Definition

1. Proper noun:
   • A major division of geologic time: The Paleozoic Era is a geological time period in Earth's history, extending from approximately 541 million years ago to about 252 million years ago. It is characterized by the diversification of life in the oceans, the colonization of land by plants and animals, and ended with the largest mass extinction event in Earth's history.

Usage Examples

• Proper noun:
  • The first complex life forms, such as trilobites, appeared during the Paleozoic Era.
  • Fossil records from the Paleozoic Era show the evolution of fish, amphibians, and early reptiles.
  • Geologists study rock layers from the Paleozoic Era to understand ancient climates and environments.

Advanced Usage

• "the dawn of the Paleozoic": Refers to the very beginning of the era, marked by the Cambrian Explosion of life.
  • The fossil record becomes much richer at the dawn of the Paleozoic.
• "late Paleozoic ecosystems": Describes the biological communities that existed toward the end of the era.
  • The formation of the supercontinent Pangaea drastically altered late Paleozoic ecosystems.

Variants and Related Words

• Paleozoic (adj): Of or relating to the Paleozoic Era.
  • Paleozoic rocks are rich in fossils.
• Paleontology (n): The scientific study of life in past geologic periods, often involving Paleozoic fossils.
• Era (n): A long and distinct period of history with a particular feature or characteristic. The Paleozoic is one of several geologic eras.

Synonyms

• Ancient life era: A descriptive synonym emphasizing the age and life forms of the period.
• Primary era: An older, less common term historically used for the Paleozoic.

Related Phrases

• Paleozoic-Mesozoic boundary: The transition point between the Paleozoic and the following Mesozoic Era, marked by the Permian-Triassic extinction.
• Paleozoic fauna: The collective animal life that existed during the era.

Related Concepts

• Geologic time scale: The system of chronological dating that relates geological strata to time, of which the Paleozoic Era is a part.
• Mass extinction: A widespread and rapid decrease in biodiversity. The Paleozoic Era ended with the Permian-Triassic extinction event.

Noun

1. from 544 million to about 230 million years ago