Ambaric Stasis

Aceria anthocoptes, a random gall miteIn what will have to be the final Daily Science Update before hiatus, Brian Thomas writes Why Do Creatures in Ancient Amber Look So Modern? He’s talking about the recent discovery of the oldest arthropods to be found preserved in amber.

Gall mites are too small to see without aid, but scientists found two of them after scanning 70,000 amber droplets from Triassic beds in Italy. How much have mites evolved in the supposed 230 million years since they were entombed in amber?

Today’s 3,500 species of gall mites live on very specific plant species, and most of them subsist on angiosperms. The majority live on the outer surfaces of their host plant, but some induce plant tissue to form swollen galls in which they live and after which they are named.

The fossil gall mites – four legged arachnids that parasitise plants – we found to have all the defining features of the modern family. This was somewhat surprising, as (as Thomas said) they usually inhabit angiosperms, i.e. flowering plants, though some do prefer conifers. Angiosperms are a class of plant that did not exist 230 million years ago, and as gall mites are highly specialised you wouldn’t have expected them to predate flowers. But given that they did exist 230 mya, there is no problem with them having existed ever since then as morphologically recognisable gall mites. It is, after all, a fairly broad (family-level, though that’s a subjective classification) category of organism, with wikipedia claiming that the 3,600 species currently known probably make up less than 10% of what is actually out there.

Thomas’ thesis for this article is:

After 230 million supposed years, gall mites are still gall mites, and most amber-encased amoebae are exactly identical to live species. If evolution was “on hold” for that long, maybe it has been “on hold” since the very beginning.

(The amoeba thing is pretty funny. Thomas has a quote: “Most of amber amoebae are morphologically indistinguishable from extant species.” Aside from the obvious ‘how do you tell the difference between amoebae?’, the new fossils being reported in that paper “can be distinguished clearly from modern species.”)

3,600+ species of gall mite seems a bit large for a ‘kind,’ although should you ignore the requirement to take them on the Ark with everything else that problem isn’t so bad. Of course, then you have to factor in how they all survived until the plants had regrown, but that’s just details. Is Thomas really claiming that they’re all part of the same interbreeding baramin? He probably has to, there’s not that much else he can do.

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2 thoughts on “Ambaric Stasis

  1. ‘Stasis’ of amber or of mites – I wasn’t sure which it was but it sounded mainly like the latter.

    This is the ‘missing footnote 2 link’: http://www.pnas.org/content/early/2012/08/21/1208464109.abstract

    Clearly the mites in the Carnian aged amber would have fed on conifers and not angiosperms (unlike the habit of many such mites today).

    I wasn’t clear from the links whether the Carnian-aged amber comes from the same species of conifer that the mite fed on (and whether the tree species in question is extant or extinct). But Thomas states: “Although varieties of the same plant live today, this particular fossil variety is probably extinct. So, perhaps these fossil mite varieties went extinct along with the extinction of their host plant variety. And extinctions do not show evolution.”

    Thomas thinks evolution must be ‘on hold’ – though not of course for 230 million years.

    I also stumbled across this: https://thebibleistheotherside.wordpress.com/2012/09/04/fossils-of-arthropods-discovered/
    ‘Michael’ thinks evolution has been falsified…

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