History of Life Flashcards

Flashcards about the history of life, fossils, dating fossils, geological timeline, extinction events, and the current sixth extinction.

Fossils

Scientists use these to understand the history of life.

Palaeontology

The study of fossils.

Palaeontologist

Scientists who study fossil evidence of extinct organisms.

Fossil

Hardened remains of dead organisms that once existed.

Sedimentary Rock

Remains of seas, rivers, lakes, and deserts formed in layers that disappeared a long time ago. Fossils are commonly found here.

Fossilization

The process by which living tissue is replaced by minerals from surrounding sediments over time, preserving the organism as a fossil.

Body Fossils

Fossils of the entire organism (bones, shells, leaves, imprints).

Mold fossil

Hollow impression of a living thing in a rock where the surface is depressed

Cast fossil

Solid mineral deposit that filled a mold where the surface is raised.

Trace Fossil

Fossils that are tracks left behind by an organism, hardened in sediment.

Coprolites

Fossilized animal excrement.

Fossils in Amber

Organisms such as insects, frogs, and lizards, stuck in sticky tree sap with the sap hardens

Frozen Fossils

Fossils preserved in blocks of ice.

Petrified Fossils

Fossils in which minerals replace all or part of an organism.

Relative Dating

A method to date fossils where newer species are found on the top layers, while older species are found on the bottom layers.

Radioactive Dating

A method to date fossils that uses radioactive elements to determine the actual age of the fossil. Also known as carbon dating.

Half-life

The amount of time it takes for half of the radioactive elements in a sample to decay.

Geological Timeline

Graphical representation that divides up the history of life on earth based on the life-forms that have existed during specific times.

Cambrian Explosion

The Cambrian period is marked by this event.

Extinction

All living individuals of a type have died out and do not exist anywhere on earth

Mass extinctions

Periods of times when almost all of the life on Earth died out