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Evolution-History of Life
Transcript of Evolution-History of Life
Anaerobic life appeared and evolved, causing the atmosphere to contain oxygen.
Few fossils exist because the animals were all soft-bodied and in the sea. A relative of modern jellyfish. http://www.blackwellpublishing.com/ridley/image_gallery/Precambrian_jellyfish.asp The fossil record became rich with evidence of marine life.
Many vertebrates and invertebrates. Cambrian Period The "Cambrian Explosion"-The diversity of life during the early Cambrian period.
First known representatives of most animal phyla evolved.
Animals had hard parts like shells that could form fossils. An artist's portrayal of Cambrian life http://eonsepochsetc.com/PreCambrian/precamb_images/precambrian.gif Ordovician and Silurian Periods Aquatic arthropods, like the ancestors of the modern octopi and squid appeared.
Some animals grew to a length of almost 13 meters.
Vertebrates appeared. (jawless fishes were among the first)
The first plants evolved from their aquatic ancestors. Birkenia- an extinct fish from the Silurian period http://www.hmag.gla.ac.uk/neil/Lesmahagow/Lesmahagow.html Devonian Period Plants adapted to drier areas, allowing them to invade more habitats.
In the seas, invertebrates and vertebrates thrived
Often called the Age of Fishes
Animals begin to invade the land The fern-like leaves of Archaeopteris, one of the first tree-like plants. It grew to an average height of about 10 meters, produced spores, and had a global distribution. http://www.ucmp.berkeley.edu/devonian/devonian.php During the Devonian Period, fish species like the gigantic Dunkleosteus swam the Earth's waters. http://www.astrobio.net/pressrelease/3497/on-the-backs-of-fishes Carboniferous and Permian Life expands over Earth's continents
Reptiles evolved from Amphibians
Winged insects evolved
Plants, including giant ferns, formed swamps
The remains of the plants formed thick deposits of sediment that became coal over millions of years, and that is where "Carboniferious" got its name. Mass Extinction A mass extinction at the end of the Permian period and the Paleozoic era that affected both life on land in oceans. 95% of life in the oceans disappeared. However, there is little certainity to the cause of this event. http://www.naturenorth.com/dragonfly/DOM/Page03_Palaeobiology.html An artist's protrayal of a Carboniferous Period forest http://www.ucmp.berkeley.edu/carboniferous/carblife.html New groups of animals evolved from others. This is an early reptile from the Carboniferous period 650 to 544 Million Years Ago 544 t0 245 Million Years Ago 544 to 505 Million Years Ago 505 to 440 Million Years Ago 440 to 410 Million Years Ago 410 to 363 Million Years Ago 363 to 290 Million Years Ago 290 to 245 Million Years Ago 245 to 65 Million Years Ago There is an increasing dominance of dinosaurs
This era is marked by the appearance of flowering plants. Triassic Period 245 to 208 Million Years Ago The surviors of the Permian extinction became the main form of life during early in the Triassic period
Often called the "Age of the Reptiles" They were very successful
Other organisms in the new ecosystem included fishes, insects, and cone-bearing plants.
The first dinosaurs appeared
Mammals first appeared- but they were very small. Evolution And The Primordial Soup Creationism This theory uses natural selection, evolution and chance to try and account for life coming from non life.
At the beginning of the Earth, everything was in a primordial soup of particles and metal and such that attracted to each other. The earth melted to form the globe and was ovlcanic.
Oceans formed. The early atmosphere was made of water vapor, methane ammonia and hydrogen.
The organic molecules that first existed would have been destroyed in an O2 based atmosphere.
The 1st life forms are thought to have been RNA based.
Life then evolved to become photosynthetic and started creating oxygen
The first O2 made the iron in the oceans rust and it sank to the bottom of the ocean.
Oxygen filled the oceans and then the atmosphere so life had to become aerobic.
Life came about by natural selection. This is the belief that there is a creator who made the Earth(intelligent design).
This is the Biblical belief and also explains how life and the universe in general is so complex, much too complex to have simply “evolved”.
Natural selection can only work on things that are alive, so that doesn’t explain how life came from non life. History of Life-The Basics Fossil Record: the order that fossils appear on the earth showing that living things have changed over time.
(Different aged rocks with older fossils, newer rocks with newer fossils)
Over 99% of all the species that ever lived on Earth are extinct. Fossils: the remains of once-living creatures
they can be a whole skeleton, parts of a skeleton, a footprint, scat, or imprint Relative Dating: determining the age of a fossil by the age of the fossils around it.
Index fossils: fossils that are only found in certain layers Radioactive Dating Radioactive elements decay at a certain rate called a half-life Geologic time scale: History of Life divided into eras, which correspond to changes in fossilized animals and plants found Miller-Urey Experiment this experiment in the 1950's tried to answer "how did life come from non life?"
Their experiment resulted in cytosine and urasil beiing made. Anaerobic environment photosynthesis and oxygen oxygen in oceans oxygen in atmosphere, aerobic environment Eukaryotic cells from aerobic bacteria Eukaryotic cells develop into protists, plants, animals...etc
multicellularity First life forms are thought to be RNA based.
No idea how DNA came about How did all of this happen?
We don't know. It just did. Ceolophysis dinosaurs from the Triassic period http://www.pbs.org/wgbh/nova/link/hist_08.html Metasequoia. Forests of these trees were common in the Triassic Period Jurassic Period 208 to 145 Million Years Ago Dinosaurs became the dominant animals on land
They "ruled" the Earth for about 150 million years, different types ruling at different times. Camarasaurus Skull http://www.livescience.com/11266-dinosaur-fossils.html http://www.rain.org/campinternet/southwest/dinosaurs/jurassic-gallery.html http://www.ceschini.com/mike/ernieworld/timeline/jurassic/jurasic.html Cretaceous Period 145 to 65 Million Years Ago Dinosaurs still dominated the land.
Leafy trees, shrubs, and small flowering plants were new in the Cetaceous Period.
Another mass extinction occurred. We know that this one was caused by an asteroid hitting the Earth. More than half of all plant and animal groups were wiped out, including all the dinosaurs. An artist's rendering of Cretaceous life http://science.nationalgeographic.com/science/photos/cretaceous-period/#/cretaceous-collection_907_600x450.jpg A f ish fossil from the Cretaceous Period Cenozoic Era 65 Million years ago to the present "Age of the Mammals"
Flowering plants flourished
Whales and dolphins are seen in ocean fossils Tertiary Period 65 to 2.8 Million Years Ago Earth's climates were generally warm and mild.
Marine animals, like dolphins and whales, evolved
Flowering plants and insects flourished
Grasses evolved, enabling animals to graze. A fossil showing a piece of foilage from the Teriary Period http://www.clemson.edu/public/geomuseum/collections/fossils/plants/elm.html A fossil showing marine life from the Tertiary Period http://www.clemson.edu/public/geomuseum/collections/fossils/plants/elm.html Quaternary Period 1.8 Million Years Ago to the Present Earth's climate cooled-caused a series of ice ages
Cliimate started to warm again 2000 years ago
Scientists say that the earliest human ancestors appeared about 4.5 million years ago, but Homo Sapiens may have evolved 10,000 years ago. Animals like Mammoths, horses, and dogs became common. Patterns of Evolution Macroevolution Large-scale evolutionary changes that happen over long periods of time.
ex: mammals evolving from reptiles Microevolution All of the evidence for evolution presented happen on a small scale.
ex: 13 species of finches Mass Extinction Either could be from a single event, or many events in the same span of time.
It wipes out ecosystems and food webs.
Once many organisms died out, the surviving organisms have more room to evolve Possible Reasons for Mass Extinction Adaptive Radiation One ancestral species develops into many different species Convergent Evolution The process of unrelated organisms developing similar characteristics The three different wings have similar bone parts. Coevolution The process of two species evolving together This bug is able to reach inside this flower. Punctuated Equilibrium States some species have hardly changed at all.
Some species had long periods of no change with periods of rapid change.
It depends on selection pressure Developmental Genes Hox genes can help see how evolution took place.
Hox genes control growth during development as an embryo.
Molecular biology found that similar hox genes are found in organisms from insects to humans. How Life Came About