Changes Over Time and Evolution

Cast

A fossil formed when dissolved minerals fill a mold and harden. Cast. A cast is a replica of a living thing made from minerals that filled its mold after it decomposed.

Evolution

The change in a species over time. Evolution. Evolution is the process by which species adapt and change over generations through natural selection.

Extinction

The death of all members of a species. Extinction. In Science, extinction is when a species completely disappears from Earth.

Fossil

The preserved traces and remains of an organism that lived long ago. Fossil. A fossil is the remains or impression of a plant or animal that lived millions of years ago, preserved in rock.

Fossil record

The history of life recorded by all the fossils we have collected. Fossil record. The fossil record is the collection of all discovered fossils that helps scientists understand how life has evolved over millions of years.

Gradualism

The evolution of a species, as a gradual change over time. Gradualism. Gradualism is a scientific concept that describes how small, slow changes over time lead to significant evolutionary developments.

Homologous structure

A similar structure in different species, like a whale fin, bat wing, and your arm. Homologous structure. Homologous structures are body parts in different species that are similar because they evolved from a common ancestor.

Mass extinction

When many species become extinct at the same time, mass extinction. Mass extinction is when a large number of different species die out quickly.

Mold

A rock fossil created when a buried organism dissolves. Mold. Mold is a type of fungus that grows in the form of multicellular filaments called hyphae.

Natural selection

The individuals best suited to survive in an environment. Natural selection. It is the process where organisms better adapted to their environment tend to survive and produce more offspring.

Primate

Mammals with features like opposable thumbs, forward-looking eyes, and a large brain, like humans, monkeys, or apes primate. Primates are a group of mammals known for their advanced cognitive abilities and dexterous limbs.

Radioactive element

An unstable element that emits particles and energy as it changes into another element. Radioactive element. A radioactive element is a substance that naturally breaks down and releases energy and particles.

Speciation

The evolution of new species from an existing species. Speciation. Speciation is the process where groups within a species evolve to become distinct species, usually due to physical separation, genetic changes, or environmental differences.

Variation

Any difference between members of the same species. Variation. In science, variation refers to the differences in traits or characteristics among individuals of the same species.