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The Cambrian (/ ˈ k æ m b r i. ə n, ˈ k eɪ m-/ KAM-bree-ən, KAYM-) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. [5] The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordovician Period 486.85 Ma.
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This timeline of Cambrian research is a chronological listing of events in the history of geology and paleontology focused on the study of Earth during the span of time lasting from 538.8 to 485.4 million years ago (dates as per 2022 revision) [1] and the legacies of this period in the rock and fossil records.
The Precambrian-Cambrian boundary lies 2.4 m above the base of the second member, which is the lowest occurrence of Treptichnus pedum. The traces can be seen on the lower surface of the sandstone layers. The first calcareous shelled skeletal fossils (Ladatheca cylindrica) are 400 m above the boundary.
The Cambrian is the first period of the Paleozoic Era and ran from 539 million to 485 million years ago. The Cambrian sparked a rapid expansion in the diversity of animals, in an event known as the Cambrian explosion , during which the greatest number of animal body plans evolved in a single period in the history of Earth.
The first occurrence of Treptichnus pedum marks the Cambrian-Ediacaran boundary in Newfoundland, although there are several occurrences some metres below.. The opening of the Cambrian period is marked by a number of biological changes, including the extinction of the Ediacara biota, the preponderance of armoured organisms (e.g. the small shelly fossils), and a "widening of the behavioural ...