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Carboniferous period

(Encyclopedia)Carboniferous period kärbənĭfˈərəs [key], fifth period of the Paleozoic era of geologic time (see Geologic Timescale, tablegeologic timescale, table), from 350 to 290 million years ago. The pl...

trilobite

(Encyclopedia)CE5 Dorsal view of a trilobite trilobite trīˈləbītˌ [key], subphylum of the phylum Arthropoda that includes a large group of extinct marine animals that were abundant in the Paleozoic era. Th...

Geologic Timescale (table)

(Encyclopedia)Geologic Timescale 1 Not an era but the time preceding the Cambrian. ...

cephalopod

(Encyclopedia)CE5 Internal anatomy of a squid, Loligo, representative mollusk of the class Cephalopoda cephalopod sĕfˈələpŏdˌ [key], member of the class Cephalopoda, the most highly organized group of mol...

glacial periods

(Encyclopedia)glacial periods, times during which large portions of the earth's surface were covered with thick glacial ice sheets. In the Pleistocene epoch, in the Carboniferous and Permian periods of the Paleozoi...

Cambrian period

(Encyclopedia)Cambrian period [Lat. Cambria=Wales], first period of the Paleozoic geologic era (see Geologic Timescale, tablegeologic timescale, table) extending from approximately 570 to 505 million years ago. It ...

Logan, Sir William Edmond

(Encyclopedia)Logan, Sir William Edmond, 1798–1875, Canadian geologist. Educated in England, he managed (1831–38) coal mines and a copper smelter in Wales. In addition to making studies of clays underlying coal...

Devonian period

(Encyclopedia)Devonian period dĭvōˈnēən [key], fourth period of the Paleozoic era of geologic time between 408 and 360 million years ago (see Geologic Timescale, tablegeologic timescale, table). It was named (...

Silurian period

(Encyclopedia)Silurian period sĭlo͝orˈēən, sī– [key] [from the Silures, ancient tribe of S Wales, where the period was first studied; named by the British geologist R. I. Murchison], third period of the Pal...

Phoronida

(Encyclopedia)Phoronida fərŏnˈədə [key], small phylum of slender, wormlike marine tube-dwellers, typically found in temperate, shallow seas. About 10 species are known. Although the body is free in the tube, t...