EAPS 11200 Lecture Notes - Lecture 23: Supercontinent, Ceratopsia, Ornithopod
16 Apr 2019
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Document Summary
Early cretaceous tectonics and climate: continued rifting of pangea, modern configuration of continents, high sea level, greenhouse climatic conditions, driven by undersea volcanoes. Late cretaceous tectonics and climate: supercontinent breakup and rifting accelerated, oxygen minimum zone (intervals of low dissolved oxygen, sea level drops about 67 ma, oxygen isotopes and plant communities indicate a cooling of the polar regions. Cretaceous marine life: high sea level and warm conditions meant that the oceans were teeming with life, microorganisms forming the bases of food webs were major contributors to marine sediments. Cretaceous microorganisms/organisms: diatom - single-celled phytoplankton, with an ornate microscopic skeleton, rudist - a form of clam with unequal valve sizes. Impact of a bolide may have crippled ecosystems: likely an asteroid fallen from its orbit, hit the northern tip of the yucatan peninsula of. Mexico: late cretaceous was a time of major volcanic activity, gasses and dust blocked sunlight, global temperatures declined, global sea level dropped markedly.
