Pharyngula

Gogonasus andrewsae

Here’s another tetrapodomorph fish to consternate the creationists. These Devonian/Carboniferous animals just keep popping up to fill in the gaps in the evolutionary history of the tetrapod transition to the land—the last one was Tiktaalik.

i-8b2442cac1020896a08aca4650293aa3-gogonasus_skull_lat.jpg
Skull in lateral view.

This lovely beastie is more fish than frog, as you can tell—it was a marine fish, 384-380 million years old, from Australia, and it was beautifully preserved. Gogonasus is not a new species, but the extraction and analysis of a new specimen has caused its position in the evolutionary tree to be reevaluated.

Here’s a little more detail on the skull:

i-e78b276c3453fd1d99c0d0a642826aa4-gogonasus_skull_dorsal.jpg
Skull in dorsal view. ET, extratemporal bone; PO, postorbital; PP, postparietal; Spir, spiracular opening; Sp. lam., down-turned lamina of tabular for spiracular chamber; Sq, squamosal; ST, supratemporal; Ta, tabular.

And here’s the pectoral limb:

i-fcd70aa38199e54eeadd0d1117d6957e-gogonasus_limb.jpg
Left humerus, ulna and radius articulated in dorsal view. g, Reconstructed left pectoral fin in dorsolateral view.

That limb shows some interesting similarities to that of Tiktaalik, and a more detailed evaluation of the newly revealed characters has pushed Gogonasus a little higher in the tetrapod family tree. It also suggests that the pattern of limb bones is more ancient than previously thought, and some features regarded as characteristic of the tetrapod transition are rooted farther back, in more fish-like functional states.

i-53ee036e13bde58873a9a03eb9b4e7db-gogonasus_lineage.gif
(click for larger image)

a, Previous phylogenetic position of Gogonasus. b, New position of Gogonasus based on PAUP analysis of 103 characters. c, Position of Gogonasus relative to other tetrapodomorph fishes, showing pectoral fin endoskeleton comparisons.

One of the success stories of evolutionary theory is that we keep finding these organisms that fit so well into an evolutionary framework, and another is that these discoveries lead to further predictions. Gogonasus is no exception: its discovery in Australia suggests that there ought to be more transitional tetrapodomorphs waiting to be found there, and the researchers have already started looking for them.

Finally, we note that strata of similar age to those producing Gogonasus, Panderichthys and Tiktaalik, or slightly younger, have yielded tetrapod jaws in Australia and China, and also trackways attributed to two different unknown tetrapods on the Gondwana supercontinent. This indicates that the initial radiation of tetrapods from elpistostegalian fishes, with evidence currently confined to the northern hemisphere landmass of Euramerica, was probably an extremely rapid global event. Migration of some Middle?Late Devonian fishes from a Gondwana place of origin to Euramerica has been well documented. With Gogonasus now positioned phyletically close to elpistostegalians, we suggest that the current lack of fossil evidence for elpistostegalian fishes in Gondwana could be due to poor sampling. We are now exploring areas in Australia with undescribed Devonian sarcopterygian fish remains to test this hypothesis.

Any bets on whether they’ll find them?


Long JA, Young GC, Holland T, Senden TJ, EMG Fitzgerald(2006) An exceptional Devonian fish from Australia sheds light on tetrapod origins. Nature <doi:10.1038/nature05243>

Comments

  1. #1 Johan
    October 19, 2006

    YES! Two new gaps in the fossil record for the Cretinists! ;)

  2. #2 Bruce
    October 19, 2006

    I bet they do find more which always amazes me. Back when I was a pup, one of my many majors was archeology, looking for native American sites in the Northwest. Determining where the water’s edge was a thousand years ago and where a good fishing site might have been was amazingly difficult.
    So these Aussies have found the correct strata but damn, the world’s a big place. Just how hard is it to find fossils?

  3. #3 Steve LaBonne
    October 19, 2006

    Crap. Johan beat me to it!

  4. #4 C.W.
    October 19, 2006

    YES! Two new gaps in the fossil record for the Cretinists! ;)

    Nitpick: One new gap actually…;-)

  5. #5 Frans
    October 19, 2006

    C.W.
    Johan is right- read again.

  6. #6 Charles Winder
    October 19, 2006

    We are now exploring areas in Australia with undescribed Devonian sarcopterygian fish remains to test this hypothesis.

    Won’t they look silly when they find Noah’s Ark instead.

  7. #7 Rocky
    October 19, 2006

    Very wonderful reading PZ. Thank you, I don’t seem to find this type of info other than here. Now I have to Google “elpistostegalians” and learn more!
    Thanks again!

  8. #8 Stanton
    October 19, 2006

    So Gogonasus was a contemporary of the Gogo arthrodires?

  9. #9 Mena
    October 19, 2006

    FYI for people in the Chicago area, from http://www.fnal.gov/culture/Arts/:
    The First Steps on Land
    Dr. Neil Shubin, Discoverer of “Tiktaalik”, University of Chicago
    January 19, 2007 @ 8 p.m. — Tickets: $5
    Neil Shubin startled the world last year with the announcement of the discovery of the 375 million year old fossil of “Tiktaalik,” a mosaic of primitive fish and amphibian which sheds light on the transformation from life in water to life on land.

  10. #10 GvlGeologist
    October 19, 2006

    A great post. As a non-biologist, I’ve got a question. How are the bones of the Gogonasus limb as identified being the particular bones that they are listed as? In other words, I would (with my meager vertebrate anatomical knowledge) not have known that the two bones identified as a radius and ulna were those bones. Other than approximate position, do they possess particular characteristics of those bones? Or is it because of comparison on an evolutionary basis between the other intermediates? Or something I have no idea about?

  11. #11 John Stone
    October 19, 2006

    Waaaaaayyyy toooooo kewl ….

  12. #12 Zeno
    October 19, 2006

    Gogonasus is not a new species, but the extraction and analysis of a new specimen has caused its position in the evolutionary tree to be reevaluated.

    If Gogonasus needed to be repositioned in the evolutionary tree, then obviously its previous position was wrong! I can see the creationist headlines now: New Discovery Refutes Evolutionists.

    Only creationists are never, never wrong. That’s the advantage of content-free, faith-based “science.”

  13. #13 Stanton
    October 19, 2006

    And when Zeno says “content-free,” he’s referring both to creationists’ experiments, and creationists’ heads.

  14. #14 Kseniya
    October 19, 2006

    “New Discovery Refutes Evolutionists.”

    LMAO – that’s perfect.

  15. #15 Michael Hopkins
    October 19, 2006

    If there is a good fossil people able to expand the Wikipedia entry beyond a stub in the next day or so, it could be submitted for the “Did you know…” section of the Wikipedia homepage.


    http://en.wikipedia.org/wiki/Gogonasus

  16. #16 Michael Hopkins
    October 19, 2006

    If there is a good fossil people able to expand the Wikipedia entry beyond a stub in the next day or so, it could be submitted for the “Did you know…” section of the Wikipedia homepage.


    http://en.wikipedia.org/wiki/Gogonasus

  17. #17 Tommykey
    October 19, 2006

    Another fossil put in the ground by God to trick us. He just never quits, does he?

  18. #18 Gentlewoman
    October 19, 2006

    Very cool! It’s a great time to be alive and interested in science, isn’t it? My childhood dream was to be an paleontologist, so I always find stuff like this to be very exciting.

  19. #19 Rex
    October 20, 2006

    “Just how hard is it to find fossils?”

    Depends where you look. Some rocks like high-grade metamorphic rocks will simply not have fossils while sedimentary rocks are highly variable in their preservational abilities, depending on many factors.

  20. #20 Larry Fafarman
    October 20, 2006

    PZ Myers said,
    One of the success stories of evolutionary theory is that we keep finding these organisms that fit so well into an evolutionary framework, and another is that these discoveries lead to further predictions. Gogonasus is no exception: its discovery in Australia suggests that there ought to be more transitional tetrapodomorphs waiting to be found there, and the researchers have already started looking for them.

    What is the big “prediction” here? That where a particular fossil is found, similar fossils are likely to be found? How does that compare, say, with Einstein’s theory of relativity’s prediction that stars’ apparent positions would shift during a solar eclipse as a result of the bending of light by the sun’s gravity?

    Also, “transitional” or “intermediate” species like gogonasus have been known for a long time. For example, the fossil Archaeopteryx has characteristics of birds and reptiles, and monotremes today have characteristics of mammals, birds, and reptiles. Also, bats are shaped like birds and cetaceans are shaped like fish, though bats and cetaceans are not considered to be transitional or intermediate forms. So why all the hoopla about gogonasus?

    Also, though these transitional fossils provide evidence of “changes through time,” they provide little or no evidence of the mechanisms that caused these changes.

  21. #21 quantum
    October 20, 2006

    >>bats are shaped like birds and cetaceans are shaped like fish?
    Did you really read up on biology or not?

  22. #22 quantum
    October 20, 2006

    Maybe you will find a Devionian whale and a Cretacious bat!

  23. #23 zilch
    October 20, 2006

    Larry Fafarman said: Also, though these transitional fossils provide evidence of “changes through time,” they provide little or no evidence of the mechanisms that caused these changes.
    True. Most likely, God separately created all these species, one after another, and then made them go extinct, one after another, so He could sort the sheep from the goats: believers fly up to the sky, the scoffers die and then they fry.

  24. #24 Larry Fafarman
    October 20, 2006

    Quantum said,

    bats are shaped like birds and cetaceans are shaped like fish?

    Did you really read up on biology or not?

    Well, they are, aren’t they?

    Maybe you will find a Devionian whale and a Cretacious bat!

    I responded to that issue when I said that they are not regarded as transitional or intermediate forms. My point was that it is not uncommon for organisms to have characteristics of more than one phylum or class.

  25. #25 Jud
    October 20, 2006

    L. Fafarman: “My point was that it is not uncommon for organisms to have characteristics of more than one phylum or class.”

    Depends what you mean by “characteristics.” If you mean superficial appearance or gross functional physical features, then yep – there are several ways in which this might occur, such as convergent evolution. If you mean millions upon millions of identities or close similarities at the genetic/molecular levels, where those identities and similarities recapitulate and confirm the story told independently by geology (and, within geology, independently confirmed by stratigraphy, tree rings, radiocarbon dating, etc.) and other sciences, then the sharing of such “characteristics” across classes and phyla is overwhelming evidence for a particular mechanism – evolution.

  26. #26 craig
    October 20, 2006

    How many of these did they find? Is one enough to establish an entire stage of an evolutionary process… If I were to gather some skeletal remains from the right places, and be allowed the same latitude for extending a theory on single skeletal evidence from generation to generation, I could convince you that man has evolved to no longer have arms (finding a series of totally unrelated remains, one with arms, one without, and placing in between them a variety of other partially underdeveloped skeletal remains until the line is complete). Come on… there is more in common between creationists and evolutionists… FAITH!

  27. #27 Jud
    October 20, 2006

    Craig: “If I were to gather some skeletal remains from the right places, and be allowed the same latitude for extending a theory on single skeletal evidence from generation to generation, I could convince you that man has evolved to no longer have arms….”

    Errmm, no. Easy to see that most folks today have arms. Also easy to see that there are fish with fins and gills, as well as transitional forms with lungs and/or whose fins are more adapted for walking on land. So the story told by the fossil evidence jibes with what we see in the present-day descendants of these animals (in fact it jibes *because* they are the descendants).

  28. #28 Larry Fafarman
    October 20, 2006

    Jud said ( October 20, 2006 10:43 AM ) –
    the sharing of such “characteristics” across classes and phyla is overwhelming evidence for a particular mechanism – evolution.

    Many ID proponents and other critics of Darwinism accept the ideas of changes through time and common descent — they just disagree with the idea that natural genetic variation and natural selection were the sole causes of those changes.

  29. #29 Steve_C
    October 20, 2006

    Ummm… yeah the “designer”.

    Try not to laugh outloud guys…

    hehe

  30. #30 Torbjörn Larsson
    October 20, 2006

    “What is the big “prediction” here?”

    That we will find fossils, roughly intermediate in characteristics and in time, to make up a phylogenetic tree. (“Roughly” involves a lot of detailed discussions on properties of cladistics in phylogenetic trees, fossil dating and fossil characterisation, I presume.)

    If we had found Acanthostega to live before the other tetrapods, it had immediately gone against the predictions of the theory. BTW, it is really easy to see from the tree above though they show only a few characteristics.

  31. #31 Larry Fafarman
    October 21, 2006

    Torbjörn Larsson said ( October 20, 2006 07:46 PM ) –

    “What is the big ‘prediction’ here?”

    That we will find fossils, roughly intermediate in characteristics and in time, to make up a phylogenetic tree.

    Evolution theory cannot “predict” what new fossils found in the future will look like — all that can be done is determine whether fossils already found are consistent with the theory. Often the theory is twisted or bent to make fossil finds conform to the theory — for example, the theory of punctuated equilibrium was invented in an attempt to explain away the unexpectedly large number of missing links. In the theory of punctuated equilibrium, it is argued that the periods of evolution were too short to leave much of a fossil record.

  32. #32 Ichthyic
    October 21, 2006

    as usual, Larry, you are incorrect. several recent major finds WERE in fact predicted, both in kind and in placement.

    go figure.

    have you started taking your meds yet? I mean, I know your brother told us to go easy on you, but really, you do set yourself up constantly.

  33. #33 Ichthyic
    October 21, 2006

    …Don’t make me post that thread where your brother exposes your condition, Larry.

    you wouldn’t like that.

  34. #34 Torbjörn Larsson
    October 21, 2006

    “Evolution theory cannot “predict” what new fossils found in the future will look like — all that can be done is determine whether fossils already found are consistent with the theory.”

    Well, AFAIK there is attempts of detailed predictions, but they are difficult, perhaps too difficult. OTOH, tiktalik was predicted to exist with general features, rough time and rough habitat. Which is why it was found, BTW.

    But that isn’t a problem, most observations are of this nature. For example, when particle colliders make their runs, each individual event is recorded and checked for consistency with the theory. This is because there is no way to predict how an individual collision will look like due to fundamental QM even if somehow the coarsegraining problem could be solved. So if such experiments are enough to confirm a theory and arrive at measurements with 13 significant digits, they sure are enough to confirm biology too, don’t you think?

    Postdictions (observations found afterwards to be consistent with old or newly constructed theory) is okay too, if you wondered about the limits of observations. But for obvious reasons postdictions aren’t seen as good examples to falsify theories with. We need predictions for that.

    “Often the theory is twisted or bent to make fossil finds conform to the theory”

    Fundamental mistake. Theories change. The scientific debate is alive. This isn’t dogma, remember?

  35. #35 Torbjörn Larsson
    October 21, 2006

    “Which is why it was found, BTW.”

    I should stress this more. This is an excellent example of how evolution science has progressed from being a passive observer (dig for general fossils where they are found) to active experimenter (predict where specific fossils are to be found). You can’t be much more predictive and experimentative than this!

  36. #36 snarky
    October 21, 2006

    “has caused its position in the evolutionary tree to be reevaluated.”

    see you are always changing the facts! That proves that evolution is false!

  37. #37 Larry Fafarman
    October 21, 2006

    Ichthyic said ( October 21, 2006 06:51 AM ) –

    …Don’t make me post that thread where your brother exposes your condition, Larry. you wouldn’t like that.

    Don’t start a flame war here, Ichthyic. PZ Myers wouldn’t like that. Because I can post comments here by means of anonymous proxies (this comment is posted by anonymous proxy), he can delete my comments but he cannot block them except by enabling universal comment moderation, which would be a great inconvenience to himself and to the readers. Without comment moderation, my nasty comments — as well as yours — could sit on this blog for some time before he finds and deletes them.

  38. #38 PZ Myers
    October 21, 2006

    Making threats to inconvenience me or my readers means you’re gone, bozo.

  39. #39 Torbjörn Larsson
    October 21, 2006

    Yet another creo’s innards exposed. Touché!

  40. #40 Larry Fafarman
    October 21, 2006

    PZ Myers | October 21, 2006 01:02 PM

    Making threats to inconvenience me or my readers means you’re gone, bozo.

    Y’r th n wh s gn, y lsy scmbg. t s frly bvs wh strtd t hr: chthyc.

    nt nly hv mnd t spm yr lsy ss, bt my strt spmmng Pnd’s Thmb gn t, smthng hvn’t dn n mnths.

    n f my fvrt tctcs s pstng flms lt t nght s thy r nt fnd nd dltd fr svrl hrs.

  41. #41 Torbjörn Larsson
    October 21, 2006

    Missouri-Larry dropped his link at the time he went koo-koo-kook. An impostor, or merely living up to the IDiot role?

  42. #42 Torbjörn Larsson
    October 21, 2006

    Oh, disemvoweled. IIRC that is expressly ip-based here. Forget my question.

  43. #43 Larry Fafarman
    October 21, 2006

    ll rght, Slzy PZ. ‘ll pst my mssgs lt t nght s tht thy wn’t b fnd s qckly.

  44. #44 Larry Fafarman
    October 21, 2006

    Torbjörn Larsson said,
    Missouri-Larry dropped his link … An impostor?

    Wrng — jst dcdd t stp bthrng t fll t n.

  45. #45 Steviepinhead
    October 21, 2006

    The disemvowelled maroon said:

    natural genetic variation and natural selection were the sole causes

    Yet another neuron-bereft twit who has only the vaguest grasp of the numeric and grammatic import of the word “sole.” A fish? A flounder?

    Still more evidence that CreaIDiot maunderings are composed via the mix-and-toss word-salad method. If you claim this random error-ridden variation produces sensible statements (though the soundness of your case for “sensible” is, let’s say, not exactly ready to bear live loads), why couldn’t it just as well generate the “new information” needed for speciation and evolution?

    You don’t know: you’re still fishing for flounders.

  46. #46 Ichthyic
    October 21, 2006

    I never tire of pointing out just who Larry really is:

    One, Larry was banned from PT for exactly the kind of posting behavior and flagrant disregard for the board rules he exhibits here.

    Two, regardless of him saying he’s from Missouri, he lives near L.A. in CA.

    Three, he really does have some mental incapacity. It’s not an attempt to “flame” as Larry put it, but simple fact, as documented by his brother, Dave, some time ago on Ed Brayton’s blog.

    Larry even tried to fake a loging as his own brother to deny it.

    bottom line, there really is no point in debating Mr. Farfromsane.

    anybody who doubts it can check out the old thread on Ed’s blog for themselves.

    http://scienceblogs.com/dispatches/2006/05/fafarman_take_3.php#c096404

    if that’s not enough, you can easily enough get quick access via google to his ramblings on holocaust “revisionism”, the incorrect nature of “meteor theory”, and numerous other bits and pieces of insanity.

    taking larry at all seriously will only result in giving yourself a brain aneurysm.

  47. #47 Ichthyic
    October 21, 2006

    In the immortal words of Larry’s brother Dave:

    It is not good to humor him.

  48. #48 Larry Fafarman
    October 21, 2006

    t’s lk ths, PZ. chthyc strtd t nd h s cntnng. f y wld g ftr hm nstd f m, ths wld stp.

  49. #49 Ichthyic
    October 21, 2006

    What would stop, Larry?

    your attempt to violate the board rules and wishes of the blog owner, and essentially threaten terrorism if you don’t get your way?

    Sounds like a call to homeland security is in order.

    frankly, if booting all my posts would get you to recognize how sick you are, I’d be happy.

  50. #50 Steviepinhead
    October 21, 2006

    Neener, neener, neener. PZ, PZ, Ichthyic’s bein’ mean to me!

    PZ’s already got kids, Larry, younger but far more mature than you.

    Sad, really, this whole Larry thing.

  51. #51 Larry Fafarman
    October 21, 2006

    What would stop, Larry?
    your attempt to violate the board rules and wishes of the blog owner, and essentially threaten terrorism if you don’t get your way?

    Wht brd rls? Thr r nn. Wht trrrsm? vrythng m dng s prfctly lgl. f PZ dsn’t lk my psts, h cn gnr thm, dlt thm, r whtvr.

  52. #52 Ichthyic
    October 21, 2006

    he banned you larry, and you continued to threaten to post here, just like on PT, by using proxy aliases, and dared him to find your posts.

    legal’s got nothing to do with it.

    same reason we banned you at PT.

    you just don’t get it, do you?

    but then, self diagnosis is certainly not your strong suit, is it.

    continue to post away, farfromsane.

    you’ll get no further argument from me.

  53. #53 Torbjörn Larsson
    October 21, 2006

    Sad.

  54. #54 John Long
    December 7, 2006

    Thanks for your excellent coverage of our new fossil fish find, the work is still on-going with the specimen and we hope to shed more light on Gogonasus’s anatomy in the near future.

    Also there’s a new book just out on the entire Gogo fish fauna, with more pictures of Gogonasus and its discovery, that might be of interest to your readers -

    Long, J.A. 2006. “Swimming in Stone-the amazing Gogo fossils of the Kimberley.” PB, with colour plates. Fremantle Arts Centre Press, West Australia. 320pp. ISBN 1921064331.

    Cheers
    John

  55. #55 Johinen
    May 17, 2008

    Great information PZ and great pictures you gave alot more detail than alot of the other sites I checked out

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