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Origins: How did it all begin?

Origins: How did it all begin?. How do we know how “Old” things are?. Sedimentary rock rock formed from sand/mud settled on the bottom of seas, lakes, marshes and deserts Dating : 1- Relative~ geologic time scale; sequence of species

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Origins: How did it all begin?

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  1. Origins:How did it all begin?

  2. How do we know how “Old” things are? • Sedimentary rock • rock formed from sand/mud • settled on the bottom of seas, lakes, marshes and deserts • Dating: • 1- Relative~ geologic time scale; sequence of species • 2- Absolute~ radioactive dating; age using half-lives of radioactive isotopes

  3. How do we know how “Old” things are?

  4. How did “life” begin? • Miller & Urey 1953 experiment • performed an experiment simulating early Earth conditions • H2O, methane CH4, ammonia NH3, H2 • Proposed gases were combined with water vapor and electricity • ALL 20 amino acids, nitrogen bases, & ATP formed

  5. What was Earth like in the beginning? • Earth’s Early Atmosphere • Mostly Hydrogen cyanide & CO • Produced by volcanism & heavy bombardment of asteroids • Evidence of water at 3.8 BYA • 1st life forms • 3.6 BYA • Simple prokaryotes appear

  6. What was Earth like in the beginning? • First photosynthetic organisms • 3.4 BYA • Cyanobacteria or blue-green algae • Great Oxygenation Event • 2.4 BYA • Due to photosynthesizing cyanobacteria • Formed stromatolites

  7. What was Earth like in the beginning? • 1st Eukaryotes • 2 BYA • Green algae (Reproduces sexually & photosynthetic) • Endosymbiosis (mitochondria) • 1.2 BYA • Animal diversity • 543 MYA

  8. How many extinctions have occurred throughout Earth’s history? • Permian (250 million years ago) • Worst mass extinction • 95% of all species • Bacteria feeding frenzy & massive volcanism • Cretaceous (65 million years ago) • KT Impact • Death of dinosaurs • 50% of marine species • Low angle comet

  9. What are the benefits of extinctions? • A mass extinction: • 1) encourages the rapid evolution of surviving species by opening ecological niches. • 2) makes room for the evolution of unique characteristics as dictated by an organism's environment • Loss of predators • Less competition for resources

  10. Who was first to break the water barrier?(475 MYA) • Terrestrial plants • Had to overcome some problems with living on land: • Drying out – needed the cuticle as an outer covering • Obtaining water – grew roots • Breathing out oxygen – develop stomata • Structural support – plants (and animals) had to have support to stand up straight • Reproduction – co-evolution with pollenating insects, utilized wind and other animals (ex-burrs) to spread seeds

  11. What were the 1st land invertebrates? (400 MYA) • 1st animals to break from the water boundary was probably worms • Evolved in lakes, not oceans • Fossilized arthropods (insects) show same pattern of evolution as plants

  12. What were the 1st land vertebrates? (360 MYA) • Ancestors of amphibians – similar to lobed fin fish • Lived in river deltas • Needed to keep their skin moist • Had lungs and gills • When the water dried up, the “fish” would burrow into the mud and wait for the water to return • Could crawl from pond to pond • ESCAPE PREDATION

  13. From water to land… • Amphibians Overcoming Obstacles • Structural support – had to get a better connection to the shoulder and pelvic girdles • Drying out – didn’t solve this yet… • Breathing – developed lungs • Reproduction – still laid eggs in water • Sensing the environment – the 1st ear

  14. Amphibians THEN Reptiles (300 MYA) • Reptiles • Evolution of the amniotic egg • Allowed eggs to be laid on land without drying out • Developed scales to prevent from drying out

  15. The 1st Mammals (200 MYA) • Evolved from reptiles with mammalian traits • Were small and furry and looked a lot like modern mice • Were also warm-blooded and produced milk • Still laid leathery eggs • Were alive throughout the entire age of dinosaurs • Therapsids

  16. Living fossils • Aardvark • Nocturnal, burrowing mammal • Ancient arrangement of its chromosomes • Elephants are closest living relatives

  17. Living fossils • Red panda • Closely related to: • Bears • Skunks • Weasels • Raccoons • Barely related to giant pandas

  18. Living fossils • Platypus • Monotreme • One of the most venomous animals in the world • Have 10 sex chromosomes

  19. Living fossils • Hagfish • Only living animal with a skull but no vertebral column • Fossils can be found from 330 million years ago

  20. Living fossils • Hoatzin • Most debated living bird because the evolutionary tree is missing so many branches • As chicks, they retain claws on the ends of their wings

  21. Living fossils • Horseshoe crab • Not crabs or even crustaceans • Closely related to arachnids • Been around for 450 million yrs

  22. Ginkgo

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