To understand what factors control species colonization and extirpation within specific paleoecos... more To understand what factors control species colonization and extirpation within specific paleoecosystems, we analyzed radiocarbon dates of megafaunal mammal species from New York State after the Last Glacial Maximum. We hypothesized that the timing of colonization and extirpation were both driven by access to preferred habitat types. Bayesian calibration of a database of 39 radiocarbon dates shows that caribou (Rangifer tarandus) were the first colonizers, then mammoth (Mammuthus sp.), and finally American mastodon (Mammut americanum). The timing of colonization cannot reject the hypothesis that colonizing megafauna tracked preferred habitats, as caribou and mammoth arrived when tundra was present, while mastodon arrived after boreal forest was prominent in the state. The timing of caribou colonization implies that ecosystems were developed in the state prior to 16,000 cal yr BP. The contemporaneous arrival of American mastodon with Sporormiella spore decline suggests the dung fungus spore is not an adequate indicator of American mastodon population size. The pattern in the timing of extirpation is opposite to that of colonization. The lack of environmental changes suspected to be ecologically detrimental to American mastodon and mammoth coupled with the arrival of humans shortly before extirpation suggests an anthropogenic cause in the loss of the analyzed species.
Background/Question/Methods It is not clear how North America's Pleistocene megafauna became ... more Background/Question/Methods It is not clear how North America's Pleistocene megafauna became extinct. Fossil remains of this vanished community are abundant in the wetlands of Orange County NY, where they are usually found in well-stratified fine sediments rich in microfossils. This formally-glaciated region was just under the southern edge of the Wisconsinan ice sheet at last glacial maximum. As such, it frames the extinction window, thus providing an opportunity to study the timing and pattern of an extinction process that appears to have been complete by 11,000 radiocarbon years before present (14CyrBP). We report two recent finds and their paleoenvironmental context. Among a number of previously accelerator mass spectrometry (AMS) -dated specimens of the local Pleistocene fauna, these appear at the temporal boundaries of the extinction event for this region: a stag-moose (Cervalces scotti) discovered eroding from the side of a drainage ditch beside a fallow field of the Blac...
The Champlain Sea, the most recent interior seaway of northeastern North America, resulted from l... more The Champlain Sea, the most recent interior seaway of northeastern North America, resulted from late Pleistocene recession of the Laurentide Ice Sheet (LIS) and subsequent isostatic depression of the Champlain and St. Lawrence valleys (Gadd, 1988; Rayburn et al., 2007; Cronin et al., 2008, 2012). This sea existed for about 4000 years, from 13.1 to 9.0 ka (Cronin et al., 2008), and Champlain Sea sediments contain abundant marine microfauna (e.g., foraminifera, ostracods; Cronin, 1988; Hunt and Rathburn, 1988) and macrofauna (e.g., bivalves, mammals; Harington, 1988; McAllister et al., 1988; Rodrigues, 1988). Here we report the discovery of a new specimen of phocid seal from southern Champlain Sea sediments (Fig. 1), and its age. We also report the age of a previously described Phoca vitulina (harbor seal) from a nearby locality (Ray, 1983), and discuss the paleoenvironmental implications of the geographic location and ages of these two phocid specimens.
To understand what factors control species colonization and extirpation within specific paleoecos... more To understand what factors control species colonization and extirpation within specific paleoecosystems, we analyzed radiocarbon dates of megafaunal mammal species from New York State after the Last Glacial Maximum. We hypothesized that the timing of colonization and extirpation were both driven by access to preferred habitat types. Bayesian calibration of a database of 39 radiocarbon dates shows that caribou (Rangifer tarandus) were the first colonizers, then mammoth (Mammuthus sp.), and finally American mastodon (Mammut americanum). The timing of colonization cannot reject the hypothesis that colonizing megafauna tracked preferred habitats, as caribou and mammoth arrived when tundra was present, while mastodon arrived after boreal forest was prominent in the state. The timing of caribou colonization implies that ecosystems were developed in the state prior to 16,000 cal yr BP. The contemporaneous arrival of American mastodon with Sporormiella spore decline suggests the dung fungus spore is not an adequate indicator of American mastodon population size. The pattern in the timing of extirpation is opposite to that of colonization. The lack of environmental changes suspected to be ecologically detrimental to American mastodon and mammoth coupled with the arrival of humans shortly before extirpation suggests an anthropogenic cause in the loss of the analyzed species.
Background/Question/Methods It is not clear how North America's Pleistocene megafauna became ... more Background/Question/Methods It is not clear how North America's Pleistocene megafauna became extinct. Fossil remains of this vanished community are abundant in the wetlands of Orange County NY, where they are usually found in well-stratified fine sediments rich in microfossils. This formally-glaciated region was just under the southern edge of the Wisconsinan ice sheet at last glacial maximum. As such, it frames the extinction window, thus providing an opportunity to study the timing and pattern of an extinction process that appears to have been complete by 11,000 radiocarbon years before present (14CyrBP). We report two recent finds and their paleoenvironmental context. Among a number of previously accelerator mass spectrometry (AMS) -dated specimens of the local Pleistocene fauna, these appear at the temporal boundaries of the extinction event for this region: a stag-moose (Cervalces scotti) discovered eroding from the side of a drainage ditch beside a fallow field of the Blac...
The Champlain Sea, the most recent interior seaway of northeastern North America, resulted from l... more The Champlain Sea, the most recent interior seaway of northeastern North America, resulted from late Pleistocene recession of the Laurentide Ice Sheet (LIS) and subsequent isostatic depression of the Champlain and St. Lawrence valleys (Gadd, 1988; Rayburn et al., 2007; Cronin et al., 2008, 2012). This sea existed for about 4000 years, from 13.1 to 9.0 ka (Cronin et al., 2008), and Champlain Sea sediments contain abundant marine microfauna (e.g., foraminifera, ostracods; Cronin, 1988; Hunt and Rathburn, 1988) and macrofauna (e.g., bivalves, mammals; Harington, 1988; McAllister et al., 1988; Rodrigues, 1988). Here we report the discovery of a new specimen of phocid seal from southern Champlain Sea sediments (Fig. 1), and its age. We also report the age of a previously described Phoca vitulina (harbor seal) from a nearby locality (Ray, 1983), and discuss the paleoenvironmental implications of the geographic location and ages of these two phocid specimens.
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