Pharyngula

JBS Haldane is said to have responded to a question about how evolution could be disproved by saying, “A Precambrian rabbit”. What was meant by this, of course, is any substantial discovery that greatly disrupted the evidence for the chronological pattern of descent observed in Earth’s life. That pattern of descent is one of the central lines of evidence for evolution, so creationists would dearly love to find something that wrecked it — this is why they send expeditions to Africa to find a living dinosaur, Mok’ele-mbembe, or more conveniently, to Canada in search of a plesiosaur, Manipogo.

The Discovery Institute has it easy. They don’t mount expeditions, they just sit around, read scientific papers, and misinterpret them. Their latest abuse is to claim to have discovered the equivalent of a Precambrian rabbit.

A vertebrate swimming fish with camera eyes, blood vessels, digestive system, muscular swimming, and gills in the Lower Cambrian: for Darwinists, it should hardly be more surprising to find than a Precambrian rabbit.

Only it’s not in the Precambrian, it’s Cambrian. And it’s not a mammal, it’s a very primitive fish, unlike anything extant. Is anyone surprised to find ancient fish-like creatures in the Cambrian? Anyone who has been paying the slightest attention to publications about the fossils of the Burgess Shale or the Chengjian fauna in the last century?

Here’s a reconstruction of the animal that Conway Morris and Caron analyzed in a recent issue of Nature. It’s called Metaspriggina.

metaspriggina

Just for comparison, here’s Pikaia, a familiar chordate (although it’s classification is somewhat controversial) from the Cambrian. The fossil was first described in 1911.

pikaia

Here’s another Cambrian beast, Haikouichthys, described in 2002.

Haikouichthys

Here is a rabbit.

rabbit

One of these things is not like the others. Which one would surprise you, boys and girls, if it were found swimming in the shallow, silty seas beneath the relatively hypoxic skies of planet Earth, 500 million years ago? Which ones look similar, as if they are related, yet don’t look like any modern organisms?

If you can answer those two questions, you’re smarter than a creationist. There is no prize, I’m afraid that’s a rather low bar to hurdle.

What also surprises is how much the Discovery Institute press release mangles the story. For instance, they want to claim that it is more advanced than modern forms.

All these traits show that Metaspriggina was not a primitive chordate intermediate to lampreys or other extinct Cambrian swimmers, but was in fact more “derived” (advanced) in some respects than some of the alleged descendants.

They then quote a section of an article that explains that lampreys have derived structures — that their branchial anatomy is extensively specialized. What Conway Morris and Caron actually say in the paper is the opposite — that Metaspriggina had primitive or ancestral branchial structures, that they possessed two-part bars in their branchial arches, which was the ancestral condition.

A striking feature is the branchial area with an array of bipartite bars. Apart from the anterior-most bar, which appears to be slightly thicker, each is associated with externally located gills, possibly housed in pouches. Phylogenetic analysis places Metaspriggina as a basal vertebrate, apparently close to the Chengjiang taxa Haikouichthys and Myllokunmingia, demonstrating also that this primitive group of fish was cosmopolitan during Lower–Middle Cambrian times (Series 2–3). However, the arrangement of the branchial region in Metaspriggina has wider implications for reconstructing the morphology of the primitive vetebrate. Each bipartite bar is identified as being respectively equivalent to an epibranchial and ceratobranchial. This configuration suggests that a bipartite arrangement is primitive and reinforces the view that the branchial basket of lampreys is probably derived.

Notice that Conway Morris and Caron have identified Metaspriggina as a “basal vertebrate”, and that they note it’s affinities to other Cambrian forms. This is not a fish out of water; there is no evolution defying anachronism here.

The creationists even comment on the cladogram included in the paper, rather obliviously. Do they even realize that this diagram places Metaspriggina in an evolutionary context, and that it is clearly an intermediate form, more advanced than Pikaia, comparable to its rough contemporary Haikouichthys, and less derived than lampreys?

Cladogram with backbone constraint for cyclostome monophyly, and using rescaled consistency indices, showing the position of Metaspriggina as part of basal stem-group soft-bodied vertebrates. The origin and potential loss of key vertebrate structures is indicated.

Cladogram with backbone constraint for cyclostome monophyly, and using rescaled consistency indices, showing the position of Metaspriggina as part of basal stem-group soft-bodied vertebrates. The origin and potential loss of key vertebrate structures is indicated.

Seriously, what part of “basal stem-group soft-bodied vertebrate” did they fail to comprehend? Metaspriggina is an unsurprising resident of the Cambrian era…and no rabbit at all.


Morris SC, Caron JB2 (2014) A primitive fish from the Cambrian of North America. Nature 512(7515):419-22.

Comments

  1. […] Source: A fish, a rabbit — same thing, to a creationist [Pharyngula] […]

  2. #2 Matt
    United States
    September 4, 2014

    They are 100% convinced evolution is not true, and this is the best they can come up with!? It boggles the mind.

  3. #3 Jim Thomerson
    Austin, TX
    September 4, 2014

    A Precambrian rabbit would be more likely proof of time travel than a test of the evolutionary hypothesis. ;-)

  4. #4 jane
    September 5, 2014

    A fish, a rabbit – also the same thing to a strict cladist. ;-)

  5. #5 JohnnyMorales
    killeen texas
    September 6, 2014

    Creationists are definitely impressed by their own intelligence.

    So much so that they assume anything they don’t understand is naturally false, and anyone defending what they don’t understand is willfully lying.

    That being the case, they think that gives them the right to fight fire with fire and come up with actual, willful lies to explain their side, and simultaneously prove science wrong.

    Unfortunately there are quite a few people who are as lacking in intelligence as they are (their congregations I guess) and think their nonsense is proof the scientists are making things up as they go along.

    To them their nonsense makes as much sense as the scientific explanations . So it’s just as legit, and why scientists miss the point of their efforts when they point out their falsehoods in efforts to make them understand why they are wrong.

  6. #6 Noel
    September 9, 2014

    Would a “giant” human with extra teeth and larger cranial capacity do instead of a “precambrian rabbit”? Google “smithsonian giants”, I SUPPOSE as a card carry’ing scientist you’ll assume it’s all just conspiracy, but new evidence is arriving all the time!!
    btw, I’m not a creationist, but everytime i find a new story of a giant skeleton that mysteriously goes missing, I automatically think it is because it is an awkward “rabbit”.

  7. #7 BenBoy
    Montreal
    September 10, 2014

    “Richard Dawkins”:

    It is infuriating to be quoted again and again by creationists—whether through design or stupidity, I do not know—as admitting that the fossil record includes no transitional forms.-

    -Stephen Jay Gould, “Evolution as Fact and Theory,” Discover, May 1981

  8. #8 dean
    September 11, 2014

    Noel – why do results by an assortment of loons (result of your your Google suggestion) cast any doubt on science?

  9. #9 PZ | Skeptical Analysis
    September 15, 2014

    […] I need to revisit PZ Myers more often. His blog has to be just about the best commentary on creationism and other wacko. Here’s a recent post: […]

  10. #10 elektrikli zincirli vinç
    http://www.istifmakinasi.gen.tr
    September 16, 2014

    more often. His blog has to be just about the best commentary on creationism and other wacko. Here’s a recent post: […]

  11. #11 elektrikli zincirli vinç
    istanbul
    September 16, 2014

    istif makinası more often. His blog has to be just about the best commentary on creationism and other wacko. Here’s a recent post: […]

  12. #12 full akülü istif makinası
    istanbul
    September 16, 2014

    akülü istif makinesi
    more often. His blog has to be just about the best commentary on creationism and other wacko. Here’s a recent post: […]zincirli vin

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