Evolutionary History and Relationships

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Ancestor Noun

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[an-ses-ter]

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Ancestor

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An organism from which more recent and different types of organisms have evolved over long periods of time.

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Example: The image shows how different animals share common ancestors, explaining evolutionary relationships.

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Common Ancestor Noun

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[kom-uhn an-ses-ter]

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Common Ancestor

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A single ancestral organism from which two or more different species or groups of organisms have descended.

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Example: The image shows a tree diagram illustrating how humans and chimpanzees share a common ancestor.

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Fossil Record Noun

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[fos-uhl rek-erd]

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Fossil Record

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The total collection of all the fossils that have been discovered, providing evidence of the history of life on Earth.

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Example: Fossils form over time as layers of sediment cover remains, showing life history.

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Paleontologist Noun

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[pay-lee-on-tol-uh-jist]

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Paleontologist

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A scientist who studies the history of life on Earth through the examination of plant and animal fossils.

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Example: A paleontologist carefully uncovers fossils, showing how they study Earth's history.

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Radioactive Dating Noun

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[ray-dee-oh-ak-tiv day-ting]

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Radioactive Dating

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A method used to determine the absolute age of materials like rocks or fossils by measuring their radioactive content.

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Example: The graph shows how a radioactive substance decreases over time, illustrating half-lives used in radioactive dating.

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Melanosomes Noun

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[mel-an-uh-sohmz]

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Melanosomes

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Tiny structures inside cells that produce and store melanin, the pigment responsible for color in skin, hair, and feathers.

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Example: This diagram shows melanosomes inside a cell, highlighting their role in producing and storing melanin.

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Structural Homology Noun

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[struk-cher-uhl huh-mol-uh-jee]

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Structural Homology

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The similarity in the physical structures, like bones, of different species due to their shared ancestry from a common predecessor.

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Example: The image shows how different animals have similar limb structures, indicating common ancestry.

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Developmental Homology Noun

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[dih-vel-uhp-men-tl huh-mol-uh-jee]

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Developmental Homology

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Similarities observed in the developmental processes of different organisms, especially during the embryonic stage, suggesting a common ancestor.

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Example: The image shows similarities in mouse and human embryo development, illustrating common ancestry.

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Molecular Homology Noun

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[muh-lek-yuh-ler huh-mol-uh-jee]

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Molecular Homology

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Similarities in the DNA, RNA, or protein sequences between different species that indicate a shared evolutionary origin.

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Example: DNA sequences from different samples show similarities, indicating shared ancestry.

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Embryo Noun

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[em-bree-oh]

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Embryo

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An organism in its earliest stages of development, before it has been born or has hatched from an egg.

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Example: The image shows a bird embryo inside an egg, illustrating its early development stages and parts like yolk and amniotic fluid.