Strange Brigantian ?echinoid ?Proterocidaris

[tqb]

This is part of a 10 x 7cm bit of shale covered with odd plates that turned up a few years ago - I had thought I was dealing with a weird broken up bryozoan with monticules and other ornament.
I've just found a second specimen and the penny's dropped that the bits with double pores are ambulacral plates - there are a lot of them as well as various other forms.
The plate shape is very variable, from simple polygonal to blunt star. Some of them are articulated.
Some (interambs?) have regular arrangements of pits.

I'm somewhat baffled but how about something like an echinocystitoid such as Proterocidaris.?
( I don't suppose ophiocistioid plates look like this?!!)

It's hard to choose which photos to show you but I hope these give some idea.

Suggestions gratefully received, Joe!

[tqb]

Bits of the new one:

[Joe Botting]

OK... um... help?

This is seriously weird. The ambulacral plates appear to be extremely convex, like little volcanoes, which is a feature I've never seen in any echinoid. The stellate outline is another thing I've never seen.

The areas with spine bases seem a lot more normal, except for the small size relative to the ambulacrals. I was wondering at diploporite plates instead, but the spine-base areas just look *so* echinoid-like.

As you say, this doesn't really look anything like an ophiocistioid, bothriocidaroid, or anything else I can think of. I reckon it will be worth sending some pictures to Charlotte Jefferey at Liverpool, but in the meantime will keep looking for some revelations!

[tqb]

Thanks, Joe, I'll keep looking too, then!

I'd actually looked at diploporites but then realised they apparently didn't make it past the Devonian.

This Permian Pronechinus may be on the right lines:
www.nhm.ac.uk/research-curation/research/projects/echinoid-directory/taxa/taxon.jsp?id=22

and the related Proterocidaris has at least some stellate interambulacral plates.

I've found an email for Charlotte Jeffrey so will try her, thanks for the suggestion.

[Joe Botting]

Any news on this one, Tarquin? I'm intrigued to see what it turns out to be...

[tqb]

Sorry, Joe, I've not acted yet. I'll get emailing soon.

Edit: just emailed Charlotte Jeffrey.

[tqb]

No reply so far...

[Joe Botting]

Strange. She's probably just overworked, though; I believe she's got an intensive teaching term at the moment. If there's no response, then Andrew Smith will also be worth a try, of course...

Thanks for keeping us updated!

[tqb]

Thanks, Joe, I'll try him next week.

[pleecan (Peter Lee)]

Nice find Tarquin!

[tqb]

It's been a while but we've got an ID on this one, thanks to Tim Ewin at the NHM who forwarded my photos to Jeffrey Thompson.

Basically, it's an extremely rare echinoid, either a proterocidarid or lepidesthid (which are hard to tell apart) but Jeffrey feels that it's probably Lepidesthes sp. and only the second specimen to be found in England. The first one is the unique type specimen of L. howsei Jackson 1926, found in Northumberland by the then curator of the Newcastle Hancock Museum, Richard Howse.
A different species (L. caledonica) is known from a corpus of fragmentary material from a Scottish locality.

They're better known from the USA - here's the NHM's page:
www.nhm.ac.uk/our-science/data/echinoid-directory/taxa/taxon.jsp?id=65[/font]

[Joe Botting]

Excellent - thanks for the update, and congrats on the rarity! Now you need a whole one.

[tqb]

Thanks, Joe! - still looking of course but most stuff from here is fragmentary, storm damaged I guess. There is quite a lot more of it than I've shown here (and another less extensive specimen).
It's from the same location as the ophiocistioid goniodont so I'll definitely be keeping an eye on the site which is eroding quickly.

This one is looking to be Lepidesthes caledonica, known only from (a lot of) disarticulated plates from Roscobie quarry near Dunfermline - the same age, Upper Brigantian, and about 120 miles north.

[Joe Botting]

Nice... a new species would be even better, in some ways, but it's good to have comparisons to go at as well.

What do you reckon the odds are of fully articulated preservation in one layer (or more) at the site? What's the sedimentology like? Unlikely, I guess, but one can dream...

[tqb]

You do find the odd patch (lens rather than layer I think) with exceptional preservation such as brachiopods with all their spines so it's possible! There isn't that much material overall though - the shale tends to break up into very small pieces and quickly becomes mud.