It was in the Phanerozoic Eon.
The Jurassic Period of geologic time spanned from 206 to 144 million years ago. It was preceded by the Triassic Period and followed by the Cretaceous Period, all three comprising the Mesozoic Era.
The eon it lived in is the Phanerozoic, but I really don't believe that's what you're asking. It lived in the early Jurassic period of the Mesozoic era.
Eon: Phanerozoic Era: Mesozoic Period: Late Jurassic to Early Cretaceous Time range: 155 to 140 million years ago
The Jurassic time period is with the t rex and other animals
The Kentrosaurus lived during the Late Jurassic period, specifically in the Kimmeridgian to Tithonian stages, which is part of the Mesozoic era.
An eon.
an eon
The Eon. We are currently in the 4th Eon.
The opposite meaning for eon is a short period of time which can be calculated or measured.Note: The answer is based on the assumption that the questioner asked the antonym for the word eon meaning immeasurably long period of time.
I don't know the plural of eon but the answer is more than 1 eon
The Cretaceous Period was the longest period of time.
The Jurassic Period followed the Triassic.