Megafauna By: Laura Provost Pasquale Quintero Jr.

Species  About 48 species of Megafauna lived in North America during the Pleistocene Epoch  Mammoth  Mastodon  Saber-Toothed Cats  Giant Sloth  Short Faced Bear  Dire Wolf, etc.

Species

Mammoth  Genus Mammuthus  Three species of mammoth: Columbian Mammoth, Jefferson’s Mammoth, Woolly Mammoth  feet high  Weighed between 6-8 tons  1.8 mya first mammoths entered into North America  10 kya, all species of mammoth went extinct

Mastodon  Mammut americanum  8-10 feet high  Weighed between 4-6 tons  Lived in North America from about 3.7 mya to 10 kya

Saber-Toothed Cats  Two species lived in North America: Saber tooth genus: Smilodon, and Scimitar cat genus: Homotherium

Saber Tooth Cat  Canines were 7 inches long  Size of modern African lion, but anatomically different  Short, powerful legs  Not built to run fast or far  One possible use for canines: bite throat or abdomen of large prey  Other use for canines: as a social display  Went extinct 11 kya

Scimitar Cat  Canines 4 inches long  About the size of modern African lion, but anatomically different  Long forelimbs, long neck, and short, powerful hind legs  Combined strength and speed  Chased more prey than the Saber Tooth  Went extinct 11 kya

Giant Sloth  Four species of ground sloths in North America  Jefferson’s ground sloth, Laurillard’s ground sloth, Shasta ground sloth, and Harlan’s ground sloth

Ground Sloths  Spent all of their time on the ground, unlike modern sloths  About the size of an oxen  Very large claws  All were herbivores  Went extinct about 10 kya

Short Faced Bear  Extremely large, weighed 13 hundred pounds  Approximately feet tall  Went extinct 11 kya

Dire Wolf  Belonged to genus Canis, includes: wolves, coyotes, jackals, and domestic dogs  About 5 feet long  Weighed about 110 pounds  Looked familiar to modern grey wolf, but had larger, broader head and shorter legs, teeth were more massive  Teeth may have been used to crush bones  Went extinct about 10 kya

Pleistocene  Pleistocene Epoch followed the Pliocene Epoch  Transition marked by decrease in rainfall linked with the spread of ice at high latitudes  Pleistocene began when ice started to cover a large part of northern hemisphere  Ice built up because as the northern continents drifted to higher latitudes they sealed off the flow of warm water into the artic ocean, causing the top of the ocean to freeze  Once frozen it reflected incoming solar heat away in the summer and caused artic weather in surrounding areas

Origins  Megafauna crossed a glacial land bridge connecting Siberia and North America  12 kya humans migrated from Asia into the new world

Megafauna Extinctions  48 species went extinct at the end of the Pleistocene Epoch (11 kya) weighing over 20 pounds; three of every four species of megafauna greater than a 100 pounds went extinct  For the next 10 kya not a single mammalian species went extinct from North America  Scientists believe there are two major factors for extinction of the megafauna  Climate hypothesis vs. Overkill hypothesis

Climate hypothesis  Habitat destruction is one of the major causes of extinction  About kya the climate in North America was changing  Temperatures were warming, rainfall patterns changed, glaciers were melting, and seasonal changes were increasing  The more open diverse forest and nutritional substances were being replaced by denser forest with little diversity and nutritional value  This forced many megafauna species to leave their habitats because the new environments had lower carrying capacities for the large mammals  The megafauna could not adapt to the changes in their environment

Climate Hypothesis  Scientists believe that there is not enough evidence to support the Overkill hypothesis  Only 15 sites containing Clovis points have been found in North America  Kill sites containing Clovis points all contain either Mammoth or Mastodon bones, but there is no evidence of early Americans hunting other large mammals such as ground sloths, short faced bear, etc. which also went extinct

Overkill Hypothesis  Animal populations were not evenly distributed through out North America  The route taken by early Clovis through the Bering Land Bridge brought them out directly in the middle of the range of the megafauna  Mammoth and Mastodon killings led to an environmental collapse for smaller megafauna  After extinction of large megafauna humans had to rely on smaller animals, such as deer

Overkill Hypothesis  The only two other predators of the mammoth and mastodon, besides man were the saber tooth tiger and short face bear, both of which went extinct 1 kya years before  “Records from islands show that human colonists cause extinction; therefore, Clovis people caused extinction.” –Retired University of Arizona Ecologist, Paul Martin

Disease Hypothesis  Clovis hunters or their dogs carried with them a deadly microbe  Larger species (megafauna) cannot replace their offspring fast enough  Smaller animals that breed often survived

Sources  Gribbin, John and Mary. Children of the Ice: Climate and Human Origins. Cambridge, MA: Basil Blackwell,  Stone, Richard. Mammoth: The Resurrection of an Ice Age Giant. Cambridge, MA: Perseus,  Ward, Peter D. The Call of Distant Mammoths: Why the Ice Age Mammals Disappeared. New York: Copernicus,  l l l    shtml shtml shtml  archive/k html archive/k html archive/k html