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Cone Id Confirmation


Rockaholic

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I'm thinking Palaeostachya.I've highlighted the sporangiophores and it appears to me that they attach to the base of the bracts.Is there enough evidence preserved in this fossil to make an ID?Any thoughts would be appreciated.

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Well since there are no objections I'm going with Palaeostachya sp.Thanks Herb.

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I'm thinking Palaeostachya.I've highlighted the sporangiophores and it appears to me that they attach to the base of the bracts.Is there enough evidence preserved in this fossil to make an ID?Any thoughts would be appreciated.

You clearly know more about these sphenophyte cones than I do. The sporangiophores are the stalks bearing the sporangia, right? I find it difficult to see how this works exactly. The sporangiophores' position of attachment on the bracts seems to be the basis for your ID (see quote above). Could you explain how to distinguish Palaeostachya from allied cone genera such as Bowmanites, Calamostachys and Cheirostrobus? I never tried getting into detail with the cones before.

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Thanks for your reply.It introduced me to a couple of cone genera that I wasn't familiar with.My knowledge of paleontology is growing but is still limited.When it comes to fossil identification I sometimes feel like someone trying to solve a calculus problem without first learning how to add and subtract.Most of the cone genera that I'm now familiar with can be eliminated as a possible ID for this specimen just from their general appearance.I think that this cone can be narrowed down to either a Calamostachya or Paleostachya.My source of reference that drew me to the conclusion that this was a Paleostachya was Jack Wittry's The Mazon Creek Fossil Flora where sporangium (plural. Sporangia) is defined as "a case containing spores" and sporangiophore is defined as "a stalk bearing sporangia".Your post encouraged me to further investigate the term sporangiophore and it would appear,at least in botany which may differ from paleontology,that the term sporangiophore is used to describe the stem connecting the sporangia to the cone.Setting the semantics of the term sporangiophore aside it appears that one feature that differentiates Calamostachya from Paleostachya is the spore cases attachment to the cone.

Paleostachya,which has the sporangia in the axils of the bracts and Calamostachya,which has the sporangia at right angles to the whorls.Since it appears as if the stem connecting the sporangia to the cone is not often preserved one would have to speculate to some degree as to where the sporangia attach to the cone.It would also seem that the spore cases of Calamostachya are bilobed.Investigating photos on the internet it would appear that the sporangia of cones are rarely preserved and that ID's are made from general appearance.

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Edited by Rockaholic
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Thought I'd add this photo since I think I'm seeing a sporangia stalk here.

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Thought I'd add this photo since I think I'm seeing a sporangia stalk here.

Make sure this cannot be a shadow, and I think you are in pretty good shape. I attached two pages from Boureau 1971, Les Sphénophytes, biologie et histoire évolutive (see below), that may be of further help perhaps. It could be you need the French text of this particular chapter as well. If so, send me a PM.

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