Michael Marshall, environment reporter
(Image: Bruce Archibald)
Giant ants that were almost as large as modern hummingbirds invaded Wyoming 50 million years ago.
The newly-discovered Titanomyrma lubei was 5 centimetres long. That compares with the modern-day Rufous hummingbird seen next to it in the photo.
Nowadays ants this large are found only in the tropics, according to Bruce Archibald of Simon Fraser University in British Columbia, Canada and colleagues, who analysed the fossil. Archibald thinks T. lubei crossed to America from Europe via the Arctic. Earth was much warmer 50 million years ago, and temporary spikes in temperature could have briefly given the Arctic a tropical climate.