Pseudofossils are an interesting aspect of palaeontology that crop up from time to time and can make life both interesting and frustrating. I have already commented on the problems of identifying fossil bones in the field but these are a bit more specialised. Of course if you has as many different shapes as are available for all the fossils out there (think of the various shapes of the bones in just the human body, then add to that all other vertebrates and their variations, then add in shells, tracks, eggs and the rest) and the sheer number of rocks and pebbles that have odd shapes and can end up looking like fossils and you can probably see where this is going. Basically there are lots of bits of rock out there that are not fossils, but do look just like them.

This is generally only an issue for two reasons – it’s very annoying when you spot something in the field that looks like a fantastic find and turns out to be a lump of rock, and it’s even more annoying when someone brings you (by which I mean generally send you a photo) a ‘fossil’ that isn’t and then they get pissy / whiny / aggressive when you point out to them that it’s a lump of rock. I’ve not been on the receiving end of too much of the latter but I have heard plenty of it from colleagues and have stumbled through a couple of incidents on the web at various points.

p1000202To be fair, these things often look remarkably like fossils, and if they actually turn up in fossiliferous bed, it’s easy to understand why people think they are fossils. I’ve certainly seen a couple the required and double and then triple check to confirm that they aren’t bone (though some are obvious, do hunt down the ‘fossil mouse’ on display in the Natural History Museum in London). On that subject here is one that caught my eye in Mexico that I thought a few people might like, though perhaps only if you know what it looks like!

stenalorhynchus-scapHere is the pseudofossil in question (above), which to many probably looks like the lump of brown rock that it actually is. However, it bears a remarkable similarity to the scapula (the shoulder blade) of various basal reptiles, with subtleties of form you don’t even find in some poor fakes or reconstructions. Just to prove it, here is a nice drawing of the scapula of Stenalorhynchus lifted and modified from the fantastic ‘Osteology of Reptiles’ by the great A.S. Romer. We are only interested in the bone in the upper middle of the drawing hopefully you can see just how similar these things are, or at least how easy it is to mistake one for the other at a quick glance at distance in the field.

13 Responses to “Pseudofossils”

  1. 1 david Williams 30/03/2009 at 10:14 pm

    Nice post of pseudofossils. My favorites are the poop-shaped rocks from southcentral Washington, which are often sold as coprolites. Recent studies show that most likely they are not fossil feces but what might best be called earth farts: gas propelled mud that got squeezed through an opening and ended up looking remarkably like poop. Though they are not coprolites they are quite cool looking.

  2. 2 Jerry D. Harris 31/03/2009 at 12:06 am

    I think the pseudofossil phenomenon — particularly as it applies to the general public — is just a subset of the larger pareidolia phenomenon — people’s minds seem geared to trying to fit images they see into pre-set categories, probably as a means of trying to comprehend them. Paleontologists have their own pareidolia, too — as in your “rock looks like scapula” example. That’s not something that a member of the general public would come up with, but because you (and the rest of us, too!) have various scapula morphologies in our brains, our brains then try to fit visual images into those shapes, and rocks that, to others, would just be rocks, become “Is that a scapula?!?” to us.

    And yes, the word “pareidolia” should be in every paleontologist’s vocabulary…!

  3. 3 David Hone 31/03/2009 at 8:59 am

    Actually Jerry i have had something prepared for the Musings on this very subject for some time now, but perhaps not on the subject you might expect. Nice to have the formal term for it though, cheers!

  4. 4 Kyle 02/04/2009 at 8:08 am

    I had gentlewoman convinced she had found a living trilobite, scores of them she said stuck to the rocks on a hidden beach. She even had pictures… an excellent example of a chiton.

    I think some people might have teased her, but to be honest they do look similar to the casual eye, and it was a great teaching moment to discuss the difference between arthropods and molluscs…

    She was willing to learn and came away knowing a bit more about the world, and still wanting to know more…

    On the other hand there are those fake Chinese dragon fossils, made for the art trade (I hope), that some people seem to think are real.

    Favourite quote of the week:

    “I am not a rocket surgeon.”

  5. 5 David Hone 02/04/2009 at 8:46 am

    They are real though Kyle. They are protorosaurs and are found in huge numbers in China. We must have more than 100 of them in the IVPP. Now many of them are faked by sculptors (and are generally pretty obvious), but those ones are real fossils. Just about everyhting odd and reptilian here is called a dragon – ‘long’, hence Guanlong, Dilong, Tianulong, and the rest. It’s at least partly a function of the use of the word rather than an actual belief that these are ‘dragons’ as such.

  6. 6 Kyle 03/04/2009 at 2:01 am

    Thanks for the update on the protorosaurs, I’d read the cut line for the National Geographic image and noted it was a replica, and suspected the second image was a replica too (the ulna and radius seemed so large, and two fully articulated specimens… a little nicer than than the coquina, disarticulated bone fragments, and micro-fossils I’m used too from my university days*), but I had a third link that went missing… how about this little guy? ;o)

    * I remember when we didn’t even know what a conodont looked like…

  7. 7 David Hone 03/04/2009 at 8:14 am

    No problem. Happy to help out. Next time I am in the market I must get soem photos of fakes and real ones for comparison and stick them up. That one is an odd little fake, the arms are certainly based on a pterosaur and the skull si simialr too in some ways. You do see soem incredible fakes in China – certainly far better than Archaeoraptor.

  8. 8 Nick Gardner 13/07/2009 at 6:58 am

    “They are protorosaurs and are found in huge numbers in China. ”

    Really? I thought Keichousaurus was a sauropterygian. 😉


  9. 9 David Hone 29/07/2009 at 10:40 am

    I was referring to Hyphalosaurus which is there in big numbers and is (last time I checked, these things keep moving) a protorosaur.

  10. 10 Nick Gardner 29/07/2009 at 10:46 am

    Oh, well the fossils in the Nat Geo article are Keichousaurus

    I think Hyphalosaurus is a choristodere, not sure, honestly

  11. 11 David Hone 29/07/2009 at 1:37 pm

    I got that from the Jehol Biota book, but I’d certainly agree that the protorosaurs / prolacertiforms / choristoderes need a bit of work on definition and inclusive taxa. The book could certainly be out of date or only advocating one side of a complex issue – it’s a coffee table book rather than a really detailed academic tome.

  1. 1 Just a quickie « Dave Hone's Archosaur Musings Trackback on 11/04/2011 at 9:10 am
  2. 2 Not a fossil « Dave Hone's Archosaur Musings Trackback on 27/02/2012 at 8:10 am
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