Geological Time, Eras, and Fossilization — Vocabulary Flashcards

Vocabulary flashcards covering major geological eras, time scales, and fossilization concepts discussed in the lecture.

Pre-Cambrian

Era before the Cambrian (~4.58–542 million years ago); Earth forms and early life develops.

Cambrian

Period starting ~542 million years ago; rapid diversification of life (Cambrian explosion).

Paleozoic

Era from ~542 to 251 million years ago; includes Cambrian to Permian; ends with a major mass extinction.

Permian

Period (~299–251 mya) marked by a large mass extinction at its end; diversification of reptiles.

Mesozoic

Era from ~251 to 65 million years ago; age of dinosaurs; includes Triassic, Jurassic, Cretaceous.

Triassic

Period ~251–201 mya; recovery after Permian; first dinosaurs and mammals appear.

Jurassic

Period ~201–145 mya; peak dinosaur diversity; early birds appear.

Cretaceous

Period ~145–65 mya; dinosaurs dominate; ends with KT boundary extinction.

KT boundary (Cretaceous-Paleogene boundary)

Marker at ~66 mya; mass extinction (dinosaurs) linked to asteroid impact and volcanic activity.

Paleogene

Subdivision of the Cenozoic (65–23 mya); includes Paleocene and Eocene; mammals diversify.

Neogene

Subdivision of the Cenozoic (23–2.6 mya); includes Miocene and Pliocene; primate evolution continues; origin of humans.

Paleocene

Early Paleogene (~65–56 mya); mammals diversify after dinosaur extinction.

Eocene

Mid Paleogene (~56–34 mya); primate radiation; resembles modern primates.

Oligocene

Late Paleogene (~34–23 mya); further primate evolution; origin of many anthropoids.

Miocene

Period (~23–5.3 mya); important for ape evolution and early hominins.

Pliocene

Period (~5.3–2.6 mya); Australopiths appear; early Homo evolves.

Australopiths

Early hominins in Africa; bipedal; ancestors of Homo.

Homo sapiens

Modern humans; appears in Africa about 300,000 years ago.

Agriculture

Domestication of plants and animals; leads to sedentism and the rise of cities.

Sedentism

Living in one place due to agriculture; sustained human settlement.

Sedimentary rocks

Rocks formed by deposition of particles; often contain fossils in strata.

Igneous rocks

Rocks formed by cooling of molten magma or lava; not suitable for fossils.

Metamorphic rocks

Rocks altered by heat/pressure; fossils usually not preserved.

Fossilization

Process of mineral replacement of organic material, turning remains into rock.

Fossil

Preserved remains or traces of ancient organisms.

Holocene

Current geological epoch (~11.7k years ago–present); rise of agriculture and civilizations.