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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...

Apatosaurus

(Encyclopedia)Apatosaurus ăpˌətəsôrˈəs, āˌpătˌə– [key], [Gr.,=deceptive lizard], quadruped saurischian dinosaur, estimated to be from 70 to 90 ft (21 to 27 m) in length and to weigh up to 30 tons (27 ...

Leakey, Mary Douglas

(Encyclopedia)Leakey, Mary Douglas, 1913–96, British archaeologist, b. London as Mary Douglas Nicol; wife of Louis Leakey and mother of Richard Leakey. She had little formal education, but a fascination with arch...

lipids

(Encyclopedia)lipids, a broad class of organic products found in living systems. Most are insoluble in water but soluble in nonpolar solvents. The definition excludes the mineral oils and other petroleum products o...

zoology

(Encyclopedia)zoology, branch of biology concerned with the study of animal life. From earliest times animals have been vitally important to man; cave art demonstrates the practical and mystical significance animal...

skull

(Encyclopedia)CE5 Bones of skull skull, the skeletal structure of the head, composed of the facial and cranial bones. The skull houses and protects the brain and most of the chief sense organs; i.e., the eyes, ...

Chelicerata

(Encyclopedia)Chelicerata kəlĭsˌərätˈə [key], subphylum of Arthropoda, including the horseshoe crabs (order Xiphosura), the arachnids (class Arachnida), and the sea spiders (class Pycnogonida). The extinct g...

Eve, in genetics

(Encyclopedia)Eve, in genetics, popular term for a theoretical female ancestor of all living people, also known as Mitochondrial Eve. In 1987 biochemist Allan C. Wilson proposed that all living human beings had inh...

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...

Paleocene epoch

(Encyclopedia)Paleocene epoch pāˈlēəsēnˌ [key], first epoch of the Tertiary period in the Cenozoic era of geologic time (see geologic timescale) between 60 to 66 million years ago. In W North America, the upl...