The passenger pigeon was once the most numerous bird in the world, but in just half a century, it had gone extinct.

About 40,000 years ago, giant kangaroos vanished Down Under. Dental analyses suggest a varied diet, meaning climate change was not the main cause.

South Africa scientists claim they have carried out the revival of an extinct zebra-like mammal known as the quagga.

It’s heartbreaking that a species that outlived the dinosaurs now faces extinction at human hands,” said Melissa Cancino, ...