Trigonocarpus?

[historianmichael]

I recently collected this plate out of a block of shale full of Alethopteris fronds from the spoils of a coal mine in Pennsylvania. You can see some of the Alethopteris on this piece. My initial impression is that these are seeds, with Trigonocarpus serving as the kinda catch-all for Pennsylvanian fern seeds. However, I have never seen an example of Trigonocarpus that has these markings. Both of these fossils have little, golf ball-like dents on them. The fossils measure 4cm and 2.5cm respectively. Has anyone seen something like this before? Do these markings mean that these are something different than Trigonocarpus? Any help is greatly appreciated. Thanks! 

 

 

 

[Fossildude19]

@paleoflor  @fiddlehead

[paleoflor]

Not familiar with "golf ball" seeds and also couldn't find anything similar. Perhaps the dents are taphonomic in origin or maybe the dents reflect some kind of damage, e.g. from insect predation?

[Rockwood]

On 8/24/2020 at 12:34 AM, historianmichael said:

Both of these fossils have little, golf ball-like dents on them.

Wouldn't these shapes represent something involving the internal structure ?

Absent most of the decay causing elements present today it would seem a normal progression in decay of cellular structures expected there. It would look like reverse nucleation around weak points.