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17 Cards in this Set

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absolute dating
a process that allows scientists to figure out the actual (real) age of fossils
relative dating
Relative dating shows only that one fossil may be older than another fossil. This process does not tell exactly how old any fossil is. Scientists can do Relative dating by studying layers of rock. Fossils found at the bottom of a sequence of rock layers are older than fossils found at the top of a sequence of rock layers.
overproduction
most species produce more offspring than can survive
fossil
the preserved remains or traces of an organism that lived in the past.
fossil record
ll
competition
offspring must compete with each other for limited food and resources and shelter; some offspring will not survive to reproduce later on
natural selection
ll
petrified fossils
When minerals replace the buried remains of a dead organism, the remains may change slowly into a rock. 'Petri' means 'rock'.
extinct
when no members of a species are alive
gradualism
a theory that says that evolution occurs slowly but steadily; tiny changes in a species graually add up to major changes over very long periods of time.
preserved remains
kl
molds and casts
A hollow space in a sediment which is the shape of a dead organism is called a mold. When the space is filled with hardened minerals then it is called a cast.
variation
Any difference between inidividuals of the same species
radioactive elements
over time, unstable elements decay, or break down into different elements
adaptations
k
species
l
homologous structures
when similar structures are found in different organisms. For example, the arms of many animals have similar bones and other structures