One of my lads found this on the Holderness a while ago, it's hard to id so could someone id it for me please.
Looks like a plant but it could be a coprolite, Lower Jurassic - Lower Lias.
Note that the leaflets have a general opposite arrangement on the stem, albeit seeming a bit imperfect in the specimen (as commonly happens in the plants themselves). I'm not quite sure how you're seeing a potential coprolite, but on its own, that arrangement is going to be unlikely with a coprolite. The whole nodule: yes, it has muddly clasts in it, but I think those are purely due to sedimentary processes (fragments of a muddy layer that was broken-up and redeposited).
So I think the little fossil has to be a fern frond, or similar, eg.
Lyginodendron is known from Yorkshire, though I don't know where. That is a fern-like plant but it bears seeds. It is/was put in the Pteridospermeae (http://books.google.co.uk/books?id=RDWqjHyIdUoC&pg=PA107&lpg=PA107&dq=Lyginodendron&source=bl&ots=f9TkP7wqe1&sig=I_jndiVurw5KNxZNzcA5JxoM1-c&hl=en&sa=X&ei=YK2RUriuLafE0QW-hoHQDQ&ved=0CGIQ6AEwDg#v=onepage&q=Lyginodendron&f=false)
Here's a Pteridospermid frond in a nodule
Cladophlebis is another possibility, though I haven't checked its age range relative to the stratigraphy.
Thank's for all the info Mike.
I think I was seeing things! and was hoping for a spiral coprolite but never mind - next time.
We have found quite a bit of plant fossil material on the Holderness including a Calamnite like Dan finds, but it was in a block of matrix that had split along the fossil fully presenting the specimen for all to see in the middle of the beach at Holmpton, unfortunately it weighed aprox 2 tons!
...2 tons eh?
Hmmm - I suppose that's asking a bit much even for your and your lads.
You'll just have to prep it (and ease it out) in situ, then!
Dan's right - Calamites was extinct before the Jurassic. But other members of the Equisetopsida lived on. In the Jurassic it was just members of the Equisetales (today represented by just Equisetum.