E.S. Chapter 13

What percentage of geologic time is taken up by Precambrian Time?

• 50%

• 78%

• 88%

• 98%

What do scientist use to study Precambrian Time?

• fossils from tiny microscopic animals

• ore from eroded and deformed rocks

• fossils from algae and other simple plants

• fossils from dinosaurs

Which explains what Precambrian life forms were like?

• they DID NOT need Oxygen

• were ocean-dwelling organisms

• NEEDED Oxygen

• were tiny plants that used Nitrogen

During the Ordovician Period of the early Paleozoic era, the first large organisms appeared on Earth. What group did these organisms belong to?

• Corals

• Cephalopods

• Mollusks

• Trilobites

What important adaptation helped protect organisms of the early Cambrian Period?

• the ability to photosynthesize

• hard parts

• teeth

Most scientist believe the extinction of Mesozoic life was caused by what?

• A large-scale earthquake

• solar flares

• volcanic eruptions

• a collision with a large meteorite

The major animal group that replaced dinosaurs and reptiles in the Cenozoic era was?

• lobe-finned fishes

• amphibians

• mammals

• birds

Which of the following animals groups benefited significantly during the Cenozoic era by being able to give birth to live young?

• lobe-finned fish

• amphibians

• mammals

• birds