Then there is the whole other issue of the fossils themselves as dating mechanisms:
An astounding catch
Perhaps the most stunning-and famous-of these living fossils is the coelacanth. Fossils of this unusual fish first appear in strata from the Devonian period, with an estimated age of 350 million years.
For years paleontologists thought the coelacanth became extinct about 70 million years ago, since they found no fossil remains of the fish in deposits formed later than the Cretaceous period.
At least they thought that was the case until December 1938, when a fishing trawler captured a living coelacanth off the eastern coast of South Africa. Scientists were stunned. After all, the discovery was akin to finding a living dinosaur in a remote patch of jungle!
Since that first shocking discovery, fishermen and scientists have taken more specimens, all near the Comoro Islands. Researchers were dismayed to find that the inhabitants of the islands had used coelacanths as food for years, drying and salting the rare fish's meat.
The discovery of living coelacanths proved to be a profound embarrassment for those trying to use evolution to interpret the geologic record. It was especially embarrassing for those who, based on fossilized specimens, had earlier proposed the coelacanth as a prime candidate for the kind of fish that would have first crawled out of the oceans to dwell on land. Yet the discovery of a fish that was supposed to have been extinct for millions of years, one that some paleontologists had hoped was a vital missing link in the supposed evolutionary chain, hasn't led many to question their assumptions regarding the supposed evolutionary timetable.
If coelacanths were the only creatures found alive that were supposed to have been long extinct, then we might accept their discovery as an oddity that proved little or nothing. But the list of such living fossils has grown considerably in recent years.
A tree from the age of the dinosaurs
One such living fossil is a pine tree that, according to the traditional interpretation of the geologic column, was supposed to have been extinct for more than 100 million years. But that changed with a remarkable 1994 discovery:
"David Noble was out on a holiday hike when he stepped off the beaten path and into the prehistoric age. Venturing into an isolated grove in a rain forest preserve 125 miles from Sydney, the Parks and Wildlife Service officer suddenly found himself in a real-life 'Jurassic Park' standing amid trees thought to have disappeared 150 million years ago. 'The discovery is the equivalent of finding a small dinosaur still alive on Earth,’ said Carrick Chambers, director of the Royal Botanic Gardens. . .
"The biggest tree towers 180 feet with a 10 foot girth, indicating that it is at least 150 years old. The trees are covered in dense, waxy foliage and have a knobby bark that makes them look like they are coated with bubbly chocolate. ... Barbara Briggs, the botanic gardens' scientific director, hailed the find as one of Australia's most outstanding discoveries of the century, comparable to the living fossil finds of the dawn redwood tree in China in 1944 and the coelacanth fish off Madagascar in 1938 . . . The closest relatives of the Wollemi Pines died out in the Jurassic Period, 190 million to 135 million years ago, and the Cretaceous Period, 140 million to 65 million years ago" (Salt Lake City Tribune, Dec. 15, 1994, p. A 10).
Living fossils from long-dead worlds
Following is information about a few of these living fossils that either have not changed in time or were supposed to be extinct.
A find similar to the Australian discovery took place a half century earlier when the dawn redwood (species Metasequoia glyptostroboides) was discovered in China in 1941. The Encyclopaedia Britannica says of this tree:
"Discovered first as fossils in Miocene (23.7 to 5.3 million years ago) deposits, it was assumed to have become extinct until it was discovered growing in Szechwan province in China. Its distribution in the late Mesozoic and Tertiary (66.4 to 1.6 million years ago) was throughout the Northern Hemisphere" (Internet version, 2000, "Gymnosperm").
Another living fossil is the tuatara, a lizard like animal found only on several islands off the coast of New Zealand. According to Encyclopaedia Britannica, this strange creature:
"has two pairs of well-developed limbs and a scaly crest down the neck and back. Unlike lizards, it has a third eyelid, the nictitating membrane, which closes horizontally, and a pineal eye, an organ of doubtful, function between the two normal eyes. The tuatara also has a bony arch, low on the skull behind the eyes, that is formed by the presence of two large openings … in the region of the temple.
"It is this bony arch, which is not found in lizards, that has been cited as evidence that tuataras are survivors of the otherwise extinct order Rhynchocephalia and are not lizards. And indeed, tuataras differ little from the closely related form Homeosaurus, which lived 150 million years ago during the Jurassic Period" (Internet version, "Tuatara").
The Encyclopaedia Britannica adds that the tuatara is:
"a reptile that has shown little morphological evolution for nearly 200,000,000 years since the early Mesozoic" ("Evolution").
Another example is a marine mollusk that goes by the scientific name Monoplacophoran.
"In 1952 several live monoplacophorans were dredged from a depth of 3,570 m (about 11,700 feet) off the coast of Costa Rica. Until then it was thought that they had become extinct 400,000,000 years ago" (Britannica, "Monoplacophoran").
By no means are these the only examples of living fossils. These are simply examples of animals and plants that, based on where they were found in the fossil record, scientists had assumed had died out millions of years ago. Other creatures, such as the nautilus, brachiopod, horseshoe crab and even the ubiquitous cockroach, are virtually unchanged from fossils paleontologists date to hundreds of millions of years ago.