Dr. Larry Agenbroad (Northern Arizona University), principal investigator of Mammoth Graveyard, recently published a popularized account of historic and modern research on mammoths. In Mammoths: Ice Age Giants, Agenbroad and co-author Lisa Nelson describe the origins and evolution of these prehistoric beasts, many of which weighed as much as a semi truck and had tusks ten feet long. Mammoths reined over the land for more than three million years, and the authors explain what we know about how these fascinating animals lived. Most importantly, Mammoths describes how scientists have learned what they know about these prehistoric ancestors of elephants, historically and today. This includes the excavation of the largest collection of Columbian mammoth bones in the world in Hot Springs, South Dakota, where Earthwatch volunteers on Mammoth Graveyard have assisted Agenbroad for 21 years. Written for a high school-level readership, Mammoths is a valuable addition to popular knowledge of the geologic past

Voyage of the Turtle: In Pursuit of the Earth's Last Dinosaur. Carl Safina. Henry Holt and Company, 2006.