Since I have found a few trigonocarpus nuts lately, I decided to go fossil hunting for about 1 hour to see if I could find any more. At first I didn't find anything, but then after 45 minutes I went to the spot where I find most of them, and I found one partial one after 50 minutes and then after 1 hour I found this one, which I believe to be a trigonocarpus nut.
What do you think?
Does anyone like mike know?
It comes from Ossett, West Yorkshire, UK and it's carboniferous in age.
Thanks for any replies
Oh, I forgot to say it is fairly flat because of the pressure of the other rocks and if it is a nut the bark has all gone, like most of them from this location.
Is it a nut at all or could it just be a pebble?
I think I can see three ridges in your photos. That, and the general feeling I get from the photos, leads me to think it is a Trigonocarpus specimen. Yes, one could get a pebble roughly that shape, but if there were any ridges, there would probably just one, encircling it - being a layer of slighter more resistant stone. The three ridges is difficult to explain other than it being a nut such as Trigonocarpus. (Six ridges, similarly - which would be a Hexagonocarpus.)
They are commonly a bit flattened, which would have happened as the sediment slowly became lithified.
They are also found as casts - which would be the same shape as the original but lacking any of the original's internal structure. That would explain your observations of the bark being all gone.
(An internal mould is also possible, but that would be a different shape - the ridges would be much less pronounced.)
For folks unfamiliar with the shape of Trigonocarpus, there's a good illustration of it in cross section in the following eBook (search for 'Fig. 84.'). Also here - http://www.brlsi.org/museum-collections/online-museum/fossils/19080.
Anyone interested in fossil plants would find this book interesting, despite it being a century old
- Ancient Plants, by Marie C. Stopes, 1910
As an eBook from Project Gutenberg, it is free to download. My thanks to the PG team.
You're in a better position to make that decision than me, now that I've given you the info.
But to summarize: if it has three ridges (and especially if you can see them coming together symmetrically at one/both ends), and it is up to a few cm long, it pretty much has to be a fossil nut, and in your location that pretty much means Trigonocarpus.
Ok thanks for the reply. I can see three lines, so I think it is a nut, but it isn't in the best condition. They never seem to be in good condition on the surface- they are only ever in good condition when only a tiny bit of the nut is sticking out of the ground so it hasn't been eroded.
I found a better preserved piece today, but it is just the top of it. Could you help me to ID it? It has all of the bark, so this one can't be a cast. It has two visible riges, and one of them ( the one in the middle) has gone because it has broken off. Could you give your opinion on the species?
I'll post an image tomorrow.
Here is the piece I found yesterday. Can you be sure this one is a nut or is it impossible to be sure? It is 2cm, but it isn't the whole thing. It has all of the bark though.
Could this be trigonocarpus and is this one definietly a nut?
This one is quite well preserved.
Is the one which I posted a few weeks ago, which was more complete deffinietly a nut?
The last image is the first one I found and 1,2,3 and 4 are the ones I found yesterday.
I am pretty sure (very rarely can we be definite) that both are Trigonocarpus nuts.
That's going on the shape, the size, the longitudinally striated texture, the location, the geological setting, etc.
From the area where you found them, they are probably T. parkinsoni, but that is more of a statistical ID - since other species tend to come from other parts of the world. But remember, with these sorts of fossils (plant fragments) even now, we don't really have enough of the pieces of the jigsaw to define species reliably. That is why Trigonocarpus (and several other genera) is a 'form genus' rather than a true genus (as I explained in my post a month ago - http://www.nhm.ac.uk/natureplus/message/38380).
Also, as I mentioned in that posting, the NHM has one of the best collections of plant fossils in the world.
...Including T. parkinsoni from the English Coal Measures - http://piclib.nhm.ac.uk/results.asp?image=040054
I strongly suggest you make a trip to have a look at it; you'll need to contact them to arrange the visit.
It is difficult to say for sure without looking at the nuts in thin section under a microscope - to identify the minerals and to see the textures they display. Fossilization never happens in an instant: it is a long drawn-out process. While it is happening, you are dealing with a sub-fossil. You may come across the term permineralization. That also reflects a partly-fossilized state: specifically, when voids have been filled with minerals but the solid parts of the organism are still organic.
I know you'd like a simple yes or no (I can feel it!)
But life, in this case, is not that simple.
I can say that it is quite common for Trigonocarpus to be found in a permineralized state.