scuba diving
© Donald Miralle / Getty Images North America / AFP
An array of ancient animal and human bones including a wolf-like dog, elephant-like animals, sabertooth cats and other strange creatures have been found buried in an ancient graveyard at the bottom of an underwater cave in Mexico.

hoyo negro cave
© Roberto Chavez / Mexican National Anthropology and History Institute / AFP
Scientist looks at 12,000 year old bone of a teenage girl in the Hoyo Negro (Black Hole) cave in Tulum, Mexico
Experts say the "underworld of exquisitely preserved fossils" includes human remains that are over 12,000 years old and the skull of a large, short-faced bear. The Hoyo Negro pit is a natural time capsule from the Late Pleistocene era. Before it was underwater, animals would fall 60 meters into the cave to their deaths.

hoyo negro cave
© Roberto CHAVEZ / INAH / AFP
Divers collect bones in the Hoyo Negro cave in Tulum, Mexico, 2012