• 13 million years ago, a medium-sized monkey known for guarding its territory among the treetops with a fearsome “howl” started doing something new. This monkey, one of the oldest known ancestors of ...

13.3-million–13.6 million-year-old fossils from an extinct relative of the howler monkey show signs of being the first leaf-eating primate in South and Central America. Fossils from jaws of Stirtonia ...