Earth forms from space dust, rocks, and gases. It is not a nice place to live. In fact, nothing...
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Transcript of Earth forms from space dust, rocks, and gases. It is not a nice place to live. In fact, nothing...
• Earth forms from space dust, rocks, and gases.
• It is not a nice place to live. In fact, nothing lives there. © Microsoft Clipart
• First prokaryotes (single-celled organisms with no nucleus) arise.
• They are the ancestors of modern day bacteria and cyanobacteria.
• First single-celled organisms with nuclei (eukaryotes) arise.• They are the ancestors of modern day protists.
• The first soft-bodied invertebrates evolve.• They will evolve into sponges, jellyfish, mollusks,
and worms.• They are the first animals.
• The first hard-bodied invertebrates evolve.• They will become the arthropods (crustaceans, insects, and
arachnids).
• Fish first appear on Earth.• They are very similar in appearance to lampreys
of today• They are the first vertebrates.
• The first amphibious creatures crawl onto land.• They are ancestors of frogs and salamanders.• They breathe through lungs as well as through
the skin.
© G.R. Morton, 1997
• The first true reptiles appear.• They have scales, lungs, and lay eggs with hard,
leathery shells.
© Microsoft Encarta
• The first dinosaurs and the first mammals appear. They are warm-blooded.
• They will lead way to bigger dinosaurs, bigger mammals, and birds.
• Evolution of the first birds.• They are originally dinosaurs with feathers. They
also develop hollow bones to make them lighter.
• The first placental mammals evolve.• They nourish their unborn offspring with
placentas and give birth to live young.• They soon become the dominant mammalian
form on Earth.
• The first human beings appear.• They are almost like us, but not quite, being a
little smaller and a little less upright, and a lot hairier.
• Homo sapiens (us) will not show for another 1.7 million years.