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Eocene epoch
(Encyclopedia)Eocene epoch ēˈəsēnˌ [key], second epoch of the Tertiary period in the Cenozoic era of geologic time, from approximately 54.9 to 38 million years ago. The Eocene in North America was marked by th...Homo erectus
(Encyclopedia)Homo erectus hōˈmō ērĕkˈtəs [key], extinct hominin living between 1.6 million and 250,000 years ago, possibly as late as c.110,000 years ago. Homo erectus is thought to have evolved in Africa f...horseshoe crab
(Encyclopedia)horseshoe crab, large, primitive marine arthropod of the family Limulidae, related to the spider and scorpion and sometimes called a king crab (a name also used for the largest of the edible true crab...Sarcodina
(Encyclopedia)Sarcodina, the largest phylum (11,500 living species and 33,000 fossil species) of protozoans). It comprises the amebas and related organisms; which are all solitary cells that move and capture food b...sequoia
(Encyclopedia)sequoia sĭkwoiˈə [key], name for the redwood (Sequoia sempervirens) and for the big tree, or giant sequoia (Sequoiadendron giganteum), both huge, coniferous evergreen trees of the bald cypress fami...geode
(Encyclopedia)geode jēˈōd [key], hollow, globular rock nodule ranging in diameter from 1 to 12 in. (2.54–30.5 cm) or more. Most geodes are partly filled with mineral matter; they have a thin layer of chalcedon...Ramapithecus
(Encyclopedia)Ramapithecus räməpəthēˈkəs, –pĭthˈə– [key], former name for an extinct group of primates that lived from about 12 to 14 million years ago, for a time regarded as a possible ancestor of Au...pterosaur
(Encyclopedia)pterosaur tĕrˈəsôrˌ [key] [Gr., = winged lizard], extinct flying reptile (commonly called pterodactyl [Gr., = wing finger]) of the order Pterosauria, common in the late Triassic and Creta...Smith, William
(Encyclopedia)Smith, William, 1769–1839, English geologist. Through direct observation as a canal-site surveyor, Smith made a systematic study of the geological strata of England and identified the fossils peculi...reaction-formation
(Encyclopedia)reaction-formation: see defense mechanism. ...Browse by Subject
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