The La Brea Tar Pits in Los Angeles are the site of millions of fossils from the ice age. Woolly mammoths, giant sloths, dragonflies, and other plants and animals from this era have been found in these pits. Scientists at the tar pits discovered that many of the smaller animals they extracted from the pits still exist around Los Angeles today. But many of the larger mammals-such as woolly mammoths and saber-toothed tigers-are now extinct. Why do you think this is the case? What can scientists learn about Los Angeles' climate history by studying the specimens found in these tar pits?

The ice age was a period during which the average temperatures on the globe dropped significantly, in a short geological time. We know that large animals have a big volume to surface ratio so that they do not have as many problems with regulating heat in cold conditions as smaller animals; they have proportionally less surface, hence there are fewer ways for them to lose heat. Thus, large animals are well-suited for the ice age. A major factor in the extinction of such animals is a hotter climate since this makes heat regulation in the animal very hard (the animal cannot cool itself). Thus, given the findings, one can infer periods of rising temperatures in LA by the fossil record.