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722 Views 12 Replies Last post: Dec 21, 2013 9:44 AM by Dan RSS
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Dec 14, 2013 1:56 PM

Ossett trigonocarpus nut?

Hi,

 

 

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

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    • Currently Being Moderated
      Dec 14, 2013 9:50 PM (in response to Dan)
      Re: Ossett trigonocarpus nut?

      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

      - http://www.gutenberg.org/files/43976/43976-h/43976-h.htm

      As an eBook from Project Gutenberg, it is free to download. My thanks to the PG team.

       

      Mike

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        • Currently Being Moderated
          Dec 15, 2013 8:10 AM (in response to Dan)
          Re: Ossett trigonocarpus nut?

          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.

           

          Mike

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            • Currently Being Moderated
              Dec 16, 2013 8:56 PM (in response to Dan)
              Re: Ossett trigonocarpus nut?

              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.

               

              Mike

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                • Currently Being Moderated
                  Dec 20, 2013 10:23 PM (in response to Dan)
                  Re: Ossett trigonocarpus nut?

                  Dan,

                   

                  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.

                   

                  Mike

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