Within a species, there are naturally occurring differences, or __________, in traits.

An inherited trait that helps an organism survive and reproduce in its environment is an _______________.

____________ occurs when all members of a species have died.

The remains or imprints of once-living organisms are called _____________.

All of the fossils that have been discovered make up the ___________________.

A ____________ is a trace or imprint of a living thing that is preserved by geologic processes.

All of the fossils that have been discovered worldwide make up the ____________________.

An _______________ happens when every individual of a species dies.

The _________________ is the standard method used to divide Earth's long 4.6 billion year natural history into manageable parts.