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Cambrian and Ordivician Era.docx

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Department
Biology
Course
BIO3102
Professor
All Professors
Semester
Winter

Description
Cambrian and OrdivicianCambrian Era 540 MYA origin of animals burrowers and swimmersUp until now everything has been singlecelled even the large aggregates were considered a bunch of single celled organisms stuck together with no mechanism of communication MultiCellular Life seemed to arise almost at onceDuring the late Cambrian era there was a huge vast area of shallow seas sitting in the primary productivity zone of the planet along the equator The first multicellular forms start to feed on the primary producers There is a possibility that the first multicellular organisms actually predate the Cambrian a period in time when there was a massive increase in the biodiversity of multicellular animals on the planet There were so many new animals that suddenly appeared in the Cambrian rocks that biologists refer to it as the Cambrian explosionused as evidence against Darwins theory of gradual changeBurgess ShalesContain fossils of animals that were dying and landing in sediments that had no oxygen and sediments kept building on top of themThese fossils contain things that had shells and the fossils of softbodied animals also known as the invertebratesThere are hundreds to thousands of fossils of these organisms perfectly preserved invertebrates Contains a set of animals that have never been seen before Very weirdDiscovered by Walcot the head of the Smithsoniumhe pronounced them arthropods but never let people look at themTwo grad students from England opened up the fossil beds and evaluated these amazing fossils of these strange creatures Burgess Shales Unusual InvertebratesThe animals in the Burgess Shales fossils are so strange and not similar to any animals we see today and since they do not look like what we see today this means that when multi cellular life arose it was at its most diverse and complex The amount of diversity and complexity has been diminishing over time instead of increasingThere are about 30 animal body plans that appear in the Burgess Shales that are still here today like wormy structures exoskeletons and mollusks The thing is there are a lot sets that have never made it through time Contradicts Darwins Theory of gradual change
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