A partially enrolled specimen
This is the best enrolled Phacops that I ever found from the Mahantango.
How many Trilobites can you find in this picture?
I've heard that the genera name Phacops has been superseded by Eldredgops but I'm finding it hard to locate information to confirm that fact. It seems to be a 50/50 battle among sellers with most references to Eldredgops being assigned to Trilobites from the Silica Shale.
Speaking of which, here is an enrolled specimen in situ from the Silica Shale in Sylvania, Ohio.
I checked the Paleodb.org website and found plenty of info for the genera Phacops, but when I put Eldredgeops in the search it only came up with a family name but no references other than this : J. J. Sepkoski. 2002. A compendium of fossil marine animal genera. Bulletins of American Paleontology 363:1-560 [J. Alroy/J. Alroy/M. Carrano]. It seems that Sepkoski has been busy writing papers as I often see his name associated with Devonian period fossils. However the one reference to Eldredgeops isn't even a paper which describes the reasoning, it's just a list of genera.
This site (http://www.fossilmuseum.net/Fossil_Galleries/TrilobitesOhio/crassituberculata/phacops.htm) even gives you a reason for why "some prefer" Elderdgeops.
re: Eldredgeops vs Phacops- The distinction has to do with the number of facets in vertical alignment in the eyes. Don't recall what the number is, but basically the eastern community had more(or less?) than the western community.
ReplyDeleteIIRC, it is the western community that retained the name.
I wouldn't put trust in any identification from any but the most knowledgeable dealer. A problem IDing a critter to the specie level is that very few can do it, and generally only those that study that particular family. Hence, the distrust if IDs... especially on the internet.
Many times I have seen an ID on the internet, and when I ask "why that specie", the response is usually "it looks like this" or that picture??? That ain't how its done!
Oooh, nice finds.
ReplyDeleteI agree that species Id is very difficult and for the most part I only ID (and refer to) fossils at the genera level, unless I can find more information somewhere that helps to differentiate; such as Cincinnatian collectors being able to tell a Gravicalymene from a Flexicalymene.
ReplyDeletehahaha
ReplyDeleteHey now, I'm a Mohawkian geek. ;)
As I'm sure you know, one of the best starting points are the papers specific to that formation. That will at least give one an ideal where to start.
Help me please. I have been going to a locality out by Hancock, Washington County Maryland for a year, and I still can not figure out the age. According to the geologic map, it should be Rose Hill Formatio (Creasaptown Ironstone), but, I have found Devonian aged brachiopods. Also, a species of pelycopod thats only found in the Mississippian. I have no idea what the age is.
ReplyDeleteThe geology around Hancock, Maryland is pretty much Silurian to Devonian age rock. The pelecypod you found may be mis-identified or could be something that was left by another collector as they were cleaning out their findings. Some of the brachiopods that are found in the Rose Hill formation look similar to Devonian forms so maybe that is what's causing the confusion. I'd suggest going to the Fossil Forum (link is in the right column) and post some pictures of your finds. The people on there will be able to help ID and give you some info on your finds. -Dave
DeleteYeah, thanks for the help. I was going through some boxes of the fossils and found a trilobite (curled up and a bit weathered) that looks like Calymene cresapensis from the Rose Hill. Thanks for the help, and I really do like the website.
ReplyDeleteSorry to say this so late, but the site is actually closer to Sideling Hill than Hancock. Also, I've read about some formations here in the Appalachians, and the rocks seem to match the description of the Greenbrier Limestone the best, being a red- gray limestone and minor shale. Am I wrong?
DeleteThat could be the case and would match more with the pelecypod you found. Some Devonian brachiopod forms do extend up into the Mississippian but not many. I've not really collected the Greenbrier Limestone so I don't have any experience to draw on to help you.
DeleteI think it's actually early Ordovician in age. I found no spiriferids in my first trip, only some possible orthids, algal piecesand a trilobite. Plus some rock is dolomite. I think maybe a collector left some Spielberg behind. Forgive me if I'm wrong, I'm an amateur.
DeleteSorry, dumb auto correct, I ment spiriferids.
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