Key Concepts in Evolution, Fossils, and Geologic Time

Macroevolution

the broad evolution above the species level.

Sedimentary rock

most fossils are found here, such as PLANT FOSSILS that are about 300 million years old.

Radiometric dating

a common technique to determine a fossil's age, based on the decay of radioactive isotopes.

Half-life

The time required for 50% of the parent isotope to decay. 1 half-life is 5730

C-12

a CARBON ISOTOPE and is the most common in organisms when they are alive

C-14

a RADIOACTIVE ISOTOPE, relatively fast, and has a half-life of 5,730 years (can also be in a living organism)

Uranium-238

decays slowly; it has a half-life of 4.5 million years

The geologic record in the Eras

Cenozoic, Mesozoic, Paleozoic

Permian

The biggest mass extinction

Stromatolites

are layered rocks that form when certain prokaryotes bind thin films of sediment together. They are 3.5 billion years old and are found in oxygen

Cambrian Explosion 1.5

1.5 billion years ago (535-525), there was a sudden increase in the diversity of many animal phyla.

Tiktaalik

the first four-legged vertebrate. 375 mya

Archareafructus sinensis

the first flowering plant discovered.

Plate tectonics

the continents are part of the great plates of the Earth's crust that essentially float on the hot, underlying portion of the mantle

Adaptive Radiation

periods of evolutionary change in which groups of organisms from many new species whose adaptations allow them to fill different ecological roles, or niches, in their communities.

Heterochrony

an evolutionary change in the rate or timing of developmental effects.

Paedomorphosis

the sexually mature stage of a species may retain body features that were juvenile structures.

Homeotic genes

determine where features like wings and legs will develop, or how plant flower parts are arranged

Age of the planet and solar system

4.6 billion years old

Earliest direct evidence of life eon

Archaean

Atmospheric oxygen/photosynthesis age

2.7 billion years old

Origin of jawed vertebrates

450 million years ago

Concretions

hard, compact mass of sedimentary rock pacted around a fossil

Where are stromatolites found?

How long ago did prokaryotes originate on the time scale?

45 minutes

How long ago did eukaryotes occur on the time scale?

15 minutes

When did flowering plants first appear?

140 million years ago

What is considered the first flowering plant discovered?

Archaefructus sinensis

How long have humans been around?

200,000 years

cambrien explosion

535-525 sudden increase in diversity of phyla

What are the 5 mass extinctions?

Ordovician, Devonian, Permian, Triassic, Cretaceous

How long does it usually take for life's diversity to recover after a mass extinction?

5 to 10 million years

How long was that time period following the Permian extinction?

about 51 million years