OFFICIAL Evidence of Evolution - Fossils (Vocabulary Flashcards)

Vocabulary-style flashcards covering key concepts from the notes on fossils, fossilisation, and dating methods.

Fossil record

The history of life preserved in rocks, which is incomplete due to biases in fossil formation, preservation, discovery, and access.

Fossil

Any preserved trace or remains left by an ancient organism.

Body fossils

Preserved parts of organisms, such as bones, teeth, shells, hair, or skin.

Trace fossils

Preserved evidence of activity, such as footprints, casts, faeces, tooth marks, or burrows.

Artefacts

Objects deliberately made or modified by humans, used as evidence of past activity.

Relative dating

Dating that places specimens in order from oldest to youngest without giving an exact age.

Stratigraphy

Study and analysis of rock layers (strata) to determine relative ages.

Index fossils

Widely distributed fossils that existed for a short time, used to correlate and date strata.

Absolute dating

Dating that provides an approximate numerical age (in years) rather than a precise date.

Radiocarbon dating (Carbon-14 dating)

Absolute dating using decay of Carbon-14 to Nitrogen-14; half-life about 5730 years; effective up to ~60,000 years.

Potassium-Argon dating

Radiometric dating using decay of potassium-40 to argon-40; half-life ~1.25–1.3 billion years; useful for very old rocks.

Potassium-40

Radioactive isotope that decays to Argon-40.

Argon-40

Noble gas produced by the decay of Potassium-40.

Isotope

Variant of an element with the same number of protons but different numbers of neutrons.

Fossilisation

Process of becoming a fossil, requiring rapid burial, hard parts, low oxygen, dry/alkaline soils, and undisturbed conditions.

Rapid burial

Quick covering of remains by sediment or ash, aiding preservation.

Hard body parts

Bones, teeth, shells and other durable parts that survive long-term preservation.

Absence of oxygen (anoxia)

Low-oxygen conditions that slow decay and help fossil preservation.

Dry, alkaline soils

Soil conditions that promote mineral preservation; acidic soils can dissolve minerals in bones.

Incomplete fossil record reasons

Destruction, non-discovery, inaccessibility, incomplete fossilisation, or too few specimens.

Fluorine analysis

Technique that compares fluorine uptake in bones to estimate how long they've been buried.

AMS (Accelerator Mass Spectrometry)

A dating method that counts individual atoms, allowing very small samples to be dated.

Half-life

Time required for half of a radioactive substance to decay.

Atmospheric C-14 variation

Fluctuations in C-14 levels in the atmosphere that affect radiocarbon dating accuracy.

Correlation of rock strata

Matching layers of rock from different areas to determine their relative ages.

Principle of superposition

In undisturbed strata, younger layers lie above older layers.

Disturbances in rock layers

Events (tectonic activity, re-burial) that disrupt original layering and complicate dating.