Wednesday, August 12, 2009

Unidentified Silurian Brachiopod

The following are pictures of an unidentified brachiopod from the Silurian Period. It was found in Louisville Kentucky in the Louisville Limestone layer.

I do not see a match for it in the Fossils of Ohio book.
Look at all the sinusoidal lines spaced on top of each other is this next picture.


7 comments:

Anonymous said...

Any chance it could be Devonian? This is a dead-ringer for the Devonian Spinatrypa or Invertrypa. Both occur in North America, and I have dozens of specimens of Spinatrypa from Middle Devonian rocks of the Northwest Territories, Canada. According to the Treatise on Invertebrate Paleontology, the difference between Spinatrypa and Invertrypa is in the convexity of the valves: Spinatrypa has a more convex brachial valve, Invertrypa has a more convex pedicle valve.

If you're 100% certain it's Silurian, then it's a mystery to me. No (or at least not many) Silurian rocks in western Canada!

Great blog, BTW!

Cheers,
--Howard (Calgary, AB, Canada)

Fossil Detective said...

Thanks for reading the blog.

It could be Devonian Period. I found in an area with the Silurian Period Halysites, Coenites, and Eridophyllum corals. Of course, everything is in loose dirt and on a slope. So the little rounded brachiopod could have washed down from the Devonian layers.

It is really rare to find brachiopods in the coral zones I am looking at. I am not sure if it is an Invertrypa after looking at these pictures from the Indiana State Museum: http://museumcollections.in.gov/detail.php?record=0&v=2&s=Invertrypa+cf.+I.+spinosa&type=browse&t=objects&f=object_type&d=

I will try and post some more brachiopod images for you to study.

Anonymous said...

I did some googling around, and found a few clues. First, I found a geological map of Kentucky, which shows (as you no doubt already know) that there's a lot of Devonian rocks around Louisville. Looks like the Jeffersonville and Sellersburg limestones outcrop in the Louisville area. Apparently both are fossiliferous. Then I found this paper online: http://www.uky.edu/OtherOrgs/KPS/poky/files/pokych04-01-32.pdf

Which lists, among the Sellersburg fauna in the Louisville area (see page 229), "Atrypa spinosa. Googling around some more, you can find that the author of this species is Hall, 1843. Still more googling turns up a species of Spinatrypa* called S. spinosa (Hall, 1843). Coincidence? I kinda doubt it. I suspect that someone has synonymized (renamed) A. spinosa Hall, 1843 as S. spinosa (Hall, 1843). You never see the two species names listed in the same publication. Since "A. spinosa" is listed as occurring in the Louisville area, this could be a good possibility for your unknown specimen.

*Note: the genus Spinatrypa was erected in 1951 by Stainbrook, so of course, any publications older than this won't list Spinatrypa. This abstract: http://gsa.confex.com/gsa/2002NC/finalprogram/abstract_29618.htm
says that "...Spinatrypa...is abundant in the Upper Devonian rocks of the Appalachian basin...". You might also try the other species listed here, S. hystrix

Nice specimen, BTW!

Cheers,
--Howard

Anonymous said...

Oops, looks like the URLs I pasted into the message got chopped off. Try href="http://www.uky.edu/OtherOrgs/KPS/poky/files/pokych04-01-32.pdf"this (page 229) and href="http://gsa.confex.com/gsa/2002NC/finalprogram/abstract_29618.htm">this. :-)

--Howard

Anonymous said...

D'oh! Sorry to mess up your blog--I can't seem to get the hang of these URLs!

Try: http://www.uky.edu/OtherOrgs/KPS/poky/files/pokych04-01-32.pdf

and

http://gsa.confex.com/gsa/2002NC/finalprogram/abstract_29618.htm

--Howard

Fossil Detective said...

Thanks for all your research Howard. The patterns on the shells do match up to the Spinatrypa. Do the ones you encounter have the multiple sinusoidal patterns where the valves come together?

I will check the Nettelroth book on Kentucky Silurian and Devonian Shells found on the Kentucky Paleontological Society (KPS) website.


I will try to post some Canadian Burgess Shale soft body invertebrate fossil pictures in the coming days.

Anonymous said...

I've emailed you a couple photos of typical Upper Devonian Spinatrypa specimens from northern Canada. The front view shows that the "multiple sinusoidal patterns where the valves come together" is very similar.

Cheers,
--Howard