Topic 3: Paleobiology and Macroevolution

Vocabulary-style flashcards covering key terms and definitions from the Paleobiology and Macroevolution lecture notes.

Paleobiology

The study of ancient life through fossils to understand biology, ecology, and evolution of extinct organisms.

Macroevolution

Large-scale evolutionary patterns above the species level, including speciation, extinction, and major transitions.

Fossil Record

Physical evidence of past life; primary data for evolutionary history, often incomplete due to preservation biases.

Strata

Layers of sedimentary rock; youngest are usually on top and are used for relative dating.

Sedimentation

Process by which sediment accumulates and buries organisms to form rocks.

Fossilization

Process by which remains become fossils, including mineral replacement, permineralization, molds, casts, and impressions.

Permineralization

Minerals fill and preserve the porous tissues of organisms, forming stone-like fossils.

Molds, Casts, Impressions

Fossil forms where an organism leaves an impression (mold) or is filled with minerals (cast).

Soft-bodied Organisms

Organisms lacking hard parts; less likely to fossilize compared with hard-bodied species.

Radiometric Dating

Dating rocks by measuring decay of unstable isotopes and their half-lives.

Parent Isotope

Radioactive isotope that decays to a stable daughter product.

Half-life

Time required for half the parent isotope to decay into its daughter product.

Carbon-14 Dating

Radiometric dating using 14C decay to 14N; effective for relatively recent fossils (tens of thousands of years).

Geological Time Scale

Hierarchical system (Eons, Eras, Periods, Epochs) used to date Earth’s history.

Eon

Largest unit of geological time in the time-scale hierarchy.

Era

Subdivision of an eon; e.g., Paleozoic, Mesozoic, Cenozoic.

Period

Subdivision of an era, such as Jurassic or Cretaceous.

Epoch

Subdivision of a period; e.g., Paleocene, Miocene.

Continental Drift

Theory that Earth's continents move over time due to plate tectonics.

Plate Tectonics

Movement of rigid lithospheric plates on the semi-solid mantle, driving continental drift.

Pangaea

Ancient supercontinent that split into Laurasia and Gondwana

Laurasia

Northern portion of the ancient supercontinent Pangaea.

Gondwana

Southern portion of the ancient supercontinent Pangaea.

Dispersal

Movement of organisms away from their origin to new areas.

Vicariance

Geographic separation of populations by barriers or environmental changes.

Disjunct Distribution

Populations of the same species found in widely separated geographic areas.

Biogeographic Realms

Large geographic regions with distinctive, historically connected biotas.

Nearctic

Biogeographic realm covering North America (and Greenland in some schemes).

Palearctic

Biogeographic realm covering Europe, North Africa, and northern Asia.

Neotropical

Biogeographic realm covering South and Central America and the Caribbean.

Afrotropical

Biogeographic realm covering sub-Saharan Africa.

Australian

Biogeographic realm covering Australia and New Guinea with many endemics.

Convergent Evolution

Independent evolution of similar traits in distantly related lineages due to similar environments.

Endemism

A species being restricted to a particular geographic area.

Adaptive Radiation

Rapid diversification of a lineage into multiple species occupying diverse niches.

Mass Extinction

Rapid, global spike in extinction rates eliminating many lineages in a geologically short time.

Background Extinction

Normal, background rate of extinction occurring over long timescales.

KT Extinction

Cretaceous–Paleogene boundary mass extinction, largely due to an asteroid impact.

Iridium Layer

Elevated iridium concentration at the KT boundary, indicative of extraterrestrial impact.

Chicxulub Crater

Impact crater off the Yucatán Peninsula linked to the KT extinction event.

Exaptation

A trait evolved for one function later repurposed for a new use.

Genetic Tool Kit

A set of conserved developmental genes that control body plan formation across animals.

Homeobox Genes

Genes controlling development and body plan organization, part of the genetic tool kit.

Hox Genes

A subset of homeobox genes that pattern anterior-posterior body plan during development.

Pax-6

A master regulatory gene important for eye development and light-sensing organs.

Transitional Fossils

Fossils showing intermediate characteristics between major groups, supporting evolutionary links.

Phyletic Gradualism

Hypothesis that evolution occurs through slow, continuous morphological change.

Punctuated Equilibrium

Hypothesis that most species experience long periods of stasis punctuated by brief speciation events.

Allometric Growth

Differential growth rates of body parts leading to changes in morphology.

Heterochrony

Changes in timing of developmental events, producing diverse morphologies.

Paedomorphosis

Retention of juvenile features in the adult form due to developmental timing changes.

Archaeopteryx

Early feathered dinosaur with features linking reptiles and birds; example of exaptation in flight evolution.