Sunday, February 1, 2015

Longispina mucronata brachiopod from the Ludlowville formation

I picked up this slab of chonetid type brachiopods while visiting a small quarry off Geer Rd. in Madison County, NY. The rock found there is a portion of the Upper Ludlowville formation (Devonian, Givetian stage) which has these zones of shell "pavement". Most of the shells I can't really identify beyond "Chonetid type" because to distinguish between the genra you'd need to see if they had spines growing off the hinge line. As the spines are delicate they often get broken off before the shell gets buried.

I was happy enough with the slab as is but, as I looked at some of the individual shells more closely, I found one that appeared to have spines preserved. I always do a happy dance when this happens but especially so in this case because I was able to determine that the species is Longispina mucronata.

The slab

A close up view of the shell. You can see the horizontal spine poking out of the left side of the hinge line.

Not satisfied with just a close view from my camera I took the piece up to my microscope and took a picture there. Here is a much closer view of the spine and I was pleased to see two more parallel to it coming from points farther in along the hinge line.

I've annotated this version of the above picture with what I interpret are the spines in white and the shell outline in red.

I have found a shell that I've called Longispina before in the Mahantango Formation (Devonian, Givetian stage) of PA, but this specimen looks a little different.

I also have a specimen that is labelled as Longispina lissohybus from the Silica Shale (Devonian, Givetian stage) of OH, but there are no spines preserved on that specimen.

No comments:

Post a Comment