Coelacanths and Hoatzins: Two Living Fossils Darwin Wants Back

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Posted on January 25, 2014 in Birds, Darwin and Evolution, Dumb Ideas, Marine Biology

Two creatures have found their way onto many creationist Powerpoint slides, but evolutionists want to use them, too.

Coelacanth

Creationists have long pointed to the fish Coelacanth as a challenge to Darwinian evolution.  This “living fossil” was thought long extinct by evolutionists till discovered alive and well in 1938, showing little or no evolution since the presumed “age of dinosaurs.”  Moreover, it was found not using its bony fins for locomotion, ruling it out as a transitional form to four-legged land dwellers (tetrapods).

Mark Robinson and Chris Amemiya (Seattle) want it back in the Darwin hall of fame.  Writing in Current Biology, they admit that finding one alive was “perhaps the most notable zoological find of the last century” and “as surprising and unexpected as finding a T-rex,” but they quickly dispelled any intentions of ceding one to the creationists:

The existence of living coelacanths offered the possibility of significant insights into the early origins of the tetrapods (Figure 1), the group comprising amphibians, reptiles, birds and mammals, which is to say, ultimately, insights into our own evolutionary origins.

For support, they merely asserted that tetrapods evolved from fish.  The evolutionary tale lives on, even though coelacanths are virtually the same as their ancestors over a period period lasting from 200 million to 70 million years ago (when they disappear from the fossil record), and are found today still swimming and no closer to walking on land.  The interviewer even popped the big question (bold italics in original):

How do you make a fish into a land animal? The rise of terrestrial vertebrates is a fascinating success story of evolution. The obstacles for an invasion of the land by fish, exquisitely adapted for life in the water as they are, stretch the imagination. A body previously supported by the water column must now be able to support itself in air, necessitating limbs with strong skeletal elements rather than the delicate fin rays of bony fish; gills that efficiently extracted oxygen dissolved in water must be replaced with lungs for extracting oxygen from the air; and as water becomes a precious commodity that must be conserved, more efficient ways to excrete waste products that don’t rely on an unlimited water supply need to be found. Even the senses must be significantly overhauled to match the unique demands of the terrestrial environment.

The only hint of empirical evidence is a reference to some HOX genes in the coelacanth genome – but those are high-level developmental switches common to many vertebrates.  The rest is more assertions and suggestions, e.g.: “the coelacanth’s fins might be thought of as containing the rudiments of the autopod structure.”  If so, they have remained rudiments since they were last seen in the fossil record, reappearing after a 70 million year gap just the same as before.

Inquiring minds want to know about the living fossil claim.  Robinson and Amemiya skirt this one with (1) credit to Darwin, (2) push-back on the claim, (3) affirmation of the claim with more evidence-challenged assertions:

Is the coelacanth a ‘living fossil’? There has been some push-back concerning the oft-used phrase, living fossil, with regard to the coelacanth. The term was coined by Charles Darwin, and is operationally used to indicate that a species is a surviving representative of an ancient lineage that still retains some key features shared with archaic fossils. Typically such a lineage will have survived one or more mass extinctions. Examples of living fossils often cited include the sharks, ginkgo trees, metasequoia, lampshell brachiopods, horseshoe crabs, and as defined here surely the coelacanth. However, a common misconception is that the phrase implies that evolution has not acted on the organism over these long timescales, something that is clearly shown not to be true for coelacanths based on gross differences in the skeletal morphology of fossilized specimens, especially of forms prior to the Mesozoic. While it is difficult to measure the rate of morphological evolution of extinct coelacanths, analyses of the coelacanth’s protein coding genes have shown, enigmatically, that its relative rate of molecular evolution is slower than that of other fishes and tetrapods. The implications of this relative rate difference remain speculative with respect to the morphological evolution of the coelacanth.

They just contradicted themselves.  They said that fossilized specimens evolved rapidly, but they also evolved slower than other fishes.  Which is it?  Whatever the implications, they “remain speculative,” as evidenced from this paragraph itself.  “We have lots to learn about this iconic species,” they concluded.

Hoatzin

Another animal that has graced many a creationist Powerpoint slide is the hoatzin – a strange-looking bird that lives in South America.  When evolutionists have offered up Archaeopteryx as a transitional form, pointing to dinosaur-like claws on its wings, creationists would point to living hoatzins, 100% bird, whose young have claws on their wings, too – the implication being that claws do not imply evolution.

Now, an article in Science Daily tries to make the case that the ancestors of hoatzins originated across the globe in Europe, based on some bones stored in Paris found a hundred years ago.  Named Protoazin parisiensis (“proto-Hoatzin from Paris”), the fossil bird has been reinterpreted to say that “hoatzins lived in Europe as early as the late Eocene, i.e. around 34 million years ago.”  But then, how did they get to Africa and South America?  These birds can only fly short distances.  A theory rescue device was nearby: basically, they were already globally widespread, but their mammal predators migrated across land bridges and wiped them out in selected regions, leaving only a few relicts left in South America.

Little detail, however, was provided about their “evolutionary history.”  Presumably the ancestors were as hoatzin-like as the living ones.  As for the claws on the chicks, they are not vestigial, because they “enable the hatchlings to climb trees.”  Nothing was said about dinosaurs, Archaeopteryx or anything a visitor to a creationist presentation would be curious to hear about.  According to the article, these clawed birds appeared abruptly, claws and all, tens of millions of years after the dinosaurs went extinct.

Creationists, you can continue to use your slides.  Evolutionists have added no new information.  They have only paraded their naked emperor Charlie down the street again.  How did you like that “fascinating success story of evolution”?  They listed all the difficulties of getting a fish to crawl on land, and never said how mutations hit the jackpot.  So typical.  “We have no evidence, but evolution is a FACT!  Creationists are unwashed ignoramuses lying for Jesus!  Keep them out of the schools or else the next generation will be plagued with scientific illiteracy!”  Don’t be intimidated.  Just remember the little boy using his innocent eyes, exclaiming what should be obvious if it weren’t for “scientific” indoctrination, “The emperor is naked!”

 

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