Schizotreta pelopea brachiopod from the Coburg formation

This is the last post dealing with fossils I've found in the Coburg formation for now. As I have only been to the quarry a few times, and the Coburg does not yield many loose fossils, I have only a small percentage of the fauna that are known from the formation. An inarticulate brachiopod is the focus of today's post but I am not sure of the name. From the look of it I would say Orbiculoidea sp. but William Hessin's book "South Central Ontario fossils" does not list that genus. Instead he lists a similar species called Schizotreta pelopea. 

The Coburg formation is Ordovician in age (late Ordovician, Katian/Mohawkian stage).
This fossil was collected from the St. Mary's Limestone Quarry in Bowmanville, Ontario. I used William Hessin's book "South Central Ontario Fossils", 2009, Self Published, pg. 120 to help identify it.

Lingula coburgensis Brachiopod from the Coburg formation

Lingula is a genus of Brachiopods that is extant today with fossils that have been found back to the Cambrian period. Over that time they show very little change with only minor variation on the theme. Why change something if it's already working?!

Here is a specimen of Lingula coburgensis from the Coburg formation.  I found it while on a field trip to the St. Mary's Cement Quarry in Bowmanville, Ontario, Canada. The shell is phosphatized and so retains some color while other brachiopod shells, made of Calcite or Aragonite, loose their color when fossilizing. Specimens of this species are fairly common in the Coburg Fm. but they are delicate and often break while trying to extract them from the hard limestone matrix. The specimen below shows some damage including a rectangular window of shell that is missing. Otherwise the fossil is very nice with a deep mahogany color and thin concentric growth lines.  It's embedded in the matrix so I don't have a way to show my usual view of the shell from different perspectives. You will have to make due with some angle shots that show just how flat the shell is.

The Coburg formation is Ordovician in age (late Ordovician, Katian/Mohawkian stage).
This fossil was collected from the St. Mary's Limestone Quarry in Bowmanville, Ontario. I used William Hessin's book "South Central Ontario Fossils", 2009, Self Published, pg. 117 to help identify it.

Rafiniesquina robusta Brachiopod from the Coburg Fm.

I have found a number of Strophomenid type brachiopods on my trips to collect in the St. Mary's Cement Quarry, but it is hard to distinguish between them some times. The two specimens below I believe are Rafiniesquina robusta, based on William Hessin's book, "South Central Ontario Fossils". The shell is a good size and highly convex with the margins extending perpendicularly to the valves for a good distance. Unfortunately the pedicle valve is not visible or I could look for other unique features to help identify the fossil.

Specimen #1 pedicle valve

Specimen #1 anterior

Specimen #1 left profile

Specimen #1 right profile

Specimen #2 pedicle valve

Specimen #2 anterior

Specimen #2 left valve

Specimen #2 right valve

The Coburg formation is Ordovician in age (late Ordovician, Katian/Mohawkian stage).
These fossils were collected from the St. Mary's Limestone Quarry in Bowmanville, Ontario. I used William Hessin's book "South Central Ontario Fossils", 2009, Self Published, pg. 127-128 to help identify them.

Flexicalymene sp. Trilobite from the Coburg Fm.

Next to Isotelus, Flexicalymene is the most common trilobite in the upper Ordovician. The same is not true in the Coburg formation as I have found only a few parts over the trips I've made. Below is a small, partially enrolled specimen that, unfortunately, is missing part of the cephalon. Based on William Hessin's book, "South Central Ontario Fossils", I think it may be Flexicalymene croneisi.

And this is an isolated pygidium.

The Coburg formation is Ordovician in age (late Ordovician, Katian/Mohawkian stage).
These fossils were collected from the St. Mary's Limestone Quarry in Bowmanville, Ontario. I used William Hessin's book "South Central Ontario Fossils", 2009, Self Published, pg. 172 to help identify them.

Sinuites angularis gastropod from the Coburg Formation

Gastropod fossils from the Paleozoic tend to not have any shell preserved with some exceptions to that rule. In this case, it is true. Sinuites angularis is a common gastropod from the Coburg formation and is a planispiral snail. That means that it's shell forms a spiral that wraps upon itself but stays in the same plane (it doesn't curve off in one direction or another. Generally these look like rounded blobs when found in the field and some searching will yield good specimens.  As it is so blob like, the pictures below are the best I can do to try and show you the specimen from different angles.

The Coburg formation is Ordovician in age (late Ordovician, Katian/Mohawkian stage).
This fossil was collected from the St. Mary's Limestone Quarry in Bowmanville, Ontario. I used William Hessin's book "South Central Ontario Fossils", 2009, Self Published, pg. 135 to help identify it.

Hindia sp. sponge from the Coburg fm.

When you see a small rounded pebble looking thing on the ground, you often think it is just a water worn pebble. However, when you find it in a limestone quarry among freshly blasted rock, it might just be a small sponge called Hindia sp.  I've found one example of this at the St. Mary's Cement Quarry and I believe it is from the Coburg formation (as that is 90% of the exposed and quarried rock). However, William Hessin's book, "South Central Ontario Fossils", only mentions it being present in the Verulam formation.  It could either be that Hinda sp. is rare in the Coburn,  I picked this up from a part of the Verulam formation, or it got transported during a blast.  In any case, I don't have any that I know of from the Verulam either so this is still a win for me.

Hessin reports that there are two species of Hinda known from the Verulam formation but that they differ in the size and arrangement of the surface pores. I have not yet had a chance to view this specimen under a microscope so I am sticking with Hinda sp. for now.

I have found this genera also in the Lower Devonian of Oklahoma and the Lower Devonian of New York.


The Coburg formation is Ordovician in age (late Ordovician, Katian/Mohawkian stage).
This fossil was collected from the St. Mary's Limestone Quarry in Bowmanville, Ontario. I used William Hessin's book "South Central Ontario Fossils", 2009, Self Published, pg. 58 to help identify this fossil.

Ectenocrinus canadensis crinoid from the Coburg formation

I'm told by fellow collectors that Ectenocrinus canadensis is the most common crinoid that is found in the Coburg formation. I've managed to find one or two examples but the genus is very small and easily overlooked. Below is the best example that I have found but is only a calyx with partial arms that has been squished flat. E. canadensis has a very small calyx and almost seems to be composed primarily of arms.  Ectenocrinus sp. is also very common in certain layers of the Fairview and Kope formations in Kentucky. I'll show some of those specimens in a later post.

The Coburg formation is Ordovician in age (late Ordovician, Katian/Mohawkian stage).
This fossil was collected from the St. Mary's Limestone Quarry in Bowmanville, Ontario. I used William Hessin's book "South Central Ontario Fossils", 2009, Self Published, pg. 232 to help identify this fossil.

Pseudogygites sp. Trilobite from the Coburg Fm.

By far the biggest attraction at the St. Mary's Cement quarry is the possibility of finding the trilobite Pseudogygites latimarginatus. In the Coburg formation they can get pretty large and make for a nice prize when found.  They are also found in the overlying Whitby formation, but I will show you those fossils in another post.  P. latimarginatus oval shaped with a large, flat, shield like pygidium that has strong ornamentation on it. It has a strong axial lobe with radiating ribs extending to the margin.  I've not found a full specimen in the Coburg formation yet so most of what I have are pygidiums.

This is best preserved specimen that I've found.

I kept this sample as an indicator of the size they could attain. If the fossil had been complete it would have been 6" across!

On one trip to the quarry, a friend found a large lab of rock with nine+ examples of P. latimarginatus on it. Most were in great shape but a few were lesser specimens. He cut them out of the rock with a saw as the slab was far too large to haul away. I was lucky to receive one of the lesser pieces that I can use as an example and to inspire me to keep looking. 

The Coburg formation is Ordovician in age (late Ordovician, Katian/Mohawkian stage).
These fossils were collected from the St. Mary's Limestone Quarry in Bowmanville, Ontario. I used William Hessin's book "South Central Ontario Fossils", 2009, Self Published, pg. 200 to help identify them.

Dalmanella testudinaria brachiopod from the Coburg formation

Today's fossils are what I believe to be Dalmanella testudinaria. I am not entirely 100% certain on this only because there are a number of other genera and species that look very similar. The Coburg formation does not often yield loose brachiopod fossils as the rocks are composed of more limestone than shale. Based on William Hessin's book, "South Central Ontario Fossils", D. testudinaria is the most common brachiopod that looks like what I've found with other genera and species occurring in other formations.  D. testudinaria  has a round shape to the shell with coarse ribbing that radiates from the beak. The pedicle valve appears to be more convex while the brachial valve is relatively flat. The brachial valve also has a very subtle sulcus.

Specimen #1 Pedicle valve

Anterior

Brachial valve

Posterior

Left profile

Right profile

Specimen #2 - Pedicle valve (this specimen appears to have finer ribs than the specimen above but that could be a result of preservation and remnant matrix).

Anterior

Brachial valve

Posterior

Profile

The Coburg formation is Ordovician in age (late Ordovician, Katian/Mohawkian stage).
These fossils were collected from the St. Mary's Limestone Quarry in Bowmanville, Ontario. I used William Hessin's book "South Central Ontario Fossils", 2009, Self Published, pg. 124 to help identify them.

Ryhnchotrema capax & Ryhnchoterma increbescens Brachiopods from the Coburg Formation

One of the more common species of Brachiopod in the upper Ordovician is Ryhnchotrema. This genus of Ryhnchonellids are generally small and roughly triangular in shape with little to no hinge line. Two species are found in the Coburg formation, R. capax and R. increbescens. Their shell shape is the only easy way to tell them apart as both species have a sulcus with three folds, both have ornamental concentric growth lines, and both can be found in the same layers of the Coburn formation.  

R. capax has a more rounded or rectangular form while R. increbescens is very triangular and ends with a sharp beak on the pedicle valve.

Rynchotrema capax

Ryhnchoterma increbescens 

Pedicle valve

Anterior

Brachial valve

Posterior

Left profile

Right profile

The Coburg formation is Ordovician in age (late Ordovician, Katian/Mohawkian stage).
These fossils were collected from the St. Mary's Limestone Quarry in Bowmanville, Ontario. I used William Hessin's book "South Central Ontario Fossils", 2009, Self Published, pg. 130 to help identify these fossils.