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Right, let's get back to talking fossils. Finally, something I know something about (not that that's stopped me before) - I work on these Vendian fossils, and have had the privilege of doing fieldwork on the Winter Coast of the White Sea, Russia, where a lot of 'em may be found. I'll throw this out: I need a new, radical phylogenetic affinity for the Vendian fossils like I need a hole in my ethmosphenoid. So far, this biota has been put into living phyla of the Animalia; an extinct phylum that is the sister taxon to the Animalia; an extinct kingdom of Odin-knows- what affinities; macroscopic algae; giant protists similar to forams or xenophyophorids; and now lichens/fungi. If someone out there could write a paper "showing" that these fossils were in fact giant bacteria, we'd have all five of Margulis's kingdoms represented plus a new one; it actually wouldn't be too hard to write a believable paper like that. This doesn't really help those of us who want to do something with these fossils - to use them to understand a pivotal point in the history of the Earth's biota. It's bloody difficult to actually get anywhere with these fossils if any possible paleobiological hypothesis involving them can be met with, "But So-and-So made a convincing argument that your fossils aren't what you say they are, they're giant killer beets from the Planet Weebo." It's not so much that diversity of hypotheses is an evil thing - I'll say one thing for it, it keeps me from getting overly complacent about any of my own ideas - but everyone seems to want to create One Big Taxonomic Affinity that encompasses every Vendian macrofossil. Retallack has pointed out that some Vendian fossils with preserved tissue structure may be interpreted as lichens; e.g. Petalostroma, Paramecia, maybe some of the "carbon films," maybe Ernietta. This could well be true; it's certainly worth further study - but then, based on some very specious taphonomic data, he concludes that practically every Vendian body fossil is some kind of lichen. This is like saying that every Carboniferous fossil is a strophomenid. Zhuravlev did the same thing, interpreting almost every macrofossil as a big protist; Seilacher did the same thing with his "vendobiontan" model. But there's no reason why any one hypothesis should cover every damn fossil of a certain age; it's not that way in the Phanerozic; what is it about these Vendian things? This post is getting long, so I'll save my specific gripes at Retallack's procedure for later, if anyone's interested - suffice it to say that his study is not isotaphonomic. I'll just add one thing more: There's a rather annoying tendency in the field of Vendian paleo to take functional hypotheses for proof of systematic affinity. In other words, the hypotheses that these organisms lacked a mouth, lacked tentacles, had a tough integument, fed by photosymbiosis or osmotrophy, etc. etc. are taken to mean that they couldn't have been cnidarians, which, as we all know, are tentaculate squishy predators. Even if such hypotheses are true, they don't indicate much from a phylogenetic point of view. A fair number of cnidarians have a reduced digestive system, reduced or no tentacles, tough organic structures, osmotrophic feeding, and/or photosymbionts, yet cnidarians they remain. Ditto for other metazoans. Ditto for protists. I conclude that we have too many plausible models and not enough testable hypotheses for the paleobiology and systematics of the Vendian macrofossils (oops, that's the "Ediacara fauna" for any Australians reading this). I'm trying to work out ways to rectify the situation; comments appreciated. I can send literature citations, more data, more arm-waving, etc. to anyone who's interested. Do svidaniya, i vsego khoroshego, Ben Waggoner Rogue Graduate Student Museum of Paleontology University of California -------------------------------- "Ecrasez l'infame!" -- Voltaire --------------------------------
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