Return to Book List Grade 2   Clues from the Past   Life Today     When the needs of animals are not met, they may die.   Just like the dinosaurs from the Mesozoic era, some animals of the Cenozoic era became extinct when their needs were not met.   Even today, some living things become extinct when they can not live with changes on Earth.   Living things can die out from natural causes, such as sickness.   Plants and animals can die because of changes to their homes that are caused by people.   Many modern plants and animals are close to becoming extinct.   Living things that are close to becoming extinct are called endangered.   Today, pitcher plants and West Indian manatees are endangered.   People need to help keep safe the places where plants and animals live, so they do not die out.