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Bradley, Goettle. 1997. "Living Fossil" in the San Francisco Bay Area?" Tideline. Vol 17 No. 1 1-3.  Anteriodorsal view of a vernal tadpole shrimp out of water. Photo by Larry SerpaBy Bradley Goettle What is a Living Fossil? Quick!! How many "living fossils" can you name? Would you believe that there is a "living fossil" right here in the San Francisco Bay area? The Don Edwards San Francisco Bay National Wildlife Refuge, located in the South San Francisco Bay, has seasonal freshwater pools which contain the vernal pool tadpole shrimp (Lepidurus packardi), a freshwater crustacean "living fossil." The vernal pool tadpole shrimp derives its name from looking somewhat like a frog or toad tadpole at first glance, and from being found only in "vernal" pools (temporary springtime pools). Now you ask, exactly what is a "living fossil?" A living fossil is an organism living today that appears to be identical to specimens in the fossil record. The most famous example is probably the coelacanth (Latimeria chalumnae), a primitive, lobe-finned fish from the Cretaceous Period. Coelacanths were known only from their abundant fossils until a live coelacanth was recovered by a deep-sea trawler in the Indian Ocean in 1938. This fish still lives in the ocean depths, virtually unchanged from its fossil ancestors of approximately 70 million years ago. Tadpole shrimp are considered living fossils because their basic body characteristics have remained the same for millions of years. General |
Last updated:
May 27, 2008
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