EAS201 Lecture Notes - Lecture 29: Cambrian Explosion, Horizontal Gene Transfer, Great Unconformity
2 May 2020
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Occurs at the end of the precambrian/start of the cambrian (onset ~ 542 mya) Most major animal phyla appeared abruptly in the fossil record without obvious precursors. Some of the earliest cambrian animals are sponges, predatory worms, molluscs (ex. snails), brachiopods, archaecyathids (reef-building organisms), and arthropods. Animals need a certain level of oxygen to evolve. It is thought that in the cambrian, oxygen levels in the ocean reached a threshold where complex life forms such as animals could evolve. Maybe there was increased continental erosion that sent more calcium to the oceans allowing for the formation of skeletons and shells. Extensive weathering of landmass entirely missing from the rock record (great. Control how different regions of the embryo develop into specific organs. It took time for animals to develop these. The process whereby genetic material is transferred between organisms. Also identified as a possible factor in the acquisition of the biochemical capability of biomineralization.
