When you start cataloguing the natural wonders of the world, Los Angeles, California, which is known for its artifice, glitz and traffic jams, probably isn't what comes first to mind.
But, Los Angeles is home to the La Brea Tar Pits which have produced: "Hundreds of thousands of fossils of Late Pleistocene animals and plants have been recovered at this one site." It is the most productive fossil dig in the world and has produced bones of animals (many extinct) that range from 50,000 years old to a few centuries old. An astonishing 70% are carnivores because "an herbivore ended up trapped in the sticky tar, and was feasted upon by carnivores, which then themselves ended up getting stuck too."
Twilight Beasts has an excellent profile piece on the site.