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.

Golden Triarthrus eatoni trilobite from the Whetstone Gulf formation

A recent addition to my collection is this piece of black shale from the Whetstone Gulf formation, Ordovician (Sandbian stage) near Worth, NY. It's been prepped to expose some exquisitely preserved Triarthus eatoni trilobites cavorting on an algal frond. The fossils are preserved by pyrite and minute details of the trilobites are present such as their antennae and legs. Some specimens also have the gills and mouth parts preserved. This rock comes from a layer similar to the one exposed in Beecher's Trilobite Bed which is a famous area in Cleveland Glen near Oneida, NY. It was excavated and prepared by the group known as Gold Bugs. Check out their website for some great pictures of other fossils they have found as well as info on the deposition and excavation of the fossils.

Trace fossils from near Avoca NY

Among the rocks in the large road cut north of Avoca, NY on I-390 (that I blogged about a couple of days ago) were these trace fossils. The rocks are of Upper Devonian age (Fransian stage) from the Gardeau formation of the West Falls Group. At that time the shore line was just east of Avoca and the paleoenvironment was a near shore shelf that was very close to stream and river deltas. These trace fossils probably represent worms burrowing through the substrate in search of food particles.

This one appears to be the top of a vertical burrow where the worm living inside would extend itself out and sweep the nearby sediment for food. The pinwheel like pattern could be an example of the creature systematically covering all the area around the burrow.

These traces are of horizontal burrows, possibly in a very shallow, tidal environment.