Recent article about the La Brea Tar Pits in the NYTimes:
... The tar pits have so many fossils precisely because of the tar, which one can still see bubbling to the surface in spots throughout Hancock Park. The gooey asphalt that trapped and entombed the animals turns out to be a great preservative. Thousands of perfect skulls and nearly complete skeletons representing more than 200 vertebrate species have been retrieved from the death trap.
Among them are many giant beasts, including mammoths, mastodons and the short-faced bear. (Only its snout was short; the bear stood more than 11 feet tall, much larger than today’s grizzly, polar and brown bears.) There are two species of bison — one of them with seven-foot horns — and some animals not typically associated with North America, including camels that stood taller than modern dromedaries....