Fossils

Fossils

Preserved remains, impressions, or traces of organisms that lived in the past, commonly preserved in sedimentary rock.

Fossil Record

The cumulative body of fossil evidence documenting evolution, biodiversity changes, extinction events, and past ecosystems over time.

Conditions for Fossilisation

Rapid burial, low oxygen (anoxic) conditions, and the presence of hard body parts, which together slow or prevent decomposition.

Fossil Location Hotspots

Regions like lake and river edges, caves, and volcanically active areas (ash falls) where rapid burial protects remains from decay.

Soil pH & Fossil Preservation

Alkaline soils preserve bone minerals, whereas wet acidic soils dissolve bone unless anaerobic conditions (like peat bogs) completely preserve soft tissue and bone.

Perimineralisation & Petrification

The process where mineral-rich groundwater deposits minerals into the pores of bone or tissue, turning the organic matter into rock while preserving fine structure.

Carbonisation

The compression of buried organic matter over time that drives off volatile elements, leaving behind a thin carbon film outlining the organism's details.

Mould Fossils

Impressions left in sediment after an organism's hard parts dissolve or decay, preserving its shape without retaining biological material.

Cast Fossils

Three-dimensional replicas of an organism formed when a mould is subsequently filled with secondary minerals or sediment.

Rarity of Fossilisation

The principle that few organisms become fossils due to rapid decay, destruction by scavengers, weathering, erosion, and the lack of hard body parts.

Incomplete Fossil Record

Gaps in evolutionary history caused by the strict conditions required for fossilisation, geological destruction of rock layers, and human sampling bias.

Human Sampling Bias

The potential misrepresentation of past biodiversity due to research funding priorities, site accessibility, and regional human activities like mining or construction.