Saturday, January 25, 2020

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.

Thursday, January 23, 2020

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.

Tuesday, January 21, 2020

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.


Sunday, January 19, 2020

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.

Friday, January 17, 2020

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.

Wednesday, January 15, 2020

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.

Monday, January 13, 2020

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.

Saturday, January 11, 2020

Dictyonema sp. graptolite from the Coburg Formation

The second the three Graptolites species that I've found in the Coburg formation is Dictyonema sp.  It appears as a net like carbon coating on the rock face. Mostly you find them on small fragments of rock but occasionally you will get a big slab where you can get a feel for how big some of the colonies could get. Dictyonema is a genus that is extant from the Ordovician all the way thru to the Devonian but it is hard to get a species because most fossils are not preserved well enough.

On this sample, there is also some Melanostrophus sp. Graptolites.




Here is a link to the Baltic fossil ID website, FOSSIILID.info which has some more examples of this Graptolite.

Here are other examples of this Genus that I've collected in the Silurian aged Rochester shale, and Devonian aged Windom shale.

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.

Thursday, January 9, 2020

Melanostrophus sp. graptolite from the Coburg Formation

Graptolites are mysterious lifeforms that lived primarily in the early Paleozoic era. They often formed colonial structures that floated in the water column. Melanostrophus sp. is an odd member of the group in that it does not form straight, segmented colonies. Instead they have curved or wavy structures. According to William Hessin's book "South Central Ontario Fossils", some paleontologists have considered Melanostrophus sp as a type of annelid worm. Whatever the case, this fossil is somewhat common in the upper layers of the Coburg formation and appears as a black carbonaceous coating on limestone surfaces.




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. 264 to help identify it.

Tuesday, January 7, 2020

Sowerbyella sericea brachiopod from the Coburg formation

One of the more common brachiopod fossils found in the Coburg formation is Sowerbyella
sericea. This genus ia also common throughout the Ordovician across the US.  S. sericea is a rectangular shaped shell that has a convex pedicle valve with a concave brachial valve. In the Coburg formation it is often found on the surface of limestone layers covered by shale. At other times I've found them within the limestone layers when I am splitting rocks. At that time they will take on a shiny, silvery sheen as the shells are un-weathered and possibly damaged from the splitting.

Here is a plate with dozens of examples of this species present.



On the back side of the plate are some of the un-weathered fossils I mentioned earlier.


This is another sample where the specimens of Sowerbyella sericea overlap one another in a kind of pavement. This is likely the result of a storm current that swept up the fossils and deposited them in a jumbled heap.




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. 125-126 to help identify them.