Our time machine goes back to prehistory in this extract from our new book, How To Find Old Los Angeles.

It doesn’t get much more Old L.A. than the last ice age, when extinct megafauna with jazzy names like dire wolf, saber-toothed cat and mastodon ambled along the dirt trail that we know today as Wilshire Boulevard. Sometimes they’d stop to drink at the cool reflecting pools, unaware that beneath the sheen of rainwater lurked pits of deadly, semi-liquid oil. Thousands of animals were trapped and sank beneath the surface, where their bones turned to stone. Today, you can peep into the working excavation pits where paleontologists painstakingly extract interesting bits from the tar matrix, or tour the 1960s-era Page Museum with its world class fossil collection. But be alert while roaming the park grounds: tar continues to bubble up through the earth, and while you’re unlikely to be trapped, you might just wreck your sneakers.