How long ago did Earth form?
About 4.56 billion years ago
What do scientists use to study Precambrian time?
fossils from tiny microscopic animals
Which of the following gases was not found in Earth's original atmosphere?
Oxygen
Which of the following describes how Earth's atmosphere changed during Precambrian time?
The amount of oxygen is released
Most scientists believe the extinction of Mesozoix life was caused by
A collision with a large meteorite
Which span of geologic time spans covers the majority of Earth's history?
Precambrian
One group of reptiles, characterized by the fossil Archaeoptery, led to the evolution of
birds
Which animals did not survive the Mesozoic extinction?
dinosaurs
What likely contributed to the extinction that marks the end of the Mesozoic Era
a meteorite collision
Why did many plants die at the end of the Mesozoic?
Dust from a meteorite collision blocked sunlight
What caused many events of mountain building in western North America, Europe and Asia during the Cenozoic?
Plate movements
Some continents contain large core areas of Precambrian rocks called
Shields
How are mammals distinct from reptiles?
Mammals have body hair
A large meteorite is believed to have caused the massive extinction that occurred at the end of the?
Mesozoic era
The extinction of the dinosaurs at the end of the Mesozoic benefited. during the Cenozoic?
mammals
What mounts of eastern North America formed during the late Paleozoic Era?
Appalachian
The breakup of what supercontinent occurred during the Mesozoic Era?
Pangaea
Body hair and more efficient lungs and. allowed mammals to lead more active lives than reptiles.
hearts
How was the atmosphere after Earth's formation different from todays's atmosphere?
Very little free oxygen; little plant life, if any, volcanic, CC02, H2O. sulfur, vapor
Place the geologic eras in proper order from oldest to most recent
1.Precambrian 2. Paleozoic 3. Mesozoic 4. Cenozoic
What are some advantages of hard parts, such as shells?
Protective coatings, makes for better fossils
Explain some of the factors that make it difficult for geologists to learn about the Precambrian era.
Rock cycle has destroyed most of these old rocks . Most fossils hard to make because most are one celled organisms.