2020 Ontario Trilobite Hunting

[Kane]

B is also for bugs, so let's get to those. First up, the proetids. Pictured is the first and only example of Crassiproetus I've found in this material. It was in my "all day" rock along with four other species (I term "all day" rock as the one rock per trip that seems to pay out for hours of splitting, while other rocks tend to be underwhelming or blank). The second image is of a typical and far too common Pseudodechenella. The reason I bucketed it was on account of exploring a slightly different layer that contained some fairly roughly preserved fossils and corals that came out in hues of purple and pink. 

[Kane]

A good pair of eyes are needed to spot the fragments of these trilobites. The hardy, but (for me) largely elusive Odontocephalus. So far, apart from the one bit of eye/cheek in the second image, I've only found the front margin denticles. 

[Kane]

When the rock is dirty, sometimes the only signal of a trilobite is its negative, such as was the case here. Sadly, the positive was in very poor shape.

[Kane]

But no fear of not obtaining more Anchiopsis anchiops pygidia. Some are still partially buried, so some quick scribe work will reveal those. 

[Kane]

And, finally, what I consider to be Coronura fragments. The first image contains two fragments that do not belong to each other (found in different layers of this rock). The very pustulose appearance, and shape, make me reasonably certain these are trilobite parts, and maybe bits of cephalon. Whether or not they are Coronura is not something I can determine as I cannot find many photo plates of that genera as it is. Perhaps @piranha to the rescue?

 

The second is a bit of a heartbreaker. It is a nice, wide impression. The positive had long eroded away, as it was set vertically within a joint in the rock. As you can tell by the measurement grid, this would have belonged to a fairly substantive specimen. Throughout the same rock were a few isolated segments of about this width, or even just a part of a segment. 

 

I'll likely be leaving this spot alone for a bit to get back through my site prospecting list. I've kept duplicates of some of the non-trilobite fossils to hand around to our fossil folks at some point in the future.  

 

So, in summary, the Onondaga material has furnished me with these five trilobite taxa:

 

Anchiopsis anchiops

Coronura sp.

Crassiproetus ?crassimarginatus

Odontocephalus sp.

Pseudodechenella sp. 

 

[Monica]

What a lot of finds! 

 

Congrats on a successful hunt, Kane!

[Kane]

Thanks, Monica.  

And with all that heavy hammering and hauling, I could use today off. 

[FossilDAWG]

I'm sure your birthday trilobite will still be there tomorrow.  Happy bday! 

Don

[Tidgy's Dad]

Those rostroconches really are amazing. 

Also love the brachiopods, gastropods and trilobits too. 

Very interesting to see the fossils from this formation that i didn't know anything much about. 

[piranha]

The "Coronura Coronation" thread!

 

Coronura aspectans figures from: Stumm 1954 / Hall & Clarke 1888

 

Hall, J. & Clarke, J.M. 1888

Palaeontology VII. Containing Descriptions and figures of the Trilobites and other Crustacea of the Oriskany, upper Helderberg, Hamilton, Portage, Chemung and Catskill Groups. Geological Survey of New York, Natural History of New York, Palaeontology: Volume 7:1-236

 

Stumm, E.C. 1954

Lower Middle Devonian Phacopid Trilobites from Michigan, Southwestern Ontario, and the Ohio Valley.

Contributions from the Museum of Paleontology, University of Michigan, 11(6):201-221

[Kane]

2 hours ago, FossilDAWG said:

I'm sure your birthday trilobite will still be there tomorrow.  Happy bday! 

Don

Thanks for the wishes, and I certainly hope so! 

1 hour ago, Tidgy's Dad said:

Those rostroconches really are amazing. 

Also love the brachiopods, gastropods and trilobits too. 

Very interesting to see the fossils from this formation that i didn't know anything much about. 

Thanks, Adam.  There's a significant bit of carry-over of fauna into the Hamilton Group (about 44-56% from what I've read, mostly brachiopods). One of the very best brachiopod experts has written quite a bit on them. If you can get your hands on any  of Arthur James Boucot's work, you'd be in brachiopod heaven!

56 minutes ago, piranha said:

The "Coronura Coronation" thread!

 

Coronura aspectans figures from: Stumm 1954 / Hall & Clarke 1888

 

Thank you, Scott! I figured the pygidium impression couldn't be anything else, but the pustulose bits now can be placed alongside it. 

Zounds, I really need to locate a copy of Hall & Clarke! It seems that so many of my queries as of late are to be found there, a bit on the dated side as it may be. I do recall that image from Stumm, of course (I have many of the Ontario trilo classics on the iPad, which I bring with me on digs as a kind of compact field manual / de facto camera  ). 

[piranha]

Hall & Clarke 1888 text Hall & Clarke 1888 plates

[Kane]

Amazing! I had thought these were not available/digitized! 

[piranha]

                   

[Kane]

Spent the afternoon in Formosa yesterday. No showstoppers, but some neat stuff regardless. The little mountain has been changed forever now that I've come with serious tools. 

 

Starting this off with non-trilobite stuff. A good assortment of steinkerns and fossils. Platycerids, nautiloids, bivalves, etc. In the group shot, one of those bivalve steinkerns in the middle has both valves. The large gastropod with the low turret on the right was a neat find, and a healthy size (also shown in hand). That big brach in hand has original shell and both valves. The tiny pair is a high-spired gastro with a tiny rostroconch friend. Deb found the wee rostro. I didn't keep some of the larger nautiloids as I already have a bunch. 

[Kane]

The profusion of Crassiproetus bits was getting ridiculous. I kept setting them aside (taking only one or two of the nicest ones -- not that I need more) until it was just getting silly. I did pick up this neat nautiloid steinkern with what I assume would have been some moulted Crassiproetus glabella having washed into the void. I am reminded of some fascinating papers I've read of trilobites being found in nautiloid chambers. This is not an instance of a bug looking for temporary shelter, but likely a kind of sediment in-wash of an abandoned shell. 

[Tidgy's Dad]

Nice finds.

That rock looks pretty hard.

Showstoppers? Not likely at the moment as all the shows have been stopped already. 

[Kane]

Just now, Tidgy's Dad said:

Nice finds.

That rock looks pretty hard.

Showstoppers? Not likely at the moment as all the shows have been stopped already. 

Very true!  

Believe it or not, the rock itself is actually not that hard. It fractures fairly easily along various planes/joints. The whole thing was a massive reef knoll/bioherm, so the only bedding planes occur in pockets or outside the knoll. It is also very vuggy in spots, and almost all of it was subject to serious diagenesis in the form of remineralization and the presence of cementum (which also, sadly, accounts for more steinkerns than actual shell material of the gastros and nautiloids). Some very neat crystal growth in the vugs, though! For the most part, there is a lot of crinoid packstone in all of this -- and only individual bits, never really stems or even calyxes. 

 

The very top of the bioherm is capped with stromatoporoids, and was subject to a bit of occasional subaerial exposure. The very bottom is the genesis of the reefal complex with builders, then binders, and then bafflers (ok, now all of this is likely more than anyone might ever want to know about this stuff  ). 

[Tidgy's Dad]

1 hour ago, Kane said:

(ok, now all of this is likely more than anyone might ever want to know about this stuff  ). 

Not me.

This is exactly the type of detail I like to know so that i can build up pictures of the site and paleoenvironment in my head. 

And then I compare with sites of roughly the same age that I've encountered. Reef formation is fascinating. 

The stromatoporoid reefs always interest me too. 

[Monica]

Nice stuff, Kane!  The big gastropod and brachiopod are beauties, as are the itty bitty gastropod and rostroconch pals   Congrats on a successful hunt yesterday!

[Peat Burns]

On 4/1/2020 at 5:44 PM, Kane said:

And this one rock, a slab about a metre wide and long, and about 50 cm deep, was so full of brachs that it seemed more brach than matrix.

And some of them were huge. 

Oh, and rostroconchs. Zillions of them. 

[Peat Burns]

On 4/5/2020 at 7:10 AM, Kane said:

Rostroconchs galore + gastro steinkerns (and one tiny brach with both valves -- I pocketed a few of these if they were intact). But have a look at those large rostroconch. For as much as these are a bit of a nuisance in my layers, I was impressed with these ones.

  

[ClearLake]

I, like others, am just amazed at the number of rostoconchs!  I have always considered them a relatively rare mollusk, but of course that could be my mistake.  That’s just the way it has been where I have collected. They are really nice looking ones too from what I can see. My former thesis advisor would be drooling over those were he still around! 

[FossilNerd]

23 hours ago, Tidgy's Dad said:

Not me.

This is exactly the type of detail I like to know so that i can build up pictures of the site and paleoenvironment in my head. 

Well said Adam! I also enjoy, and appreciate, the detailed descriptions and extra information. 
 

@Kane

I’ve been scarcely on TFF for a few days and look what I’ve missed! Great find my friend! Some of those rostroconches are beautiful and I’m fond of the stromatoporoid. I have a soft spot (or better yet, a “spongey” spot) for those with well defined mamelons. 

 

The bugs are also nice of course! Fingers crossed that you get to find more, better detailed, and complete, Odontocephalus. 

 

[Kane]

On 2020-04-07 at 6:55 PM, Peat Burns said:

You do know I am collecting a few of these for you, right?  

On 2020-04-08 at 1:00 AM, ClearLake said:

I, like others, am just amazed at the number of rostoconchs!  I have always considered them a relatively rare mollusk, but of course that could be my mistake.  That’s just the way it has been where I have collected. They are really nice looking ones too from what I can see. My former thesis advisor would be drooling over those were he still around! 

They are generally quite rare... except in some locations like here. Abundant to the point of monotony! If there was a rostroconch-trilobite trading post, I would be there!

On 2020-04-08 at 8:15 AM, FossilNerd said:

Well said Adam! I also enjoy, and appreciate, the detailed descriptions and extra information. 
 

@Kane

I’ve been scarcely on TFF for a few days and look what I’ve missed! Great find my friend! Some of those rostroconches are beautiful and I’m fond of the stromatoporoid. I have a soft spot (or better yet, a “spongey” spot) for those with well defined mamelons. 

 

The bugs are also nice of course! Fingers crossed that you get to find more, better detailed, and complete, Odontocephalus. 

 

I'll save the stroma for you if you want it.  If there are any other (non-trilobite) things you want from my spots, just let me know and I might be able to ship them out to you when I can.

 

 

Sorry for the delay on your lovely responses to this post. I will be in the field tomorrow with the Onondaga spot all to myself. More for me! -- and for others.  If people need brachs and bivalves, I'm sure I can supply. 

 

And you, too, @Tidgy's Dad -- I owe you a massive, expensive, multi-location package. Let me continue building your box.