Mass Extinction Events and the Evolution of Life on Earth

These flashcards cover key vocabulary terms related to mass extinction events and the evolution of life on Earth, based on the provided lecture notes.

Paleozoic Era

A geological era that lasted from about 541 to 252 million years ago, known for the emergence of extensive marine life and the first land-dwelling organisms.

Cambrian Explosion

A significant period about 541 million years ago during which there was a rapid increase in the diversity of life forms, particularly multicellular organisms.

Mass Extinction

A widespread and rapid decrease in the biodiversity on Earth, occurring at the end of geological eras or significant ecological disruptions.

Plate Tectonics

The scientific theory explaining the movement of the Earth's lithosphere that has shaped the planet's surface and influenced mass extinctions.

Volcanism

The eruption of molten rock, gases, and ash from a volcano, which can significantly alter the atmosphere and climate, potentially leading to extinction events.

Invertebrates

Animals without a backbone, which dominated the Earth's fauna during the Paleozoic Era.

Extinction Event

A large-scale event in which a substantial percentage of the species on Earth become extinct in a relatively short period.

Mass Extinction Events - Five Main Events

The five significant extinction events in Earth's history that are typically attributed to causes such as volcanic activity, climate change, and meteor impacts.

Mesozoic Era

The era following the Paleozoic, known for the dominance of dinosaurs and the appearance of mammals and birds.

Ediacaran Biota

The group of life forms from the Ediacaran period, recognized for their simple multicellular organisms predating the Cambrian explosion.

Geological Time Scale

A timeline used by geologists and paleontologists to describe the timing and relationships of events in Earth's history.

Biotic Changes

Changes in the biosphere, particularly the interactions between living organisms, which can influence extinction rates and species evolution.

The Burgess Shale

A famous fossil field in Canada known for its well-preserved Cambrian soft-bodied organisms, providing insights into early multicellular life.

Ecological Arm's Race

An evolutionary struggle between interacting species, leading to adaptations and counter-adaptations, often seen during periods of diversification.

Meteorite Impacts

Collisions of meteoroids with Earth, which can lead to significant ecological changes and mass extinction events.

Adaptive Radiation

The rapid evolution of diversely adapted species from a common ancestor when opportunities arise, such as after mass extinction.

Biodiversity

The variety of life in a particular habitat or ecosystem, often assessed in terms of the number of species.

Cenozoic Era

The current geological era, which started about 66 million years ago, marked by the emergence and dominance of mammals.

Trilobites

Extinct marine arthropods that were prevalent during the Paleozoic era and are a significant part of the fossil record.

Carbon Cycle

The cycle in which carbon is exchanged among the biosphere, geosphere, hydrosphere, and atmosphere, crucial for supporting life.

Geophysicists

Scientists who study the physical processes and properties of the Earth, including plate tectonics and its impact on geology.

Ordovician Extinction

The first major mass extinction event approximately 440 million years ago, resulting in a significant loss of marine species.

Permian Extinction

The largest mass extinction event in history, occurring around 250 million years ago, where about 95% of marine species and 70% of terrestrial life were lost.

Mesozoic Era - Dinosaurs

The era known for the rise of dinosaurs, characterized by three periods: Triassic, Jurassic, and Cretaceous.

Fossil Record

The history of life on Earth as recorded by fossils, which provides evidence of organisms that existed and their evolutionary changes over time.