Proterozoic eon
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Definition
Proper noun 1. The Proterozoic Eon: A geological eon spanning from approximately 2,500 million years ago to 541 million years ago. It is the second eon of the Precambrian supereon, following the Archean and preceding the Phanerozoic Eon. This period is characterized by the development of stable continents, increased atmospheric oxygen, and the emergence of more complex life forms, including bacteria, fungi, and primitive multicellular organisms.
Usage Examples
- Proper noun:
- Fossil evidence from the Proterozoic Eon shows the first signs of eukaryotic life.
- The Great Oxidation Event, a major rise in atmospheric oxygen, occurred during the Proterozoic Eon.
- Scientists study rock formations dating to the Proterozoic Eon to understand early Earth conditions.
Advanced Usage
- "The Proterozoic": Often used as a shortened form to refer to the Proterozoic Eon.
- The fossil record from the late Proterozoic is more extensive than from earlier eons.
Variants and Related Words
- Proterozoic (adj): Of, relating to, or denoting the Proterozoic Eon.
- Proterozoic rocks are found on every continent.
- Neoproterozoic Era (n): The most recent era within the Proterozoic Eon.
- Mesoproterozoic Era (n): The middle era within the Proterozoic Eon.
- Paleoproterozoic Era (n): The earliest era within the Proterozoic Eon.
Synonyms
- Proterozoic: (When used as a noun to refer to the eon)
- Precambrian (late): (Informal, as the Proterozoic constitutes the later part of the Precambrian)
Related Terms and Context
- Geological Time Scale: The Proterozoic Eon is a major division within this scale.
- Banded Iron Formations: These are characteristic rock types from the early Proterozoic, indicating changes in ocean chemistry.
- Snowball Earth: Hypothesized global glaciation events that may have occurred during the Neoproterozoic era.
Noun
- from 2,500 to 544 million years ago; bacteria and fungi; primitive multicellular organisms