Fossils can be found throughout the geologic history of earth, going back billions of years. Here we explore one of the most exciting of times, the Cambrian, when many of the major groups of animals familiar to us today first appear as conspicuous fossils.

2025年1月11日 · Cambrian Period, earliest time division of the Paleozoic Era and Phanerozoic Eon, lasting from 538.8 million to 485.4 million years ago. The Cambrian System, named by English geologist Adam Sedgwick for slaty rocks in southern Wales and southwestern England, contains the earliest record of abundant and varied life-forms.

Some Cambrian organisms ventured onto land, producing the trace fossils Protichnites and Climactichnites. Fossil evidence suggests that euthycarcinoids, an extinct group of arthropods, produced at least some of the Protichnites. [67]

Almost every metazoan phylum with hard parts, and many that lack hard parts, made its first appearance in the Cambrian. The only modern phylum with an adequate fossil record to appear after the Cambrian was the phylum Bryozoa, which is not known before the early Ordovician.

2012年10月28日 · Marine animals with mineralized skeletons make their first appearance in the shallow seas of the Cambrian, though only "small shelly fossils" (tiny shells, spines and scales from early metazoans) and trace fossils are preserved for the first ten million years or so.

2025年1月11日 · The most common fossils in Cambrian rocks are trilobites, which evolved rapidly and are the principal guide fossils for biostratigraphic zonation in all but rocks below the Atdabanian Stage or those of equivalent age.

Fossils known as "small shelly fauna" have been found in many parts on the world, and date from just before the Cambrian to about 10 million years after the start of the Cambrian (the Nemakit-Daldynian and Tommotian ages; see timeline).

2025年1月22日 · The Cambrian Period marks an important point in the history of life on Earth; it is the time when many kinds of invertebrates and the first vertebrates—fishes—appeared in the fossil record. The Burgess Shale contains the best record of Cambrian animal fossils including soft-bodied forms.

Except for enigmatic forms, all modern animal phyla with a fossil record, except bryozoa, are represented in the Cambrian. Because some life became mineralized, the possibility of fossil formation greatly increased.

Cambrian sediments found in Canada, Greenland, and China have yielded rarely fossilized soft-bodied creatures such as marine worms buried during undersea mud avalanches.