Mesozoic

American  

[mez-uh-zoh-ik, mes-, mee-zuh-, -suh-] / ˌmɛz əˈzoʊ ɪk, ˌmɛs-, ˌmi zə-, -sə- /

adjective

1. noting or pertaining to an era occurring between 230 and 65 million years ago, characterized by the appearance of flowering plants and by the appearance and extinction of dinosaurs.

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noun

1. the Mesozoic Era or group of systems.

Mesozoic British  

/ ˌmɛsəʊˈzəʊɪk /

adjective

1. of, denoting, or relating to an era of geological time that began 250 000 000 years ago with the Triassic period and lasted about 185 000 000 years until the end of the Cretaceous period

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noun

1. the Mesozoic era

Mesozoic Scientific  

/ mĕz′ə-zō′ĭk /

1. The era of geologic time from about 245 to 65 million years ago. The Mesozoic Era was characterized by a drastic change in plants and animals. In the early part of the Mesozoic, ferns, cycads, and ginkgos were dominant; later, gymnosperms and angiosperms developed. Dinosaurs also first appeared in the Mesozoic and, with the exception of birds, became extinct at the end of the era.

2. See Chart at geologic time

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Other Word Forms

• post-Mesozoic
  adjective

Etymology

Origin of Mesozoic

First recorded in 1830–40; meso- + zo- + -ic

Example Sentences

See Examples For:

Mesozoic

Mitchell’s film, which follows a family of four in 1982 as they realize their entire quaint suburban neighborhood has somehow been transported back to the Mesozoic era, has understandably swept audiences off their feet.

From Salon ● Aug. 20, 2026

Scientists now believe the split between octopuses and their 10-armed relatives happened in the Mesozoic era, not hundreds of millions of years earlier as previously thought.

From BBC ● Apr. 8, 2026

These findings suggest that some of the earliest Mesozoic marine tetrapods expanded quickly into multiple ecological roles and spread widely across the planet.

From Science Daily ● Feb. 25, 2026

As a result, they represent the oldest clearly recognizable group of Mesozoic marine tetrapods.

From Science Daily ● Feb. 25, 2026

Sometimes too you will see the term Phanerozoic used to describe the span encompassing the Cenozoic, Mesozoic, and Paleozoic eras.

From "A Short History of Nearly Everything" by Bill Bryson