Cretaceous period

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Definition
  1. Proper noun:
    • The Cretaceous Period: A major division of geologic time, the third and final period of the Mesozoic Era, spanning from approximately 145 to 66 million years ago. It is characterized by a warm climate, high sea levels, the dominance of dinosaurs, and the appearance and diversification of flowering plants (angiosperms) and modern insects. The period ended with the Cretaceous–Paleogene (K–Pg) extinction event.
Usage Examples
  • Proper noun:
    • Tyrannosaurus rex lived during the Cretaceous Period.
    • The Cretaceous Period is known for the first widespread appearance of flowers.
    • Scientists study rock layers from the Cretaceous Period to understand dinosaur ecosystems.
Advanced Usage
  • "the Cretaceous": A common shortened form used to refer to the Cretaceous Period.
    • The continents continued to drift apart during the Cretaceous.
  • "Late/Early Cretaceous": Terms used to specify subdivisions within the period.
    • This fossil dates to the Late Cretaceous.
Variants and Related Words
  • Cretaceous (adjective): Of, relating to, or denoting the Cretaceous Period.
    • Cretaceous rocks are often rich in chalk.
  • K–Pg boundary (noun): The geologic signature marking the end of the Cretaceous Period and the beginning of the Paleogene Period, associated with a mass extinction.
  • Mesozoic Era (noun): The geologic era comprising the Triassic, Jurassic, and Cretaceous periods.
Synonyms
  • The Cretaceous: (The shortened form is the primary synonym in geological contexts.)
Related Phrases
  • End-Cretaceous extinction: The mass extinction event that concluded the period.
    • The end-Cretaceous extinction led to the demise of non-avian dinosaurs.
Noun
  1. from 135 million to 63 million years ago; end of the age of reptiles; appearance of modern insects and flowering plants

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