Two Days in the Ordovician

[Kane]

Since I had no plans for the Canada Day  long weekend, I opted to hop a train out to the eastern part of Ontario to dig around at two locations, one with uppermost Bobcaygeon Fm, and the other in the uppermost Gull River Fm (which underlies the Bobcaygeon). Plenty of interesting (and occasionally irritating!) wildlife in my travels, and the weather was none too hot and sticky. 

 

So on to some trip photos...

 

 

"First blood" was drawn within twenty minutes of getting started on a clear, early morning. This partially buried Ceraurus plattinensis is complete, although the tail is tucked underneath. A fair size for the species.

[Kane]

 

Also buried (this time under brachiopods, mostly) is a Calyptaulax callicephalus. Just like the first trilobite and every other trilobite in this report, prep should make all the difference.

 

 

I'm usually one to leave incomplete trilobites in the field unless they are rare, or if they are a consolation prize for not finding a complete example. I ritually get Bathyurus and Raymondites confused (I'm sure a few moments hunting down the most recent revision would clear that up for me). In any event, the tuberculate structure on the cranidium suggests to me possibly Bathyurus (Raymondites) ingalli. 

 

 

A bit smaller and flatter than the first cheirurid, another good candidate for prep. I'm comfortable giving this one the label of Ceraurus globulobatis on account of what I seem to see as a dual series of axial nodes that Gabriceraurus dentatus lacks.

 

 

Another Calyptaulax, albeit appearing a bit disarticulated. We'll see what prep says.

 

 

Bumastoides sp. They all too often appear flattened, pending the layer. It can be a real treat to find one that is robust. 

[Kane]

And then the next day it was on to the Gull River Fm. The layers shift quickly from ugly and hummocky limestone to way too argillaceous material that falls apart in one's hands to more stable thick limestone beds. 

 

 

Isotelus gigas pieces are ridiculously abundant. 

 

 

...To the extent I couldn't resist picking up a few parts.

 

 

And a few more. The large pygidium is 7 cm wide, or just shy of 3".

 

 

This cranidium provides evidence that they could attain to a healthy size.

 

 

Parts are fun, but nothing beats finding a complete specimen. This one is on very flaky rock, so a lot of glue and careful prep (if not some tasteful resto where needed) will hopefully make this one a stunner. Some paraloid will also be needed on the back side of the rock. Once I uncover the cephalon, I estimate it should be around 12-13 cm in length, or roughly 5". 

 

 

Bathyurus, for which the Gull River Fm is well known for, eluded me except as tantalizing parts.

 

 

And more sad parts. The only hopeful one of the bunch here might be the piece at the bottom which may be enrolled. 

 

 

Thaleops are also said to be common in this formation. Not so much on this day for me. This tiny steinkern of a pygidium was all the fossil fates would afford me.

 

 

I was not expecting to encounter too many cheirurids, but they started showing up in numbers. The best one on this small plate would be the ventral. There also seems to be something lumpy-bumpy interesting on its left lower side. 

 

 

For whatever reason, they almost always wanted to appear ventrally. The shorter spines and formation tells me these are good candidates for Ceraurus gabrielsi.

 

 

A somewhat unfortunate Bumastoides. In fact, three were encountered that day. The first did not survive extraction. The second is this scrappy piece here. The third showed some promise, but upon closer inspection it did not have a head, so it was leaverite.

 

 

This ranked as the cutest find of the day, a very tiny Calyptaulax (8mm) that had not yet grown into its eyes. Finding these wee ones is also small testament to how closely one needs to look at each surface as this could easily be missed.

 

Overall, not a bad outing, yet nothing truly amazing. I've had much better times in the field, and a lot worse, so this trip ranks as passable to me. I'm itching to get some of these on the prep bench. 

 

[Ludwigia]

Looks like you made some very good finds this time around.

[Denis Arcand]

Thanks for sharing your fossil hunting trip to Eastern Ontario. Your report is well written and includes many excellent images. I found the trilobites comparison particularly instructive. Identifying your discoveries with their scientific names in italics was the icing on the cake!  I am not finding many trilobites, but your knowledge is nonetheless appreciated, I'm sure it will come in handy one day.

 

Edited Wednesday at 12:01 AM by Denis Arcand

[ntloux]

Very nice.