Pharyngula

Nigersaurus, a Cretaceous hedge-trimmer

Blogging on Peer-Reviewed Research

Last August, when I was at the Sci Foo camp, Paul Sereno brought along the skull of one of his latest discoveries…and whoa, is it ever a weird one. This is Nigersaurus taqueti, an herbivorous dinosaur with specializations for ground-level grazing. Look at this picture; in reality, it’s even more striking.

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Those jaws and teeth—they are so neatly squared off and flat-edged. In addition, the skull itself on the spinal column is turned habitually downward. This is a creature that kept its face pressed to the ground as it nibbled its way across the landscape.

Another feature that was apparent is that the skull is awesomely light — it’s mostly empty spaces with a delicate webwork of bony struts holding it together. It’s so specialized it’s almost comical, and you can imagine something like this appearing on the Flintstones as a lawn mower or hedge trimmer.

Bora has more, and you can read the original on PLoS.


Sereno PC, Wilson JA, Witmer LM, Whitlock JA, Maga A, et al. (2007) Structural Extremes in a Cretaceous Dinosaur. PLoS ONE 2(11): e1230. doi:10.1371/journal.pone.0001230

Comments

  1. #1 David Marjanovi?, OM
    November 15, 2007

    This is what was predicted for a low, or ground grazer to look like by many people.

    It’s way, way beyond all descriptions. The lower temporal fenestra is in front of the eye. The upper temporal fenestra is gone. All teeth, without one exception, are part of the precisely straight toothrows that are broader than the rest of the skull. The snout points almost vertically downward. The vertebrae are hollow — not foamy, but hollow. It boggles the mind!

    Evidence of massive callouses on the feet of prehistoric men from their use as car brakes?

    Not going to fossilize, but we can expect specializations in the ankles and knees, at least…

    Wow, that is strange. Is there anything alive today with a jaw like it?

    Nope — neither alive nor dead.

    I hope to hear more about how this thing likely fit in.

    Fig. 4 of the paper is a tree.

    They think it ate mosses and ferns.

    The paper says ferns and horsetails and doesn’t mention mosses… that said, horsetails are actually ferns… :-)

    Is this common in biology?

    No.

    Is it a requirement of the journal?

    Yes, and it’s a good idea.

    may I ask why the reference cited dismisses the possible use of gastroliths in sauropods?

    People used to assume that all rounded pebbles found near a sauropod were gastroliths. That isn’t the case. Even when found inside a skeleton, they are often far too soft for such use, the number and position is never right, and so on. It just doesn’t fit together. Incidentally, crocodiles have gastroliths but don’t use them for chewing; I saw an X-ray movie about this at a congress in May.

  2. #2 David Marjanovi?, OM
    November 15, 2007

    It’s way, way beyond all descriptions.

    ARGH! I mean predictions.

  3. #3 David Marjanovi?, OM
    November 15, 2007

    I’m imagining big brown horse eyes with eyelashes (nocturnal animal).

    You can’t get eyelashes on an animal that has neither hair nor feathers, so eyelashes are unlikely…

    per say

    Ouch! The whole thing is Latin: per se “by itself”.

    Do you know how funny that sentence looks to a herpetologist (or pretty much any neontologist, for that matter)?

    You missed the sentence in the paper that says its neck is so short: only 13 vertebrae, only 130 % the length of the back!

    “A” before a word that starts with consonants like “h” and “an” before words that start with vowels like “e”.

    Americans don’t pronounce the h in herb and therefore, apparently, not the one in herbivorous either. Must be because it’s (of course) silent in French herbe “grass”.

  4. #4 David Marjanovi?, OM
    November 15, 2007

    By aspiration he means pronounciation of the dominating letter, in this case the “h”.

    Nope. Aspiration is a slightly misused technical term for saying [h].

  5. #5 David Marjanovi?, OM
    November 15, 2007

    1 a: audible breath that accompanies or comprises a speech sound

    Yep. That’s the non-misused version. Aspiration of [p] produces an English p (as opposed to a French one). Aspiration of nothing produces [h]. The English p contains a [h] sound, sort of. And that’s my point.

    why the depictions of nigersaurus in the flesh show them having spiky things down their toplines?

    Because they were found in a particularly well-preserved fragment of a relative of Diplodocus. Nigersaurus is fairly closely related, so there’s a reasonable chance it had those spikes, too. (They don’t contain bones.)

    If this critter was grazing early grasses

    Highly unlikely, because it’s much older.

    Permanent teeth are a mammilian adaptation, aren’t they?

    Yep, and as the paper says, Nigersaurus had sped up the rate of tooth replacement to once per month.

    scientists are HOT!

    He’s already married, to one of his coauthors (Gabrielle Lyon).

  6. #6 David Marjanovi?, OM
    November 15, 2007

    I got stuck on the body of… er… ick… Dubya… (shudder).

    Ouch. My heartfelt condolences.

  7. #7 David Marjanovi?, OM
    November 16, 2007

    Modern mammals that browse or graze, and that must sort through or move inedible debris (horses and giraffes, for example), have very mobile and sensitive upper lips. From the reconstruction, it doesn’t look as if this is the case for Nigersaurus; what’s the current thinking (if any) on facial muscle structure and function in sauropods?

    Don’t take the ruminants too seriously. They lack upper incisors; they gather plants with their lips and then rip them off with their lower incisors and a horny ridge in the place where the upper incisors would be. Not so in Nigersaurus, which seems to have done the gathering and the cutting at once, as usual. Like a lawnmower.

    In the UK and elsewhere, the rule is a bit complicated to spell out. It’s “a” before a single-syllable word with a sounded “h” or a word of more than one syllable with a sounded “h” and a stress on the first syllable.

    But in “hippopotamus” the stress is on the third syllable…

    IMHO the use of “an” in front of pronounced h is just a failed effort to make English look even more like French than it already is. Or does anyone natively speak according to this rule?

  8. #8 David Marjanovi?, OM
    November 17, 2007

    Also, I’d guess that the lack of facial muscles to move the upper lip would limit the flehmen response, observed in many mammals, which is used to facilitate transfer of pheromones to the vomeronasal organ.

    Sure. But then, birds lack the vomeronasal organ… I’m not sure if it leaves traces on the skull bones…

    Watch a horse graze some time…it pushes leaves, sticks, and other debris away with the upper lip, and shears off grass blades between upper and lower incisors.

    Dinosaurs generally seem to have done without that. (Especially the beaked ones, of course.)

    ————-

    So secondary stress counts, too… I see.