Tetrapod Zoology

Tet Zoo picture of the day # 26

i-56c8721731e01467aaa791f52a55845d-Placodonts fig 2 resize.jpg

The other day I had to prize the skeletal jaws from a dead hedgehog. Well, ok, I didn’t have to… And what’s with all the Green woodpeckers Picus viridis that are around at the moment? Still, I remain very very busy with day-jobs and conference preparation, but in the interests of – as promised – keeping Tet Zoo ticking over, here is a lovely picture that will have many of you cock-a-hoop with excitement. My god, I’m turning into Mark Witton…

… no, of course not. The picture depicts (left to right) the basal placodont Placodus gigas from Middle Triassic Germany, the cyamodontid cyamodontoid Cyamodus from Middle Triassic Germany, the southern Alps and Poland, and the henodontid cyamodontoid Henodus chelyops from Upper Triassic Germany. Placodus gigas was about 3 m long. Placodonts are just brilliant. They’re basal sauropterygians (within Sauropterygia they’re the sister-taxon to Eosauropterygia: the clade that includes nothosaurs, pistosaurs and plesiosaurs) and – except for one Lower Jurassic tooth described in 1931 – their fossils are restricted entirely to the Triassic. I’ve love to say more, but I can’t. I will later on, I promise.

The picture above is taken from Naish (2004: pdf available).

Ref – -

Naish, D. 2004. Fossils explained 48: placodonts. Geology Today 20, 153-158.

Comments

  1. #1 Mark Witton
    August 3, 2007

    “My god, I’m turning into Mark Witton…”

    Not that there’d be anything wrong with that, being the dashing young devil that he is.

  2. #2 Zach Miller
    August 3, 2007

    Very nice picture, Darren! How long did it take you to draw all the individual plates on Henodus’ shell? That kind of detail work drives me mad (thus, none of my dinosaurs have individual scales or scutes!). Placodonts are fantastic little critters and never get their due time in the spotlight. These are the only three taxa that are ever mentioned, though, in regard to the family. Surely there must be more members? And is Placodus the outgroup to a mostly-armored family, or are the armored placodonts a specialized exception to the rule? I look forward to a more robust post about the strange little buggers!

  3. #3 Norman
    August 4, 2007

    “The other day I had to prize the skeletal jaws from a dead hedgehog. Well, ok, I didn’t have to…”

    I want this to be the first sentence of the next presidential State Of the Union address. I guess it would have to be, “My fellow Americans, the other day I had to prize the skeletal jaws from a dead hedgehog…”

  4. #4 Darren Naish
    August 4, 2007

    Thanks for comments. I too look forward to the day when a US president talks of hedgehogs, or indeed actually knows what a hedgehog is :)

    Zach: I’m sending you the pdf. How long did it take to draw the scutes on Henodus? I don’t know – probably too long, and even then I screwed them up (the carapace is shown as far too asymmetrical, but I gave up caring eventually). There are indeed more taxa than these three, the majority of which belonged to the armoured clade Cyamodontoidea (in total there are around 11 currently recognised placodont genera). Two genera that are successively more distant out-groups to Cyamodontoidea – Placodus (with multiple species) and Paraplacodus (with the type species P. broilii alone) – are the only unarmoured forms (Saurosphargis – similar in some details to Paraplacodus and lost during WWII – may also have been unarmoured).

  5. #5 Mike
    August 4, 2007

    That pic of Cyamodus was quite a surprise. If I’d come across it elsewhere I’d have assumed it was some Japanese cartoon samurai lizard. An effect heightened by showing the three critters appearing to swoop in on Godzilla from above. Excellent post just for the pic.

    BTW, re your asymmetrical Henodus, you spin it as depicting an animal that had been ill or injured early in life, thus accounting for the assymetry, rather than just being the product of an as yet underdeveloped artistic talent. Not all ancient animals were perfect examples of their kind, so there’s a surface plausibility.

  6. #6 DDeden
    August 4, 2007

    Well, my question’s not about woodpeckers, hedgehogs or placodonts, but rather a conundrum regarding bats & biosonar.

    Dolphins evolved a unique method of echolocating at high speed via bone conduction and oil compartments in the lower jaw as in Odontocetes, completely hydrodynamic and internalized and sensible.

    Bats however use the typical terrestrial mammal method of external pinnae (swivel-able I guess) to hear the echoes in front of them AFAIK. How does flying at high speed work with wide open pinnae that are funneling both echoes and wind into their ear? Isn’t that extremely anti-aerodynamic? Have they developed some secret wind-proof sound gathering scoop (vibrissae? skin flap?) that lets the air flow through but sends the sound straight to the eardrum?
    I’m sure there is some very interesting acoustic channelling happening. Care to share a secret or two?

  7. #7 Zach Miller
    August 4, 2007

    Many thanks for the PDF, sir.

  8. #8 Nick Gardner
    August 5, 2007

    I’d appreciate a copy of the PDF as well if possible. Interesting work, Darren. I appreciate your detail. D:

  9. #9 Richard Stretton
    August 6, 2007

    I’d love a copy of the pdf too please, along with any others from your Fossils explained series you have going. Thanks,

    Rich

  10. #10 Anthony Docimo
    August 8, 2007

    hi.
    I would greatly appreciate a PDF as well, if I may recieve one.
    I have a tiny question: did Placodonts make it to England or elsewhere in the UK?

    super artwork, good sir; first-class. (I’d only previously seen pics of the desmostylian-toothed one on the left, and the flattened-turtle-looking one on the right) thank you for the center one.

    [from Darren: thanks for the kind comments. Yes, placochelyid placodont fossils are known from the Rhaetian bonebed of SW England; I'm sending you the fabled pdf]

  11. #11 David Marjanovi?
    August 12, 2007

    They’re basal sauropterygians (within Sauropterygia they’re the sister-taxon to Eosauropterygia: the clade that includes nothosaurs, pistosaurs and plesiosaurs)

    I’ve never understood why Rieppel resurrected this particular usage of Sauropterygia, and why Eosauropterygia is a part of Sauropterygia. In fact, the PhyloCode now recommends against the latter. Why not use Euryapsida and Sauropterygia instead of Sauropterygia and Eosauropterygia?

    However, I’d greatly appreciate the pdf. I had no idea of the Early Jurassic tooth, for example…

    How does flying at high speed work with wide open pinnae that are funneling both echoes and wind into their ear? Isn’t that extremely anti-aerodynamic?

    Yes, it is. I suppose the extra effort is simply worth it. I have no idea, however, if any research has been done on this topic.

  12. #12 Zach Miller
    August 13, 2007

    I’m drawing a Henodus for the next edition of the Boneyard, and I have a question about its shell: is the scute pattern known for sure? And if it is, can anyone direct me to a good picture o fit? And how about that skull? Darren, I love your paper, but the drawing comes out fuzzy when printed out.

    Thanks!

  13. #13 anna
    February 23, 2009

    omg that looks sooooo weird what is it?

  14. #14 David Marjanović
    February 23, 2009

    anna, why on the planet didn’t you read the second paragraph of the post before commenting on it?!?