Cretaceous saber-toothed dryolestoid "squirrel" Cronopio from Argentina demonstrates that the evolution of enlarged stabbing teeth
http://news.sciencemag.org/sciencenow/2012/04/ice-age-ankle-biters.html
I forgot about the date)... but remembered as soon as I saw that the "teeth" were emerging from the animal's NOSTRILS (wait, what?!). :-D
-- Donna Braginetz