A fossil is the remains or evidence of a once-living organism preserved in rock. This definition emphasizes that fossils represent biological material from the past that has been maintained through geological processes.

Permineralization is a common fossilization process where minerals infiltrate the porous remains of organisms, gradually staining and preserving their structures. This method replaces the original organic material with minerals while retaining the organism's details.

Fossils are most commonly found in sedimentary rocks because these rocks form from the layering and compaction of sediments. The gentle conditions during their formation help preserve the remains of organisms.

Paleontology is the scientific study of fossils and ancient organisms. It focuses on understanding the evolution, relationships, and environments of past life on Earth.

A trace fossil records the activity or behavior of an organism, such as footprints, burrows, or feeding marks. Footprints provide indirect evidence of how an organism moved or interacted with its environment.

Radiometric dating uses the decay rate of radioactive isotopes to provide an absolute age for rock layers. This method gives scientists a precise numerical age for the rocks containing fossils.

The law of superposition is a key principle in geology that states that in undisturbed sedimentary sequences, the oldest layers are deposited at the bottom and the youngest at the top. This helps geologists determine the relative ages of rock strata.

Rapid burial is crucial for fossilization because it protects organic remains from decay and scavenging. Quick coverage by sediment preserves the detailed structure of the organism.

A mold fossil is formed when an organism leaves an impression in the sediment that later hardens into rock. This impression captures the external details of the organism without preserving its original material.

Sedimentary rocks are created through the slow deposition and compaction of sediments under relatively low temperature and pressure. These conditions are ideal for preserving the remains and structures of organisms.

Carbon dating measures the decay of carbon-14 to estimate the age of organic materials. It is effective for dating items up to around 50,000 years old, making it useful for relatively recent fossils.

Index fossils are species that were widespread but existed for a relatively short period. Their presence in various rock layers helps geologists correlate the ages of those layers across different geographic areas.

Lithification is the process where sediments are compacted and cemented into rock. This process is essential for preserving fossils as it stabilizes the sediment and protects the fossil remains within.

Chemical processes such as permineralization are vital for fossil formation as they replace the original organic material with minerals. This replacement helps retain the fine structural details of the organism for scientific study.

Calm aquatic environments, such as lake beds or river deltas, allow sediments to settle and rapidly bury organic remains. This protective setting minimizes decay and disruption, increasing the likelihood of fossil preservation.

Fossil assemblages consist of multiple species whose varying ecological needs offer insights into the conditions of their environment. Their diversity and distribution help reconstruct factors like climate, water depth, and substrate types from the past.

Taphonomy examines all the steps that occur from the death of an organism to its eventual fossilization. It takes into account decay, transport, and the chemical and physical processes that affect preservation, providing a comprehensive view of fossil formation.

Fossil inversion occurs when tectonic forces such as folding or faulting alter the original sequence of sedimentary layers. This disruption challenges the straightforward application of the law of superposition, requiring geologists to carefully analyze the geological history.

Lagerstätten are fossil sites with exceptionally preserved remains, including soft tissues that are normally lost during fossilization. This outstanding preservation provides valuable information on the anatomy, behavior, and ecology of ancient organisms, broadening our understanding of past life.

CT scanning and similar imaging technologies enable researchers to examine the internal anatomy of fossils without any damage. This non-destructive approach provides three-dimensional data that can reveal hidden structures and improve our understanding of fossil morphology and evolution.