Paleobiology and Macroevolution

Vocabulary flashcards covering key terms from the lecture notes on paleobiology and macroevolution.

Paleobiology

The study of ancient life through fossils to understand the history of life and macroevolutionary patterns.

Macroevolution

Large-scale evolutionary changes above the species level, including origins, diversification, and extinctions.

Fossil record

Physical evidence of past life used to infer morphology, ecology, and evolutionary history.

Strata

Layers of sedimentary rock that preserve fossils and reveal the sequence of deposition.

Sedimentation

The process of sediment settling and accumulating to form layers that trap and preserve organisms.

Fossilization

The preservation process by which organic remains become fossilized, often through mineral replacement or impressions.

Permineralization

A fossilization process where minerals fill pore spaces in originally organic material, turning it to stone.

Molds

Impressions left in sediment after the organism decays, forming a hollow shape.

Casts

Mineral-filled molds that create a replica of the organism.

Impressions

External marks or imprints of organisms preserved in sediment.

Radiometric dating

Dating rocks by measuring the decay of unstable isotopes and their products.

Parent isotope

The original radioactive isotope that decays into daughter isotopes.

Daughter isotope

The product into which a parent isotope decays.

Half-life

The time required for half of a radioactive parent isotope to decay.

Carbon-14 dating

Radiometric dating using 14C to date organic material, effective up to tens of thousands of years.

Relative dating

Estimating age based on position in strata and sequence of deposition, not exact years.

Absolute dating

Determining the exact numerical age of rocks or fossils.

Phanerozoic

Eon that covers most of animal life and the bulk of the fossil record (about 541 Ma to present).

Hadean

Earliest eon of Earth’s history before life began, including formation of Earth.

Archean

Eon preceding Proterozoic; early Earth with first life forms.

Proterozoic

Eon with early life and rising atmospheric oxygen prior to the Phanerozoic.

Paleozoic

Era of early animal and plant diversification within the Phanerozoic.

Mesozoic

Era of dinosaurs; middle life; ends with a mass extinction at the K-T boundary.

Cenozoic

Era after the dinosaurs; age of mammals and birds.

K-T extinction

Cretaceous–Paleogene extinction event about 66 Ma, wiping out most dinosaurs.

Chicxulub crater

Impact crater in the Yucatán Peninsula linked to the K-T extinction.

Iridium layer

A thin global layer enriched in iridium at the K-T boundary, evidence for an asteroid impact.

Plate tectonics

Theory that Earth’s lithosphere is broken into plates that move over the mantle.

Continental drift

Movement of continents due to plate tectonics over geological time.

Pangaea

Supercontinent assembly in the late Paleozoic that later fragmented into Laurasia and Gondwana.

Laurasia

Northern supercontinent that formed from Pangaea’s breakup.

Gondwana

Southern supercontinent formed from Pangaea’s breakup.

Panthalassic Ocean

Global ocean surrounding Pangaea before it broke apart.

Tethys Ocean

Mesozoic ocean between Laurasia and Gondwana.

Rift

A linear feature where tectonic plates pull apart, leading to continental breakup.

Vicariance

Fragmentation of a geographic range by barriers, promoting speciation.

Dispersal

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

Biogeographic realms

Large regions with distinctive, historically related plant and animal life.

Wallace’s Line

Biogeographic boundary separating faunas of Asia and Australia.

Convergent evolution

Evolution of similar features in unrelated lineages due to similar environments.

Adaptive radiation

Rapid diversification of a lineage into multiple ecological roles after entering a new niche.

Mass extinction

Rapid, global loss of a large number of species in a short time.

Background extinction

Normal, low-rate extinction that occurs as environments change.

Transitional fossil

Fossil showing intermediate features between ancestral and derived forms.

Phyletic gradualism

Evolutionary pattern with slow, continuous morphological change.

Punctuated equilibrium

Pattern of long stability with brief bursts of rapid change and speciation.

Allometric growth

Different growth rates of body parts producing morphological differences.

Heterochrony

Change in the timing of developmental events affecting form.

Paedomorphosis

Retention of juvenile traits in the adult form due to altered development.

Exaptation

Traits evolved for one function later co-opted for another function.

Archaeopteryx

Early feathered dinosaur–bird transitional fossil with both dinosaur and avian traits.

β-keratin

Protein found in feathers, supporting their evolution in fossils.

Genetic tool kit

Conserved set of developmental genes that orchestrate body plan development.

Homeobox genes

A family of regulatory genes with conserved sequences that control development.

Hox genes

Homeobox genes that determine body plan along the head-to-tail axis.

Pax-6

Gene important for eye development; an example of a conserved developmental control gene.

Cambrian explosion

Rapid diversification of animal phyla early in the Cambrian period.

Hyracotherium

Earliest known horse ancestor, small with multiple toes.

Mesohippus

Intermediate horse-like ancestor showing limb and dentition changes.

Merychippus

later horse ancestor with further limb evolution toward running.

Pliohippus

More advanced horse ancestor closer to modern horse anatomy.

Equus

Genus that includes modern horses, zebras, and donkeys.