Field of Science

Seriously, What Is This Thing?

So there weren't too many people speculating about the identity of that mysterious figure (hi, Adam!) As it happens, there was a reason I'd put it out there: the reason being, I really don't have any idea what it is either.

Spinita spp., from Kordè in Koren' (2003). 1: S. sanashticgolica, 2: S. cryptosa, 3: S. spinoglobosa.

The figure comes from a Russian book, Атлас ископаемой фауны и флоры палеозоя Республики Бурятия ('Atlas of the Palaeozoic fossil fauna and flora of the Republic of Buryatia'), edited by T. N. Koren' and published in 2003 in Ulan-Udè. Buryatia is a Russian republic in south-eastern Siberia, wrapping around the eastern and southern coasts of Lake Baikal. The fossils shown above come from the Lower Cambrian (the Botomian stage in the Russian system) of the Eastern Sayan Mountains. Going by the appearance of the figures, I presume they're being examined as thin sections, a commonly used method for studying Palaeozoic microfossils. Though as microfossils go, these are definitely on the large side: the specimen figured as 1a is a centimetre long and three millimetres wide. The other specimens are smaller, about half a centimetre in length.

When I saw these figures, I was just mystified. Their describer, K. B. Kordè, regarded them as a new class of 'Nemathelminthes', claiming that 'the first impression that is created from the described material is that they are representatives of the Kinorhyncha or Gastrotricha'. I'm not sure that I would agree with that. I found myself wondering if they were even animals, though I was hard pressed to think what else they might be. Not being familiar with the interpretation of thin sections, the thought did cross my mind to ask how certain can we be that these are even fossils, but I think that may be a bit uncharitable. Kordè also suggested that a break in the apparent cuticle of the S. sanashticgolica specimen about halfway along the flattened side (interpreted as the venter) might be the mouth. If so, that would be very unlike any kinorhynch or gastrotrich I've heard of. Could be a flatworm, I suppose, though Kordè then goes on to read the cluster of spines at one end (as magnified in figure 2b) as marking the anus which would seem to put paid to that! Said spines, or papillae, or whatever, are also supposed to have medial channels that Kordè interprets as nephridia.

All in all, I can't express anything other than confusion about this one. Certainly I haven't been able to find any further commentary on these enigmas; a Google search for Spinita sanashticgolica brings up just one result, an offhand mention in this book which seems to be just referring to it as found in the same formation as another fossil. Confusingly enough, that mention seems to date from 1986, a good seventeen years before Koren' (2003) was even printed: whether that indicates that the latter publication was not actually the first time the description of Spinita saw print, or whether this genus saw time floating around in unpublished communications, I have no idea.

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