Fossil footprints suggest early humans walked in North America 23,000 years ago

Fossilised human footprints were found at the White Sands National Park in New Mexico (NPS/AP)

Fossilised footprints discovered in New Mexico indicate that early humans were walking across North America around 23,000 years ago, researchers said.

The first footprints were found in a dry lake bed in White Sands National Park in 2009.