Extinct Animals of North America Poster Extinct mammals of North America primarily consist of Pleistocene megafauna that vanished approximately 10,000–13,000 years ago, including mammoths, mastodons, saber-toothed cats, dire wolves, and giant ground sloths. These species, often hunted by early humans, died out due to a combination of rapid climate change and overhunting, also known as the overkill hypothesis. For more information on the Extinct Animals of North America visit: A-Z Animals, Live Science, and The History Channel  as they offer guides, species lists, and identification tips. The Extinct Animals of North America Poster is a colorful collage of scientifically accurate illustration of various types of extinct North American Mammals. The artistic design is complete with both common and scientific names. The poster is shipped in a sturdy 2″ mailing tube with plastic endcaps. The posters can be signed or customized by the artist upon request.