BIO 1130 Final: Cambrian and Ordovician Periods lecture notes.doc
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Many organisms are found in the shell deposits. Laurentia (plate in which north america ultimately emerges) surrounded by continental shelf. Shallow water, lots of sunlight, warm = primary productivity. Contains sets of animals that have never been seen again. Animals from burgess shales bear little resemblance to animals today. When multicellular life arose, it was at its most diverse and complex when it first occurred; the amount of complexity has been diminishing over time. Contrasts idea that diversity increases and darwin"s idea of slow gradual change. 30 animal body plans appear in the burgess shales and some still exist today. Phylogeny starts from colonial cells (choanoflagellate cells) (origins of animals) Cell that has a cell body and flagellum and a microcollar surrounding body. Origins of animals; ancestral cell to all organisms. Cell that has a cell body and flagellum (1) and a microvilli that forms a collar surrounding the flagellum at the centre.