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Tentatively putting feelers out there for the possibility of trading for a Cooksonia plant fossil and/or rhynie chert plant fossil material. I may be up for considering other plant material, but those are the main two I'm after. I have a little bit of everything except for invertebrates or dinosaur material (though I do have a little bit of fossil plant material from the Jurassic), so feel free to shoot me a pm and we can discuss things further. Thanks!
araucaria1959 posted a topic in Fossil IDHello, due to my interest in early land plants (in my area, I collected lots of plants in pragian and emsian strata), I bought two specimens of purported Cooksonia from the Wenlock Limestones, Wenlock Edge, Shropshire, UK. For the first of the depicted specimens, I got also the information about the exact locality (Shadwell Quarry). Since the matrix looks exactly the same, the second specimen is probably also from that quarry. If so, these specimens would be among the oldest macrofossils of land plants; though spores that are attributed to tracheophytes go back into the second half of the ordovician, the oldest uncontroversial tracheophyte macrofossils are from Wenlock times and assigned to Cooksonia. That's what makes this unimpressive stuff so interesting. However, I have my doubts; this time not because of its size (like the one from the Bertie Group), but because of the fully marine setting. Wenlock Limestones in general, and Shadwell Quarry also, are famous for corals and brachiopods - typical for a marine setting (possibly near the shore). Since early Cooksonia were very tiny plants, it seems quite implausible to find them together with corals and brachiopods. That's an unusual taphonomic situation for land (or shoreline) plant fossils. On the other hand, the second specimen (and that's why I bought it though I already had the first one) shows a circular structure that may well be a Cooksonia sporangium. Its diameter is about 3 - 4 mm (scale: match = 45 mm) and it shows some structures on the "cup", though not good enough preserved for further identification. It may well be that one looks at the upper side of a sporangium. If so, it is detached from the tiny stem, since the stem continues. Since Cooksonia sporangia (and those of other very early land plants) were situated terminally, the position of the purported sporangium in my second specimen can not be its original position. I hoped to find lots of information about the earliest occurrences of Cooksonia in that area in the internet, but that's not true (there are, however, reports of Cooksonia from Shropshire from younger strata, e.g. Pridoli and Lochkovian). There is a website about Shadwell Quarry, but it doesn't even mention Cooksonia: http://fossil-world.lefora.com/2010/06/07/wenlock-edge-stuff/ This stuff remembers me a lot of the coral reefs from the middle devonian of the Eifel area where I never found any fragments of land plants - though the land vegetation was already much more resistant in the middle devonian than at Wenlock times. However, there is a single hint for Cooksonia in Wenlock Limestones of Shropshire on another website: http://fossil-world.lefora.com/2010/06/07/wenlock-edge-stuff/ That's all I got so far - and so my doubts remain. Since this is an international forum, perhaps someone knows more about that? 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