BIO 3102 Study Guide - Pinacoderm, Diploblasty, Body Plan

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11 Jul 2014
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Near end proterozoic: (2 billion years as single celled protists) Explosion of unicellular life (some bigger than others) Continental land masses arising from ocean near end of proterozoic. Cambrian and ordovician periods: consumed carbon dioxide, therefore carbon dioxide levels decrease. Something changed in the ancient oceans (filled with bacteria, single celled protists, etc. ) Snowball earth: (2 or 3 cycles had occurred during earth"s lifetime) Earth was completely covered by ice and snow. No primary productivity during this time period: underneath ocean, still getting volcanic gases, sulphur gases. Near equator, there is a slushy, icy things: allows some of the aerobic protists and bacteria to form and survive. Earth was frozen over however, near the equator it was much warmer allowing more forms of life to form there. Experiments in multi-cellular life before cambrian (only a hypothesis) Fossilized sponges (evidence that sponges did exist): sponges filtration of water to trap protists, archae, bacteria ect. (because the ocean was a soup .