paleontology - unit 2

Paleontology

Scientific study of ancient life through fossils to understand evolution, interactions, and environments.

Fossil

Preserved remains or traces of ancient life, often formed when biological materials are replaced or encased by minerals.

Taphonomy

Study of how plant and animal remains are deposited and preserved, including environmental effects.

Processes that destroy bones before fossilization

Scavenging, decomposition, weathering, gnawing, or other natural breakdown.

Permineralization

Process where minerals infuse into the pores of bones, preserving their structure.

Recrystallization

Process where original materials are replaced with new minerals during fossilization.

Sedimentary rock

Rock formed by the deposition and compression of mineral, rock, or organic particles — where fossils are usually found.

Stratigraphy

Study of rock layers (strata) and the sequence of geological events they represent.

Stratum

A single rock layer; plural = strata.

Geologic deep time

The vast span of Earth's history revealed through rock layers, fossils, and geological processes.

Cosmic Calendar

Visualization created by Carl Sagan to compress 13.8 billion years of cosmic history into one calendar year.

Age of the universe

Approximately 13.8 billion years.

Law of Superposition

In undisturbed sedimentary layers, the oldest rocks are on the bottom and youngest on top.

Relative dating

Determines the order of events without giving a specific numerical age.

Absolute dating

Determines an object's actual age in years, often using radiometric methods.

Biostratigraphy (Faunal Dating)

Uses index fossils with known time ranges to determine the relative age of rock layers.

Geomagnetism

Dating method that examines magnetic field reversals recorded in rocks.

Index fossil

A fossil of a species known to have existed during a specific time range, used for dating layers.

Radiocarbon dating (Carbon-14)

Method for dating organic material up to about 50,000 years old using the decay of carbon-14.

Carbon-14 half-life

5,730 years.

Potassium-Argon dating

Radiometric dating method for volcanic rocks using the decay of potassium-40 to argon-40 (half-life: 1.25 billion years).

Isotope

Atoms of the same element with different numbers of neutrons.

Radioisotope

Unstable isotope that decays over time into a stable form.

Half-life

Time it takes for half of the radioactive atoms in a sample to decay into a more stable form.

Molecular clock

Method estimating species divergence based on DNA mutation rates.

Mutation

Change in an organism's DNA sequence; can be inherited or acquired.

Geologic time scale divisions

Eon → Era → Period → Epoch → Age.

Eon

Longest unit of geologic time (billions of years).

Era

Major division within an eon (hundreds of millions of years).

Period

Division within an era (tens of millions of years).

Epoch

Division within a period (millions of years).

Age

Smallest division of geologic time (thousands of years).

Phanerozoic Eon

Current eon; divided into Paleozoic, Mesozoic, and Cenozoic eras.

Mnemonic for geologic time order

"Eons Exist Prior To Everything After" or "Evil Elephants Play Every Afternoon."

Hadean Eon

Earliest eon; Earth forms.

Archaean Eon

Life first appears.

Proterozoic Eon

Oxygenation of atmosphere and multicellular life.

Cenozoic Era

"Age of Mammals"; current era of life.

Paleogene, Neogene, Quaternary

Periods of the Cenozoic Era.

Pleistocene and Holocene

Epochs of the Quaternary Period.

Greenlandian, Northgrippian, Meghalayan

Ages of the Holocene Epoch.

Elemental analysis

Technique used to determine which elements and how much of each are present in a material or sample.

Biogeochemistry

Study of chemical, physical, geological, and biological processes that influence Earth's environment.

Atom

Smallest unit of matter retaining the properties of an element.

Atomic mass

Number of protons plus neutrons in an atom's nucleus.

Democritus

Proposed that all matter is made of tiny, indivisible particles called atoms.

Aristotle

Proposed that all matter was made of four elements (earth, water, air, fire) plus aether for celestial bodies.

Jabir ibn Hayyan

Developed early chemical processes such as the synthesis of acids.

Jöns Jakob Berzelius

Developed methods to measure composition of compounds and elemental ratios.

Dmitri Mendeleev

Created the periodic table of elements.

Niels Stensen (Nicolaus Steno)

Pioneered stratigraphy and proposed the Law of Superposition.

Molecular mutation rate

The speed at which DNA mutations occur; used to calibrate the molecular clock.

Morris Goodman

Developed the molecular clock concept for estimating species divergence.

Taphonomic processes

Natural events (e.g., decay, scavenging) that affect how remains become fossilized.

Fossil record

All known fossils and their placement in rock formations and sedimentary layers, showing the history of life on Earth.

Deep time

Concept that Earth's history spans billions of years, far beyond human timescales.