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Post by Froggie on Aug 18, 2005 20:23:00 GMT -5
Joe, Lucy (Hi Lucy!  Joe already met me on another thread) ... Not really a Welsh thing, but as it was on the news recently it might be of interest to the lurkers on this forum to hear your views on the beast. A link to the BBC for reference and a picture: news.bbc.co.uk/2/hi/science/nature/4156544.stm |
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Post by hallucygenia on Aug 19, 2005 14:34:52 GMT -5
Hello Froggie!
It is indeed a strange beastie, and I've no idea what it is! Unfortunately it isn't in the book of Chinese fossils I have, and the picture doesn't really show very much - I'll have to wait till I can get to the library next week. I do agree with Jon Todd that it's a bit pointless erecting a new phylum for it. It's very easy to identify phyla now, after 500 million years of divergence. Back then, when everything was diverging from everything else, the concept of phylum is a bit meaningless. There are probably a lot of Cambrian fossils that are ancestors of more than one phylum - I wouldn't like to say which phylum they should be put in. Perhaps the answer is just to admit that, for some things, trying to put them into a phylum isn't particularly useful. Personally, I'd be more interested in knowing what all its bits were - what are those things that look like segments in the photo, for example? Are they muscles? Bits of the gut? Markings on the surface of the animal? I'm sure all that will be in the paper, once I get a chance to read it. It would just be nice if the BBC gave some details...
To go off on a completely unrelated rant, science reporters often pick up on the least interesting bits of a story. For example, I read something the other day along the lines of "scientists now think that there was a huge volcanic eruption which might have killed the dinosaurs" - talking about the Deccan traps. That isn't news! There probably was something new in the research that was being (mis)reported, but I have no idea what it was. This isn't an isolated example. I'm sure some newspapers have better science reporting, but I tend to pick up a free newspaper at the station every morning, and as I'm not paying for it I'm not going to complain too much. It would be interesting to know how many journalists that report science actually have science qualifications - I suspect not many.
Alright, rant over. I feel much better now.
Lucy
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Post by Froggie on Aug 20, 2005 8:23:02 GMT -5
Heh, I quite agree with your rant, I get that in my field too. Most often they will ignore the fact that there has been an incremental improvement in our knowledge and present something which has merely been expanded on as some big new discovery. Which often leaves me wondering "What? Where's the news in that?" until I find the small print or track down the original ...
Your point about phyla is very reasonable. Any ideas you'd share about how better to represent the relationshiops between these early forms? After all, thats what phyla and so on were designed to do for modern animals.
Anyway, perhaps once you've seen the original paper you could summarise a few of the more interesting points here for those of us who don't have access to that journal? (Shameless self-interest here!)
(gosh, I feel like I'm a TV chat show host; definately that kind of style here)
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Post by Joe Botting on Aug 23, 2005 3:21:04 GMT -5
Hiya Froggie & Lucy,
I'm back, and I've just been reading the paper. It's... well, it's unusual. The paper spends most of the time arguing that it's a mollusc, with a muscular foot and that the lateral bars are gills. It then uses the dubious nature of the interpretations ("giving only weak support") to prove that "a molluscan affinity for this animal, therefore, is porly grounded." They use this to infer that it's an independent group of animals, close to the molluscs.
I have serious problems with their interpretation of various structures. The transverse bars, for example, are regarded as gills, but it isn't clear why. They're in approximately the right place, but in most cases they're straight and undeformed, so if they're gills then they must be supported by struts. They are also very organic-rich (more so, in fact, than the muscular foot, it seems!), which again is a tad unusual. I'm not sure what they are, but to say that they're gills seems rather leaping to conclusions (anomalocarids, those wonderful Cambrian and perhaps Ordovician predators, also have enigmatic transverse bars in some specimens). Even if they are, that is more suggestive of arthropods than molluscs, since the latter usually have discrete gill structures rather than a serial array running the length of the body!
The 'tentacles' are equally worrying in that their structure is entirely unclear in the photographs. They could just as easily be appendages, and if they are tentacles, they were remarkably rigid ones, always showing the same shape.
The authors make it quite clear that the distinct head wth stalked eyes rules out a primitive mollusc interpretation, although these features did appear in later molluscs (like a slug's head, for example). They also note the absence of a radula, the scraping tool that defines almost all the group.
As for the muscular foot... well, it could be, but on the other hand, it could be not. The structure is a featureless oval covering much of the underside (they probably can be confident of that!). It could equally well be interpreted as a protective ventral cuticle. It's just too uncertain to base the entire paper on, which is effectively what they've done.
Personally, I think the authors make the mistake of interpreting features in one way that implies a mollusc relationship, and not reassessing them when the results don't quite make sense. Their arguments against an arthropod affinity are very weak, and they don't mention anomalocarids at all, despite covering comparisons with much remoter fossils. To be honest, it looks like someone decided what they wanted it to be, and then squeezed it in any way they could.
And as for the media celebrating the discovery of a 'new phylum...' one can only groan vociferously. It's an interesting beastie, to be sure, though!
Joe
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Post by hallucygenia on Aug 23, 2005 17:15:24 GMT -5
Joe's summarised the paper, and I haven't got much to add to what he said. The animal's name is Vetustovermis planus, not Vetustodermis - someone at the BBC can't type!
What is interesting is that the species comes from both Chengjiang, China and Emu Bay, Australia, so whatever it was, it was fairly widespread. The authors of the paper also point out similarities of Vetustovermis to various Burgess Shale beasties - Amiskwia, Odontogriphus and Nectocaris. So working out what this thing is might help to ascertain what the other beasties are too.
Froggie - I think the best way of talking about early Cambrian things is to discuss their relationships with modern phyla, without necessarily trying to force them into one.
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Joe already met me on another thread) ...
