Elephant foot CT scan
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Elephant's sixth 'toe' revealed by CT scan

A mysterious bony growth found in elephants' feet is actually a sixth "toe", scientists report.

For more than 300 years, the structure has puzzled researchers, but this study suggests that it helps to support the elephant's colossal weight.

Fossils reveal that this "pre-digit" evolved about 40 million years ago, at a point when early elephants became larger and more land-based.

The research is published in the journal Science.