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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.
The Cambrian explosion (also known as Cambrian radiation [1] or Cambrian diversification) is an interval of time beginning approximately in the Cambrian period of the early Paleozoic, when a sudden radiation of complex life occurred and practically all major animal phyla started appearing in the fossil record.
The "Cambrian substrate revolution" [1] or "Agronomic revolution", [2] evidenced in trace fossils, is a sudden diversification of animal burrowing during the early Cambrian period. Before this "widening of the behavioural repertoire", [ 3 ] bottom-dwelling animals mainly grazed on the microbial mats that lined the surface of the substrate ...
The middle Cambrian to early Ordovician is characterized by persistent elevated extinction rates that are thought to have been maintained by anoxic conditions. [ 4 ] A decrease in the anoxic conditions of the Cambrian, and an increase in euxinic conditions (or an increase in hydrogen sulfide concentrations) of the Early Ordovician are also ...
The Maotianshan Shales (帽天山页岩) are a series of Early Cambrian sedimentary deposits in the Chiungchussu Formation, [2] famous for their Konservat Lagerstätten, deposits known for the exceptional preservation of fossilized organisms or traces.
The Ellesmerocerids were the only shelled cephalopods known to have survived the end-Cambrian extinction; all subsequent cephalopods are thus thought to be derived from these forms, which diversified throughout the Ordovician period. Early cephalopods had fine shells that could not cope with the pressures of deep water. [2]
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 ...
It is known from the Middle Cambrian Burgess shale and Early Cambrian deposits from the Czech Republic. It consists of a dense mass of entangled, twisted filaments. It may have been free-floating or grown on other objects, although there is no evidence of attachment structures. Morania: Cyanobacteria: Cyanophyceae: Walcott Quarry