Fieldwork update

After a month, fieldwork is nearly over. After the two weeks in Hell's Mouth, we went fossilologising near Bala for another week. This trip has definitely been a success, although of course we have to keep quiet about our finds until they're published, so we can't tell you about the preserved intestine of a hyolith, or the nicely segmented worms, or the beautifully preserved sponges.
I can tell you that I injured my thumb on a sharp rock while hammering (nothing bad, but it did bleed alarmingly). Everyone else, while being sympathetic, then kept referring to fossils sticking out like a sore thumb, asking about rules of thumb for distinguishing sponges from random blobs, and whistling the Thumbelina song.

Tomorrow is for sorting the rocks out, putting some of them in the post to China, and sending the rest to various collaborators. After that one more day of fieldwork, and then a short holiday. We're going to Cornwall, which is mostly granite, so we won't get distracted by finding more fossils. After that, we're visiting the NHM to look at various fossils, and possibly visit some other museums/libraries as well if time allows.

In case anyone has been trying to email me: I haven't been able to access my email for a month, and I'm hoping it's just a peculiarity of the internet in this hotel, and my account isn't permanently broken. Anyway, if you've been trying to contact me, I'm not ignoring you.

Lucy

The gap in posts is because we've been in a remote part of North Wales, and haven't had internet access. This is where we were: Hell's Mouth Bay on the Llyn Peninsula. You can see that the exposure is quite good. The rock are the sandstones and mudstones of the Hell's Mouth Bay Formation, with the sandstones tending to stand out. The formation is of Early Cambrian age, so a bit older than the rocks that we normally look at. We went here because of a report from the 1950s of abundant sponge spicules throughout the beds. Our thinking was that abundant sponge spicules = complete sponges somewhere in the sequence, and this did prove to be the case, although it took a lot of work to find them.

We stayed in  a nice little holiday cottage a few hundred metres from the rocks. Thoroughly enjoyed eating British food again - the refrain of the two weeks was "I haven't eaten X in six months!" where X could be, for example, proper chips, hummous, oat cakes, vegetarian sausages...

Anomalocaridids ahoy!

Fossils, a photo by hallucygenia on Flickr.

It seems that the Famous Fezouata Biota of Morocco is turning up the goods again. Hot on the heels of last year's announcement of just how good these rocks in southern Morocco are turning out to be (http://news.bbc.co.uk/2/hi/science/nature/8678459.stm), here's another paper in Nature by Peter Van Roy and Derek Briggs:
http://www.nature.com/news/2011/110525/full/news.2011.318.html

We should say that we're not overly surprised. In fact, this is what we've been telling you all we can't tell you about, ever since we came back from the last fieldtrip. Now, however, the work is done, the cat is out the bag, and we're free to put up silly photos. The cat in question is among the largest arthropods ever found: a monstrous, primitive creature with grasping appendages and a pineapple-ring mouth... yes, it's everyone's favourite: an anomalocaridid!*

What you see before you is an array of pieces of anomalocaridid in the hotel restaurant in Zagora. It turns out there are probably pieces of 6 specimens in this unceremonious pile, and you can see in the biggest ones the wide segments going across the body. You might also notice that they're all bits... there's not a single complete one amongst them (I know they're a metre long, but even so... shouldn't we have made the effort?).

All these specimens were found in a small area, in drainage channels down the side of a hill. How long they had been weathering there is anyone's guess... but a good while. The anomalocaridids were preserved whole inside huge nodules (silica-iron-manganese, apparently), and as the hillside weathered in, they broke off, piece by piece. So, finding them took some trawling up and down the channels, and sticking them together was perhaps the best jigsaw I've ever had the pleasure to have a go at. It's a shame someone lost half the pieces. Still, you take what you can get in this line of work.

So why is this find important? Well, it's big and scary (bigger and scarier than any known before, in fact), and it's also the youngest example. These monster predators (probably the only larger animals in the Cambrian seas were sponges) were thought to have gone extinct in the Cambrian. The Fezouata Biota is showing that these survived into the Ordovician along with everything else, and indeed were positively thriving. The number of specimens in a small site is startling, the size is disconcerting... just think what it would have been like swimming amongst them and trying to avoid being eaten...

*If the word "dinosaur" appeared in your mind at this point, however briefly, go home and meditate on your iniquity until suitably chastened. Yes, you, Neil.

Another swallowtail

Papilio polytes, a photo by joe with a camera on Flickr.

This is a swallowtail butterfly feeding on a pomegranate tree, photo taken by Joe at Xuanwu Lake, near the institute. We went to have lunch by the lake a few days ago, saw this flying around and, after some chasing, got this photo. The butterfly's wingspan is roughly 10 centimetres, to give you an idea of size. The photo hasn’t been manipulated apart from being cropped; the background looks odd because the photo was taken against the sky using flash.

We're off back to the UK for six weeks of fieldwork this weekend. We're hoping to be able to keep the blog updated fairly regularly, although we won't have internet access for at least some of the time.

freya cardigan 2

freya cardigan 2, a photo by hallucygenia on Flickr.

Just a very quick post to say that the cardigan didn't come unravelled when it was cut open, and it's now very handy on slightly chilly evenings.

On a totally unrelated topic, we had heard that there is an Irish pub in Nanjing, and had been meaning to go for a while. Last night we finally got there, and it is indeed an Irish pub, with Guinness adverts, beer, chips and an excellent selection of single malts. The barmaids wore kilts. Live music two nights a week, although not the night we went. There were more Westerners there than we’ve seen in one place since we came here. A place we’ll definitely be going back to, although not too often as it’s fairly pricy.

A bit on butterflies

Papilio polytes, a photo by joe with a camera on Flickr.

Just a quick one, because it's getting late. I suddenly realised I've not done anything about the creepy-crawlies for a while, and thought I'd go for the more palatable variety for once. No, not literally.

Butterflies are everywhere. Most of them, of course, are little white ones, like you've got in your gardens (more or less - I've no idea what the species are). There are, however, a whole stack of other things that are much more impressive... including birdwings, huge fritillaries, and swallowtails. Swallowtails are all over the place, and many different species - the familiar type that occasionally gets spotted in Norfolk (mostly yellow with black speckles), and lots of others. In particular, there are quite a few black ones with a few dashes of colour - this one is Papilio polytes.

The problem is, they never sit still. You see them flying everywhere, but normally high up on the magnolias, and they barely settle for a second. Even when they do, their wings are fluttering so much you can't get close to a picture of them. This one finally took pity on us - it appeared out of nowhere, and plonked itself on a bush next to me. It waited for one photo, then off - but that's a lot better than normal.

Other beasties are coming out too. We're seeing baby mantises quite commonly, huge centipedes and millipedes (had a gorgeous ten-centimetre-long black and yellow one crawling all over me today), and there was also a squashed amblypygid on the pavement. I really, really want to meet a live one of those. If I do, you'll be the first to know, so stay tuned...

p.s. we're getting ready for our summer fieldwork trip to Wales at the moment - flying out in a week's time, and will hopefully see some of you over the next couple of months.

Practical geological dating...

Lower-Middle Cambrian boundary?, a photo by joe with a camera on Flickr.

On one of the Guizhou forays, we drove most of the way up a mountian to one of the Miao villages at Kaili. We then walked up the rest of way, to get to a building site... walkways, quarries, handrails (necessary in places)... and grand, triumphant proclamations that here, at this very spot, is where the Early Cambrian became the Middle Cambrian.

More accurately, the section is a potential stratotype for the base of the Middle Cambrian (stage C3). What does that mean? Well, one of the basic problems in interpreting the geological past is correlating rocks from one place (or continent) to another. We can't just date everything by using radiometric methods (it's very expensive, only works for certain types of rock, and normally isn't that accurate for single data points), so we've got to correlate them. To do that, you need to pick a point to correlate them with... that's a stratotype.

The stratotypes mark the base of each unit of geological time (or will once they're all decided); there, and only there, are the time units defined. If we say that some rocks in Wales are of Middle Cambrian age, it means that we've got a very good reason for believing that it was deposited after the point in time that is marked on a rock, up a mountain in China (and before wherever the base of the Late Cambrian is defined, of course). At its simplest, the reason might be that it contains a group of trilobites that only appear in China above that level; normally the arguments involve lots of cross-correlation, for example with Norway, then Estonia, then in turn with Iran, then with Malaysia, which finally lets us correlate with China... It's an odd concept, but when you think about it, it's the only good way of doing it. Nothing else is reliable or meaningful for making sure that people in all continents are really talking about the same time.

A committee chooses each site very carefully. Does it have a mixture of different fossils that can be used for correlation? Does it coincide with local changes in sea level or sediment changes that could confuse things? Is the structure chopped about by faults? Is there a good pub nearby? Actually, the latter plays little part, unless you need a two-hour helicopter ride to get to the place (which is a problem for one of the other candidates, in Siberia.)

This one, in the Kaili Formation, isn't too bad. There are lots of trilobites, which are useful for dating things, but few of other groups (no acritarchs, for example, which would be better). It's not been metamorphosed, but there are a few small faults. It's not easy to get to (up a mountain near Kaili City), but could be a lot worse. I understand the decision on which section gets the honour is due in a couple of months... can you all stand the tension?