Which came first, the nail or the claw?
The answer is unclear, but researchers have discovered a clue: an early primate that had a toe bone with features of both a grooming claw and a nail.
A fossil of the 47-million-year-old primate, Notharctus tenebrosus, had a lemur-like grooming claw on its second digit, but it was flattened, a bit like a nail, according to a new study in the journal PLoS One.
Read more: http://www.nytimes.com/2012/01/17/science/primate-fossil-adds-to-claw-toenail-debate.html?_r=1