EXTINCTION EVENTSand

EVOLUTION

A great reference for this class is:The Great Extinctions by Norman MacLeod C 2013 Natural History Museum London & Firefly Books

“In terms of size, mammals are an anomaly, as the vast majority of the world’s existing animal species are snail sized or smaller. It’s almost as if, regardless of your kingdom, the smaller your size and earlier your place on the tree of life, themore critical is your niche on earth: snails and worms make soil, and blue-green algae create oxygen, mammals seem comparatively dispensable, the result of the random path of evolution over a luxurious amount of time.”

Elisabeth Tova Bailey The Sound of a Wild Snail Eating

The Tree of Life

MammalsAre in here

PERIOD STAGE Percent Family Extinction (Observed)

Percent SpeciesLoss (Estimated)

Percent Genus Extinction (Observed)

Percent Species Loss (Estimated)

End ORDOVICIAN Hirnantian 26 77-91 60 82-88

DEVONIAN Frasnian 22 70-88 57 79-87

End PERMIAN Changhsingian 51 93-97 82 93-97

End TRIASSIC Norian 22 70-88 53 76-84

End CRETACEOUS Maastrichtian 16 57-83 47 71-81

THE BIG FIVE EXTINCTION EVENTSObserved & Estimated Extinction Losses

Ripple MarksThe preservation of ripple marks and other evidence of past environments and the animals that lived in them (fossils) never ceases to amaze.

These ripple marks are not from any extinction event, but I wanted you to see the distinctive marks that all can recognize and those who study such things can tell so much about how they were made. Including the depth of water, the flow direction and then the rocks can also tell the age they were deposited, by the fossils within them or below and above them.

These ripple marks are in the Grinnell Formation more than a billion years old

EVOLUTION

Migration: Species move from areas of crowding into new less crowded areas, it is why the chicken crosses the road

Adaption: In the new environment these species must adapt to the newly found conditions to survive.

Reproduction: The organisms begin to adapt to the new environment and reproduce creating random mutations.

Selection: This mutations eventually result in some adaptable groups surviving and others dying off.

Speciation: The species eventually begins to change due to the mutations and some survive better creating new species.

EXTINCTION

An extinction event opens up many new environments that other species can move into, then thrive in, and go through the stages above.

Early extinctions were marine and later ones both marine and terrestrial because organisms were unable to colonize the land until an ozone layer developed to protect them from ultraviolet radiation. This did not occur until the early middle Paleozoic.

Are Extinction Events Cyclical? There is strong evidence that they are based on various celestial cycles including the wobbleof the Earth’s axis to our solar systems position in its galactic orbit.

PERMIAN TRIASSIC CRETACEOUS

DEVONIAN

ORDOVICIAN Mississippian Jurassic

Miocene

Silurian

Cambrian

PANGAEA Super Continent

TOTAL GENERA THROUGH THE PHANEROZOIC ERAThe Cambrian to the Present Holocene

The Present

INFLUENCES ON THE POPULATIONS OF GENERA REPORTED

The bias of the fossil record

No one to study earlier geologic genera alive

Erosion erasing the fossil record

THE DIVERSITY OF LIFE

Commonly Seen Kingdoms

PANGAEA

AsteroidsThe changes in sea levels and currents is a result, in part, Asteroids hit the earth with extreme force. The reverberations can be felt around the world. The impact site is completely destroyed.

Cosmic Radiation

Cosmic Radiation is radiation being emitted from outer space and the Sun. It is theorized that being exposed to too much cosmic radiation can mutate genes, which can potentially weaken a species' genepool in the future. Since the radiation comes from space and the Sun, it is extremely difficult to avoid the radiation. Supernova remnants are one source of cosmic radiation.freshwater. The denser, saltier water

Acid Rain

Acid rain forms when sulfur dioxide and/or nitrogen oxides are put out into the atmosphere by volcanoes or man. The chemicals get absorbed by water droplets in the clouds, and eventually fall to the earth as acid precipitation. Acid rain increases the acidity of the soil which affects plant life. It can also disturb rivers and lakes to a possibly lethal level.at marine

life depends on. Ocean floor spreading and rising also

Climatic Heating and Cooling

Climate Change is caused by a number of things. The effect that climate has on extinction is very big. The biodiverse Earth can't keep up with the rapid changes in temperature and climate. The species are not used to severe weather conditions and long seasons, or a changing chemical make-up of their surroundings. As more species die, it is only making it more difficult for the survivors to find food. The warmer climates we are used to present-day are perfect for diseases and epidemics to thrive.

Changes in Sea Levels or Currents

The changes in sea levels and currents is a result, in part, of the melting freshwater. The denser, saltier water sinks and forms the currents that marine life depends on. Ocean floor spreading and rising also affects sea level. A small rise in the ocean floor can displace a lot of water onto land that is all ready occupied. The gases from the volcanic activity can also be absorbed by the water, thus changing the chemical composition, making it unsuitable for some life.a changing

chemical make-up of their surroundings. As more species Large Volcanic Eventsdie, it is only making it more difficult for the survivors to find food. The warmer climates we are used to present-

EXTINCTION CAUSES

METEORITE IMPACTs

Woodbury Crater

Wetumpka Crater

NORTH AMERICANIMPACT SITES

IMPACT EVENTS

MANICOUGAN CRATER, CANADA(40 miles in diameter)

Chicxulub CraterMexico's Yucatan Peninsula

(93 miles in diameter)

This is the impact that is thought to have been a contributing factor in the extinction at the end of the Cretaceous.

GLACIATION

Maximum Extent of ice in Europe during the Pleistocene

GLACIATION

Maximum Extent of ice in North America during the Pleistocene

LARGE IGNEOUS PROVINCES

Siberian Traps

Pacific Province

Deccan Plateau

Columbia River Basalts

Caribbean Sea

Ethiopian HighlandsBrazilian Highlands

Iceland

SUPER MAGMA EJECTIONS

DECCAN TRAPSA part of the Cretaceous Extinction Event

SIBERIAN TRAPSA large volcanic Mantle Plume Eruption thought to have been part of the Permian Extinction Event

EXTINCTION EVENTS SUMMARY

FREQUENCY:

Cambrian Ordovician SilurianDevonian Mississippian PermianTriassic Jurassic CretaceousMiocene

CAUSES:

Meteorite (Bolide) Impacts Large Igneous ProvincesClimatic Changes Plate TectonicsCosmic Radiation Sea Level FluctuationsAcidification

Ediacaran Fauna Overview Video