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550 million years ago, during the beginning of the Paleozoic era, the Grand Canyon area was part of a prehistoric continent known as Euroamerica. What would now be the west coast of North America was tilted about 90 degrees on it's side and straddled the equator.
The coastlines were frequently flooded and drained again as the oceans advanced and retreated. Deposits like the Tapeats Sandstone, Bright Angel Shale and Muav Limestone were created as a result of these advancing and retreating ocean waters. Ocean dwelling life forms such as the trilobite, which were extremely numerous during this time period, can often be found as fossils within these layers. Fossil records also exist for inarticulate brachiopods and mollusks as well as a number of other animals that lived during the early Paleozoic era. Towards the end of the Paleozoic era the continents had started to come together and began formation of the supercontinent known as Pangea. The seas were now more dominated by creatures such as the articulate brachiopods and corals. Trilobites were still around but their numbers had been reduced. By 245 million years ago, the end of the Permian period, the trilobites and many other creatures had succumbed to a mass extinction. Some forms of articulate brachiopods managed to survive and still exist in today's oceans. They prefer to live in very cold waters such as those found near the polar regions or where the ocean waters are very deep. |
Fossil Mollusk 
Fossil Brachiopod 
Fossil Crinoid and Coral |