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araucaria1959

Silurian Plant, Bertie Formation

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araucaria1959

Hello,

here is a plant fossil from the Bertie Formation, Locality Fiddlers Green; I bought it some time ago. It was labeled Cooksonia, but I have doubts.

Since Cooksonia was a tiny plant, the specimen is rather large (scale = matchstick = 45 mm). The supposed sporangium is 9 mm wide, the stem 4 - 5 mm. I also miss any defining features of tracheophytes (no tracheids). There seem to be some inhomogenities or structures in the area of the widest circumference of the supposed sporangium, but possibly this is only the texture of the sediment.

So I question whether this is a tracheophyte at all; possibly algae?

What do the specialists say who are experienced with material from the Bertie Formation?

I know there was a discussion about similar stuff in this forum, but my specimen looks something else:

http://www.google.de/imgres?q=Bertie+Formation&hl=de&tbm=isch&tbnid=djMOJqpiUXSCAM:&imgrefurl=http://www.thefossilforum.com/index.php/topic/30693-fossil-plants-from-the-bertie-formation/&docid=diABCSiJrM3ybM&imgurl=http://www.thefossilforum.com/uploads/monthly_07_2012/post-1408-0-70995100-1342307334_thumb.jpg&w=200&h=161&ei=kKqFULiXNJDKsgaUgoGoDg&zoom=1&iact=hc&vpx=347&vpy=333&dur=1672&hovh=128&hovw=160&tx=109&ty=59&sig=113038706526856147472&page=3&tbnh=128&tbnw=160&start=54&ndsp=28&ved=1t:429,r:18,s:54,i:304&biw=1246&bih=857

I would be happy if it's really Cooksonia ... but I cannot believe it so far.

Thanks,

araucaria1959

post-7430-0-85099400-1350938473_thumb.jpg

post-7430-0-98289800-1350938491_thumb.jpg

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pleecan

I think it is a Cooksonia... this is one of my main hunting grounds ... I think the formation may be Williamsville formation Bertie Group.. I don't recall finding Cooksonia in the Fiddlers Green formation but definitely in the Williamsville formation, Late Silurian.

Edited by pleecan

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Malcolmt

The texture looks like plant material from the Bertie. I have never seen cooksonia from the fiddlers green material. The ones I have found have all been from the Williamsville A formation. I think I agree that it is probably not cooksonia. Does not look like inocalus the other plant that we tend to find there. I will look and see if I can take some pictures of some that I have and then post to this thread. It looks more like the object they call "the sperm" It is unkown as to what it really is. Some believe it to be part of a plant, others think it might be a free swimmer and others speculate that it may have been a mud burrower or something that attached to the lagoon floor.

Edited by Malcolmt

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araucaria1959

Thank you for that link. One problem I have is the enormous size of my specimen. It is not clear to me whether the scale on the pictures in the link mentioned above are mm oder 1/10 inch. If it's 1/10 inch, it could work. Then the circumference of my specimen is only little wider than the circumference of the largest specimen in the pictures.

Cooksonia is not monophylic and more like a morphogenus; it encompasses a wide range of types. Does anyone know what species of Cooksonia occur in the Bertie Group (at least the specimens that are assigned to Cooksonia without doubts) ?

araucaria1959

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araucaria1959
araucaria1959

Thank you very much for that link. With a maximal width of the sporangium of 6 mm, the specimen in the first picture of that link is not so much smaller than my specimen. And with regard to its asymmetry, my specimen is possibly distorted and flattened. With that in mind, I agree now that it is probable that it is really Cooksonia sp.! :)

Here is a link to the abstract from the paper you mentioned:

http://onlinelibrary.wiley.com/doi/10.1111/j.1095-8339.2004.00332.x/abstract

araucaria1959

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