Fossils and Dating techniques

Fossils

preserved remains and traces of organisms

Mould Fossil

Impression of an organism has been left on the rock, creating a cavity where the organism decayed

Cast fossil

minerals can be fit into the cavity where an impression of an organism was left

petrified fossil

When organic material has been replaced with minerals and rock, most bone fossils are petrified

Trace fossils

Evidence of an organisms activity, more frequent than petrified fossils

Transitional fossils

Rare fossils depicting the intermedeol phase of evolution between an organisms ancestral form and its descendants.

gradualism

The theory that evolution is a steady, gradual divergence of lineages

Punctuated equilibrium

The theory that evolution can be both stable, and rapid if there is a sudden change in environment

fossil dating methods

Absolute dating, Comparative dating methods, stratigraphic correlation, index fossils

Absolute Dating

Assigning a numerical age to the fossil via the physical and chemical properties of the rock

Radiometric Dating

Determines the predictable rate of decay of naturally occurring radioactive isotopes for Absolute dating.

half life

measures time taken for half of the radioactive isotope to decay

Carbon Dating

type of Radioactive dating that measures the decay of carbon-14 into nirtogen-14, accurate for samples up to about 50 000 years old

Comparative Dating Techniques

Determining the age of a rock relative to other similar rocks nearby based mostly on their stratum.

Stratigraphic Correlation

Comparative dating technique that estimates the relative age of a fossil using similar igneous rock

igneous rock

Rock that can be dated with uranium or potassium

index fossils

fossil found used in stratigraphic dating that can be date due to being found in igneous rock. it is easily identifiable and abundant.