More than 99 percent of all life forms have gone extinct during the 3.6-billion-year history of life on Earth. Other organisms have changed dramatically, but not our extreme survivors. Evolution may have altered their physiology and behavior, but their body plans have stood the test of time. How have these living links with Earth's prehistoric past survived? The search for answers is leading scientists to new discoveries about the past--and future--of life on Earth. The survival secrets of some of these ancient creatures could lead to new medicines and treatments for disease.   Written in a lively, entertaining voice, Extreme Survivors provides detailed life histories and strange "survival secrets" of ten ancient animals and explains evolution and natural selection. Extensive back matter includes glossary, additional facts and geographic range for each organism and a geologic timeline of Earth.