Page 93 - The Restless Earth Fossils

2 Fossils

calcite A form of the mineral calcium carbonate.
cambrian explosion Rapid diversification of life that began
540 million years ago.
carbonization Preservation of an organism as a thin carbon
film.
casts Preservation of the overall shape and exterior detail of
an organism.
catastrophism Theory that fossils change drastically at times
because of major catastrophes that destroy most living
things.
cenozoic era Period of time from 65 million years ago to the
present.
chordate An animal that possess a nerve chord along its back.
conifers Seed plants with cones, like pine trees.
contour lines Lines on a geological map that indicate
elevation.
coprolite Fossilized dung.
cycads Primitive seed plants that flourished in the Mesozoic
Era.
darwin, charles Nineteenth-century scientist who convinc-
ingly described the process of evolution through mutation
and natural selection.
deposition Gradual accumulation of sediments at the bottom
of a water column.
dna (deoxyribonucleic acid) The compound that serves as
the genetic code for organisms.
ediacarans Sheet- or leaflike marine creatures that lived just
prior to the Cambrian Period.
eons The largest blocks of geological time, measured in billions
of years.
epochs Subdivisions of time within eras.
eras Subdivisions of time within eons.
erosion Process of breaking up and carrying away rocks by the
actions of wind, water, and temperature changes.

RE_Fossils2print.indd 92 3/17/09 9:00:55 AM