The jaws of Zigrasimecia

Behold the fearsome maw of the extinct ant Zigrasimecia ferox:

modified from figure 7 (Perrichot 2014)

The image is from an upcoming paper by paleomyrmecologist Vincent Perrichot, and the preferred food of this spike-mouthed creature is unknown. One hopes, for the preys’ sake, that it wasn’t anything with a sensitive nervous system!

Sphecomyrmine ants like Zigrasimecia are puzzling for students of evolution. These extinct insects aren’t just a straightforward blend of ancestral wasp traits and derived ant traits. While these animals do possess a measure of each, they’ve also grown a uniquely sphecomyrmine suite of characteristics. Like, for example, highly specialized nightmare spiky death mouthparts.

These ants were surviving in the times of the dinosaurs doing something that no modern insects do- though exactly what that was is unclear- and given their strange appearance it is unlikely they were directly ancestral to today’s species. Instead, Zigrasimecia and relatives are probably an early offshoot on the ant tree, a manifestation of a predatory niche that worked until it didn’t. Here’s hoping against steep odds that someone uncovers an amber specimen holding the unfortunate mystery prey.

source:  Perrichot, V. 2014. A new species of the Cretaceous ant Zigrasimecia based on the worker caste reveals placement of the genus in the Sphecomyrminae (Hymenoptera: Formicidae). Myrmecological News pre-print, accessed via ResearchGate 1/5/2014.

15 thoughts on “The jaws of Zigrasimecia”

  1. That’s . . bizarre. What did they use those for?

    They seem to fragile to be used on other arthrapods and overkill for soft bodied prey.

    The first thought that sprung to mind was ‘filter feeding’ which is kind of wacky for an ant.

    Maybe they were a utility thing? Like the ‘beards’ some ants help them carry sand?

      1. That’s a very good comparison. There’s a scale at which micro-serrations become less viable for grabbing flesh, even slippery stuff, and tiny ants like this are close to it. The jaws effectively form “rasps,” rather than flensing or peircing jaws.

        1. Yeah, the teeth in those combs are what . . . a smidge over a micrometer apart or something? It seems like they’d be a bit on the fragile side, wouldn’t they?

          Of course, the bonus frustration is that for all we know there’s nothing around like what they ate too. Almost all the similar feeding structures I’m aware of are aquatic. For all we know they had a symbiotic relationship with a spider that let them live off a moss that tended to grow annoyingly quickly on their setae in exchange for letting them crowd out other antish critters that might go after its’ eggs. Nature never does anything in a vacuum.

          Actually that sounds kind of cool.

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  3. Alfred Buschinger

    “Sphecomyrmicine ants like Zigrasimecia” – Shouldn’t this read “Spcomyrmine”? According to AntWiki the subfamily name is Sphecomyrminae. Otherwise: Fascinating!

    1. Vincent Perrichot

      As suggested by James Trager below, the species is known only by three complete specimens so far and these are too precious to be cut / fragmented. The only way would be a virtual dissection by tomography but again, James’ comment is highly relevant given that they cannot eat solids. The holotype was actually scanned using X-ray synchrotron microtomography because I was very curious to get more details on the mouthparts, but unfortunately the scan failed with that particular specimen, and I did not want to wait further for the description. I’ll have to try again ultimately…

  4. Pretty sure no one will be sacrificing any of the few and precious 100-million year old amber specimens for a gut dissection. In any case, if they’re like modern ants, they cannot eat solids, so the likelihood of identifiable materials being in the gut would be very slim.
    But I must say, I am somehow reminded of Venus fly trap leaves. One wonders if these ants might have waited for something to wander in, then clamp the prison door shut on the prey?

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