Brachiopods from the Utica Shale

I'll wrap up my series on fossils I found in the Utica Shale (Ordovician, Darriwillian stage) with this post concerning some Brachiopods that were among the specimens I brought home.

The first specimens are of Leptobolus insignia which are fairly common and scattred throughout the black shale. The appear to be a Lingulid type of brach which means they are inarticulate. Perhaps they lived in the mud or just on the surface of it.

Not much details in those pics because the shells are so small, only 1-3 mm in size. Here are some photos from my microscope or three different specimens.

The only other Brachiopod I found is this one that I think is a Paucicrura rogata.

It's much larger than the tiny inarticulate brachs. I'd say it got swept in by currents or a storm.

Possible coprolites from the Utica Shale

I found two interesting fossils in the Utica shale (Ordovician, Darriwillian stage) while looking for Trilobites this past fall. Both appear to be crushed and disarticulated remains of Triarthrus eatoni Trilobites. The difference between these specimens and others that are disarticulated is that these show no hint of organization and are broken into shapes not normally seen in molts. There are also small brachiopods scattered among the remains. I'm thinking these are corprolites from a large cephalopod or other predator who ate Triarthrus eatoni. The Brachiopods could be present because they colonized the coprolite as a hard substrate in an otherwise muddy sea floor.

Specimen #1

Specimen #2

Problematica fossil Sphenothallus from the Utica shale

One of the strangest fossils I found while collecting in the Utica shale (Ordovician, Darriwillian stage) has to be Sphenothallus. When I saw my first specimen in the field I thought it was nothing more than a deformed cephalopod but kept a sample for reference. Later on a friend of mine, Tim, who was collecting with me at the same locality that day and who also found a similar specimen, posted a picture to the Fossil Forum. Member "Fossilcrazy" (John) responded with an ID and showed some specimens he'd found in Canada in related rocks.

My specimen

Apparently Sphenothallus is a mystery fossil with no modern counterparts. Current theory has them related to either corals or worms (as noted by "Fossildude19" on the above thread).

This past week I've been sorting and cleaning some of my finds from the earlier collecting trip in the fall. I found two more examples of this enigmatic fossil. The first was on a large plate associated with Graptolites and small Brachiopods.

The second was found purely by accident as I was trimming down a large chunk of rock. A small piece split off and I saw the Sphenothallus fossil. I was able to recover both halves of the fossil but it's not as well preserved as the other two specimens.

Cephalopods from the Utica Shale

Orthoconic cephalopods are also found in the Utica shale (Ordovician, Darriwillian stage) and can get somewhat large. The downside is that they are not preserved very well it can be difficult to definitively ID any specimen. These are some that I found this past fall on Nowadaga Creek. This first one is pyritized but not a great many details are retained.

Others are just impressions in the shale.

This specimen, however, does show evidence of sutures and chambers.

Various publications have ascribed the cephalopds found in the Utica shale variously to Endoceras,  and Geisonoceras. I posted pictures of a specimen I purchased back in 2011 here.

Geniculograptus typicalis graptolite from the Utica Shale

Among all the Triarthrus eatoni fossils that are found in the Utica shale (Ordovician, Darriwillian stage) at Little Falls, NY there are also many species of graptolite. The only species that I found was Geniculograptus typicalis but it occurred in profusion in places.
 

Some had really good detail preserved while others were just carbon films

 Sometimes they were also associated with Triarthus eatoni remains.

Triarthrus eatoni trilobites from the Utica shale

Following up on my previous post, these are Triarthrus eatoni trilobites from the Utica shale near Little Falls, NY, (Ordovician, Darriwillian stage). These are frequently found disarticulated and thus are most likely molts rather than post mortem burials.

Molt with the cranidium separated from the rest of the body. Note the free cheeks still in place beneath the "floating" cranidium.

This specimen is missing the free cheeks or librigena.

Both of the above specimens were purchased at my local club show and have since been traded away to my friend Gery in France. I made my first ever visit to the site this past summer with a group of friends from the Fossil Forum. While I did not find any complete specimens, I did find quite a bit of material.

The loose cranidiums were likely the most common fossils found.

You could also find lots of mostly articulated specimens that were missing just their cranidiums. To me this indicates that the trilobites molted by splitting their exoskeleton along the seams of the cranidium and then crawled out. 

Sometimes you just found the free cheeks as pairs or singles.

Utica Shale fossils from New York

While at the DMS show in Newark a few weeks ago I purchased these plates of Ordovician aged Utica Shale from Little Falls, NY. One of the clubs I belong to, the DVPS or Delaware Valley Paleontological Society, sometimes has a trip up to the locality but thus far I have not had a chance to get there. From what I have read, the Utica Shale is Cincinnatian in age and thus corresponds with the deposits in Ohio and Kentucky, although I don't know precisely which formation or layer.

Here is a compressed cephalopod, likely Orthoceras.





This piece of shale has a few Graptolites of the genus Geniculograptus (formerly known as Climacograptus). A similar species is found in the Southgate member of the Kope Formation.



Here is a page from the Dry Dredgers web site that shows some of these Graptolites as found during a field trip (scroll to the bottom of the page).