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Pennsylvanian aged mystery-Gall or something else?


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Hi all, 

Upon examining some of my finds from this hunt about a month ago, I realized that there was an anomaly on one of the Neuropteris ovata pinnules. Initially I brushed it off as nothing more than an anomaly, but last night while I was doing some reading I came upon an intriguing paper on insect galls from the Carboniferous. Some of the gall fossils included bore a striking resemblance to the gall on my frond, and so I figured I would make a post to see if any of you had an idea on what it could be. 

Here is the frond, in full view:







Closer inspection of one of the pinnules reveals a small, oval-shaped bump:








This bears a striking resemblance to some of the galls included in this paper (it is not paywalled). Specifically, it resembles #7 in the first figure. I hesitated to include the image directly in this topic so as to not violate any Forum rules (if it is not a violation I can include it here as a reply).



Although it superficially resembles a gall, I am looking for other opinions as I have no experience in this field. 


Here are my thoughts on why it could, or could not be a gall:


It could possibly be a gall for multiple reasons. First off, the morphological similarity is quite striking. Secondly, the paper states that ", occurs commonly on a variety of seed-fern foliage throughout the late Middle Pennsylvanian to Early Permian". This is from a late Pennsylvanian deposit (Connellsville Sandstone of the Conemaugh group) so it fits quite nicely into that time frame. Also, epibionts are quite common in this deposit, specifically Microconchus. They are preserved in a relatively similar fashion (mold-cast). 


There are a few reasons why it could also not be a gall. First of all, I have never heard of galls coming from deposits in the Appalachian basin, though this may simply be due to my own ignorance and/or a lack of literature. Also, this anomaly is isolated, which is a derivation seen from many of the galls included in the above paper. Finally, random nodules and concretions do occur sporadically throughout this deposit, so it could always be mineral growth. And finally, my simple lack of knowledge prevents me from making a confident ID either way. 


So, what do you all think? I'd love to hear some of your opinions as to what it could be! And on the off chance that it is a gall, should this specimen be donated?



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