Geologic Time
Scale

Culmination of mountain building followed by erosion and moderate, short-lived invasions of continental margins by the seas . Rise of modern plants, animals, and man.  Evolution of HUMANS during the last 5-8 million years.


Transition from archaic mammals to modern orders and eventually families.  Early warming trends were reversed by the middle of the period to cooler and finally to glacial conditions.

Extensive mountain building at the end, climate cooled worldwide.  Extinction of archaic birds and many reptiles by the end of this period.

First reptilian birds .  Reptilian diversity was high in all habitats.  Climate was warm and stable with little seasonal variation.

Earliest dinosaurs , flying reptiles, marine reptiles.  Primitive mammals appeared.  Continents were high with few shallow seas. Climate warm.

Rise of primitive reptiles.   Extinction of the trilobites.  Climate was cold at the beginning but warmed progressively. Widespread extinctions at the end of this period.  

Earliest know insects, large arthropods. Climate generally warm and humid. Extensive coal producing swamps. Many specialized amphibians and the first appearance of reptiles

Extinction of some fish lineages and expansion of others. Beginning of large coal production swamps. Extensive radiation of amphibians.

Explosion of fish and disappearance of many jawless varieties. First winged insects and tetrapods. Land was higher climate cooler.

Earliest know land animals . Primitive plants. Rise of fishes. Abundant trilobites.

Earliest know vertebrates. Primitive plants. Trilobites and cephalopods abundant.

Extensive shallow seas. Brachiopods and trilobites common.

Primitive water dwelling plants and animals. Changes in the lithosphere produced major land masses and shallow seas.

Oldest know life (mostly indirect evidence).   Formation of the earth and slow development of the lithosphere, hydrosphere and atmosphere. Development of life in the hydrosphere.