History of Life on Earth

What does this system mainly use to determine and date these events?

• Fossil evidence and rock layers

• Astronomical observations

• Weather data

• Ocean currents

Which statement below best explains the importance of this division?

• It makes the study of history more complicated

• It helps scientists arrange Earth’s history in chronological order based on major life and environmental changes

• It is used only to identify fossils

• It focuses only on the age of human civilization

Which of the following events most likely occurred during this eon?

• Formation of Earth’s crust and earliest oceans

• Rise of dinosaurs

• Diversification of mammals

• Development of flowering plants

What does this eon signify in Earth’s history?

• The appearance of the first simple cells

• The time when multicellular organisms and diverse species began to flourish

• The disappearance of most life forms

• The period before the formation of the moon

Which of the following key developments happened during this era?

• Early humans appeared

• Mammals became dominant on land

• Marine invertebrates, fishes, and the first land plants appeared

• Dinosaurs evolved and dominated the Earth

Which of the following events best characterizes this era?

• Formation of the first oceans

• Extinction of dinosaurs and rise of mammals

• Dominance of dinosaurs, emergence of birds, and appearance of the first flowering plants

• Expansion of glaciers and Ice Ages

Which of the following occurred during this time?

• The first reptiles appeared

• The earliest forms of human ancestors evolved

• Most invertebrates became extinct

• Marine life disappeared

What best describes this event?

• A massive volcanic eruption that reshaped the planet

• A sudden appearance of various complex organisms in the oceans

• The extinction of reptiles

• The rise of mammals and birds

Which major event changed life on Earth and ended the Mesozoic Era?

• The first appearance of humans

• The mass extinction of dinosaurs

• The formation of the ozone layer

• The rise of invertebrates

Which of the following describes what took place during this period?

• First appearance of multicellular organisms

• Rapid evolution of mammals and emergence of humans

• Extinction of marine species

• Origin of the first reptiles