Precambrian

== English == === Alternative forms === Pre-Cambrian === Etymology === From pre- + Cambrian. === Pronunciation === (Received Pronunciation) IPA(key): /priːˈkam.bɹɪ.ən/ (General American) IPA(key): /priˈkæm.bɹi.ən/ (Canada) IPA(key): /priˈkeɪm.bɹi.ən/, /priˈkæm.bɹi.ən/ Hyphenation: Pre‧cam‧bri‧an === Adjective === Precambrian (not comparable) (informal, geology) Relating to the time and geology dated before the Phanerozoic ==== Translations ==== === Proper noun === Precambrian (geology) The Precambrian supereon; spanning from the formation of the Earth around 4.6 billion years ago to the emergence of hard-shelled creatures 541 million years ago. ==== Usage notes ==== The International Commission on Stratigraphy, which attempts to standardize the vocabulary of the field, is revising the boundaries between time periods based on physical-science methods rather than the kinds of fossils present. The boundary between the Precambrian and the Phanerozoic has been changed from time to time and will be subject to change, as will the eons listed as Hyponyms below. ==== Synonyms ==== (geological supereon): Cryptozoic (archaic) ==== Antonyms ==== Phanerozoic ==== Hyponyms ==== (geological supereon): Hadean, Archaean, Proterozoic - eons ==== Coordinate terms ==== (geological supereon): Phanerozoic ==== Translations ====