Triassic

American  

[trahy-as-ik] / traɪˈæs ɪk /

adjective

1. noting or pertaining to a period of the Mesozoic Era, occurring from 230 to 190 million years ago and characterized by the advent of dinosaurs and coniferous forests.

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noun

1. Also Trias the Triassic Period or System.

Triassic British  

/ traɪˈæsɪk /

adjective

1. of, denoting, or formed in the first period of the Mesozoic era that lasted for 42 million years and during which reptiles flourished

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noun

1. the Triassic period or rock system

Triassic Scientific  

/ trī-ăs′ĭk /

1. The earliest period of the Mesozoic Era, from about 245 to 208 million years ago. During the early part of the Triassic Period the supercontinent Pangaea was located along the equator; by the end of the Triassic it had started to split up. Land life diversified in the Triassic in response to the mass extinctions of the end of the Paleozoic. Conifers, cycads, marine reptiles, dinosaurs, and the earliest mammals first appeared.

2. See Chart at geologic time

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Other Word Forms

• post-Triassic adjective

Etymology

Origin of Triassic

1835–45; Trias the three-part series of strata characterizing the period (< German < Greek triás; triad ) + -ic

Example Sentences

In the Triassic period - between about 250 and 201 million years ago - the wall was a tidal flat, which later became part of the Alpine chain.

From BBC • Dec. 16, 2025

This animal, the flightless and tree-climbing lagerpetid, was first identified by scientists in 2016 and lived during the Triassic period between 242 and 212 million years ago.

From Science Daily • Dec. 9, 2025

The species lived at the end of the Triassic period, during which the first dinosaurs and the ancestors of mammals started to appear, the researchers said.

From Barron's • Oct. 16, 2025

By the end of the Triassic, the dung record revealed, dinosaurs dominated all levels of the ecosystem and their nondinosaur rivals had waned.

From Science Magazine • Nov. 27, 2024

“They lived from the late Triassic to the Cretaceous period, though technically they’re not dinosaurs,” Kavita says in a know-it-all sort of way.

From "Dragons in a Bag" by Zetta Elliott