Topic 3: Paleobiology and Macroevolution

50 vocabulary flashcards covering key concepts from the Paleobiology and Macroevolution lecture notes.

Fossil record

The physical evidence of life in the past; primary data about the evolutionary history of many organisms.

Sedimentary strata

Layers of sediment that accumulate over time, forming rocks in which fossils are preserved.

Fossilization

The process by which organic remains are preserved as fossils or as impressions.

Permineralization

Fossilization where minerals fill pore spaces and replace organic material, turning it into stone.

Molds, casts, impressions

Fossils formed as external impressions or when minerals fill in spaces to create replicas.

Soft-bodied organisms

Organisms lacking hard parts; fossilization is less likely for them.

Anoxic environments

Oxygen-poor settings that can influence preservation of fossils.

Relative dating

Estimating the age of rocks/fossils by position in strata rather than absolute age.

Law of superposition

In undisturbed strata, younger layers lie atop older layers.

Radiometric dating

Estimating rock age by decay of unstable isotopes into stable elements.

Parent isotope

An unstable isotope that decays to a daughter isotope.

Half-life

Time required for half of a radioactive substance to decay.

Carbon-14 (14C)

Radioactive carbon isotope used for dating organic matter up to ~50,000 years.

14C dating

Dating method based on decay of 14C to 14N and the 14C/12C ratio.

Geological time scale

Framework dividing Earth's history into eons, eras, periods, and epochs.

Hadean

Earliest eon; formation of Earth.

Archean

Eon with early life and origin of single-celled organisms.

Proterozoic

Eon with more complex life and atmospheric oxygenation events.

Phanerozoic

Eon of visible life; includes Paleozoic, Mesozoic, and Cenozoic.

Cambrian explosion

Rapid diversification of animal life at the start of the Phanerozoic.

Plate tectonics

Theory that Earth's lithosphere is divided into moving plates.

Continental drift

Movement of continents relative to each other over time.

Pangaea

Supercontinent that existed and later broke apart into Laurasia and Gondwana.

Laurasia

Northern supercontinent comprising North America, Europe, and Asia.

Gondwana

Southern supercontinent comprising South America, Africa, Antarctica, Australia, India, and Madagascar.

Breakup of Pangaea

Separation of Pangaea into Laurasia and Gondwana and subsequent continental drift.

Vicariance

Fragmentation of a once-continuous distribution by external barriers.

Dispersal

Movement of organisms away from their origin to colonize new areas.

Biogeographic realms

Large geographic regions with distinctive assemblages of species.

Nearctic

Biogeographic realm covering North America up to central Mexico.

Palearctic

Realm covering Europe, North Africa, and much of Asia.

Neotropical

Tropical Americas realm.

Afrotropical

African biogeographic realm.

Australian (Australasian) realm

Region including Australia and nearby lands with many endemics.

Sino-Japanese

East Asian biogeographic realm including parts of China, Japan, and Korea.

Oriental

Indo-Malayan region; South and Southeast Asia biogeographic realm.

Madagascan

Madagascar and nearby islands biogeographic realm.

Convergent evolution

Independent evolution of similar traits in unrelated lineages due to similar environments.

Monotremes

Egg-laying mammals such as platypus and echidnas.

Marsupials

Mammals with a pouch for carrying offspring; prominent in Australia and the Americas.

Placental mammals

Mammals with a placenta; most living mammals belong to this group.

Adaptive radiation

Rapid diversification into multiple ecological niches after new opportunities.

Mass extinction

Large-scale extinction events across many lineages in a short time.

Permian extinction

Largest mass extinction (~252 Mya) wiping out many groups.

Cretaceous–Paleogene extinction (K–T)

Mass extinction ~66 Mya that included non-avian dinosaurs.

Chicxulub crater

Impact crater on the Yucatán Peninsula linked to the K–T extinction.

Exaptation

A trait co-opted for a new function beyond its original use.

Archaeopteryx

Transitional fossil showing dinosaur and bird features; evidence for bird evolution.

Homeobox genes

Conserved regulatory genes that control development of body plans.

Hox genes

Subset of homeobox genes that specify anterior-posterior axis during development.