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Post by Joe Botting on May 15, 2006 6:53:57 GMT -5
They just keep coming. Back at the famous (well, modestly well-known, at least) Llandegley Rocks site, we have finally found a specimen of the lon-awaited bothriocidaroid (primitive sea-urchin - like thing). It's not the one I found as an undergrad, and promptly lost before I realised it was something interesting; no, this one's nowhere near as well preserved (as my memory of the first one, if not the reality), but it is twice the size. The next surprise is that it's not a bothriocidaroid at all; it is, if anything, a true echinoid, or more likely, an ancestral state to both. It's very similar to a thing called Bromidechinus, described from the states only a few years back. And ours is the first from below the Upper Ordovician, being from the Middle Ordovician. Not bad, really. Entertainingly, it's on a slab that also contains by far the biggest starfis I've seen from the inlier. Both are overlapped by at least one, and probably two or three, juvenile crinoids (probably the "common" Cefnocrinus samgilmouri). I'm working on preparing the things, which is hard going in a silicified sandstone. My Dremel tool does little more than polish it at the moment... And the best bit? I picked the slab up a few weeks ago, and assumed it was a poorly preserved mass of Cefnocrinuses. Admittedly, it wasn't obvious, but something like this doesn't half make one look a little silly!  Ho-hum. It all comes out in the wash, as they say. Now we're planning our next trip. ;D Joe |
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Post by neuropteris on May 19, 2006 10:51:54 GMT -5
Sounds like an interesting piece of rock Joe! Its always nice to get a variety of beasties in the same chunk - sort of makes up for the all the many many more which come out blank (in my experience anyway!). Still, makes it more fun when one finally does turn up.
Will we be seeing pictures when its prepped?
All the best
Andy
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Post by Joe Botting on May 20, 2006 4:51:35 GMT -5
Hi Andy, Good to see you're still around! We'll certainly get some pictures of the echinoderms up here when we get a chance. The preparation is good fun, but I'm basically there, I think. The starfish seems to be lying sideways, and only three arms are clearly visible - one of them seems to have been detached, as well. The central body is part-obscured by stubborn sediment, and a crinoid, which also doesn't help. I've been using an old dentist's drill as well as a rotary thing, but I'm going to have to get better tools if I'm doing much more of this sort of thing... which hopefully I will be! ;D The coincidence of having the starfish and the echinoid on the same slab is really quite strange; we've got lots of other blocks of the same bed, which in general have nothing except one species of crinoid (very rare examples of other species, and one small, possible cystoid). We've been looking at the site for ten years, and this is the fourth certain specimen I've seen (no new ones since 1998). Either coincidence is working overtime, or there's distinct patchiness in the echinoderm population; it's something to keep an eye on, anyway. Last I heard, Xenarachne was heading off somewhere for a conference, but hopefully he'll be commenting on your beastie at some point! In the meantime, if you've got anything else from those nodules to show us, please feel free...  Cheers, Joe |
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Post by neuropteris on May 21, 2006 4:37:19 GMT -5
Hi Joe
On the prepping I use a ST and an HD pen supplied by Ken Mannion which does the job on the carboniferous and Yorkshire coast stuff I usually work on. They, and the compressor required to power them can be very noisy so if your doing your prepping at home you have to hope you have patient neighbours! (I do mine in an old coal cellar under the kitchen so its well insulated for sound and doesn't matter about clouds of rock dust floating about). Haven't plucked up the courage to get an air abrasive yet.
I'll have a look for some more items to put up.
All the best
Andy
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Post by Joe Botting on Jul 4, 2006 16:31:08 GMT -5
Bother, I forgot to reply to this! Sorry Andy! It's good to hear the drawbacks of these pneumatic pens, since they seem to be more or less the only serious hammer-action preparing tools that are easily obtainable - at least, easily for a hefty fee! The importance of the impact on neighbours shouldn't be understated either - at the moment we're living in a first/second floor maisonette in a suburban semi. It doesn't bear thinking about!  Have you got much else from Ken Mannion? I've looked at his site and it seems pretty good and reasonable, but it's always good to have a review from someone that has used it. I may not be able to get a pneumatic thingy right now, but I could do with some preparing needles and the like... Cheers, Joe |
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Post by neuropteris on Jul 5, 2006 5:00:50 GMT -5
Hi Joe
The ST and the HD are the only tools I've got from Ken but I can recommend them. I have been through a fair few nibs though which I have a habit of breaking. They are strong down the length but more brittle laterally so it doesn't take much torque for them to break off. My HD is currently in need of a little attention - it works but the nib seems to be slightly warped and I can't get it out of the pen anymore. I generally use the HD for the yorkshire coast stuff and a combination of the HD and ST for the Carboniferous - HD to remove bulk matrix and the ST for more delicate work. I've found the ST works quite well on carboniferous limestone aswell. The only other tools I use are my trusty tooth brush and pot of superglue and a dremel for smoothing off tool marks. Kens very helpful though so if you tell him what you're working on I'm sure he could recommend something.
Still out collecting in the coal fields although the find frequency is drying up a bit as the quarry is filled in (which is some ways is a good thing since there's only a finite amount of storage space in the house!) Did find another mystery nodule last week which turns out to be a Pteridosperm pollen organ....which was nice.
Andy
PS any news from Xenarachne yet?
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Post by Joe Botting on Jul 6, 2006 8:59:13 GMT -5
Thanks, Andy - interesting about the importance of avoiding lateral pressure on the tip - it's something I wouldn't have thought of.
Xenarachne has just gone off again to somewhere else, so it may yet be another couple of weeks before he has time to put his mind to it... but I've sent a reminder.
Good luck with finding more space in your house! ;-)
Joe
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Post by Joe Botting on Jul 8, 2006 9:09:05 GMT -5
We have broadband! As a result, we can actually do something useful with images at last, and here's one of the echinoid and starfish... i5.photobucket.com/albums/y159/joseph00/efa3e299.jpgIt really isn't easy to see, but the echinoid is upper right and the starfish lower right, with only three arms clearly visible. Stare at the echinoid a while, and you might start to see the ambulacrae - the lines of plates with pores in that mark the rows of tube feet. It's not a fantastically clear specimen from a distance, but on the other hand, we can hardly expect that with something this rare. The important thing is that the details are all there when you look closely... Joe |
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