Utente:Spock/Sandbox: differenze tra le versioni

Versione delle 18:45, 31 mag 2007

Versione delle 19:02, 9 lug 2007

Riga 121:

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| align="RIGHT" nowrap | 450 Ma

| [[Image:Centipede.jpg|right|125px|[[Centipede]]]] [[Arthropod]]s, with an exoskeleton that provides support and prevents water loss,<ref>"<cite>The waxy cuticle of arachnids and insects prevents water loss and protects against desiccation</cite>" [http://www.nhc.ed.ac.uk/index.php?page=24.25.312.330 Natural history collection: arthropoda]</ref> are the first animals to move onto land.<ref>"<cite>For hundreds of millions of years, animal life resided only in the oceans. And then about 400 million years ago, fossil tracks suggest that an animal called a eurypterid left the water to walk on land. Maybe it was fleeing enemies, maybe it was searching for an easy meal, or maybe it was seeking a safe place to lay its eggs.</cite>" [http://www.pbs.org/kcet/shapeoflife/episodes/conquerors.html The shape of life. The conquerors. PBS]</ref> Among the first are [[Myriapoda]] ([[millipede]]s and [[centipede]]s), later followed by [[spiderAraneae|spiders]]s and [[scorpion]]s.

Over the next ten million years, the two [[Ordovician-Silurian extinction events]] occur. Taken together, these constitute the second mass extinction event.