Interlude E

Fossils

Ancient remnants of once living organisms that were buried and preserved after lithification.

Lithification

The process by which sediments compact under pressure, expel connate fluids, and gradually transform into solid rock.

Paleontology

The study of fossils.

Paleontologist

Someone who studies fossils.

Sedimentary Rock

Rocks formed from the accumulation of sediments, in which fossils are primarily found.

Anoxic Conditions

Oxygen-poor environments that promote the fine preservation of fossils.

Fossilization

The process through which fossils form.

Frozen or Dried Body Fossils

Whole bodies that get frozen or completely dried out and buried.

Amber

A fossilized tree sap that can trap and preserve insects.

Tuff

Rock formed from volcanic ash, which can also contain fossils.

Molds

Indentations in the rock that form when an object, such as a shell, is pushed into soft sediment.

Casts

Protrusions that form in rock when molds are filled with sediment.

Carbonized Impressions

Flattened molds and casts that leave only carbon impressions on the sediment.

Permineralized Fossils

Fossils formed through the precipitation of minerals in porous materials like wood or bone.

Robert Hooke

A scientist who concluded that the majority of fossils consist of extinct species.

William Smith

A geologist who observed that fossil organisms occur in specific beds of sedimentary strata.

Erosion

The process by which rock and soil are broken down and carried away, potentially exposing fossils.

High Energy Environments

Settings where high energy conditions break up fossil remains.

Fossil Preservation

The condition and quality of a fossil as a result of the burial context.

Bones, Teeth, Shells

Hard minerals from animals that can be buried and preserved into rock.

Chemical Reactions

Processes that can remove organic material from remains, leaving only carbon.

Footprints

The impressions left by organisms that can also fossilize when buried.

Sedimentary Strata

Layers of sedimentary rock that can help date fossils.

Nickolas Steno

The scientist who argued in 1669 that components of organisms can be incorporated in rock without losing their shape.

Extinct Species

Species that no longer exist and are often found as fossils.

Volcanic Ash

Fine particles that can form tuff and potentially contain fossils.

High Water Levels

Conditions that lead to the burial of organisms, ultimately contributing to fossil formation.

Rock Types

Different classifications of rocks; fossils are primarily found in sedimentary rock.

Fossil Record

A historical message of life's past based on fossil discoveries.

Context of Burial

The conditions surrounding how and where fossils are deposited.

Groundwater

Water that is held underground in the soil or in pores and fractures of rock.

Minerals

Inorganic substances that can precipitate and contribute to the formation of permineralized fossils.

Protolife

The earliest protein-like organic chemicals formed from chemicals that emerged when seawater evaporated.

Archaean fossils

Fossils of early life forms that date back to about 3.7 billion years ago.

Cambrian explosion

A period of rapid evolutionary development during which a vast number of shell-bearing invertebrates appeared.

Phylogeny

The study of evolutionary relationships among organisms.

Natural selection

The process by which individuals with favorable traits are more likely to survive and reproduce.

Mass extinction

A widespread and rapid decrease in the biodiversity on Earth, often caused by catastrophic events.

Extremophiles

Microbes that can survive in extreme environments, such as hot springs and salt lakes.

Preservation potential

The likelihood that an organism will be buried and eventually transformed into a fossil.

Extraordinary fossils

Fossils that include not just hard parts but also soft tissues, preserved under special conditions.

Taxonomic classification

The hierarchical arrangement of organisms into categories based on observable characteristics.

Stromatolites

Layered sedimentary structures formed by the growth of cyanobacteria, representing some of the earliest evidence of life on Earth.

Miller-Urey Experiment

An experiment demonstrating that several organic compounds could be formed spontaneously by simulating the conditions of early Earth's atmosphere.

Endosymbiotic Theory

The theory that proposes that mitochondria and chloroplasts in eukaryotic cells originated from prokaryotic cells living inside larger host cells.

Adaptive Radiation

A process in which organisms diversify rapidly from an ancestral species into a multitude of new forms, particularly when a change in the environment makes new resources available, creates new challenges, or opens new environmental niches.

Trace Fossils

Indirect evidence of past life, such as footprints, burrows, or coprolites, rather than the remains of the organism itself.

Protein-like organic chemicals

Early chemical structures that formed protolife, often emerging from evaporated seawater.

Evaporated seawater (early Earth)

A condition on early Earth that facilitated the formation of protolife from chemicals.

Early life forms

Organisms that existed in the distant past, such as those represented by Archaean fossils dating back about 3.7 billion years ago.

Rapid evolutionary development

A characteristic of periods like the Cambrian explosion, where many new species appear quickly.

Shell-bearing invertebrates

A diverse group of animals lacking a backbone and possessing shells, which appeared in vast numbers during the Cambrian explosion.

Evolutionary relationships

The patterns of ancestry and descent among organisms, studied in phylogeny.

Favorable traits

Characteristics that increase an individual's chances of survival and reproduction, central to natural selection.

Survival and reproduction

The outcome for individuals with favorable traits, leading to the perpetuation of species through natural selection.

Biodiversity

The variety of life on Earth at all its levels, which decreases significantly during a mass extinction event.

Catastrophic events

Major geological or environmental changes, often causing mass extinctions.

Microbes

Tiny organisms, including bacteria and archaea, some of which are extremophiles capable of thriving in harsh conditions.

Extreme environments

Habitats with conditions such as very high temperatures (hot springs) or high salinity (salt lakes), where extremophiles can survive.

Hot springs

Geothermally heated bodies of water that are an example of an extreme environment where extremophiles thrive.

Salt lakes

Inland bodies of water with high concentrations of dissolved salts, serving as extreme environments for halophilic extremophiles.

Fossilization process

The sequence of events through which an organism's remains are buried and transformed into a fossil.

Burial of organisms

A crucial first step in the fossilization process, increasing an organism's preservation potential.

Soft tissues (fossils)

Parts of an organism like muscle, skin, or organs that are rarely preserved but can be found in extraordinary fossils under special conditions.

Hard parts (fossils)

Durable components of an organism, such as bones, teeth, or shells, which are more commonly preserved in the fossil record.

Special preservation conditions

Unique environmental factors (e.g., anoxic conditions, rapid burial) that allow for the fossilization of soft tissues, leading to extraordinary fossils.

Hierarchical arrangement (biology)

The organizational structure used in taxonomic classification, ranging from domain to species.

Observable characteristics

Features of organisms that can be seen or measured, used as a basis for taxonomic classification.

Layered sedimentary structures

Physical formations, such as stromatolites, built up by microbial mats over time.

Cyanobacteria

Photosynthetic bacteria, instrumental in forming stromatolites and contributing to Earth's early oxygen atmosphere.

Earliest evidence of life

Remains or traces, like stromatolites, that indicate the presence of life billions of years ago.

Organic compounds (early Earth)

Complex carbon-containing molecules, such as amino acids, believed to have formed spontaneously under early Earth conditions, as simulated by the Miller-Urey Experiment.

Early Earth's atmosphere

The gaseous envelope surrounding Earth billions of years ago, which was vastly different from today's, lacking free oxygen and involved in abiogenesis.

Mitochondria

Organelles within eukaryotic cells responsible for cellular respiration, thought to have originated from free-living prokaryotes via endosymbiosis.

Chloroplasts

Organelles found in plant cells and other eukaryotic photosynthetic organisms, responsible for photosynthesis, also believed to have prokaryotic origins via endosymbiosis.

Eukaryotic cells

Cells characterized by a membrane-bound nucleus and other organelles, which according to the Endosymbiotic Theory, incorporated prokaryotic cells.

Prokaryotic cells

Simple cells lacking a membrane-bound nucleus and other organelles, believed to be the ancestors of mitochondria and chloroplasts through endosymbiosis.

Host cells (endosymbiosis)

The larger cells that engulfed prokaryotic cells, leading to the development of eukaryotic organelles like mitochondria and chloroplasts.

Ancestral species (adaptive radiation)

A single species from which many new, diverse species evolve rapidly to fill various ecological niches.

Environmental niches

The specific role and position a species has in its environment, including its resource use, interactions, and habitat, often exploited during adaptive radiation.

Footprints (fossil)

A type of trace fossil that provides evidence of an organism's movement.

Burrows (fossil)

A type of trace fossil indicating areas where organisms dug into sediment for shelter or food.

Coprolites

Fossilized feces, a type of trace fossil that can reveal an ancient animal's diet.

Indirect evidence of past life

Clues like trace fossils (footprints, burrows, coprolites) that show an organism's activity rather than its physical remains.