Definition

1. Proper noun:
   • The Devonian period: A geological period of the Paleozoic Era, spanning from approximately 419.2 million to 358.9 million years ago. It is often called the "Age of Fishes" due to the diversification of fish, and also saw the first significant appearance of amphibians and forests on land.

Usage

• The term Devonian is primarily used as a proper noun in geological and paleontological contexts to refer to this specific time period in Earth's history.
• It is often used attributively (like an adjective) to describe rocks, fossils, or events from that time.

Examples

• Proper noun:
  • The first amphibians evolved during the Devonian.
  • These limestone deposits are of Devonian age.
  • The study focuses on Devonian marine ecosystems.

Advanced Usage

• "Devonian extinction": Refers to one of the major mass extinction events that occurred near the end of the Devonian Period, affecting marine life.
  • The Late Devonian extinction was particularly severe for reef-building organisms.

Variants and Related Words

• Devonian Period: The full formal name.
• Devonian System: The stratigraphic rock record formed during the Devonian Period.

Synonyms

• Age of Fishes: An informal name for the Devonian Period, highlighting its key biological feature.

Related Phrases

• Upper/Late Devonian: Refers to the later part of the period.
• Lower/Early Devonian: Refers to the earlier part of the period.
• Middle Devonian: Refers to the middle part of the period.

Noun

1. from 405 million to 345 million years ago; preponderance of fishes and appearance of amphibians and ammonites