Use the Table Below to Answer the Questions That Follow

Name: ______Date:______Period:______

Geologic Time Scale – Unit 2 Study Guide 2

Use the table below to answer the questions that follow.

1.  The earliest known birds appeared about 160 million years ago. When did this occur in the geologic time scale?

2.  The oldest rocks in California, which are more than 1,000 million years old, are located in the eastern deserts and the eastern Transverse Ranges (San Bernardino and San Gabriel Mountains). When were these rocks formed?

3.  Between 1,000 and 400 million years ago, all was quiet in western North America with its coastline east of California, probably in Utah and Idaho. But then about 75 million years ago the oceanic crustal material in the Franciscan formation was thrust up against the Sierran block, extending the boundary of the North American plate further west. When did this occur in the geologic time scale?

4.  An ancient sea star estimated to be 8.5 million years old was found when excavating during building construction in LA a few years ago. When was this sea star alive in terms of geologic time?

5.  The renowned Ice Age occurred during the Pleistocene (1.8 million to 10,000 years ago). Most of the northern continents were covered by enormous glaciers or ice sheets. Beginning 1.7 million years ago, ice sheets began to develop on the highlands in North America and Europe and spread over the northern half of North America and a quarter of Eurasia. When did the Pleistocene Ice Age occur?

6.  Mastodons originated in Africa and migrated to North America about 15 million years ago where they survived until the end of the last Ice Age about 10,000 years ago. In terms of geologic time, when did the Mastodons migrate to North America?

7.  A team of paleontologists from the American Museum of Natural History and their colleagues have described the oldest, most complete fossil skeleton yet found of a primitive rabbit. The 55-million-year-old fossil animal, named Gomphos elkema is the oldest complete skeleton by about 20 million years and shows that some early lagomorphs, the group of animals that includes rabbits and hares, had a surprisingly modern, rabbit-like way of moving around. What was the period and era during which this rabbit ancestor lived?

8.  An American Museum of Natural History entomologist has described the oldest spider web—a rare 110-million-year-old fossil preserved in a pencil-thin rod of amber along with the insect and arachnid prey snagged by the silk. It is uncommon to find fossilized spiders or their silk. In this case, the amber preserved 26 silk strands (many connected to one another), glue droplets produced by the spider to better trap insects, and a diverse array of prey captured in the web, including a fly, a mite, a beetle, and a wasp. When was this spider on the hunt in terms of the geologic time scale?

9.  The first reptiles appeared on land about 285 million years ago, when did this occur in terms of the geologic time scale?

10.  Land plants developed about 400 Ma and spread quickly over the continents because there was little competition. When did this occur in geologic time?

11.  During the end of this era 90% of all life on Earth died out. This era is the ______Era.

12.  This period is known as the Age of the Fish when fish became abundant between 417 mya and 354 mya. When did this period occur in the geologic time scale?

13.  Dinosaurs first appeared on Earth about 215 million years ago. When did this occur in the geologic time scale?

14.  Dinosaurs became extinct about 65 million years ago. When did this occur in the geologic time scale?

15.  The Cretaceous, Jurassic, and Triassic are all periods in the ______Era.

16.  Humans and their ancestors have been around for about 4 million years. When did this occur in the geologic time scale?

17.  Humans with modern features appeared about 100,000 years ago. When did this occur on the geologic time scale?