Triassic
adjective
Tri·as·sic
trī-ˈa-sik 
: of, relating to, or being the earliest period of the Mesozoic era or the corresponding system of rocks marked by the first appearance of the dinosaurs see Geologic Time Table
Triassic
noun
Examples of Triassic in a Sentence
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The ecology and geography of temnospondyl recovery after the Permian – Triassic mass extinction
Before joining Discover Magazine, Paul Smaglik spent over 20 years as a science journalist, specializing in U.S. life science policy and global scientific career issues.
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Paul Smaglik, Discover Magazine, 4 Mar. 2025
Standing near the hulking Megalosaurus, which dates from the Middle Jurassic period, Todd points out Cretaceous and Triassic specimens on either side of the beast.
—Yannic Rack, Smithsonian Magazine, 29 Aug. 2023
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Paul Smaglik, Discover Magazine, 4 Mar. 2025
Standing near the hulking Megalosaurus, which dates from the Middle Jurassic period, Todd points out Cretaceous and Triassic specimens on either side of the beast.
—Yannic Rack, Smithsonian Magazine, 29 Aug. 2023
Cite this Entry
“Triassic.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/Triassic. Accessed 31 Oct. 2025.
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Triassic
adjective
Tri·as·sic
trī-ˈas-ik
: of, relating to, or being the earliest period of the Mesozoic era of geological history marked by the first appearance of dinosaurs
also
: relating to the corresponding system of rocks see geologic time
Triassic
noun
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