SAO PAULO (AP) — Sloths weren’t always slow-moving, furry tree-dwellers. Their prehistoric ancestors were huge — up to 4 tons (3.6 metric tons) — and when startled, they brandished immense claws. For a long time, scientists believed the first humans to arrive in the Americas...
After the recent discovery of a destructive mussel in the Sacramento-San Joaquin River Delta, some experts say California officials have failed to effectively enforce laws designed to protect waterways from invaders carried in ships’ ballast water. A state law enacted 20 years ago...