What Is a Living Fossil?
Living fossils are plants or animals that exist today that are close enough to specimens in fossil records to be considered virtually identical. So far there are over 500 known living fossil species.
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Bacteria
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Cyanobacteria, sometimes called blue-green algae, are the oldest known living fossils, dating back 3.5 billion years. Living forms have been compared to fossilized specimens found in Precambrian rock with the help of powerful electron microscopes.
Plants
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Many of today's plants closely resemble their fossilized ancestors, including fig, maple, walnut, willow, birch and magnolia to name a few. One class of plants, the cycads, which resemble palm trees, dates back to the Jurassic period and can still be found in tropic and subtropical areas.
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Insects
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The insects visiting your garden today are not much different than their prehistoric relatives, though today's specimens tend to be smaller. Species identified with fossils include dragonflies, cockroaches (a 300 million year old fossil specimen was found in a mine in Ohio that was 3.5 inches long) and ants.
Mammals
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Bats, shrews and squirrels all have their fossil record counterparts. The opossum, which has fossils dating roughly 70 million years, is considered the world's oldest living mammal. It is also the only native marsupial in the North American continent.
Water Creatures
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The ocean is home to many creatures that have not changed much since prehistoric times. Sharks date back to the Devonian period, lobsters and crayfish to the Jurassic and certain jellyfish have fossil relatives dating back 500 million years. Crocodiles and alligators are also considered living fossils.
Famous Fossil Fish
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One of the most famous living fossils is the Coelacanth (pronounced "see-la-kanth"). Thought to be extinct until its discovery off the coast of South Africa in 1938, this fish first roamed the oceans 400 million years ago.
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References
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- Photo Credit Image by Flickr.com, courtesy of jenny cu
