mirrored file at http://SaturnianCosmology.Org/ For complete access to all the files of this collection see http://SaturnianCosmology.org/search.php ========================================================== [1][BACK] [2]Change Colors [3]358 Scores [4]358 Calendar [5]Heywood Courses [6]Office [7]Searches [8]Organizations [9]Periodicals [10]News [11]Web Sites [12]Style [13]Web Weavers [14]Base Maps [15]UWSP Geo Dept [16]UWSP Campus PLEISTOCENE EXTINCTIONS [17]Causes [18]Endangerment [19]Pleistocene Timing [20]Pleistocene Origin [21]101 Calendar [22]Historical Era [23]Birds Map [24]Mammals Map [25]References [26]358 Calendar There are significant obstacles to explaining the mass disappearance of organisms at the end of the last "Ice Age". One is that the extinctions do not coincide well with the timing of major environmental changes. The graph below shows large mammal extinctions (just for North America), yet the peak does not coincide closely with the last glacial maximum, the Bering land bridge, the arrival of humans, or development of societies. A second problem (not obvious in the graph below) is the selectivity of extinctions; only large carnivorous and scavenging birds suffered similar losses--few plants, smaller mammals, reptiles, fish, insects, or smaller birds disappeared during the late Pleistocene extinctions. [27]North America Pleistocene Mammal Extinctions adapted from [28]Piliou, E. C. (1991) and others [29][BACK] _________________________________________________________________ A third challenge to explanation is a geographic discrepancy between Pleistocene extinction waves at separate locations. The timing map below indicates that apparent peaks of disappearance for large animals differed between continents, which implies regional, biome, or realm-centered rather than global triggers. [30]World Pleistocene Extinction Timings [31][BACK] _________________________________________________________________ And as if any explanation is not elusive enough, there is further the discrepancy between the origin of the survivors versus that of the lost. Among North American Pleistocene large mammals, the listing below suggests an enormous inequity in likelihood for becoming extinct, and high incidence appears strongly associated with North American origin (or presence exceeding one million years). Few Old World origin newcomers" disappeared; many New World large mammals did. The selectivity is suggestive of differential resistance to some pathogen, and there is at least some parallel to the catastrophic declines of Native Americans following the arrival of Europeans during the 15th Century. [32]Origin Extinction Disparity compiled from [33]Kurten, B. (1988) and others For the present, the unsatisfying conclusion is that we do not truly know--and we may never know--what caused the selective and uncoordinated late Pleistocene extinction wave. If there ever is an "answer", it likely shall invoke some synergistic effect of several (if not all) of the factors that various researchers have proposed. [34]Causes [35]Endangerment [36]Pleistocene Timing [37]Pleistocene Origin [38]101 Calendar [39]Historical Era [40]Birds Map [41]Mammals Map [42]References [43]358 Calendar [44][BACK] [45][Next] You are visitor # to this Web page since 30AUG01. [46]N. C. Heywood maintains this page, last updated 30AUG01. References 1. javascript:backhistory() 2. javascript:WinOpenChgColor() 3. http://www.uwsp.edu/geo/faculty/heywood/Geog358/endangr/Endangr/Scores.htm 4. http://www.uwsp.edu/geo/faculty/heywood/Geog358/endangr/Endangr/Calendar.htm 5. http://www.uwsp.edu/geo/faculty/heywood/Geog358/endangr/Util/Courses.htm 6. javascript:WinOpenTextOffi() 7. javascript:WinOpenSearches() 8. javascript:WinOpenOrganizations() 9. javascript:WinOpenPeriodicals() 10. javascript:WinOpenNews() 11. javascript:WinOpenWebSites() 12. javascript:WinOpenStyle() 13. javascript:WinOpenWebWeave() 14. javascript:WinOpenMaps() 15. javascript:WinOpenGEO() 16. javascript:WinOpenUWSP() 17. http://www.uwsp.edu/geo/faculty/heywood/Geog358/endangr/ExtCause.htm 18. http://www.uwsp.edu/geo/faculty/heywood/Geog358/endangr/Endangr/endanger.htm 19. http://www.uwsp.edu/geo/faculty/heywood/Geog358/endangr/Pleistocene/PleistoExt.htm 20. http://www.uwsp.edu/geo/faculty/heywood/Geog358/endangr/Pleistocene/PleistoExt.htm 21. http://www.uwsp.edu/geo/faculty/heywood/Geog101/101syll5.htm 22. http://www.uwsp.edu/geo/faculty/heywood/Geog358/endangr/HistExti.htm 23. http://www.uwsp.edu/geo/faculty/heywood/Geog358/endangr/extinctb/extinctb.htm 24. http://www.uwsp.edu/geo/faculty/heywood/Geog358/endangr/extinctm/extinctm.htm 25. http://www.uwsp.edu/geo/faculty/heywood/Geog358/endangr/Reference/EndExtRf.htm 26. http://www.uwsp.edu/geo/faculty/heywood/Geog358/Calendar.htm 27. file://localhost/www/saturnian/files/extinction/PleistoExt.htm#regiontiming 28. http://www.uwsp.edu/geo/faculty/heywood/Geog358/endangr/Reference/EndExtRf.htm 29. javascript:backhistory() 30. file://localhost/www/saturnian/files/extinction/PleistoExt.htm#origindisparity 31. javascript:backhistory() 32. http://www.uwsp.edu/geo/faculty/heywood/Geog358/endangr/HistExti.htm 33. http://www.uwsp.edu/geo/faculty/heywood/Geog358/endangr/Reference/EndExtRf.htm 34. http://www.uwsp.edu/geo/faculty/heywood/Geog358/endangr/ExtCause.htm 35. http://www.uwsp.edu/geo/faculty/heywood/Geog358/endangr/Endangr/endanger.htm 36. http://www.uwsp.edu/geo/faculty/heywood/Geog358/endangr/Pleistocene/PleistoExt.htm 37. http://www.uwsp.edu/geo/faculty/heywood/Geog358/endangr/Pleistocene/PleistoExt.htm 38. http://www.uwsp.edu/geo/faculty/heywood/Geog101/101syll5.htm 39. http://www.uwsp.edu/geo/faculty/heywood/Geog358/endangr/HistExti.htm 40. http://www.uwsp.edu/geo/faculty/heywood/Geog358/endangr/extinctb/extinctb.htm 41. http://www.uwsp.edu/geo/faculty/heywood/Geog358/endangr/extinctm/extinctm.htm 42. http://www.uwsp.edu/geo/faculty/heywood/Geog358/endangr/Reference/EndExtRf.htm 43. http://www.uwsp.edu/geo/faculty/heywood/Geog358/Calendar.htm 44. javascript:backhistory() 45. http://www.uwsp.edu/geo/faculty/heywood/Geog358/endangr/HistExti.htm 46. mailto:nheywood at uwsp.edu