Last weekend managed to get out with two Fossil Forum friends to Arkona. I dug exclusively in the Hungry Hollow Member in search of my bucket list trilobites -- a full Crassiproetus, Pseudodechenella, and the pustular Eldredgeops iowensis southworthi. Long story short, they are still on my bucket list!
But other more modest finds were had. I went ahead and gave them a preliminary abrasion to clean off the matrix and mud. When these were found in the field, they tend to be difficult to pick out given the wet, muddy nature of the rock. The Hungry Hollow doesn't really part along bedding planes in most spots except in the more crumbly shaly partings. When they dry, it takes cleaning to figure out why you took it home with you in the first place!
Here is a group shot of a few, including two gastropods Spinplatyceras:
A first for me. I have found placoderm pieces above (in the grey shale widder) and below (in the Arkona Formation), but never in the Hungry Hollow Member before.:
I'm not in the habit of taking coral home, but this one had a neat shape. As the Hungry Hollow is sometimes more coral than matrix, one gets kind of sick of coral!
A closeup of the large gastropod. Still needs another round of abrasion, but shows most of the diagnostic details. As they got larger, they tended to lose their spiny protuberances. This one has some remaining stubs. Usually if there are Spinplatyceras, crinoids are never far off as these gastropods tended to attach to the anal opening of crinoids to feed on its waste. Yummy. I've yet to find one of these with a crinoid attached.
This hot mess (at the moment) is likely a Pseudodechenella. Nearly complete, but missing some of its left side. The nature of the matrix and the preservation makes trilobites somewhat fragile. Currently, it sits underneath a hard, crusty layer of stubborn crinoid and bryozoan bits. This will not be the world's fastest prep.
When I found this Crassiproetus pygidium, all that was showing was a hint of brown shell. But, once under abrasion, I was able to reveal it in its entirety. Moulted partials are more the norm in this strata, making finding a complete one ten times harder than finding a complete Greenops upstairs in the grey Widder shale.
With much of this side of the continent baking in high, hot summer, indoor activities seem the rational course of action. I managed to doodle two more (Canadian) bugs into life. These are taking a ridiculous amount of time to complete now as I do fuss over every crack, dimple, and pustule, while trying to make sure they occupy the majority of the page. There's probably about 30 hours of work total on these two:
No fossil collecting plans etched in stone as of now, but I'm hoping to get out somewhere once the mercury dips a bit. Until then, maybe another drawing and some prep at the bench, trying to stay cool.
It is very near the one year anniversary of my getting back to the pencils after a few decades' hiatus. Of course, my subject is trilobites as I live and breathe them! I've noted a great deal of progress in my technique in the last year, and since I'm in between fossil collecting trips, this short post hopefully underlines the point.
Like night and day. Of course, the one on the left was a fifteen minute quick sketch, and the one I completed today took about fifteen hours. I've learned a lot in the last year, and set up a number of tough challenges in my pursuit to create photo-realistic illustrations. This will make illustration #33 out of my planned 50 before I scan, print, and bind them in a book. Part of the reason I gave up drawing so long ago was because I had stagnated. Life without the prospect of meeting challenges and to be in a constant state of becoming seems empty to me -- and that is something that follows me from drawing, to preparation, to just about all things I do.
And just a tiny update to round out this blog post. A Fossil Forum friend was very kind in sending me a partial Thaleops from the Stewartville Member of the Galena Formation (Southeast Minnesota) for preparation. Here was how she found it in the field:
And this was after a few hours of prep:
I've been working on a few other pieces as of late, most of which are not yet complete (I swap between multiple projects). I still have a few Gravicalymene in my queue, a faded Ceraurus, lots of Penn Dixie rollers, and the list goes on. But for now, something I did manage to complete after about four hours of some sticky/hard matrix between the segments and some crush/crack issues.
Before and after of this Flexicalymene senaria. None too shabby. One of the most challenging aspects of preparing any Flexi is getting the matrix out from those deep glabellar furrows (the nodular areas on the cephalon at top). Also, negotiation around the sometimes delicate eyes and anterior cephalic spathe, but in this case the crush damage to the cephalon meant work there to reveal more of an anterior brim would not reveal more than more matrix. That being said, the spathe is there. Not a bad representative of the species, either, being about 3.5 cm long.
This will be a smorgasbord post, including one drawing, splitting some gifted shale from abroad, and two prospected sites + finds.
First up, my most recent use of the pencils:
Next, a lot of Conausaga shale (Cambrian) from Georgia, USA gifted to me by my forum friend who came to visit. I took him to Arkona, but we didn't come away with much. I did only slightly better on a second visit when my friend Roger made his annual visit to Canada. But here is a few of the bigger chunks from the 5 gallon bucket:
I made a first pass through these to break them down a bit further, leaving some other chunks outside in the bucket to collect rainwater. They split easier when water-logged. Preservation is a bit dodgy in this shale, but the trilobites are numerous, dominated by Aphelaspis brachyphasis. Here is a shot of an interesting deposition littered with a few trilobites:
A collection of pieces with confirmed trilobites:
Closeups of a few of the trilobites themselves:
My first stop in prospecting for new Ordovician sites was in search of the Whitby Fm shales. Viable Ordovician spots are few and far between as access is restricted given that only one quarry in Ontario permits us biannual visits, development, private property, or provincially protected parks that forbid collecting. This means we are having to fall back on prospecting for new sites, many of which are quite small and require more work to reveal. The pocket I was working was so tiny that it was exhausted in half an hour. Here is some assemblages of Pseudogygites latimarginatus moults. Sadly, nothing complete, but complete ones are rare.
I did take home this chunk for further splitting:
Site number two involved the highly diverse and fossiliferous Verulam Fm. Outcrops of this formation only occur in some creeks, and in quarries. For us trilobite hunters, the Verulam and Bobcaygeon Fms have the most diversity of any formation in Ontario. For obvious reasons of not wanting to see the site plundered by over-collecting, I am not posting any location details -- not even pictures of the strata! We have to take extra care these days given the paucity of productive sites. Here is some typical litter:
All layers were largely dominated by Isotelus gigas, with some examples of other trilobites in the mix. The Isotelus usually appear as fragments, some of which would have belonged to 30+cm individuals if complete. But I'll save the best (trilobites) for last. First up are some typical shell bed hash plates from the uppermost part of the layers. All of the layers contain gastropods, brachiopods, some crinoids, trilobites, and nautiloids. Bryozoans were noticeably absent from most layers.
A weathered nautiloid displaying calcite-filled siphuncle:
I tend to pocket the gastropod steinkerns, mostly of the Fusispira sp. Here is an assortment of steinkerns (gastropods and a few nautiloids near the bottom right) and three brachiopods (Rhynchotrema?).
Let's get to some trilobites. Incomplete ventral examples of Ceraurus and a juvenile Isotelus sporting the long genal spines.
Heads up. One fairly large Flexicalymene senaria cephalon (over an inch wide) buried in matrix, and a juvenile Isotelus gigas.
On the left is a half complete Isotelus from the shell bed layer. Finding them even this intact within such a sifted, turbid zone is uncommon. On the right is the fine specimen Deb found with an exquisitely preserved left eye. The eyes are the most vulnerable area on these bugs, prone to easy breakage. I'll be able to prep this nicely, even if it is not fully complete.
My trip-maker is this 3ish inch semi-enrolled Isotelus. Both eyes are missing, and some parts of the shell are missing, too. The prep is going to have to be delicate as cracks tend to run all through the fossil, and the skin -- although thick -- is very flaky.
I spent about 4.5 hours at this site and only managed to examine about a quarter of it. This was not an all-out excavation visit, but an exploratory scouting mission to track the layers themselves to better guide future visits. For me this is very exciting as it is getting very hard to find viable locations in the Ordovician of Ontario. I hope to get back there again this summer. But it is back to the Devonian for me with two other potential sites to prospect next weekend.