Smithsonian National Museum of Natural History Geologic Time The Story of a Changing Earth
Presented by the Department of Paleobiology.
The Cambrian
Contents
Eon Overview
The Cambrian Explosion
The Burgess Shale Fauna
"Age of Trilobites" and the Cambrian Fauna
Plate Tectonics at the Start of the Paleozoic
Evidence
Ottoia prolifica
learn more
sample
Mollusks
Burgess Shale fossils
Hallucigenia
Trilobites
Cambrian algae
Archaeocyath reef
Wiwaxia
Cambrian rocks
references and links
Foundational Concepts
Dating Methods
Earth Processes
Life Processes
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Plate Tectonics at the Start of the Paleozoic
The Cambrian began after the end of the Marinoan ice age, one of several instances in the past when ice was widespread on Earth's surface. This marked a shift from late Proterozoic icehouse conditions, during which much of the world was cold and ice covered. The Cambrian was quite the opposite, with global warming leading to greenhouse conditions. This climate change was probably linked to major changes in the positions of the continents.

During the Cambrian, the large Proterozoic landmass (Rodinia) broke up and plate-tectonic movements pushed North America, Siberia, and Gondwana, as well as smaller landmasses, toward the equator. Eventually, in Cambrian time, most of the land was in tropical, subtropical, and temperate climatic zones; the ice masses melted and oceans flooded the continental shelves. Marine life flourished in shallow, warm-water continental-shelf environments and limestone deposition became common; Cambrian limestones are known from all parts of the world.




Overview | The Cambrian Explosion | The Burgess Shale Fauna
The "Age of Trilobites" and the Cambrian Fauna | Tectonics at the Start of the Paleozoic



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