Thursday, November 29, 2012

Hustedia mormoni brachiopod from Kansas

Hustedia mormoni is a small rynchonellid type brachiopod that is common in Pennsylvanian aged rocks. This specimen came from Kansas, but that is all the label says. I found this specimen in the Yale Collection that has a provenance of: Late Pennsylvanian, Virgilian, Shawnee Grp, Oread Ls.

Brachial valve

Anterior

Pedicle valve

Posterior

Profile


Here is another link to a specimen from Missouri.

Tuesday, November 27, 2012

Strophonella reversa from Iowa

These next specimens, which come from Rockford, Iowa, I purchased from a seller on E-bay. They are Strophonella reversa and come from the Lime Creek formation.Compared to other members of the Strophomenida order, these are relatively robust fossils which display the typical curvature of the Pedicle valve, but the Brachial valve is not as convex.

Pedicle valve

Anterior

Brachial valve

Posterior

Profile

Four specimens side by side to show the variation within the species.


The above specimens came from the Cerro Gordo member of the Lime Creek Formation, which is Upper Devonian (Fransian) in age.

Sunday, November 25, 2012

Douvillina arcuata from Iowa

In line with my previous post regarding Douvillina, here are some examples from the upper Devonian of Iowa.

Pedicle valve

Anterior

Interior of Pedicle valve

Posterior

Profile


Here is a second specimen

Pedicle valve

Anterior

Interior of the Pedicle valve

Posterior

Profile

Four different specimens to show the variation within the species.

A Thank You goes out to my friend Nathan for giving me these specimens that he collected from the Cerro Gordo Member of the Lime Creek Formation (Fransian stage of the Devonian) near Rockford, Iowa.

Friday, November 23, 2012

Xenocyathellus thedfordensis coral from Arkona

My fall trip to collect at Arkona was successful in adding new species to my collection as well as expanding my knowledge of the local stratigraphy. Both were helped along by a new friend, Darrell, whom I'd met before on another trip. He explained and showed me some of the narrow horizons where particular fossils can be found within the Arkona shale. He's been collecting at the site for many years so it's good to get some of his first hand knowledge. Darrell had pointed out the Microcyclus bed to me and then handed me the specimen below of the more uncommon Xenocyathellus thedfordensis which can also be found in that horizon.






I'm going to have to keep my eyes open more when I'm next back at Arkona so I can find one of these uncommon fossils for myself!

Another picture from the Friends of the Univeristy of Michigan Museum of Paleontology illustrates some other specimens of Xenocyathellus thedfordensis.

Wednesday, November 21, 2012

Orbiculoidea truncata from 18 Mile Creek

Not much to show with this specimen. It's a single fossil of an inarticulate brachiopod called Orbiculoidea truncata. I found it along the cliffs that line Lake Erie near 18 Mile Creek. It likely came down from the Windom shale as I found it in an area that had the Wanakah shale covered by talus from the overlying rock.


The Wanakah shale is part of the Ludlowville formation which is Devonian (Givetian stage) in age.

Monday, November 19, 2012

Hederella filliformis on a Sterolasma coral from 18 Mile Creek

As you walk along the shore of Lake Erie, next to the cliffs, you will find quite a few examples of the rugose coral Sterolasma rectum eroded out of the rock. This particular specimen features some Hederella filliformis bryozoans encrusting it's surface.


Note in the above picture how the Hederella grows facing down while the coral grows facing up. What I think this represents is the coral being tossed by waves until the calice is embedded in the mud. This could have happened after the coral had died. Once in it's new position the Hederella colonized the surface and grew in the direction of the currents where it would have a better chance at catching food.

Here is a closer view of the Hederella colony that I cobbled together from several shots that I took with my Zorb microscope camera.


The rest of the coral is barren but a very good example of Sterolasma rectum.

The calice is well exposed and somewhat intact as well. Most specimen I find have much of the calice walls broken off as they are somewhat thin and fragile.

This specimen likely came from the Wanakah shale (part of the Ludlowville Formation) which is middle Devonian (Givetian stage) in age.

Saturday, November 17, 2012

Ancyrocrinus anchor from 18 Mile Creek

While searching along the cliffs that line the shore of Lake Erie near 18 Mile Creek I found this rather unique fossil. It's the very base of a stem with four "roots" that would have angled off giving it a look like a grappling hook. Based on my experiences this is an anchor for a crinoid called Ancyrocrinus bulbosus.
 .



Looking down the stem towards the base. Note the square shape of the stem which is diagnostic for the species.


To see a more complete specimen of this odd holdfast click here for an image from the database of the Friends of Michigan Museum of Paleontology.

I've found these kinds of fossils in my local Mahantango formation and blogged about it here.

This fossil was found along the shoreline of Lake Erie near the mouth of 18 mile creek. Based on the book "Geology and Paleontology of 18 Mile Creek" by Amadeus Grabau, (pg. 146-147), this species is typically found in the Moscow shale (since promoted to Formation status) which corresponds to the Windom shale. As the Windom shale is present along Lake Erie, and was exposed particularly well in the area I was hunting, I am going to assign that as the former resting place for my fossil.

Thursday, November 15, 2012

Erismatopterus levatus fossil fish from the Green River Formation

Below are a couple of small plates from the Green River formation in Wyoming with the fry (juvenile) of a trout perch called Erismatopterus levatus. I bought them from a dealer at a local show this spring.





Based on the book "Paleontology of the Green River Formation with a Review of the Fish Fauna", by Lance Grande, Bulletin 63, Geological Survey of Wyoming, pg. 122-124, these fossils are found primarily in fossil lakes Gosiute and Unita. They are uncommon except for mass mortality zones possibly caused by short term lake temperature rises in the summer.

Click over to This Post I wrote two years ago about the Green River formation to see some diagrams of where the various fossil lakes that compose the formation once existed.

Tuesday, November 13, 2012

Lissostrophia cooperi brachiopod from the Henryhouse formation

Here is a tiny brachiopod that I picked up off E-bay called Lissostrophia coooperi. It comes from the Henryhouse formation near Ada, Oklahoma. The original label indicated it was Productella sp. but a search through the texts could not turn up anything like that from the formation. I finally traced the identity to Bulletin 78 from the Oklahoma Geological Survey: "Stratigraphy and paleontology of the Hunton Group in the Arbuckle Mountain Region"pages 77-78, plate 12.

A group of the fossils in my hand

Pedicle valve

Anterior

Brachial valve

Posterior

Profile


The Henryhouse formation is Silurian in age and often referred to as "Niagaran" which would roughly correspond to the Aeronian thru Gorstian stages of the ICS (439-421 mya).

Here is a reference , by Thomas Amsden, that describes Lissostrophia cooperi from The Journal of The Washington Academy of Sciences, vol. 39:pages 202-203,(1949)

Sunday, November 11, 2012

Large colony of Fistulipora (?) from Arkona

I'd forgotten about this next piece until I was organizing my finds from Arkona. It's a very large portion of a bryozoan colony that came from the Hungry Hollow member of the Widder formation.



Trying to determine the species would require thin sectioning of a portion so that the internal structures could be studied. Based on the "Check List of Fossil Invertebrates Described from the Middle Devonian Rocks of the Thedford-Arkona Region of Southwestern Ontario", There are three species described from the Hungry Hollow member: F. huronensis, F. incrassata and F. vesiculata with the former two being the most common.







These are common fossils but I don't find many large colonies like this. The Hungry Hollow member of the Widder formation is middle Devonian (Givetian stage) in age.

Here are some Fistuliporoid colonies that I found in the Silica Shale.