A bizarre living fossil

Today’s New York Times describes one man’s obsession with an enigmatic, living deep-sea creature that looks morphologically identical to one that lived hundreds of millions of years ago. The “creature” is described in a new paper in the journal Deep-Sea Research II (reference at bottom).

In 1976, a deep-sea camera being towed over the mid-Atlantic Ridge showed images of a strange creature (or the burrow of a strange creature): sets of tiny holes forming a hexagonal pattern. Each set was 2.5 – 7.5 cm (1 – 3 in.) across. Here’s one of those early photos:

Towed camera photo

Fig. 1. One of original 1976 towed camera photos of patterns in sediment on the east wall of the axial valley of the Mid-Atlantic Ridge (all photos from original paper)

The patterns appeared virtually identical to a 500-million-year-old fossil (almost certainly of an invertebrate) from the Cambrian that was named Paleodictyon nodosum. This species represented by this fossil was thought to have gone extinct 50 million years ago:

Fossil P. nodosum

Fig. 2. Cast of fossil P. nodosum on the sole of an Eocene turbidite near Vienna Austria. Note partial erosion on right side, showing nodose pattern of vertical shafts.

The similar “appearance” of the ancient and living form prompted the authors to also classify the modern one as P. nodosum.

But what is this thing? It could be either the body parts of a creature itself or simply remants of an animal’s burrow. Whatever it is, it doesn’t look like anything else we know.

Rutgers biologist Peter Rona has spent the past 30 years trying to find out what P. nodosum is, and attempting to capture a specimen in deep-sea dives in the submersible vehicle ALVIN. Here’s a more recent image, with laser dots for scale; notice how the tubes form a dome that is raised above the substrate:

HDtv image, mid-Atlantic ridge

Fig. 3. High-definition TV image of P. nodosum at the discovery site on the Mid-Atlantic Ridge with laser beams for scale (10 cm separation). Note the shield-shaped elevation, marginal elevated rim and mote, and color (pale pink) of the area of the pattern compared with the surrounding veneer of gray calcareous lutite (image courtesy The Stephen Low Company).

So far the creature has eluded capture. On-site “erosion” studies (blowing away surface layers) have confirmed that the vertical holes are connected to each other below the surface by horizontal tunnels. Below is a reconstruction of what the creature (or its burrow) looks like in three dimensions:

3-D reconstruction

Fig. 4. 3-D plasticine reconstruction of P. nodosum (or its burrow)

The New York Times has a nice graphic showing how these tubes, when raised above the substrate in a dome-like shape (as they are in P. nodosum) trap water more readily, allowing it to circulate through the system of tubes and perhaps allowing the creature to harvest edible microorganisms.

To make a long paper short, Rona et al. think that this pattern (and that of its eponymous ancestor) could represent either a “burrow consistent with interpretation of the ancient form as a trace fossil,” or “a compressed form of a hexactinellid sponge adapted to a sedimentary substrate, which means that the ancient form is a body fossil with possible affinity to the Ediacara fauna.” Paleontologist Dolph Seilacher thinks the traces are a “kind of farm where an unknown type of worm or other organism raises miro-organisms to eat.”

Is this really a “living fossil”? Well, the ancient fossils are morphologically identical to what is produced by the present-day creature. That’s why ancient and modern forms are given the same Latin name. And there is certainly a phylogenetic connection between the two, though because the forms are separated by millions of years we can’t test their reproductive compatibility to see if they’re the same biological species. But it hardly matters. “Living fossils” are recognized by morphological similarity, not genetic identity. What is exciting is the finding of a truly unique animal of unknown affinity, and its connection with a similar creature from the Cambrian. We’re a long way from knowing all the strange creatures with whom share our planet.

___________

Paleodictyon nodosum: A living fossil on the deep-sea floor. 2009. Peter A. Rona, Adolf Seilacher, Colomban de Vargas, Andrew J. Gooday, Joan M. Bernhard, Sam Bowser, Costantino Vetriani, Carl O. Wirsen, Lauren Mullineaux, Robert Sherrell, J. Frederick Grassle, Stephen Low, Richard A. Lutz . Deep-Sea Research II. In press, available online 28 May 2009

24 Comments

  1. Torbjörn Larsson, OM
    Posted August 25, 2009 at 8:20 am | Permalink

    Link broken, but I found your photo here.

    I have a hard time wrapping my head around that the geometry (hole position and dome shape) is from several individuals behavior as opposed to one body. (And it is more exciting!)

    Then again, bees vs beehives…

    • Bertil
      Posted October 6, 2009 at 5:16 pm | Permalink

      Fascinating creature(s).
      I had the same feeling that this must be one body, but you’re right.
      Collectives can build symmetry as well 🙂

  2. James
    Posted August 25, 2009 at 8:23 am | Permalink

    I just read the intro to the article and NYT piece and it wasn’t clear to me what is known about P. nodosum. Is there an actual organism that is called P. nodosum, or is it a name for the trace fossil? From the article, it seemed as though the phenomenon may be the result of a complicated interaction more than one species.

    Paleontologists certainly don’t give binomials to trace fossils, right?

    • ivy privy
      Posted August 25, 2009 at 11:31 am | Permalink

      Is there an actual organism that is called P. nodosum, or is it a name for the trace fossil?

      If you will read the above, perhaps it will become clear to you that it is not yet known whether the fossil is a trace or an organism.

      • james
        Posted August 25, 2009 at 2:38 pm | Permalink

        I was pretty sure of that, but I was more interested in the second part of my comment–is it common to give species names to trace fossils where the maker is unknown?

      • Posted October 21, 2009 at 10:51 pm | Permalink

        I want to reply to the comment below but am not sure it will appear that way.

        I wondered the same thing too. Then again, what else is a fossil but a trace remnant of something unknown.

        That doesn’t make me feel a lot better about it overall – it seems like it might turn out to be something created by a natural process (at least as the fossilized forms were found) and not need a species name at all.

  3. ivy privy
    Posted August 25, 2009 at 8:41 am | Permalink

    This fossil was thought to have gone extinct 50 million years ago:

    That seems very unlikely. The U.S. quarter found next to it indicates it was formed in or after 1994.

  4. newenglandbob
    Posted August 25, 2009 at 9:05 am | Permalink

    Aquatic bees: Elaine Morgan will give a lecture on them next month.

    /wiseacre

  5. Posted August 25, 2009 at 9:27 am | Permalink

    The hexaganol one reminds me of one of my sons toys.
    Are they sure its not a Hama beads grid?
    http://www.hamainsa.com/images/inspirations/hexagon_angel.jpg

  6. Posted August 25, 2009 at 9:49 am | Permalink

    But a miracle could cause the same organism to appear, or just the same pattern to appear, after millions of years. Or indeed, a miracle might be responsible for the original ones.

    Teach the weaknesses in paleontology!

    Glen Davidson
    http://tinyurl.com/mxaa3p

    • Sili
      Posted August 26, 2009 at 11:55 am | Permalink

      Well, this doesn’t look like a rabbit. To me at least.

      Or perhaps it’s a timetraveller.

  7. Matthew Cobb
    Posted August 25, 2009 at 12:55 pm | Permalink

    This isn’t the first (or last) thing from under the sea that raises questions about the Ediacara etc. Last year in Current Biology, people reported traces that looked identical to burrows/traces found in rocks >1 billion years old, when there were supposedly no animals capable of making such traces. The modern traces were made by a 30mm wide mega-protists of the genus Gromia – giant amoeboids.

    You can see pics here (click on Figures/Tables – that’s free; the article is restricted).
    http://tinyurl.com/mg7hyc

    You can read my free summary of the article here:
    http://tinyurl.com/ndsvcx

  8. hempenstein
    Posted August 25, 2009 at 1:11 pm | Permalink

    P. nodosum is toadly ossum!

    (The reconstruction sorta looks like packing material for delicate instruments.)

    If there were pentamers every so often it would be reminiscent of representations of bacteriophage capsid structures.

  9. H.H.
    Posted August 25, 2009 at 4:27 pm | Permalink

    Millions-of-years-old fossilized organisms? Please! You evolutionists love a good fairy tale! Those are just impressions left in the sand from Adam and Eve’s beach volleyball game. He was a hard spiker.

    • newenglandbob
      Posted August 25, 2009 at 4:33 pm | Permalink

      H.H. we don’t want your godddit crap here. Go play with yourself. Your fairy tales don’t belong here. Let the adults talk.

      • H.H.
        Posted August 25, 2009 at 4:51 pm | Permalink

        newenglandbob, you really need to invest in a new sarcasm detector. I purposely made that one extremely obvious. I mean, beach volleyball? Come on, man. Even the the worst case creotard isn’t that overtly stupid.

      • Bertil
        Posted October 6, 2009 at 5:20 pm | Permalink

        A little bit of sarcasm is healthy 🙂

  10. Posted August 26, 2009 at 6:28 am | Permalink

    Discoveries like this one illustrate how little is known about life on earth—and fossils. Any theory based on fossil evidence is questionable at best, and belongs in the category of hypothesis rather than theory. The overarching “theory” of evolutionary science, that all life evolved from single-celled organisms beginning several billion years ago, relies on—guess what?—fossil evidence. Yet scientists cannot agree on which, if any, of the fossis represent actual single-celled organisms. Then of course we have the problem of from whence, and how, those first single-celled organisms came into being.

    Lisa A. Shiel
    author of The Evolution Conspiracy
    http://EvolutionConspiracy.com/

    • newenglandbob
      Posted August 26, 2009 at 6:37 am | Permalink

      Nothing like shameless self promotion on someone else’s blog, huh?

      I perused your blog and can easily see that you only believe what you want to believe. You actually state that DNA evidence does not show the relationship between humans and apes.

      Evolution has from the start inspired arguments, wild speculation, and personal attacks. The flimsy theory has never brought us ultimate proof that humans—or any species—evolved from ancient apelike specimens.

      right…LOL

      • gingerbaker
        Posted August 26, 2009 at 10:17 am | Permalink

        I don’t know, N.E.B. This organism shows clear evidence of intelligent design.

        God, evidently, moonlights at Moen in the showerhead section.

      • newenglandbob
        Posted August 26, 2009 at 10:23 am | Permalink

        You are right, gingerbaker, it does appear to show intelligent design, but then again, so does table salt.

        But gingerbaker, what does this have to do with my comment on Lisa A. Shiel’s comment?

      • Posted August 26, 2009 at 12:34 pm | Permalink

        I particularly liked the imaginative way Lisa used the example of the German forensic labs noticing a mistake in their DNA testing due to contaminated cotton buds received from a manufacturer. Apparently this one instance is enough to throw doubt on all the DNA sequence based phylogenies of evolutionary biology that now tie together the tree of life.

        Therefore God exists.
        Or Bigfoot.
        (I’m not sure which one is highest on Lisa’s priorities.)

    • Torbjörn Larsson, OM
      Posted August 26, 2009 at 2:38 pm | Permalink

      Any theory based on fossil evidence is questionable at best, and belongs in the category of hypothesis rather than theory. […] author of The Evolution Conspiracy

      Is this a gambit that there won’t be any pathetic answers, seeing that the blog owner, an expert on this where you aren’t, has written a whole book showing why this is wrong? Well, it’s not going to work for you, here’s my pathetic layman answer:

      First, if you accuse one science to be a conspiracy without extra-ordinary evidence to back up your extra-ordinary claim specifically, they all potentially (but not bloody likely) are according to you. Then there’s no need to have a discussion. As a US politician recently famously said to another doubter, roughly: “I can as well discuss with my breakfast table.”

      Forgetting that since it is a public blog and instead continuing to address the points you actually made:

      Second, any non-trivially connected set of hypotheses that can be tested is by definition a theory, whether they actually have been tested yet or not. Evolution qualifies, and any merited scientist can tell you so.

      Third, evolution isn’t based on fossils alone, it also makes predictions on the mentioned DNA phylogenies for example. No other theory has passed that test anyway (explaining fossil phylogeny), and the many, many more that evolution has passed on account of its many mechanisms and observations. It is actually the best tested theory we have in all of science.

    • newenglandbob
      Posted August 26, 2009 at 5:19 pm | Permalink

      Evolution is supported by data from fossils and DNA, ecology, ethology (animal behavior), geology, biochemistry, zoology, botany, virology, microbiology, embryology, anthropology, biogeography, comparative anatomy and many other research fields.


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