Evolution of Life

ANGIOSPERM: Flowering Plant.

ARCHIEBACTERIUM: Member of the prokaryotic domain Archaebacteria

ARCHEAN EON: Eon in which life arose.

BIG BANG: Model for origin of universe.

CENOZOIC ERA: The present era.

CRUST, OF EARTH: Outer zone of low-density rocks resting on the Earth's mantle.

DINOSAUR: One of a fabulous group of reptiles th

at originated in the Triassic.

EDIACARAN: One of the species with a highly flattened body that arose in the precambrian.

ENDOSYMBIOSIS THEORY: Continuing physical contact between two species, one of which lives and reproduces inside the other's body.

EUBACTERIUM: Prokaryotic cell; has a nucleoid, but no nucleus, cytoplasm, or cell membrane; most have a cell wall, some encapsulated.

EUCARYOTIC CELL:Cell having a nucleus and other membrane-bound organelles.

GLOBAL BROILING HYPOTHESIS: Theory that an asteroid impact caused the K-T mass extinction by creating a colossal fireball, the debris from which raised global air temperature by thousands of degrees.

GYMNOSPERM: Type of vascular plant in which seeds form on exposed surfaces of reproductive structures.

K-T ASTEROID IMPACT THEORY: A huge aster oid hit Earth at the K-T boundary.

MANTLE: Of Earth, a zone of intermediatedensity rocks beneath the crust.

MESOZOIC ERA: An era of spectacular expansion in the range of global diversity.

PALEOZOIC ERA: Era from Cambrian, Ordovician, Silurian, Devonian, Carboniferous, through the Permian.

PROKARYOTIC CELL: Archaebacterium or eubacterium; single-celled organism, most often walled; lacks the profusion of membranebound organelles observed in eukaryotic cells.

PROTEROZOIC EON: Period during which eukaryotic cells arose.

PROTISTAN: Photoautotroph or heterotroph unlike bacteria; some like earliest eukaryotic cells.
PROTO-CELL: Hypothetic cell-like stage between chemical evolution and the first living cell.

RNA WORLD: One model for prebiotic evolution in which RNA was the template for protein synthesis before the evolution of DNA.

STROMATOLITE: Fossilized mats of shallow-water microbial communities, mainly cyanobacteria, from Archean to precambrian.