Fossil Record
radioactive dating
Technique used to determine how old a rock is by analyzing the amounts of a radioactive isotope and its decay products in the rock.
relative age
The age of a rock compared to the ages of rock layers
absolute age
The age of a rock given as the number of years since the rock formed.
index fossil
distinctive fossil used to compare the relative ages of fossils
mass extinction
event in which many types of living things become extinct at the same time
law of superposition
states that younger layers of rock are deposited on top of older layers
chronological order
the order in which events happen in time
extinction
A term that typically describes a species that no longer has any known living individuals.
fossil record
The mineralized remains of organisms and the rock layers in which they are found, showing when and where long -dead organisms lived and how their bodies were structured.
fossils
The preserved remains or traces of organisms that once lived on Earth.
diversity
The quality or state of having many different forms, types, ideas, etc.
half life
The time it takes for half of the radioactive atoms to decay
common ancestry
When Organisms are descended from a single ancestor
paleontologist
a scientist who studies fossils to learn about organisms that lived long ago