ERTH 2403 Lecture Notes - Lecture 10: Siliceous Ooze, Cambrian Explosion, Pteropoda
26 Oct 2018
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Jellyfish (belong to cnidaria group: pteropods (ex. snails, salps (ex. primitive chordates, video, 4 billion years after creation of earth there were no animals on land, just simple organisms in the oceans. During beginning of cambrian period explosion of new species of animals began to develop that lead to diversity of animals or today called the cambrian explosion. Biology(cid:859)s (cid:271)ig (cid:271)a(cid:374)g e(cid:448)e(cid:374)t. during ediacaran period (before cambrian) first large animals evolve but they were shell-less which were soft bodied and simply absorbed nutrients to survive, and could not move. These died off and were replaced during the cambrian explosion. Theories that allowed new species to appear: 1. Increased oxygen levels (prior to cambrian, may have not been enough oxygen to support the life of the species, with increased oxygen the species evolved and diversified): 2. Evolutionary innovation (organisms learning to develop gut, immune system, anus, etc.
