Asterophyllites nodule

[Rockaholic]

This is an upper Carboniferous Mazon Creek type nodule collected from Indiana surface coal mine spoil piles.When this Asterophyllites nodule first split there seemed to be something unusual in it’s appearance so I took a photo of it and moved on and never gave it much thought.Today I was looking throught my gallery and it dawned on me what appeared to be unusual about this piece.It may be just an artifact due to separation of the leaves from the nodes during the preservation of this fossil but it appears as if the leaves don’t radiate from a single node but have a separate origin along the stem.If the leaves do attach to a single node is this an example of Asterophyllites equisetiformis?

[ZiggieCie]

Interesting fossil.

[Auspex]

It could be that, between the disassociation of the leaves and irregular spacing of the nodes, the appearance is misleading.

[fiddlehead]

A couple of quick notes. What you have is an example of Annularia spinulosa. This is the replacement name for the now discarded name Annularia stellata. This being one of the most widely distributed and recognized fossil plant forms makes this rather difficult adjustment. For reasons of name priority, a new cut off date for validly named species, and the fact that in this case all the type examples are missing and the type locality is no longer available to collect from, the old name was rejected. Sad to see it go. I believe Auspex to be correct in interpreting your fossil. One thing to note when looking at specimens with leaves attached at a whorl, is that Annularia leaves are not concentric to the node they are longer on each side, short to and bottom. they also angle away to one side. This is unlike Astrophyllities which has leaves of the same size all the way around the node, and arch equally upwards towards the tip of the axis.

Hope this helps,

Jack

[Rockaholic]

A couple of quick notes. What you have is an example of Annularia spinulosa. This is the replacement name for the now discarded name Annularia stellata. This being one of the most widely distributed and recognized fossil plant forms makes this rather difficult adjustment. For reasons of name priority, a new cut off date for validly named species, and the fact that in this case all the type examples are missing and the type locality is no longer available to collect from, the old name was rejected. Sad to see it go. I believe Auspex to be correct in interpreting your fossil. One thing to note when looking at specimens with leaves attached at a whorl, is that Annularia leaves are not concentric to the node they are longer on each side, short to and bottom. they also angle away to one side. This is unlike Astrophyllities which has leaves of the same size all the way around the node, and arch equally upwards towards the tip of the axis.

Hope this helps,

Jack

Thanks Jack as always your posts are helpfull and informative.Now you have me wondering if I’ve mislabled other specimens.This one that I labeled as Asterophyllites appears to also be a an example of Annularia spinulosa that has a deceptive appearance due the angle of compression during it’s preservation.This is another piece that I thought might be an example of Asterophyllite, preserved to look like a cross section, but now I’m not so sure.

Edited January 7, 2016 by Rockaholic