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LITHOEN

Geological time unit

Cambrian

The first period of the Paleozoic and of the Phanerozoic. Its base defines the base of the Phanerozoic Eon.

Classification

rank
period

How this record is known

2
Settled consensus
Cited as the accepted position of the discipline.

2 of 2 claims on this page cite at least one registered source. Counts describe how each statement is known, not how likely it is to be true.

What Lithoen records

Each claim states how it is known and cites its evidence.

Established538.8 Ma before present

The base of the Cambrian, and therefore of the Paleozoic and of the Phanerozoic, is placed at 538.8 million years with an uncertainty of 0.6 million years.

  • definition basis: International Chronostratigraphic Chart v2024/12, which prints this boundary age as 538.8 ± 0.6 Ma.
  • precision note: The stated uncertainty is the chart’s own; the boundary itself is defined by a GSSP, not by this number.

Evidence support: Supported by the cited evidence one source

Evidence: Cohen 2024 Primary authority

Established538.8–486.85 Ma before present

On the International Chronostratigraphic Chart (v2024/12), the Cambrian spans 538.8 to 486.85 million years before present.

Not stated verbatim by the source — derived: base of the unit x base of the next younger unit -> span

A span is not stated anywhere on the chart: the chart gives boundary ages, and the span between two of them is composed from the two lines the premises cite.

  • definition basis: International Chronostratigraphic Chart v2024/12; the chronostratigraphic counterpart of the Cambrian is the Cambrian System.
  • precision note: The chart states that numerical ages are subject to ongoing revision and do not define units; GSSPs do.

Evidence support: Derived from the cited evidence one source

Evidence: Cohen 2024 Primary authority

In the knowledge graph

Record last updated 2026-09-06. Corrections follow the published corrections policy; superseded claims are retained, never silently edited.