Spot the Tiktaalik!

As you probably know, my colleague Neil Shubin was on the team of biologists and paleontologists who uncovered the fossil Tiktaalik, a lobe-finned fish that lived about 375 million years ago. Three skeletons of this species are now known, all found on Ellesmere Island, part of the Canadian territory of Nunavet. Below in red is the place these guys had to schlep to when searching for the skeleton. (The cool part, as recounted by Neil in his book Your Inner Fish, is that they chose this area because it had sediments of the right age: the age when fish started coming ashore to begin the evolution of tetrapods. That shows that evolution is indeed predictable: you can posit when such transitional forms might have lived, and then see if they really were around then.)

 

Tiktaalik has features that make it look as if it were on the line going from lobe-finned fish to tetrapods (terrestrial four-legged creatures), including a neck, fingerlike bones that could have been the precursors of terrestrial digits, a shoulder and a wrist, spiracles on the head, (which might have indicated lungs), and a robust ribcage and pectoral girdle that could have helped it move onto land. Now it’s not clear that this creature really did venture on land. As Neil surmises, it may have just lurked in shallow water near the shore, searching for prey. But perhaps its descendants turned into tetrapods: early land-dwelling amphibians.

But did they? Since Tiktaalik was discovered in 2004, paleontologists have reported finding tracks on land that pre-dated the Tiktaalik fossils, meaning that there were already terrestrial tetrapods before Tiktaalik (ergo it couldn’t have been the ancestor of tetrapods). Here are the fossil tracks from the Nature paper, along with the paper’s caption:

Figure 2 | Trackways. a, Muz. PGI 1728.II.16. (Geological Museum of the Polish Geological Institute). Trackway showing manus and pes prints in diagonal stride pattern, presumed direction of travel from bottom to top. A larger print (vertical hatching) may represent a swimming animal moving from top to bottom. b, On the left is a generic Devonian tetrapod based on Ichthyostega and Acanthostega (from ref. 18) fitted to the trackway. On the right, Tiktaalik (from ref. 29 with tail reconstructed from Panderichthys 23) is drawn to the same shoulder–hip length. Positions of pectoral fins show approximate maximum ‘stride length’. c, Muz. PGI 1728.II.15. Trackway showing alternating diagonal and parallel stride patterns. In a and c, photographs are on the left, interpretative drawings are on the right. Thin lines linking prints indicate stride pattern. Dotted outlines indicate indistinct margins and wavy lines show the edge of the displacement rim. Scale bars, 10 cm.

In response, Neil and others have questioned whether these really are tracks, or that they could have been made by Tiktaalik or other “walking fish.” Right now the issue is unsettled, but some people claimed that tetrapods were already on land 425 million years ago: 50 million years before Tiktaalik.

The issue isn’t resolved, but it’s clear that Tiktaalik was some kind of “transitional form” that could have been related to the real ancestors of tetrapods, even if it wasn’t. In that sense it’s like the feathered dinosaurs that appear in the fossil record when flying birds were already around. These feathered dinos weren’t on the direct line to birds, but showed that there were feathered reptiles around at roughly the times birds began appearing.

But I digress. Matthew found this tweet from Neil and sent it to me with the note, “This is a very cool photo. I would be a complete failure as a paleontologist.” It’s the very first view of Tiktaalik, and was almost missed as it’s hard to see (it was found after several unsuccessful expeditions to the area). Are you a good paleontologist—could you have spotted it?

Well, the reveal is below the fold (click on “read more”):

Here’s the reveal created by Matthew, who explains:

The bottom circle shows the snout bones, the left oval shows part of the jaw (I think) and the overall arc is the shape of its head. How the hell did they spot that? (I asked Shubin, he just said you got your eye in…)

37 Comments

  1. Neil shubin
    Posted April 7, 2018 at 10:40 am | Permalink

    Yup!! Not bad for a fly guy. You might have a future career.

    • yazikus
      Posted April 7, 2018 at 10:47 am | Permalink

      I’m looking for the link now, but I so enjoyed the short video documentary about this find. I remember a geologist telling me that it ‘truly showed the joy of fieldwork’ and I have to agree. Well done!

    • Hemidactylus
      Posted April 7, 2018 at 1:15 pm | Permalink

      Thanks for the book and TV show. Own and love both. Two of my favorite things. The revelation about remnant yolking genes changed my life 🙂

      • Sigmund
        Posted April 9, 2018 at 8:12 am | Permalink

        I’m just amazed it managed to live inside a rock in such a cold place!

        On a serious note, the age of Tiktaalik is younger than some tetrapod tracks found in Valentia island off the coast of Ireland. Those are estimated to be 385 million years old and come from a time when that part of the world was connected to North America (and was located south of the equator!). There are other similar tacks found in Scotland and Australia.

  2. ThyroidPlanet
    Posted April 7, 2018 at 10:41 am | Permalink

    I love the Tiktaalik story

    It’s wonderful too that it is a relatively new story

    When I would’ve seen the snout bones, – that’s when my mind would start going into high pattern-matching activity. But it’s soon peter out – the rest is so diffuse…

    One of the Tiktaaliks is in the Harvard Museum of Natural History

  3. yazikus
    Posted April 7, 2018 at 10:41 am | Permalink

    That is wonderful. Amazing that they spotted it – and so glad they persisted in their search.
    I wonder if it is at all like mushroom hunting (most of my experience has been with morels). You look, re-look, wander about, look some more and then something clicks and you begin to see them. Something so gratifying about that feeling.

  4. W.T. Effingham
    Posted April 7, 2018 at 11:06 am | Permalink

    If my recollection is correct (IF),Dr. Shubin appeared on the Colbert Report and had a multi-faceted, informing interview.

  5. Posted April 7, 2018 at 11:08 am | Permalink

    Would it make it easier to spot if I used feminist geology?

    I saw it using regular vision but not sure how I would have seen it if I didn’t know it was there.

    • Pierluigi Ballabeni
      Posted April 7, 2018 at 11:52 am | Permalink

      Feminist geology would claim that tiktaaliks were all females, reproducing parthenogenetically.

    • Heather Hastie
      Posted April 7, 2018 at 1:33 pm | Permalink

      Well, I spotted it, and I have a humanities degree (history), and I’m a feminist! However, I also eschew this crap about feminist science, so maybe I don’t count.

      I was very proud of myself, because I saw the snout poking out before I even scrolled down to the part that said that’s what to look for. Also, I’m rubbish at science and sometimes still can’t see the “spot the” creatures even once they’re pointed out!

      • infiniteimprobabilit
        Posted April 7, 2018 at 7:32 pm | Permalink

        Well I can’t see it. I still can’t ‘see’ it, even after the reveal. How the hell anyone else could, completely baffles me. (But of course it would, wouldn’t it).

        I think my brain just takes things too… literally. It’s just rocks.

        cr

  6. glen1davidson
    Posted April 7, 2018 at 11:08 am | Permalink

    Yes, yes, I do see the red lines.

    Actually, the close-up show some apparent bones differing from the usual sharp broken bones, but until the close-up there’s no real indication of anything.

    By the way, wouldn’t they be tetrapods whether or not they walked on land? It seems like they’re feet (pods) and there are four of them, and not fins like fish have. Just thinking.

    Glen Davidson

    • glen1davidson
      Posted April 7, 2018 at 12:30 pm | Permalink

      Supposed to be “sharp broken rocks

    • glen1davidson
      Posted April 7, 2018 at 1:56 pm | Permalink

      Having looked around the web, it looks like Tiktaalik is generally not categorized as a tetrapod.

      It could probably go either way at such a transitional stage, but the consensus seems to be that tetrapods come later.

      Glen Davidson

      • gravelinspector-Aidan
        Posted April 7, 2018 at 3:28 pm | Permalink

        That’s the problem with transitional forms. They don’t carry labels in the language and terminology that humans use today. And any labels they did carry can have been erased by taphonomy (changes to the remains between death and discovery). Plus, of course, the fact that the (current) “oldest known member of the group” is almost certainly not particularly representative of the oldest actual member of that group. If the group is a real thing, and our model of the group’s evolutionary development is correct.

  7. Posted April 7, 2018 at 11:20 am | Permalink

    I could pick out the snout in the picture, knowing it was there, but I’d never have seen it in the field.

  8. Simon Hayward
    Posted April 7, 2018 at 11:31 am | Permalink

    Does this get easier with practice? I’m pretty sure I’d never see this unless it came with the red lines pre-drawn.

    Re footprints that antedate this fossil. Do we know whether all tetrapods are derived from a single ancestor at this level? Could the LCA be one step further back and still be more aquatic/fish-like, with a number of derivative species possibly including Tiktaalik? Is it unreasonable to suggest that emergence from the water (by tetrapods) only happened once, or could this have happened with multiple (likely) related species within a tight timeline but potentially wide geographic area?

    • Posted April 7, 2018 at 12:55 pm | Permalink

      It could well be that several lines of lobe finned fishes independently began the journey toward becoming tetrapods, with these putative early tetrapods that pre-date Tiktaalik being among them, and later arrivals that include Tiktaalik. One thing fairly clear about Tiktaalik is that ‘walking’ was something that evolved under water, with terrestrial walking coming later. Many modern fishes walk under water, so walking is something that evolved multiple times.
      We don’t know which extinct species in in line with the true, singular ancestor to modern tetrapods. Could be Tiktaalik, or those possible earlier ones, or something else. But what is important about all of these fossils is that they represent different stages of tetrapod evolution ‘by proxy’.

  9. Jon Mummaw
    Posted April 7, 2018 at 11:37 am | Permalink

    You can take a 3D virtual tour of the Tiktaalic skull, humerus, pectoral fin, pelvis and body fossils at the Howard Hughes Medical Institute website.

  10. Posted April 7, 2018 at 12:01 pm | Permalink

    It’s hard to see because mostly hidden behind the nightjar.

  11. Peter
    Posted April 7, 2018 at 12:02 pm | Permalink

    Criticism of the Po;ish footprints:
    Spencer G. Lucas (2015) Thinopus and a Critical Review of Devonian
    Tetrapod Footprints, Ichnos, 22:3-4, 136-154, DOI: 10.1080/10420940.2015.1063491

  12. nicky
    Posted April 7, 2018 at 12:04 pm | Permalink

    I found the Tiktaalik story absolutely fascinating.
    Between Eusthenopteron and Panderichtis on the one hand, and Acantostega and Ichtiostega on the other. Shubin et al knew where to look, and they found it! Such a strong argument in favour of evolution and a great success story for paleontology.
    What I found a mind-blowing detail is that they determined the research area using an old school textbook (IIRC).
    I could only see it because I was told it was there, and knew what its snout should more or less look like, in the field I would never have seen it.

  13. Ken Kukec
    Posted April 7, 2018 at 12:55 pm | Permalink

    … the reveal is below the fold …

    If we’re to adopt newspaper lingo for a webpage — and it is altogether fitting and proper that we should do this — isn’t the more apt phrase “after the jump,” rather than “below the fold”?

  14. Mark R.
    Posted April 7, 2018 at 12:59 pm | Permalink

    Satan did a good job hiding that fossil, but not good enough to stump Shubin. 😉

    Seriously, this story is very cool indeed.

  15. Hemidactylus
    Posted April 7, 2018 at 1:06 pm | Permalink

    Shubin’s “Your Inner Fish” on PBS has been one of the very few things shown on television worth watching. Thanks! Bought the DVD and “The Brain with David Eagleman” recently because “Closer to Truth” episodes are slowly swallowing up the DVR storage space.

    Jerry should do a TV miniseries or get himself interviewed by Robert Kuhn. He’s fine with curmudgeonly atheists.

  16. Posted April 7, 2018 at 1:12 pm | Permalink

    There’s something exciting about spotting fossils in the wild as compared to in a museum. A lot harder but so much more satisfying.

  17. Diana MacPherson
    Posted April 7, 2018 at 1:51 pm | Permalink

    Jerry, that territory is spelled Nunavut.

  18. Posted April 7, 2018 at 2:31 pm | Permalink

    It looks like just a bunch of rock to me, and I’m not even a creationist.

    • gravelinspector-Aidan
      Posted April 7, 2018 at 4:08 pm | Permalink

      It looks like a bunch of rock to me, and I’m neither a creationist nor a fly-botherer.
      Things do look significantly different in the field. You have 3d-perception (well, for most people). The rocks and bones have weathering textures, which are different one to the other. Orientation is a clue – you’ll know what the bedding direction is, so you’ll be looking for things that are conformant with that … which reminds me of a fake :
      Did people see the recent news of a Middle-Jurassic dinosaur footprint discovery on Skye? Well many years ago there was another remarkable dinosaur footprint discovered on a Scottish Island. (I don’t know when – long before my time.) The faker had no understanding of what he (she?) was trying to fake, and cut the footprint into the flat surface of a wave-cut platform, not into an exposed bedding surface.

      • infiniteimprobabilit
        Posted April 7, 2018 at 7:41 pm | Permalink

        I was actually going to say that.

        I just can’t see it even after the reveal.

        However, with binocular vision and parallax, 3-D shapes in real life are often much easier to see than photos. The brain integrates the view into a 3D ‘shape’.

        I often find that if I take a photo of a walking track in the ‘bush’, a track which is so obvious it takes no concentration at all to follow – in the photo you can’t see it! The 3D view of a path between the bushes – depth perception – is lost and all you see in the photo is a mass of green leaves. The same goes for streams, seen through the trees.

        So maybe tiktaalik was a little more evident in the field than in the photo, but even so, all kudos to the person who spotted it.

        cr

        • Diana MacPherson
          Posted April 7, 2018 at 10:34 pm | Permalink

          I can’t see it either but my brain has a hard time with things like this. I can’t figure out how things look by floor plans either.

  19. loren russell
    Posted April 7, 2018 at 3:00 pm | Permalink

    Everyone familiar with the “Tiktaalik Song” by the Indoorfins? Google it on YouTube for lols!

  20. gravelinspector-Aidan
    Posted April 7, 2018 at 3:35 pm | Permalink

    (I asked Shubin, he just said you got your eye in…)

    Which is why geology (and I’m sure, botany, assorted arthropod-ologies, and … art history, to pluck something from a very different field of study) still uses the apprentice – journeyman – master learning path. People need to learn search images, then learn to see through confounding data to recognise the search image.

  21. Julio molina
    Posted April 7, 2018 at 5:34 pm | Permalink

    I was raised to believe in god but being open minded i have been watching alot of stuff about tiktaalik and evolution in general and i am amazed i find myself not being able to stop learning as much as i can about tiktaalik and evolution in general i must say im 43 years old and after learning so much lately about evolution i find myself wishing i had got into paleontology or anything that has to do with looking for fossils like niel sabin and don Johansson i find it all so fascinating it all makes so much sense to me i wish i could get into what you great men do

    • Diane G.
      Posted April 7, 2018 at 8:20 pm | Permalink

      I hope you’ll read Jerry’s book, Why Evolution is True, if you haven’t already. It’s full of such amazing science. 🙂

  22. Christopher
    Posted April 7, 2018 at 8:36 pm | Permalink

    Ive done a fair bit of fossil hunting, although we only have the bog standard invertebrates in my neck of the ancient inland sea, and I’d like to think I’d have seen that, but who the hell knows what great finds I walk right past every time I’m out! I do completely understand that idea of “getting your eye in”, getting a search image in your brain that lets you see the specific thing you’re hunting for while the ignoring all else. That’s the same when hunting for morels each spring.

  23. Posted April 8, 2018 at 1:40 pm | Permalink

    I would never spot it!


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