Cambrian

Science / Biology / Cambrian: Geologic period that begins the Paleozoic Era 570 million years ago. Marked in its beginning by a proliferation of animals with hard, preservable parts, such as brachiopods, trilobites, and archaeocyathids.

Precambrian

Science / Biology / Precambrian: Informal term describing 7/8 of geologic time from the beginning of the earth to the beginning of the Cambrian Period of the Paleozoic Era. During this time the atmosphere and oceans formed, life orig MORE

Radiolarian

Science / Geology / Radiolarian: A group of one-celled marine animals with a siliceous skeleton that occupies shallow portions of the water column. Radiolarians have a range from Cambrian to present. MORE

Basement

Science / Geology / Basement: The oldest rocks recognized in a given area, a complex of metamorphic and igneous rocks that underlies all the sedimentary formations. Usually Precambrian or Paleozoic in age. MORE

Era

Science / Geology / Era: A subdivision of geologic time that is longer than a period but shorter than an eon. Precambrian, Paleozoic, Mesozoic, and Cenozoic are the eras of the time scale from oldest to youngest. MORE

Rodinia

Science / Biology / Rodinia: Name applied to the precambrian supercontinent. MORE

Trilobites

Science / Biology / Trilobites: A group of benthonic, detritus-feeding, extinct marine invertebrate animals (phylum Arthropoda), having skeletons of an organic compound called chitin. Trilobites appear in abundance early in the Camb MORE

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