butchered is unexpectedly high. These findings provide new evidence of a well-developed 'bone technology' employed by the late Pleistocene human inhabitants of eastern North America. In addition, these data offer circumstantial support for the hypothesis that human hunting was an important factor in the late Pleistocene extinction of mastodons. -Author
Forested landscapes are dynamic — they are always in transition and have always been in a state of constant change. Though the rates and agents of change vary temporally and spatially, change underlies the natural state of the world’s forests. Land-use patterns and disturbance regimes are two of the dynamic agents that can have profound effects on the abundance, distribution and diversity of terrestrial vertebrates (Burgess and Sharpe, 1981; Saunders et al., 1987; Wilson 1988). The need for conservation and management of forest and wildlife resources requires humans to influence the uses of land and the sizes and distributions of wildlife populations to maintain specific habitat conditions. Identification of the primary agents of change and their extent and magnitude are necessary to maintain forested ecosystems and their faunal components. An understanding of the background rates and causes of change in forested landscapes can help to guide conservation efforts on many scales.
With its temperate climate and variety of habitats, Michigan supports a diverse array of animals and plants, including fifty-four species of amphibians and reptiles. The dispersal and biology of the Michigan herpetofauna-amphibians and reptiles-is even more unique because Michigan consists of two peninsulas that project into large freshwater seas and also because it was completely covered by a massive ice sheet a relatively short time ago. In The Amphibians and Reptiles of Michigan: A Quaternary and Recent Faunal Adventure, author J. Alan Holman explores the state's amphibians and reptiles in detail and with many helpful illustrations, making this the only volume of its kind available. Holman uniquely bridges the gap between neo- and paleoherpetology and shows that Michigan's modern herpetofaunas reflect Pleistocene (ice age) and Holocene (warm period after the ice age) events, as the entire modern population was forced to re-invade the state after the last withdrawal of ice. In Part 1, Holman discusses Michigan as an amphibian and reptile habitat, including a geological, climatic, and vegetational history. Part 2 presents recent species accounts, covering all fifty-four species of amphibians and reptiles, along with their general distribution, Michigan distribution (with range maps), geographic variation, habitat and habits, reproduction and growth, diet, predation and defense, interaction with humans, behavioral characteristics, population health, and general remarks. In Part 3, Holman examines the Michigan herpetofauna in Quaternary and recent historical times and the species accounts include Pleistocene, Holocene, and archaeological records. Color photographs of major herpetological habitats in Michigan are provided and color photographs of all modern species are included. Black-and-white illustrations depict both modern and ancient speicies. Herpetologists, paleontologists, zoologists, ecologists, and general biologists, as well as anyone who loves salamanders, frogs, turtles, and snakes will appreciate the comprehensive research presented in The Amphibians and Reptiles of Michigan.
The Shawnee-Minisink site is well known for yielding fish and plant remains from Clovis contexts. New investigations at Shawnee-Minisink have provided a sample of macrobotanical remains for comparison with the ten plant species previously recovered at the site. In this paper, I reevaluate
the subsistence remains recovered during the 1970s excavations by American University and conclude that a limited number of plants were actually exploited by the site's occupants. The new macrobotantical remains from Shawnee-Minisink have provided a series of AMS dates, which offer the most
precise age estimate for Clovis in the Northeast and provide an alternative interpretation concerning the role plants played in the subsistence practices of early Paleoindians. The subsistence evidence from Shawnee-Minisink shows variation in diet, but a difference that should be expected
at large habitation sites.
How archaeologists conceive variation in the archaeological record influences the kinds of explanations they produce. By treating all variation as potentially informative, evolutionary explanations stand in sharp contrast with transformational models which regard variation as noise. I show that variation in the timing of steatite vessel manufacture is not only less problematic than Sassaman proposes, but crucial to understanding how and why this technological change occurred. Evolutionary models have the additional benefit of requiring explanations to be in the form of tested hypotheses, something not inherently required by transformational models. My conclusion-that the most common function of steatite vessels was to process red oak acorn-has thus far stood up to a range of empirical testing, making it a stronger explanation than untested interpretations. /// Como los arqueólogos conciben la variación en el registro arqueológico influye en los tipos de explicación que ellos producen. Por medio del tratamiento de toda variación como potencialmente informativa, las explicaciones evolucionistas contrastan agudamente con los modelos transformacionales que ven la variación como ruido. Yo muestro que la variación en el tiempo de producción de las vasijas de esteatita es no sólo menos problemática de lo que Sassaman propone, sino que es crucial para entender cómo y por qué ocurre este cambio tecnológico. Los modelos evolucionistas tienen el beneficio adicional de requerir explicaciones en la forma de hipótesis a comprobar, algo que no es inherentemente requerido en los modelos transformacionales. Mi conclusión-que la función más común de las vasijas de esteatita fue para procesar bellotas de roble rojo-se sostiene sobre varias pruebas empíricas, siendo una explicación más fuerte que las interpretaciones no comprobables.
Research into the earliest occupations in the southeastern United States has been underway since the 1930s, when a pattern of large-scale excavations combined with the reporting of surface finds was initiated that continues to this day. Work at Macon Plateau and Parrish Village, excavated during the New Deal, was followed by a series of stratigraphic excavations in floodplains, rockshelters, and other locales from the 1940s onward. These early studies produced a basic cultural sequence, portions of which were defined by cross-dating findings from the Southeast with discoveries made in other parts of the country. The Southeast is unique in that surveys of fluted projectile points have been conducted in every state, some since the 1940s. These surveys now encompass a wider range of projectile points and other tool forms, and the large numbers of Paleoindian artifacts found in the region suggest intensive occupation. Whether these quantities reflect the presence of large numbers of early people, or of modern collectors and extensive agriculture, remains the subject of appreciable debate. The regional radiocarbon record is fairly robust for the latter end of the period, but far more sample collection, analysis, and interpretation is needed. The regional literature is burgeoning, with research being conducted in every state, much of it funded by CRM activity.
Recent paleontological evidence suggests the North American herpetofauna has been remarkably stable taxonomically and biogeographically throughout the Pleistocene. However, this paper uses paleontological, ecological, and molecular genetic data to argue that the thermophilous and xerically-adapted Collared Lizard (Crotaphytus collaris) did not persist in the northern parts of its range during glacial phases of the Pleistocene. First, a careful review of the paleontological data used to support the stability model reveals no northern fossils unambiguously dated to glacial phases. Second, environmental conditions inferred for the Ozark Plateau and Flint Hills during glacial phases were not compatible with fitness requirements of collared lizards. Third, phylogeographic analyses of an intraspecific mtDNA gene tree suggest a recent invasion of the Ozarks and Flint Hills. Finally, microsatellite data are statistically consistent with a Holocene invasion but not with long-term occupation of the Ozarks or the Flint Hills by collared lizards. These combined data sets provide strong evidence that collared lizards are able to occupy northern parts of their range only during the warmer, drier interglacials. Other thermophilous and xerically-adapted reptilian species might be expected to show similar historical patterns.
Analyses of pollen and plant macrofossils from the Kolarik Mastodon Site provide important refinements of the late-glacial and early Holocene vegetational record for northwestern Indiana. The record spans the period from > 12,000 to ∼ 9500 years B.P. Regional vegetation from > 12,000 to at least 11,000 years B.P. consisted of open, spruce-dominated forest or woodland. Both black and white spruce were present locally, along with aspen, fir and tamarack. The mastodon recovered from the site was associated with this vegetation. Vegetation of the region between 11,000 and 9500 years B.P. consisted of pine, spruce and hardwoods (oak, ash, hickory, hornbeam). Macrofossils indicate local presence of jack pine, white pine, tamarack, spruce, fir, alder and birch (probably paper birch). A radiocarbon date from a wood sample indicates that the upper boundary of the spruce-herb pollen zone in the region may be as young as 10,800 years B.P., ∼ 1000 years younger than suggested by previous studies in northern Indiana. The age discrepancy may result from carbonate contamination of bulk lake sediments.
The Holly Oak pendant is a shaped piece of marine whelk (Busycon sinistrum) shell with two holes drilled in one end that bears an incised depiction of an extinct proboscidean (woolly mammoth or mastodon). It allegedly was recovered in 1864 from an archaeological site in Delaware. There was speculation in the 1970s as to its age and significance, and it was illustrated and cited as a Paleoindian artifact of Pleistocene age. Subsequent analyses indicated the artifact was fraudulent: The engraving probably was done in the 1880s on a shell recovered from an archaeological site. This has been confirmed by a recently obtained AMS radiocarbon date. The Holly Oak pendant is a modern forgery.
Recent investigations at the Bostrom site in southwestern Illinois demonstrate that the site was occupied by at least three successive groups of Paleo-Indians: Clovis, Gainey, and Holcombe. Of the artifacts for which lithic raw materials were identified, Clovis tools are manufactured from stone that was procured up to 1500 km from the site. Gainey and Holcombe artifacts, on the other hand, are manufactured from stone whose source areas occur within a radius of 300 km from the site. Early Archaic, Dalton artifacts are manufactured from stone procured within 150 km of the site. These lithic resource procurement patterns suggest that there is a dramatic fall-off in mobility, social interaction, or both, after the initial peopling of the area. The presence of Great Lakes and Northeastern tool types at this southerly latitude suggests that the Gainey and Holcombe economies were much broader than the stereotypical model of a caribou-based subsistence strategy.
Despite a general interest in studying technological change, archaeologists have only rarely attempted to explain the rise and fall of steatite vessel manufacture. Explaining steatite vessel manufacture requires that all information on age and spatial distribution be extensively sampled and accounted for. Documenting spatial distribution shows that steatite vessels are not restricted to a single environmental or depositional context, nor were they manufactured at all steatite outcrops. A correlation between vessel distribution and mast forest, however, was identified. Analyzing steatite vessel age reveals that the technology was present at low levels for lengthy periods of time, but the absence of a trend in age across space fails to support migration/diffusion models of spread. As a durable and portable boiling technology, steatite vessels would have offset the relatively high processing costs of mast by reducing processing time and replacement costs among mobile populations.
Significance
New radiocarbon ( ¹⁴ C) dates on American mastodon ( Mammut americanum ) fossils in Alaska and Yukon suggest this species suffered local extirpation before terminal Pleistocene climate changes or human colonization. Mastodons occupied high latitudes during the Last Interglacial (∼125,000–75,000 y ago) when forests were established. Ecological changes during the Wisconsinan glaciation (∼75,000 y ago) led to habitat loss and population collapse. Thereafter, mastodons were limited to areas south of the continental ice sheets, where they ultimately died out ∼10,000 ¹⁴ C years B.P. Extirpation of mastodons and some other megafaunal species in high latitudes was thus independent of their later extinction south of the ice. Rigorous pretreatment was crucial to removing contamination from fossils that originally yielded erroneously “young” ¹⁴ C dates.
_________________________________ Many of the ideas presented below are novel. Those wishing to use any such ideas in future publications are kindly requested to cite the author as the source, mentioning either this website posting (starburstfound.org/YDextinct/p1.html) or his respective publication whichever is most appropriate. _________________________________ 1. Geochemical Evidence Indicating an ET Cause to the Megafaunal Extinction. The Cosmochemical Evidence of the YDB Group. At the May 2007 American Geophysical Union meeting in Acapulco, a group of researchers, the so-called "Younger Dryas Boundary (YDB) group," reported interesting findings pointing overwhelmingly to an extraterrestrial cause for the extinction of the Pleistocene megafauna. Particularly significant was the report of high concentrations of iridium (Ir) and other extraterrestrial material indicators at the Allerod/Younger Dryas boundary marking the terminal horizon in the extinction of the Pleistocene megafauna which dates around 12,950 calendar years before year 2000 (b2k) on the basis of the Cariaco Basin gray scale climate profile chronology. Since iridium is over 10,000 times more abundant in cosmic dust and chondritic meteorites than it is in terrestrial crustal material, it serves as an excellent ET material indicator. Other ET markers included magnetic grains, microspherules, and fullerenes saturated with the rare isotope helium-3. Their findings, many of which are reported in the group's PNAS paper (Firestone, et al., 2007), include the following: • Firestone, et al. (2007a, 2007b) report detecting 3.75 ppb of Ir in sediment samples taken from the Allerod/Younger Dryas (AL/YD) boundary at nine Clovis-age sites, with no Ir being detectable above or below this horizon. Magnetic grain microspherules extracted from this boundary were found to contain up to 51 ppb of Ir at North American sites as well as considerable amounts of the cosmic indicators nickel and cobalt. Grains from a site in Belgium were found to contain 117 ppb Ir, equivalent to 25% of the value typical of chondrites. • Wolbach, et al. (2007) report that sediments at the base of a 12,900 calendar years B.P. carbon-rich dark layer coincident with the AL/YD boundary and containing significant amounts of soot contained high concentrations of Ir, magnetic grains, microspherules, and fullerenes abundant in 3 He. • Kobres, et al. (2007) report analysis of seven cores penetrated along the long axis of Howard Bay in North Carolina, which is one of the many elliptical depressions known as the "Carolina Bays." They find elevated Ir concentrations, abundant magnetic grains, microspherules, and carbon spherules similar to assemblages found in the YD boundary layer and conclude that these were deposited either immediately before or soon after the bay was formed.
The Late Quaternary megafaunal extinctions have been discussed for a long time, and human impacts have been proposed as a potential driver, especially in North America. However, coexistence among first humans and now-extinct megafauna has been assessed only by narrative reviews and local evaluations. This paper involves a systematic review of the literature and analyzed data using a formal meta-analytic approach to assess the chronological overlap among earliest humans and now-extinct mammals in the New World under an explicit biogeographical context. Reliable radiocarbon dates indicating First-Appearance of Humans (FAH ages) and Last-Appearance of Megafauna (LAM ages) from South and North American archaeological sites were used to compute the summary effect size. Positive effect sizes indicate the time of human–megafauna coexistence, whereas negative ones indicate lack of coexistence. The findings probabilistically indicate that humans did not coexist with megafauna throughout the New World. Therefore, humans were not the unique driver (if they had any influence) of end-Pleistocene extinctions. Subgroup meta-analyses indicate that non-Sloths, and Proboscideans and non-Proboscideans, already had been extinct when humans arrived in northern South America and Alaska/Canada. Consequently, non-human causes must have been the main driver of Pleistocene extinction in these regions without evidence of human–megafauna coexistence. Thus, assuming that humans had any influence on megafaunal extinction in the other regions of the continent (i.e., where humans and megafauna possibly coexisted), there must be multiple causes, geographically structured, for the late Quaternary extinctions.
The archaeological concepts of association, context, and provenience have been known by archaeologists since the early nineteenth
century, but the terms have not been used. Provenience is empirical and absolute; an association and a context are inferential
and relative. These fundamental concepts have seldom been the subject of thoughtful discussion except when a particular association
or context has implications far beyond the particular instance under study, such as in the context of considerations of claims
for a pre-Clovis occupation of North America. Introductory archaeology textbooks published over the past 100 years do not
always introduce the terms and sometimes fail to define them. Future discussion of the concepts should include several examples
of what qualifies as evidence of an association or context, how the inference of an association or context was derived, and
descriptions of analytical techniques used to determine if an inferred temporal association is valid.
The Ivory Pond mastodon was discovered in June, 1982, in western Massachusetts during a backhoe operation to make a stock pond on the edge of a bog. The recovered material includes several large bone slabs, chunks of ivory, and teeth from a mastodon associated with seeds of Najas flexilis and white spruce cones. Carbon-14 dates of 11,440 +/− 655 years BP (GX-9024-G) and 11,630 +/− 470 years BP (GX-9259) were returned on bone gelatin and white spruce cones respectively. Identification and analysis of pollen, wood, invertebrates, and geological features are still in process.
In the Grand Canyon the greatest vegetational changes of the last 20 000 yr occurred between 14 000-6000 yr BP with peak values between 12 000-8000 yr BP for species flux, and peak values between 10 000 and 6000 BP for change relative to the modern communities. Changes in dominant species show that Wisconsin species departed from some elevational zones before the arrival of Holocene species, suggesting lowered species richness in the interim. This interference was supported by low species numbers recorded in packrat middens between 12 000 and 9000 yr BP. Holocene species invaded within their modern elevational limits, suggesting that the controlling climatic changes had already occurred well before the invasion. These observations may explain the discrepancies between SW paleovegetation records and estimates of the timing of global changes in paleotemperatures. The observed patterns are incorporated into a model of 'vegetational inertia', which suggests that there was a 1000- to 3000-yr lag between elimination of Wisconsin dominants from marginal habitats and subsequent arrival of Holocene dominants. -Author
Calibration of the radiocarbon timescale of paleoecological records is essential if they are to be explained correctly in terms of their governing ecological or climatological controls. The differences between calendar ages and radiocarbon ages that arise from variations in 14C production through time can distort the chronologies of individual records and the interpretations based on them. Misleading impressions of synchrony or diachrony of events among multiple records can result, and estimates of the apparent duration of episodes and rates of sedimentation and local population changes can be biased. Displays of the temporal patterns of migration or extinction may also be affected. Spurious correlations may arise between records with radiocarbon-controlled chronologies and time series of potential controls that are expressed on a calendar time scale. Support for particular explanations of features in a paleoecological record may vary depending on whether radiocarbon ages are calibrated or not. This situation is illustrated using the eastern Beringian Populus subzone as an example. When the radiocarbon ages that control the timing of the Populus subzone are calibrated, the contemporaneous decrease in ice volume and increase in summer insolation are implicated as the ultimate controls of the occurrence of the subzone.
The pulse of large mammal extinctions at the close of the last ice age was a pronounced ecological catastrophe in the Western Hemisphere. Available paleoenvironmental, paleontological, and archeological data are largely concordant with the “overkill” hypothesis proposing that human predation was the cause of these extinctions. Climatic explanations fail to postulate specific mechanisms accounting for the event's timing, differential impact, geographic extent, and stratigraphic singularity. Lack of provisional acceptance of the overkill hypothesis, when no viable alternatives exist, may be in part because this unconventional hypothesis violates a strong sociocultural bias, the image of prehistoric man as the “noble savage”.
It is proposed that outbursts of cosmic ray electrons from the Galactic Center penetrate the Galaxy relatively undamped and are able to have a major impact on the Solar System through their ability to vaporize and inject cometary material into the interplanetary environment. It is suggested that one such ‘superwave’, passing through the Solar System toward the end of the Last Ice Age, was responsible for producing major changes in the Earth's climate and for indirectly precipitating the terminal Pleistocene extinction episode. The high concentrations of 10Be, NO3-, Ir and Ni observed in Late Wisconsin polar ice are consistent with this scenario. The intensities of the Galactic nonthermal radio background and diffuse X-ray emission ridge are shown to vary with Galactic longitude in the same manner as electron intensity along the proposed superwave ‘event horizon’. The high luminosities and unusual structural features which characterize the Crab Nebula and Cassiopeia A are shown to be attributable to the fact that these remnants happen to coincide with this event horizon and are being externally impacted by an intense volley of relativistic electrons travelling from the Galactic Center direction. The same cosmic ray volley is also shown to be able to account for the unusual structure of the extended radio source CTB 80.
Amino acid composition data and stable isotope ratios (14N, D, and13C) are being evaluated as sources of information to indicate the presence of non-indi-genous organics in bone samples intended for 14C analyses. The study is being con-ducted in the context of the planned measurement of Pleistocene bone samples by a high energy mass spectrometric 14C detection system. A list of the problems associated with 14C dating of bone begins with the fact that bone tissue is primarily composed of inorganic constituents. While there are variations between different species as well as between different bones and bone structures within the same animal, generally speaking, the inorganic fraction constitutes about 70 to 80 percent of fresh, dry compact bone (Herring, 1972). Using the most abundant frac-tion in early 14C analyses was reasonable, but it was quickly found that determinations on whole bone samples, which includes an inorganic fraction, usually yielded discordant values (Libby, 1955, p 45; Olson, ms, p 61-65). Experiments using the apatite component in bone have also yielded inconsistent results. Under certain conditions, 14C determina-tions on this fraction seem to yield accurate values (Haynes, 1968). How-ever, geochemical and mineralogic studies revealed a number of mecha-nisms that can significantly alter the carbon isotope values in apatite structures (Hassan, ms; Hassan, Termine, and Haynes, 1977). Such obstacles may not completely exclude use for dating bone as other re-searchers are reporting more encouraging results (Haas and Banewicz, 1980).
All radiocarbon dates from North America, associated with extinct Late Pleistocene mammals, those from levels stratigraphically later than levels with extinct forms, and dates associated with recent fauna are tabulated alphabetically by site. Dates associated with extinct fauna are cross-referenced in an alphabetical listing of species. Dates considered invalid are tabulated and are not utilized in formulating conclusions. Most herding animals, such as the Columbian mammoth, horse, camel, and bison, as well as the dire wolf, rapidly became extinct about 8000 years ago. The dates suggest a southward withdrawal from the Great Plains by the mammoth and a partial contemporaneity of Clovis elephant hunters in southern Arizona with Folsom bison hunters on the Plains. Dates for the extinction of the Imperial mammoth are probably too early. The mastodon may have survived in isolated areas after the extinction of other forms. The super bison may have become extinct earlier than 8000 years ago and Bison bison seems to have been present in some areas before the extinction of B. antiquus. Radiocarbon dates do not support the supposed late survival of the ground sloth. Extinction apparently occurred earlier in the Great Basin and Coahuila than in intervening areas.
Techniques for pragmatically interpreting arrays of radiocarbon dates are given. These include weighted averaging, statistical rejection of data, and the evaluation of contemporaneity. Commonly encountered situations are discussed with several actual examples to illustrate these procedures. This paper is Contribution No. 70, Department of Geosciences, University of Arizona.
The various lobes and segments of the southern periphery of the Laurentide ice sheet reached their maximum extension at different times between 21,000 and 14,000 yr ago, but the CLIMAP date of 18,000 yr ago is taken as a reference level to review the distribution of major vegetational formations in central and eastern United States. Tundra was apparently confined to a narrow belt peripheral to the ice margin only in the Minnesota area and from northern Pennsylvania to New England, with extensions down the crest of the Appalachian Highlands at least as far as Maryland. Some areas south of the Great Lakes may later have been marked by treeless vegetation briefly as the ice retreated. The boreal forest to the south in the central United States was dominated by spruce; the jack pine that had prevailed during previous times was apparently eliminated by the time the ice reached its maximum. In the Appalachian Highlands and the Atlantic Coastal Plain, however, jack pine occurred along with spruce, which decreased in importance southward. The southern limit of the boreal forest in the Southeast was perhaps somewhere in southern Georgia and Alabama. Oak and other temperate deciduous trees were minor components of the boreal coniferous forests especially in the southern Appalacchians, but there is no evidence yet in the southeastern states for a relic mixed mesophytic forest 18,000 yr ago similar to the rich modern deciduous forests of the region, except possibly in the Lower Mississippi Valley. The climate in much of the Southeast was apparently dry as well as cool at that time; in Florida oak/pine scrub and prairie-like openings prevailed, and all but the deepest lakes dried up.
More than 600 late Wisconsin mastodon occurrences are known from the glaciated and periglacial portions of eastern North America. Most of of them have been found in poorly drained lowlands, swamps, and valleys, and on the continental shelf. Of the 28 radiocarbon-dated mastodon bones or associated wood from the entire area of eastern North America, 80 percent are 9,000-12,000 years old. Spruce forests or open woodlands have been indicated by palynologic investigations of 18 mastodon sites; wood or cones of spruce and trees associated with spruce forests have been found at ten sites. This evidence and the distribution pattern of mastodons near the northern boundary of the area of their occurrences suggest that the mastodons of eastern North America were associated with open spruce woodlands or spruce forests. Their extinction was probably initiated by the rapidly increasing dryness 10,000-11,000 years ago, which caused first the retreat of the spruce forests into the moister lowlands and finally their disappearance from the area occupied by mastodons. A migration of mastodons from the relict spruce enclaves toward the more northerly located spruce forests was hampered because these two areas were probably separated by a rapidly expanding belt of pine and hardwood forests over the better-drained morainic, kame, and dune areas in the Great Lakes Region.
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.
Excavation at Taima-taima in 1976 recovered artifacts of the El Jobo complex in direct association with the butchered remains
of a juvenile mastodon. Radiocarbon dates on associated wood twigs indicate a minimum age of 13,000 years before the present
for the mastodon kill, a dating significantly older than that of the Clovis complex in North America. The El Jobo complex
must have evolved independently in northern South America.
I propose a new scenario for the discovery of America. By analogy with other successful animal invasions, one may assume that the discovery of the New World triggered a human population explosion. The invading hunters attained their highest population density along a front that swept from Canada to the Gulf of Mexico in 350 years, and on to the tip of South America in roughly 1000 years. A sharp drop in human population soon followed as major prey animals declined to extinction. Possible values for the model include an average frontal depth of 160 kilometers, an average population density of 0.4 person per square kilometer on the front and of 0.04 person per square kilometer behind the front, and an average rate of frontal advance of 16 kilometers per year. For the first two centuries the maximum rate of growth may have equaled the historic maximum of 3.4 percent annually. During the episode of faunal extinctions, the population of North America need not have exceeded 600,000 people at any one time. The model generates a population sufficiently large to overkill a biomass of Pleistocene large animals averaging 9 metric tons per square kilometer (50 animal units per section) or 2.3 x 10(8) metric tons in the hemisphere. It requires that on the front one person in four destroy one animal unit (450 kilograms) per week, or 26 percent of the biomass of an average section in 1 year in any one region. Extinction would occur within a decade. There was insufficient time for the fauna to learn defensive behaviors, or for more than a few kill sites to be buried and preserved for the archeologist. Should the model survive future findings, it will mean that the extinction chronology of the Pleistocene megafauna can be used to map the spread of Homo sapiens throughout the New World.
Prehistoric overkill Pleis-tocene Extinctions: The Search for a Cause
- P S Martin
Martin, P. S. (1967). Prehistoric overkill. In " Pleis-tocene Extinctions: The Search for a Cause " (P. S. Martin and H. E. Wright, Eds.), pp. 75-120. Yale Univ. Press, New Haven, Conn.
Radiocarbon: Some notes from Merlin's diary Amerinds and Their Paleoenvironments in Northeastern North Amer-ica
- R Stuckenrath
Stuckenrath, R. (1977). Radiocarbon: Some notes from Merlin's diary. In " Amerinds and Their Paleoenvironments in Northeastern North Amer-ica " (W. Newman and B. Salwen, Eds.), pp. 181-188. Annuls of the New York Academy of Sci-ences 288.
Earliest man in the New World and its implications for Soviet-American archaeology
- MacNeish
MacNeish, R. S. (1979). Earliest man in the New World and its implications for Soviet-American ar-chaeology. Arctic Anthropology 16, 2-15.
Paleolithic players on the American stage: Man's impact on the Late Pleistocene megafauna
- Martin
Martin, P. S. (1974). Paleolithic players on the Ameri-can stage: Man's impact on the Late Pleistocene megafauna. In " Arctic and Alpine Environments " (.I. Ives and R. G. Barry. Eds.), pp. 669-700. Meth-uen, London.
Differential extinction during late Pleistocene and Recent times
- Guilday
Paleoclimates and Late Pleistocene faunal provinces in North America
- Graham