Animal Evolution and Major Extinction Events

Species-scape

Visual representation of species group sizes.

Earth's Age

~4.6 billion years based on radioisotope dating.

Oldest Rocks

Dated to ~4.4 - 4.2 billion years ago.

Phanerozoic

Eon lasting from 543 million years ago to now.

Archean Bacteria

Original extremophiles, thriving in harsh conditions.

Cyanobacteria

Photosynthetic bacteria that produce oxygen.

Great Oxidation Event

Oxygen introduction by cyanobacteria, ~2.4 billion years ago.

Electron Transport Chain

Developed from endosymbiosis ~1.5 billion years ago.

Cambrian Explosion

Rapid diversification of animal phyla, 541-485 million years ago.

Late Ordovician Mass Extinction

First of five major extinctions, ~53%-85% marine loss.

Icehouse Earth

Period with glaciers at both poles.

Great Ordovician Biodiversification Event

Increased global diversity linked to oxygen rise.

Paleozoic Land Invasions

Land animals emerged after plants, around 420 million years ago.

Late Devonian Mass Extinction

Second major extinction, ~70% species loss.

Permian-Triassic Boundary

Third mass extinction, ~80% marine species lost.

Great Dying

Another name for the Permian-Triassic extinction event.

Synapsids

Mammal-like reptiles preceding dinosaurs.

Archosaurian Reptiles

Dinosaurs that rose after the Permian-Triassic Boundary.

Oxygen Delivery System

Evolved ~450 million years ago, enabling larger animals.

Trilobite

Extinct marine arthropod, key fossil indicator.

Anoxia

Absence of oxygen, leading to biodiversity loss.

Photosynthesis

Process converting sunlight into chemical energy.

Extremophiles

Organisms thriving in extreme environmental conditions.

Marine Invertebrates

Aquatic animals without a backbone, diverse groups.

Fossil Record

Historical evidence of past life forms.