These giant felines are the world's fastest land animals. Here's why.

Many mammals deliver in minutes after long pregnancies. See which species have the quickest births to help newborns thrive.

For 35 years, American zoologist Laurie Marker has been collecting and storing specimens in a cheetah sperm bank in Namibia, hoping conservationists never have to use them. But she worries that the ...

CAPE TOWN, South Africa (AP) — For 35 years, American zoologist Laurie Marker has been collecting and storing specimens in a cheetah sperm bank in Namibia, hoping conservationists never have to use ...