For 170 years, one crucial part of Arthropleura stayed hidden. Now, scans inside a fossil from France have exposed details that change what this giant prehistoric arthropod really looked like. The fossil measured only 4 centimeters, nowhere near the giants that made Arthropleura famous. Yet this small specimen, found at Montceau-les-Mines in France, ended up yielding one of the missing pieces of the puzzle. For more than a century and a ha... [4831 chars]