Three Categories of Living Fossils
by Ian Taylor
When claims are made that certain animals known only by their fossils are “extinct,” all that is really meant is that no living specimens have been found. For example, the oceans are the least explored area of this planet and undoubtedly contain many creatures that are passing into extinction without ever having been discovered. The plesiosaur may possibly be one such example. On the other hand, when species once abundant in historical times, such as the carrier pigeon, are no longer seen, it can be said with reasonable confidence that they are indeed extinct. Those discoveries that occur from time to time and stir public interest, and possibly controversy, may be divided into three categories:
1. Discoveries of living specimens of animals or plants that were first known as fossils and then declared to have been extinct for “millions of years.” These are the classic “living fossils.” For example, there was the paleotragus, a horse-sized creature related to the giraffe and said to have been extinct for 25 million years. Living herds of this animal were found in Africa in 1901, and it is now called the okapi; changing the name is one way to avoid attention and controversy. A large fish with four lobe fins – known as the Coelacanth – was fished up alive off the west coast of Madagascar in 1938; its fossil was alleged to be that of a “fish with evolving legs” and extinct for 70 million years. The live specimen was wreathed in controversy, but other “living fossils” such as the sea lily and the cycad tree have slipped by more quietly.
2. Later discoveries in the fossil record of life forms almost identical to commonly known living animals or plants, sometimes retrospectively called “living fossils.” There are hundreds of examples – from the horse to the horse-fly – but others are the cockroach, the ant, dragonflies, starfish, the King crab and the ginkgo tree. Again, all these are claimed to have lived hundreds of millions of years ago, yet are to this day unchanged. The insects in this case are often preserved in the finest detail by being trapped in amber.
3. Totally unknown animals that occasionally turn up unexpectedly. Until 1861, the gorilla was a mythological creature only rumored since Roman days, then proved when a specimen was captured and shown at the London Zoo. A similar situation occurred in the cases of the giant panda, the snow monkey and the Manchurian brown bear; the latter was discovered in 1898. Although these are not called “living fossils,” the fact that they are fairly large animals discovered long after humans had proclaimed themselves the masters of nature should give caution to the use of the word “extinction.”
The following are some more recent discoveries in the above categories, all of which serve to cast doubt on the evolutionary time scales…
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