Exam 19: The Evolutionary History of Life

The extinction of dinosaurs caused an end to the _______ between them and the mammals, thus allowing mammals to evolve to fill some ecological roles the dinosaurs had previously filled.

After the extinction of the dinosaurs the adaptive radiation of _______ set the stage for the eventual evolution of humans.

During the time of Pangaea (left in the figure below), an ancestor of modern crocodiles inhabited the region marked by the star in this map. Where would you expect to find fossils of this animal today (the map on the right)?

For insects, could there be a connection between being the first organism to fly and being the most diverse terrestrial organism today?

Many organisms decompose rapidly after death; some organisms had soft bodies; and some areas where organisms died have undergone massive geologic changes. For these reasons, the ______ record is incomplete.

The evolution of higher taxonomic groups occurs in the same way as the evolution of populations.

Descendants of _______ were among the first organisms to colonize land.

The Cambrian explosion resulted in the evolution of more than 17, 000 species of an animal known as the trilobite. The shear number of trilobite fossils found in modern times suggests that trilobites were very abundant, perhaps the rulers of the seas. Today, no living descendants of this group exist. What happened?

Why might many new species form in the aftermath of a mass extinction?

The first mammals

You are looking at the side of a cliff with many clearly visible layers of rock. In the top layer you find the fossil of a mouse. In the next layer down you find the fossil of a frog. Two layers down from that you find the fossil of a beetle, and in the deepest layer the fossil of a millipede. This is evidence that

Oxygen was one of the original gases in abundant in Earth's atmosphere before the evolution of life.

The earliest forms of life evolved and lived in _______.

Which of the following statements about the fossil record is true?

The diversity of life in the oceans has decreased through time.

The first eukaryotes evolved approximately ________ years ago.

Fossil anklebones from the ancestors of whales and the anklebones of hippopotamuses have the same shape, which is an adaptation for running on land. This suggests that

Scientists use existing fossils to predict what the transitional forms between organisms might look like. Why is it so hard for scientists to find fossils of these transitional forms?

The first group of vertebrates that could complete their life cycle without returning to water were

Ninety-five percent of marine invertebrate species went extinct during the _______ mass extinction