So I hiked up to the famous quarry itself on Saturday, on a day with remarkably clear blue skies and cool mountain air. It’s relatively strenuous – about 3 or 4 hours uphill, with a few steep sections, and then an unremitting 3 hours of knee-pounding downhill switchbacks. If you fancy seeing the quarry for yourself, you’ll need to sign up for a guided tour. The quarry is a national herritage site, so you can’t wander in there alone, nor can you take any fossils away with you. This was, of course, a source of great despair to the paleontologists on our hike, who found fossils (some relatively rare) and were forced to simply put them back on the ground and walk away. (If truly interesting pieces are found, they are put in a locked cupboard in the quarry for study and/or to show tourists like us some good specimens from the site.) There aren’t exactly fossils on every bit of loose shale, but there are a reasonable few scattered around. Enough that, for example, I ate my lunch whilst sitting on a trilobite. We spent our time in the quarry marvelling at the view (we didn’t know which way to look – out towards Emerald lake and Walcott peak, or in towards the quarry), taking commemorative pictures with Derek Briggs (who famously helped to recognise the strange character of many Burgess shale fossils) and with a toy model of opabinia, which one of the researchers had brought up with him specifically for the photo-op. Marianne Collins was also on our tour — the artist who drew many of the recreations of these creatures, including the five-eyed, long-snouted opabinia. A glorious end to a fantastic meeting.

Image: Your intrepid blogger with Derek Briggs

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One presentation that stirred things up a bit suggested that Anomalocaris wasn’t the fierce predator it is usually portrayed as (see my news story here). This animal is almost always shown munching on a hard-shelled trilobite, but it seems that maybe it was incapable of such attacks. Opinion is still divided, but even Simon Conway Morris threw up a picture of a classic reproduction of Cambrian life during his talk, featuring an Anomalocaris gripping onto a trilobite, and quipped “so here we see an Anomalocaris putting a trilobite gently to bed…”. This was met with many chuckles – not, I think, because the idea of a gentler Anomalocaris is laughable, but simply because people don’t know quite how to respond to classic ideas about Cambrian life being overturned. If the ‘gentler’ image holds up, they’ll have to redraw all the Cambrian life pictures.

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I’m writing this after a few drinks (which, as you’ll soon see, is perfectly appropriate) and after being inspired by Simon Conway Morris’s talk on the origin of body plans. I wish I could do Conway Morris’s talk justice in this blog – he is an eloquent, and funny, speaker. Suffice it to say that he recounted some of his arguments against Gould (read about that here); fought back, good-naturedly, at several other speakers at this conference who have called him wrong about some particular matters of creature identification; threatened to drink a bottle of commemorative ‘Shale Ale’ whilst at the podium in spite of Canada’s draconian laws against drinking in public; and responded to one confession of love. Of course, he also addressed some serious points of biology, concluding that perhaps, “at long last, biology is going to become predictable”. There’s one prediction I would bet money against.

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Martin Brasier of Oxford University jokingly referred to the ‘MOFAOTYOF Principle’ in his talk – the ‘My Oldest Fossils Are Older Than Your Oldest Fossils’ phenomenon. He makes fun of it (such competitions can perhaps get a bit silly), but it is the business that Brasier and his team are in – hunting down those oldest fossils of the old.

Certainly you can’t get older than the Ediacaran when it comes to animal fossils, and this was the subject of Brasier’s talk – the strange squished creatures preserved in the rocks of Mistaken Point, Newfoundland. At the end of his talk, Brasier threw up a slide showing some ‘trace fossils’ – the fossilized tracks that some worm-like or snail-like creature left behind. Such tracks are more common in younger fossil beds, when animals were more likely to be mobile (the most commonly talked about Ediacaran beast looks like a feather stuck in the seabed, and certainly didn’t get around too much). And they’re more common in shallow waters. If such tracks are from the Ediacaran deep waters, as implied, then that would be quite exciting to those in the field. It could even push back the date of complex mobile creatures – things that move intentionally in a single direction, perhaps in search of food, with a sensory system and complex muscles – by tens of millions of years. Maybe. “A lot of people have looked at a lot of rock very hard and not seen anything like this,” I overheard Guy Norbonne, an Ediacarian expert, say over coffee. “I understand it’s under review. Let’s see the paper, and see how it stands up.”

Brasier sees a bit of a shift in how people are looking at the Ediacaran. At first there was an awed acceptance that all these squishy creatures must have been the ancestors of modern animals (so there would be a soft coral, and a squidgy early worm, etc). Then the Ediacaran creatures were seen as a ‘failed experiment’, most of which went extinct. Now there is a more sober period of working out what they all were, and which ones died out and which lived on, Brasier says. This shift is one of the reasons he wrote his recent book Darwin’s Lost World, about the Ediacaran fossils (Darwin lamented that pre-Cambrian fossils had never been found; but they have been found since, and so are not a ‘lost world’ to us).

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I was slightly shocked to see a slide of ‘fossilized brains’ from the Cambrian thrown up on a slide. Brains? From the Cambrian? Turns out I was right to be shocked. “People find it hard to swallow” says Nicholas Strausfield, a neuroanatomist from the University of Arizona. He was trawling through Burgess Shale fossils of Waptia – a small shrimp-like creature from the Cambrian – looking for hints of the evolutionary relationship between insects and crustaceans, when he found 3 samples that seemed to have brain-shapes in them. “I have flattened a lobster brain, and it looks like that,” he says. You can’t tell too much from these fossils, except that the brain was apparently big enough to handle some complex sensory information from the antenae and simple eyes. Still, it’s fascinating. Strausfield (who, as the recipient of a McArthur grant, unofficially counts as a ‘genius’) switched from looking at insects to crustaceans on the principle that you ought to be able to eat what you study. Sadly, he notes, Waptia is so small it wouldn’t even make a good soup.

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The annoying thing about fossils is trying to work out what the heck the creature looked like before it was trapped in a mudslide, lost some limbs, got squashed flat, and was chemically altered by millennia of burial. This is not easy. And as Robert Sansom of the University of Leicester points out, it’s made extra difficult by the fact that some discriminating features used to identify these creatures decay faster than others. That introduces a bias in how organisms are classified, he warns. His group is doing lab tests of decay rates of different bits and pieces of animals to sort these biases out.

The lucky thing is that Burgess Shale fossils and others from the same time period around the world are strangely well-preserved. I had assumed that this was just a lucky accident of some Cambrian beasts being swallowed by a mudslide, and Walcott finding the result. But it seems to be more complicated than that. The preservation of organic carbon from these beasties is a highly unusual phenomenon, and is very rare (possibly absent?) in the fossil record for animals of younger eras. Why is this? No one knows for sure. But it might have been a combination of those animals being swamped with fine-grained clay that kept the oxygen out, and the oceans being low in sulphate, which stopped other bacteria from eating up the remains. An intriguing thought, with evidence to support it from Emma Hammarlund of the University of Southern Denmark.

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Some of the weirder Ediacaran species might not be species after all, Alexander Liu of Oxford University has told the conference. There’s a brand of squidgy Ediacaran fossils known collectively as ‘pizza discs’. They are all round, and have bumpy bits – of up to 1-cm height in the fossil record – randomly scattered in the middle. These bumps are not consistent from one pizza disc to the next – each disc is individual. This makes it hard to identify the characteristics that define the creature that left the fossil print. So hard, in fact, that Liu wonders if it’s not a specific creature after all. Some tell-tale hints in some pizza discs hint that maybe they are the slightly-decayed remnants of other, already-known species, he told the conference. Liu, who works in Martin Brasier’s group, has even rotted some modern jellyfish and seaweed bits in the lab and made modern fossils of them, to confirm that this does indeed create irregular, lumpy shapes (no huge surprise there). His conclusion – that blobby bits that don’t look like much might, in fact, be blobby bits that aren’t anything much special – is so intuitively obvious that I can’t help but think he’s right. Depending on who you talk to, though, downgrading the Pizza disc from a creature to a bit of garbage might be slightly controversial.

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Yet more history from Desmond Collins, who talked today about the work that has gone on in the Burgess Shale since the 1970s or so. Collins himself was in charge of many further explorations of the shale, and even has a quarry named after him (as does the original discoverer Charles Doolittle Walcott, and a handful of others, but only a handful). Collins is clearly on a first name basis with both all the people who have explored the shale, and also all the creatures who have turned up in the rocks. He showed a fabulous slideshow of weird and wonderful creatures preserved in the shale, most of which you can see in the Royal Ontario Museum’s online photo collection. Surprisingly (to me), many of the creatures revealed have still not been properly described – including the one called the ‘Collins monster’.

Collins’ stories are full of freak snow storms during trips up to the shale, accidental finds of great fossils, and lovely little details that make the stories come alive: from the rat (which he also knows the name of… Robert I think it was) who licked their dishes clean for them when they were short on water, to the goats who licked the salt left on the rocks by the camp’s mandated bathroom site (the goats would unfortunately kick bits of shale onto the camp in the process, until the researchers got permission from the park authorities to move the camp and pee wherever they liked). In 1995, while shoveling out vast amounts of fallen shale from the original quarry site, they found a block of ice encasing newspapers left behind on Walcott’s expeditions.

Photos show how the Burgess Shale sites have changed and expanded over time – the original Walcott quarry is now some 3 times bigger than it originally was, thanks to researchers attacking the rocks with crow-bars, jack hammers and circular saws (they weren’t allowed to use dynamite, as Walcott did, much to Collins’ dismay). About half of Walcott’s original quarry ledge has been preserved for historical reasons. The rest has been hacked away to reveal yet more finds. Looking at the panoramic shots of the mountains, one can’t help but think there must be many, many more possible quarry sites – it’s fantastic to imagine what weird wonders remain to be found.

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Quote of the day goes to Kevin Peterson of Dartmouth College, who began his talk with a dedication to Wonderful Life, the book that popularized Cambrian creatures. “If it weren’t for Wonderful Life we all wouldn’t be here. Or at least I wouldn’t be,” he said. “I brought this book to a bar in Montanna and read it in one sitting, over 12 beers. I developed my first man crush – I was in love with Simon Conway Morris.” (He means this as a joke, of course… no actual romance here). Conway Morris was one of the researchers who reinterpreted the Burgess Shale fossils in the 1960s, unveiling their truly bizarre characteristics, and is giving a talk here tomorrow… perhaps someone should warn him of Peterson’s unrequited feelings.

Meanwhile Peterson has gone on to work on annelids – which he confesses are really just ‘boring segmented worms’. There has been a problem in the worm world that genetic evidence gave a different sort of family tree than did morphology… in fact genetics seemed to put molluscs and other distinctly non-wormy creatures nested in within marine worms, which was surely not right. Indeed it would have meant there were a bunch of worms missing from the Cambrian fossil record. Peterson’s group has been using micro-RNA evidence to sort it out, showing that the earlier genetic evidence was simply wrong in this part of the family tree (though he still doesn’t know why). Worm dilemma sorted. Micro-RNA analysis, it seems, has a great potential for sorting out such family tree mysteries, though of course you need modern, living species to analyze – it doesn’t exactly help to identify Ediacarian creatures.

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If you can’t tell the difference between an embryo and a giant bacterium, then things have got to be pretty bad. But Frank Corsetti of the University of Southern California, Los Angeles, gave the audience a persuasive argument today that at least some spherical bodies found in the fossil record, thought to be eggs or embryos, are indeed probably giant sulphur bacteria instead. Certainly I can’t tell the difference from the pictures, and nor, apparently, can the experts.

These particular fossils are not from the Burgess Shale, nor even from the Cambrian, but from the Neoproterozoic Doushantuo Formation in China, which holds fossils from some 600 million years ago. Not only do some spherical blobs in this record look a lot like a modern sulphur bacterium called Thiomargarita, but this little bug is also known to spit out phosphate, which is required for the particular kind of fossilization found in this formation. Coincidence? Corsetti thinks not.

This kind of confusion about what the heck a fossil represents – plant or animal, whole animal or part of one, egg or bacterium – is rampant throughout paleontology. Peoples’ notions of what they expect to find can deeply influence their description of morphology and identification of fossils, notes famous Yale paleontologist Derek Briggs over lunch. I comment that what you need is a kind of blind experiment, whereby naïve graduate students who know nothing about the subject are asked to describe the morphology of some new fossil. “That is, actually, what happens,” is the witty rejoinder (not, it has to be said, with noble intentions, but by happy accident as a result of students not doing their homework). Seriously, Briggs notes, it would be interesting to see what would happen if scientists could approach fossils without any baggage. That’s a difficult experiment to conduct. Instead of facing such challenges, we go for dessert.

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