"If most of us are ashamed of shabby clothes and shoddy furniture, let us be more ashamed of shabby ideas and shoddy philosophies... It would be a sad situation if the wrapper were better than the meat wrapped inside it." Albert Einstein Albert Einstein

What does it mean for an organism to be extinct?

It existed some time in the past, but has no surviving members.

Can you name any organisms that have become extinct?

Carolina ParakeetPassenger Pigeon Neanderthal ManMammoth Saber Toothed TigerDinosaurs Tasmanian Tiger

What does it mean to be endangered?

Species that may become extinct because their population is small.

Extinction is the process of natural selection. It occurs when a species does not adapt to changes in the environment fast enough. Changes in the environment include habitat change and habitat destruction

CAROLINA PARAKEET

Tasmanian Tiger

Passenger Pigeon

Mammoths

IT IS OFTEN DIFFICULT TO TELL FROM THE FOSSIL RECORD WHEN MASS EXTINCTIONS HAVE OCCURRED. THE FOSSIL RECORD IS NOT COMPLETE. ORGANISMS HAVE TO DIE IN CERTAIN CIRCUMSTANCES TO END UP AS FOSSILS.

SCIENTISTS GENERALLY AGREE THAT THERE HAVE BEEN 6 MAJOR EXTINCTIONS IN GEOLOGIC TIME. Late Cambrian Late Ordovician Late Devonian End Permian - GREATEST MASS EXTINCTION Late Triassic End Cretaceous - KT EXTINCTION - THE END OF DINOSAURS

THE LATE CAMBRIAN EXTINCTION LIFE REALLY TOOK OFF IN THE CAMBRIAN. THERE WAS A GREAT DIVERSITY OF LIFE IN THE SEAS AT THAT TIME. AT THE END OF THE CAMBRIAN, THERE WAS A MASSIVE DIE-OFF. THE REASONS ARE NOT ENTIRELY CLEAR, AS MANY OF THE ORGANISMS HAD SOFT BODIES AND DID NOT LEAVE MANY FOSSILS. IT IS SUSPECTED THAT THE EXTINCTIONS WERE THE RESULT OF A CHANGE IN SEA LEVEL THAT CHANGED THE ENVIRONMENT OF THESE MARINE CREATURES.

THE LATE ORDOVICIAN EXTINCTION THIS EXTINCTION OCCURRED ABOUT 440 MILLION YEARS AGO. THE CAUSE IS THOUGHT TO HAVE BEEN AN ICE AGE THAT RESULTED IN TYING UP MUCH OF THE WATER IN ICE SHEETS. MANY SPECIES LOST UP TO 50% OF THEIR MEMBERS. SCIENTISTS THINK THAT THIS EXTINCTION OCCURRED IN TWO PHASES.

THE LATE DEVONIAN EXTINCTION THIS EXTINCTION TOOK PLACE ABOUT 365 MILLION YEARS AGO. SCIENTISTS THINK IT OCCURRED OVER A PERIOD OF ABOUT 3 MILLION YEARS. ABOUT 70% OF ALL SPECIES VANISHED. SCIENTISTS ARE NOT IN AGREEMENT WITH THE REASONS, BUT MANY THINK IT HAD TO DO WITH CLIMATE CHANGE, AS MANY OF THE SPECIES LOST WERE WARM WATER SPECIES.

THE END PERMIAN EXTINCTION ABOUT 245 MILLION YEARS AGO, THE LARGEST EXTINCTION TO EVER OCCUR HAPPENED. AS MANY AS 96% OF ALL MARINE SPECIES AND 3/4 OF ALL LAND SPECIES WERE LOST. SEVERAL CAUSES HAVE BEEN PROPOSED, INCLUDING SEA LEVEL CHANGE, VOLCANIC ACTIVITY, AND AN ASTEROID COLLISION. THE MOST IMPORTANT FACTOR SEEMS TO BE CILMATE CHANGE.

POSSIBLE REASONS FOR PERMIAN EXTINCTION: -IMPACT -VOLCANISM -FORMATION OF A SUPER CONTINENT -CLIMATE CHANGE -GLACIATION -OTHER

GORGONOPSIA

A CYANOGANTHUS A MEMBER OF THE THERAPSIDA - MAMMAL LIKE REPTILES

THE LATE TRIASSIC EXTINCTION THIS IS ONE OF THE LESS SIGNIFICANT EXTINCTIONS. ABOUT ONE QUARTER OF ALL SPECIES DISSAPEARED ABOUT 208 MILLION YEARS AGO. THE VACANT NICHES WERE FILLED BY THE DINOSAURS. AT LEAST TWO EXTINCTIONS WERE INVOLVED. CLIMATE CHANGE SEEMS TO HAVE BEEN THE MAJOR FACTOR.

THE END CRETACEOUS EXTINCTION THIS IS ALSO KNOWN AS THE K/T EXTINCTION. ABOUT 85% OF ALL SPECIES DISAPPEARED, IN PARTICULAR THE DINOSAURS. SOME SPECIES INCLUDING CROCODILES, TURTLES, LIZARDS, MAMMALS, AND BIRDS MADE IT THROUGH WITH LITTLE EFFECT. METEOR IMPACT SEEMS TO BE THE MOST PROBABLE CAUSE.

SOME OF THE THEORIES OF MASS EXTINCTIONS ARE: ASTEROID IMPACT VOLCANIC ACTIVITY CLIMATE CHANGE SEA LEVEL CHANGE COSMIC RADIATION AND CANCER NICKEL POISONING EGG EATING MAMMALS

AT THE END OF THE LAST ICE AGE AROUND 11,000 YEARS AGO, 2/3 OF ALL LARGE MAMMALS DISSAPEARED FROM NORTH AMERICA. WAS THIS A NATURAL OCCURRENCE OR DID WE EAT THEM?

THOUGHTS ON EVOLUTION AND EXTINCTION 99.9% OF ALL SPECIES THAT HAVE EVER LIVED ARE NOW EXTINCT. THE POSITION OF AN ORGANISM ON AN EVOLUTIONARY TREE DOES NOT INDICATE ITS INFERIORITY OR SUPERIORITY. IT SIMPLY INDICATES THAT ORGANISM WAS ADAPTED TO THE ENVIRONMENT THAT EXISTED AT THAT TIME.

MANY SCIENTISTS ARGUE THAT WE HAVE A MASS EXTINCTION UNDERWAY RIGHT NOW. WE ARE LOSING SPECIES VERY RAPIDLY DUE TO HABITAT DESTRUCTION AND CHANGE. THE AVERAGE RATE OF EXTINCTION FOR ALL SPECIES IS BETWEEN 10 AND 100 PER YEAR. FROM RAINFOREST DESTRUCTION ALONE, WE ARE LOSING ABOUT 27,000 SPECIES A YEAR.

FOR MAMMALS, THE SPECIES LIFETIME IS ABOUT 1 MILLION YEARS. SOME HAVE SURVIVED AS LONG AS 10 MILLION YEARS. THERE ARE ABOUT 5,000 KNOWN SPECIES OF MAMMALS. THE AVERAGE SPECIES LOSS IS ONE EVERY 200 YEARS. WE HAVE LOST 89 IN THE PAST 400 YEARS AND 169 ARE LISTED AS CRITICALLY ENDANGERED.

I = P X A X T HUMAN IMPACT POPULATION AFFLUENCE TECHNOLOGY AT THE END OF THE LAST ICE AGE, WE ENTERED THE HOLOCENE EPOCH (11,500 YEARS AGO). PAUL CRUTZEN, A NOBEL PRIZE WINNER, HAS PROPOSED THAT WE SHOULD NAME A NEW EPOCH, STARTING IN THE MID 1800’S, THE ANTHROPOCENE (THE AGE OF HUMANS). IN 1800, ONLY 3% OF THE GLOBAL POPULATION LIVED IN CITIES. TODAY, IT IS 50% AND RISING. ON THE UPSIDE, CITIES USE LESS ENERGY PER CAPITA AND POLLUTE LESS PER CAPITA THAN RURAL AREAS.