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Lecture

Cambrian and Ordovician periods.docx

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Department
Biology
Course
BIO1130
Professor
All Professors
Semester
Fall

Description
Cambrian and Ordovician periodsIntroductionAt the end of the Proterozoic many changes happen to the things inhabiting the ocean at a microscopic at first but soon explodes into a huge diversity of multicelled organisms This introduces the Cambrian periodPossible multicellular organisms before Cambrian period dying at the end of the ProterozoicoEvidence from two fossils foundEdiacaran and DoushantuooPossible ancestors to modern day phylaSponges jelly fishThe biodiversity at the beginning of the Cambrian is known as the Cambrian ExplosionoAt the end of the Cambrian period mass extinction of most of the animals that came to be in the Cambrian explosionoStill wasnt considered one of the 5 major extinctions knownAfter the mass extinction of the marine organisms introduced the Ordovician period another period that mostly dealt with marine organisms not landabout 30 different body plans of current phyla survive from the extinctionoAncestors of some modern species knownStarfish and relativesFirst snailsMollusksoBryozoan colonies form and diversifyFeeds using a unique lophophoreoGreen algal begins to grow on landNear the end of the Ordovician period the first of the 5 mass exctinctions occuroBelieved to be an ice age causing ocean levels to drop exposing continental shelveso50 of generations dieobryozoans and trilobites surviveWhy do we call it the Cambrian explosion
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