Chapter 10: Fossils and Geologic Time

Fossils

The remnant or trace of an ancient living organism that has been preserved in rock or sediment after lithification.

Paleontology

The study of fossils.

Paleontologists

Scientists who study fossils.

Evolution

The progressive change over time in characteristics of species that has led to the appearance of new species.

Fossilization

The process of forming a fossil.

Mold

An indentation in rock that is created when materials are pressed into soft sediment.

Cast

Sediment that preserves the shape of an organism that once dissolved or weathered away.

Trace fossils

Footprints, feeding traces, burrows, and dung that organisms leave behind in sediment.

Permineralization

The process by which minerals precipitate in porous material, such as wood or bone, underground.

Cambrian explosion

The remarkable diversification of life that occurred at the beginning of the Cambrian Period.

Phylogeny

The evolutionary relationships among organisms.

Natural selection

The process by which individuals with favorable traits are more likely to survive and reproduce.

Extinction

Occurs when the last members of a species die.

Biodiversity

The overall variation of life.

Geologic time

The span of time since the Earth’s formation.