Transcript Slide 1

• 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.
• First vascular land plants.
• They were fern-like organisms.
• 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.
• ClipArt courtesy of Microsoft ClipArt
• Amphibian image courtesy of Morton, G.R.
retrieved August 27, 2002 from
http://www.glenn.morton.btinternet.co.uk/transit.htm
• All other images © Microsoft Corporation.
Microsoft Encarta Encyclopedia 2002.