Earth's Evolution Through Geologic Time

Goldilocks zone

The perfect distance from a star in order to sustain water.

Big bang theory

Cosmological model that explains the sudden development of the universe through expansion from a hot, dense state. ~14 BYA.

Nuclear fusion

The process by which two or more small nuclei fuse to make a bigger nucleus.

Supernova

A gigantic explosion in which a massive star collapses and throws its outer layers into space. Releases heavy elements formed at the star's core.

Solar nebula theory

The theory that describes how stars (like the Sun) and planets form from contracting, spinning disks of gas and dust.

Protoplanets

Regions of condensed matter that serve as a starting point for the formation of a planet.

Hydrogen Helium Methane Ammonia Carbon dioxide Water vapor

Composition of Earth's primitive atmosphere

Solar wind

The continuous flow of charged particles from the sun that permeates the solar system. Blew away the lighter gases in the Earth's early atmosphere. Stronger by the time a star is newly formed.

T-Tauri phase

A phase characterized by strong winds from the star; these winds were able to clear the solar system of any of the left over gas; proto-sun went through this phase.

Outgassing

The process of releasing gases from a planetary interior, usually through volcanic eruptions. Caused the formation of the early atmosphere.

3.5 billion years ago

Estimate of when the first living organisms showed up on the planet. Estimate on when oceans were formed.

Cyanobacteria

Photosynthetic, oxygen-producing bacteria (formerly known as blue-green algae). Produced the early form of oxygen in the atmosphere. Oldest fossil found (3.5 BYO).

Banded iron formations

Unique, shallow marine deposits made up of alternating bands of chert and iron oxides that formed due to locally high oxygen levels produced by stromatolites.

2.2 billion years ago

Estimated time when significant amounts of oxygen appeared.

1.5 billion years ago

Estimated time when oxygen levels in the atmosphere stabilized.

Carbon dioxide Sulfur dioxide Hydrogen sulfide

Dissolved in the primordial oceans that caused them to be acidic.

542 million years ago

Time when marine organisms begin secreting calcium carbonate to form shells and hard parts. Beginning of the Cambrian period.

Precambrian

Informal unit of geologic time consisting of the first three eons during which earth formed and became habitable. 88% of geologic time.

Hadean Archean Proterozoic

Divisions of the informal Precambrian eon. Eons individually.

Acasta gneiss

Oldest known rock. ~4 BYO.

Rodinia

A supercontinent older than Pangaea that formed about 1.1 billion years ago and began to break up about 750 million years ago. Formed during the Precambrian.

Gondwana

Supercontinent that existed before Pangea, more than 500 million years ago.

Supercontinent cycle

The process of change during which supercontinents develop and later break apart, forming pieces that may merge once again in geologic time to make yet another supercontinent.

Phanerozoic

Means visible life. The most recent eon, began about 540 million years ago during the opening of the Cambrian.

Paleozoic Mesozoic Cenozoic

Era divisions of the Phanerozoic eon.

Laurasia

Late Paleozoic, Northern Hemisphere continent composed of the present-day continents of North America, Greenland, Europe, and Asia.

Gondwanaland

Southern half of Pangaea. Consist of the continents of Africa, South America, India, Australia, and Antarctica when all the continents were a single landmass.

300 million years

Amount of time needed to form Pangaea.

Caledonian Mountains

Formed by the collision of Norway and Greenland.

Ural Mountains

This north-south range separates Siberia from the rest of Russia. It is commonly considered the boundary between the continents of Europe and Asia. Formed by the collision of North Asia and Europe.

Appalachian Mountains

A mountain range in the eastern United States extending from Quebec to the Gulf of Mexico. Formed by the collision of North America and Africa.

Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian

Divisions of the Paleozoic era.

Triassic, Jurassic, Cretaceous

Divisions of the Mesozoic era.

Morrison formation

Formed by the regression of the Sundance Sea due to Nevadan Orogeny. Famous for abundant dinosaur fossils.

165 million years ago

Beginning of the breakup of Pangaea. Began between Africa and North America. Birth of the Atlantic Ocean.

Laramide orogeny

Late Cretaceous to Early Cenozoic phase of the Cordilleran orogeny; responsible for many structural features of the present-day Rocky Mountains.

Tertiaty and Quaternary

Divisions of the Cenozoic era.

Paleogene and Neogene

Subdivisions of the Tertiary period. Individual periods as well.

Paleocene, Eocene, and Oligocene

Epoch divisions of the Paleogene period.

Miocene and Pliocene

Epoch divisions of the Neogene period.

Pleistocene and Holocene.

Epoch divisions of the Quaternary period.

3.8 billion years ago

Estimated time of the beginning of life on Earth.

Hospitable environment Chemical raw materials to form DNA, RNA, and proteins Amino acids

Requirements for life

Methane Ammonia

Where the first amino acids were first synthesized

Prokaryote

Appeared 3.6 BYA. First known organisms, singe-celled, DNA not separated, used solar energy to create sugar.

Stromatolite

Layered rock that results from the activities of prokaryotes that bind thin films of sediment together. Fossil evidence of stromatolites.

Eukaryote

Appeared 2.1 BYA. Microscopic, water-dwelling, multi-cellular, cells have nucleus.

Green algae

Photosynthetic protists that include unicellular, colonial, and multicellular species with grass green chloroplasts; closely related to true plants.

Cambrian explosion

A burst of evolutionary origins when most of the major body plans of animals appeared in a relatively brief time in geologic history; recorded in the fossil record about 545 to 525 million years ago. Abundance in jellyfishes, sponges, worms, mollusks, and arthropods.

Cambrian

Golden age of trilobites.

Ordovician

The period of the first armor-plated fishes with jaws, cephalopods, and corals .

Silurian

Age of the first true land plant fossils.

Devonian

Age of fishes. Lobe-finned fish was able to adapt to terrestrial environments.

Mississippian

First fossil conifer trees.

Pennsylvanian

First reptile fossils.

Permian

The time period known for the first mammal-like reptiles (Dimetredon). Last time trilobites were found. Ended with the Great Dying.

The great Permian extinction

70% of land and 95% of marine organisms dead. Worst extinction event. Diversified the succeeding life forms. Began in the oceans due to oxygen reduction.

Climate change + biological forces Asteroid impact Volcanism at current-day Siberia

Possible causes of the great Permian extinction.

Paleozoic era

The part of geologic time 570-245 million years ago ; invertebrates, fishes, amphibians, reptiles, ferns, and cone-bearing trees were dominant.

Mesozoic era

Middle life (245-144 million years ago); rise of mammals and dinosaurs; the rise of birds; extinction of dinosaurs, rise of flowering plants.

Cenozoic era

Era that began about 66 million years ago, known as the "Age of Mammals and Flowering Plants".

Gymnosperm

A woody, vascular seed plant whose seeds are not enclosed by an ovary or fruit. Dominant trees of the Mesozoic. Prefer dry climates; no need for standing water source. Cycads, ginkgoes, conifers. Best fossils preserved in Arizona.

65 million years ago

End of the Cretaceous. Extinction of dinosaurs.

K-T extinction

About 65 MYA. Caused by asteroid impact in the Gulf of Mexico. 52% of marine genera went extinct, 18% of land vertebrate families, including the dinosaurs, went extinct. Might also be caused by Deccan Trapp volcanism or a nearby supernova explosion.

Angiosperm

A flowering plant which forms seeds inside a protective chamber called an ovary. Helped the development of new species of animals that feed on seeds.

Increase in size Increase in brain capacity Specialization in teeth to accommodate diet Specialization in limbs to accommodate lifestyle

Four directions of development

Marsupial

A mammal, such as a koala, kangaroo, or opossum, whose young complete their embryonic development inside a maternal pouch called the marsupium.

Placental

A type (subclass) of mammal. During the Cenozoic, placentals became the most widespread and numerous mammals and today are represented by upward of 20 orders, including the primates