Biology Chapter 14: Fossil Formation

Fossils

• A fossil is any preserved evidence of an organism.
• Organisms that are buried rapidly in sediment are preserved and can become fossils.
• Fossil formation occurs when organisms die, are buried by sediment, and minerals replace the spaces created by bones and hard parts of the organism.
• Erosion can expose fossils.

Paleontologists

• Paleontologists are scientists who study fossils.
• They read and record fossils to learn about the diet and environment of ancient organisms.

Dating Fossils

• Relative dating finds the age of a rock by comparing rock layers.
• The Law of Superposition states that younger layers are on top of older layers.
• Radiometric dating measures the decay of radioactive isotopes to determine the age of rocks.
• Half-life is the time it takes for the amount of a radioactive isotope to decay.
• Geologists use the half-life of isotopes to determine the age of rocks.

Geological Time Scale

• The geological time scale shows major geological and biological events in Earth's history.
• The Precambrian era spans the first 4 billion years of Earth's history.
• The Phanerozoic eon is divided into the Paleozoic, Mesozoic, and Cenozoic eras.
• The Paleozoic era saw the Cambrian explosion, mass extinctions, and the emergence of life on land.
• The Mesozoic era was marked by the evolution of dinosaurs, birds, and mammals.
• The Cenozoic era saw the evolution of mammals as dominant land animals and the emergence of humans.

Early Ideas about Life

• Spontaneous generation was an early idea that life could arise from non-life.
• The theory of biogenesis states that living organisms produce new living organisms.
• Louis Pasteur's experiment showed that microorganisms cannot arise spontaneously.

Modern Ideas about Life

• Biologists believe that life arose from a series of chemical events on Earth.
• The primordial soup hypothesis suggests that organic molecules could have formed in the early Earth environment.
• The Miller and Urey experiment showed that inorganic compounds can produce simple organic molecules.
• Later experiments showed that precursors to nucleotide bases can form with simpler molecules in early Earth environments.

Levels of Organization within the Biosphere

• The biosphere is the part of the Earth where life exists.
• Biomes are groups of ecosystems with a similar climate.
• A community is a group of populations that interact in an area.
• A population is a group of the same species that interbreed and produce offspring.
• A species is a group of similar organisms that can interbreed and produce offspring.

Interactions with the Environment

• Ecology is the study of the interactions among organisms and their environment.
• An ecosystem is the area where these interactions take place.
• Biotic factors are living, while abiotic factors are non-living.
• Aquatic and terrestrial ecosystems support different forms of life.
• Biodiversity is the variety of organisms in an ecosystem.
• An organism is a single living thing within an ecosystem.
• A habitat is a place where an organism obtains the necessary resources.
• A niche is the unique job of an organism in an ecosystem.