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foraminiferan

(Encyclopedia)foraminiferan fərămˌənĭfˈərən [key], common name for members of the class Foraminifera, large, shelled ameboid protozoans belonging to the phylum Sarcodina. Most foraminiferan shells are calca...

Olduvai Gorge

(Encyclopedia)Olduvai Gorge ōlˈdəwāˌ, –vāˌ [key], a feature of the E African Rift Valley in Tanzania. Erosional processes have exposed geological strata in the gorge dating to the lower Pleistocene epoch, ...

Cradle of Humankind

(Encyclopedia)Cradle of Humankind, extensive archaeological site, c.180 sq mi (470 sq km), encompassing dolomitic limestone caves containing numerous hominin fossils, Gauteng and North West prov., South Africa, c.3...

Oligocene epoch

(Encyclopedia)Oligocene epoch ŏlˈəgōsēnˌ [key], third epoch of the Tertiary period in the Cenozoic era of geologic time, lasting from 38 to 24 million years ago. More of North America was dry land during the ...

Iguanodon

(Encyclopedia)Iguanodon ĭgwănˈədŏn [key] [Gr., = iguana tooth], herbivorous ornithiscian dinosaur, characterized by teeth similar to those of the iguana, a horny beak, spikelike thumbs, and a powerful tail...

Fossil Butte National Monument

(Encyclopedia)Fossil Butte National Monument: see National Parks and Monuments (table)national parks and monuments (table). ...

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 ...

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...

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