Mole skull and paw showing 6th digit, X-ray

Direct X-ray projection of a mole (Talpa europaea) skull and paw onto Fine-Grain X-ray film. The projection was then enlarged from 50 mm to 150 mm using a Microfocal X-ray. Moles are mammals which spend most of their time burrowing tunnels underground. They have a 6th digit on each front paw which is in fact a wrist bone which has extended like a claw. It is thought to develop later than the other 5 digits and helps the mole dig.