Lazarus Taxa – Living Fossils Today

From KHouse.Org

Whenever a creature considered extinct suddenly shows up living and swimming around, we should all pay attention – even if the life form is “just” a heat-loving plankton. The green unicellular species Dapsilidinium pastielsii was recently found in Southeast Asia after having been supposedly killed off during the Ice Ages, appearing in the tropical warmth of the Indo-Pacific Warm Pool. The tiny green dinoflagellate isn’t alone. In April, a shrimping boat caught an 18-foot goblin shark off Key West. After taking pictures of the strange fish, the fishermen released the rare shark back to the water and eventually contacted National Oceanic and Atmospheric Administration Fisheries Service (NOAA) to let the scientists know. One other goblin shark was documented in 2002 in the Gulf of Mexico, but these fish are believed to go back 125 million years, and biologists know very little about them.

The goblin shark and D. pastielsii are just one of many “Lazarus taxa” — creatures once thought to be extinct, only to be “resurrected” by appearing as real living, breathing organisms long after having disappeared from the fossil record. The chipmunk-like Rugosodon eurasiaticus shows up in the fossil record 170 million and 35 million years ago, and yet was recently found running around China. It’s a member of the multitberculates family, a group of early rodents long considered extinct. The aardvark is found in the fossil record about 55 million years ago looking almost exactly like it does today. The Laotian Rock Rat was found in 1996 after having been thought “dead” for 11 million years. The adorable chevrotain — or “mouse deer” — in southeast Asia today looks just like it did 20 million years ago.

These creatures are fun to find, like treasures long thought lost, but they also poke like sticks into the spokes of Darwinian evolution.

The Significant Coelacanth

In 1938, men fishing off the east coast of South Africa caught a peculiar fish that was identified as a coelacanth (“SEE-le-canth”). This find shocked the paleontological world, because the coelacanth was a fish thought to have died out with the dinosaurs at the end of the Cretaceous Period 65 million years ago. Additional specimens of the coelacanth have since been found in the waters of the Comoros, Kenya, Tanzania, Mozambique, and Madagascar.

Yet, while the coelacanth is believed to have reached its present form 400 million years ago, researchers studying the fish have observed it changing to adapt to its environment. That is, while the coelacanth supposedly hasn’t changed much in the past 400 million years, there is still flexibility in its gene pool after all.

“We have thus been able to show that despite their slow evolutionary rate, coelacanths continue to develop and are potentially also able to adapt to new environmental conditions,” Kathrin Lampert, researcher at the Ruhr-University Bochum in Germany, said.

It isn’t as though the world hasn’t changed a bit since the ancestors of today’s coelacanths were petrified in mud. If the fish has had the genetic variability to change, it certainly has taken its time getting around to it. The Dapsilidinium pastielsii would also have been expected to change over its millions of years of life, even if its children found a refuge in a warm ocean pool.

Big Black Gaps

The fossil record hasn’t given us a complete record of life on earth in a tidy series of layers, each containing neatly tagged representations of each type of animal that lived in a location at any time. There are gaps. The coelacanth shows up in the fossil record with the dinosaurs and then doesn’t appear in more recent fossil layers. Yet it’s still alive and swishing. It’s been here all along, but its bones are only preserved in older layers. (How much older… is a question.)

To deal with the massive gaps in the evolutionary fossil record, Stephen Jay Gould and Niles Eldredge proposed the Punctuated Equilibria theory (Punk Eek to the irreverent) in 1972. They argued that evolution didn’t occur gradually the way Darwin thought it did. Rather, they proposed that evolution took place in spurts. Since these changes were rare and since fossilization was a relatively rare phenomenon, evolutionists should expect gaps in the fossil record, they said.

At the same time, the coelacanth does show itself in the fossil record. So do the goblin shark and D. pastielsii. These aren’t missing links; they are species we know once existed. Punk Eek and Gradualism both have a problem because they’ve proposed imaginary missing links that we just plain do not see at all. They also propose change over time, and when creatures show up unchanged after millions of years of existence, with a variation still available in their genetic code, that raises questions.

Living Fossils

Fossils like these, as well as the Metasequoia, the Nightcap Oak, the Chacoan Peccary (a pig) or Mountain Pygmy Possum were all once thought to have died out millions of years ago, only to be “surprise!” found alive and well after all, relatively unchanged from the way their family members looked before they were locked in stone.

Weak Assumptions

Paleontologists are hurting for missing links, and even the few they have are lined up on tenuous evidence. The coelacanth demonstrates the danger of paleontologists’ making assumptions about the internal organs or DNA of creatures based on their skeletons.

Prior to its being found alive, the coelacanth had been considered a link between fish and land animals. Paleontologists had suggested that the swim bladder of the coelacanth had turned into a lung which allowed it to breathe when it crawled out onto land. When a living coelacanth swim bladder was examined, though, it ruined that idea. The swim bladder was thin and filled with fatty tissue and in no position to act like a lung, no matter how much the scientists wanted the coelacanth’s lobed fins to act like crawling arms.

Don’t be confused. When scientists say life has “evolved,” they are right. Families and genera of creatures do change over time. There were once marmot-like gophers with horns and giant sloths as large as VW busses. Yet, the gophers were still gophers and the sloths were still sloths, and on the whole were not so different from the same creatures we see today. Rather than showing a convenient series of evolutionary steps, the fossil record continually shows specific groups of creatures that display wide variety within their groups.

Further Reading

  • ‘Living Fossil’ Fish Still Evolving
    — UPI
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