Pennsylvanian plant?

[Older The Better]

You guys did better than I had hoped on the last one, I’ve found many small pieces of this plant around in creeks, but I went down to a gravel bar and there were huge chunks lying around some larger than a dinner plate. I assume when they built the bridge upstream they blasted them loose. Rocks are Pennsylvanian age in se Kansas. The last pic from what I’ve found shows leaf scars. Does anybody recognize what plant this is?

 

Amazon Forum Fav 👍

Treasure of Victoria Peak - Grab it through Amazon!

[Mine Shaft]

No, but my father in law showed me places around Zelienople, Pa i collected a lot of fossil Fern/daisy/bark and weird looking stuff.

 

[old digger]

Those specimens are cool! They look quite similar to tree bark.

 

[Red-Coat]

I’d love some hours of digging where you’re making these finds.

The fossils you’re showing here are generally what we would collectively group into “Stigmaria” for the Pennsylvanian period. That’s what is known as a “form genus”, where the assignation is largely based on the shape and appearance of what we find, rather than a true assignation to actual genera or species of plants. We don’t have nearly enough information for detailed assignment to individual plant species. Nevertheless, we’re pretty sure that they represent portions of “Lycopsid” trees such as Sigillaria and Lepidodendron. Something like this:



These were tall trees, up to 50 meters in height, and given that they were growing in swampy and marshy environments they needed extensive root structures to anchor and stabilise them in an upright position. Certainly we find parts of the trunk and even semi-complete trees occasionally; but in some cases we aren’t completely sure whether the fragmentary fossils we find are from portions of the trees that were above the ground or below it (including the possibility of aerial roots and being temporarily submerged in water/mud). The Stigmaria grouping is generally regarded as representative of root systems. Rhizomes, rhizophores and massive highly-branched roots with rootlets extending from them. This kind of thing:



The scars you observed might be leaf scars, but most palaeontologists believe that the vast majority of the circular scars we see are the attachment points for rootlets. There is a school of thought that, despite having the form and function of roots, these rootlets may have been biologically modified leaf structures as a genetic adaptation. The counter opinion is that they were true roots, resembling what we can see today on the closest living relatives of Lepidodendron… small aquatic and semi-aquatic quillworts in the genus Isoetes.

 

[Older The Better]

Perfect, I hadn’t seen the root system explained before that makes sense why the surfaces are textured the way they are. This info is great i show my fossils to grade school classes from time to time while this would be a bit technical, the better I understand the better I can teach.