Tomorrow is back to work (or, 87 days until the end of the semester). I'm getting an early start on the season, mixed with post-season activities. On January 3rd, I spent about four hours out at my spot reducing bigger blocks into smaller ones. Not much at all was found that I was going to bring home, and certainly no lichid fragments save for one that was simply not worth it. But, at least I was out there before the snows came.
I didn't take more than a photo of this one as an interesting an illustrative example of a bedding plane with a sponge. Looking more closely, there are at least three rostroconch in the mix, a few trilobite pieces, a rugose coral, and maybe a few brachs. This photo was more about the bumpy sponge, however.
I got in the lab a few days ago as well to prep this trio of Eldredgeops rana rollers from the Arkona mudshale. I mostly relied on abrasion. This stuff cracks as it dries, so I needed to stabilize a few spots with cyanoacrylate. The bugs in this stuff are generally smaller than those at Penn Dixie, and those that are approaching that size are usually very poorly preserved. In this case, these are near Penn Dixie proportions, and just a little bit crushed. Their delicate, flaky nature in the Arkona meant that I had to leave some of the matrix in place -- and particularly where they crush leaving a kind of sharp crest rather than a rounded area. In the process, an eye flew off the bottom ventral, but I miraculously retrieved it from the blast box debris and glued it back on.
A good fossil friend of mine recently purchased a large lot of unprepared Moroccan bugs from the Devonian layers of Jbel Mrakib. He was kind to peel me off four of the easier pieces (mostly phacopids and proetids -- nothing with ridiculously complicated spines). This will be practice for me, and my first Moroccan bugs for preparation. The matrix is much harder than anything from my collecting areas, but the CP can get through it. My first go is not going terribly well, but I'll keep at it. These are all common bugs, so I expect to ruin a few as I learn. The question will be if my tools are up to the job.
And yesterday I completed a drawing I had barely started a week before going to Jamaica.
So, that makes three out of five regular fossil-related activities to kick off 2020: collecting, preparation, and illustration. Hopefully it won't be long until a few new articles come my way so that I can fulfill the research portion as something to make the daily work commute on the bus more tolerable. The fifth activity is to continue some remote prospecting work to identify more potential sites for 2020. So far, I have about five locations, two of which span larger areas that may contain multiple outcrops. There are also a few must-revisit locations, too. Just 87 more days until collecting and in-person prospecting can be added again to the mix.
It is still rather remarkable that I'm able to get out for fossil adventures this late in the year, although there is no doubt that winter will have its final say in the days to come, possibly as soon as New Year's Eve.
On December 27, myself and two other collecting comrades made our way to another part of the Devonian of Ontario for an all-day dig event at an undisclosed location. The focus may have been on crinoids, but other stuff came out, too.
Preservation can be a bit iffy on this material, but here is a crinoid terminating at the top with a calyx and its attendant spinplatycerid. It will look a lot nicer once I get it in the prep lab.
A collection of calyxes, still dusty from the field. The one near the bottom still has some of its arms showing. These should all prep out nicely.
A calyx parked between an interesting plant fragment above, and crinoid arms below.
Closeup of the underside of a calyx showing the stem/cup attachment.
A real oddball we found. This is plant material, but note the fascinating barbs.
Trilobites, too, although they tend to show up rather small in this layer (larger ones are quite flaky and do not preserve well). A trio of Eldredgeops rana rollers on the left, and a mini roller on the right (a few millimetres wide!).
In all, a good outing and everyone came away with something. But today (December 28), it is back to my spot for another go at the Amherstburg material in search of more lichids and the dim hope of a complete proetid before the snows be a-blowin'. I'll update this post later with whatever I may find if I don't strike out.
Managed to spend two more days at my site. No major fireworks to close out the collecting season, which I officially put to bed on December 30th, 2019. I'm mostly left with second- and third-best rocks at this point that tend to be harder and more often blank or small bits. Still somewhat productive, though.
An Echinolichas in pretty poor shape. I found another similar one the day before that was in even worse condition. That being said, it pays to split the harder/blanker intervals as this lichid likes to appear alone.
Bit of a blurry shot since I was too lazy to bring out the Olympus, but it is likely another tiny Mystrocephala stummi.
I picked these up because they were interesting. The first is a completely chert-ified rugose coral slice, and the second is a monster Strophodonta brachiopod.
It is always sad to bid farewell to a collecting season, but there are a few things I won't miss... The brutally tough stone, the bullet-like shards that strike my shins and face, the tedious process of having to unlock rock that stubbornly holds on even if it wiggles, the endless parade of corals and rostroconchs.
And I've already dipped into post-season activities in spending a few hours in the prep lab and getting back to drawing and research. This blog will not be left in winter silence!
"Yes, this was the last day... I mean it this time!" -- Given the number of times I called an end to the 2019 fossil season (November 1st, 20th, and 26th), I seem to have embodied the postmodernist novel's unreliable narrator.
But when the temperatures are going above freezing, and there is little to no snow on the ground, why would I wait until spring? As the winter forecast is calling for brutal snowstorms, the polar vortex, and likely a long delay for spring, getting out there whenever the conditions are lined up makes complete sense. This is the unexpected surprise opportunity after returning from Jamaica.
These are the shortest days of the year, so I had to wait until about 8 am for the sun to rise, and then another hour for it to warm things up a bit. When I reached my Amherstburg Fm site, the ground was still frozen (including some of the rocks), with some snow and ice. But after a few hours the temperature soared to about 6 Celsius(!), but not warm enough to melt the snow in the rocks' shadows.
It was not the trip of all trips, but I did okay for this being late December.
This was first blood: a Crassiproetus crassimarginatus pygidium. This, and several other proetid pygidia, I left in the field since it would have taken too much effort to reduce the matrix just for these. And, like most trips, this was the rock that would pay out while subsequent rocks would be largely duds.
More "leave 'em in the field" specimens, mostly of the large brachiopod, Strophodonta. How big? The largest of the bunch has a width of about 3+ inches (~7.5 cm).
The nice articulation of this rostroconch (Conocardium cuneus) persuaded me to bring it home.
The tripmaker was also a heartbreaker. Pictured here is an Acanthopyge contusa pygidium, but with very nicely defined pygidial spines. Sadly, it's an impression that I noticed some time after I had been steadily reducing the bloc, and my search for the positive was to no avail -- likely lost to flying hammer blows or as a chip fallen through the cracks. I also found an actual positive of another example, but the preservation is so poor that I can't bring myself to post it here.
But it isn't over yet. Today promises to reach 8 degrees celsius, full sun, so I'll be returning. This post will be updated later.
Another not so productive day; plenty of rock split, but nothing much to show for it. A good chunk of time is spent searching for the right rocks. The fossiliferous ones with trilobites are very hard to find amid the usual blank, sparse, or complete blanks. I thought I would dedicate this portion to the process.
Scouting the right rock requires a bit of eyeballing of the outside to determine what sort of fauna (if any) would be on the inside. I also go by colour and texture, so if it is grey-white, tan, or brown, then I might go to town. Those rocks that have these features but appear blank on the outside or with too many tightly packed black wispy mineralization lines are generally either blank, filled with mineralization trails with the occasional small rostroconch or coral, or just sandy matrix supported colonial coral tubes with nothing else. If the matrix grain is too large (like sand), it is unlikely to support much else but coral and small brachs. If the rock is too fissile, it is usually also too bituminous and contains a few toppled corals and mostly dimpled stromatoporoids -- which is an indication that I'm too high up at the cap of the reef, which may have been subaerial or at least far too high energy for anything but the sturdiest to settle.
Finding a rock that meets the criteria of colour, texture, and promising vertical appearance does not guarantee that the interior will be a "trilobonanza" either. Some of these may contain just shredded bryozoans and a few small brachs, amid some toppled and broken rugose corals. When seeing that, I know the deposition conditions were far too sediment-worked and high energy to support trilobites. They may also be incredibly dense so that there is no chance of hitting a bedding plane. And by dense, I mean even harder to split than they already are. That stuff breaks in fractured, conchoidal chunks wherever the rock is weakest. Not good.
Once I come upon one of those rare rocks that seem to meet my criteria from experience with this material, I spot check the top and bottom where possible to get a sense of what "chapter" I am in the story. I know, for instance, that a top portion containing large horn coral means I have to split down a few inches below it. After that, I may also see if I can cleave a piece vertically or work my way down that way to pinpoint the busy bedding planes.
One indication that shows promise is in finding larger fauna, such as big brachiopods and intact fenestellate bryozoans. Of course, if the plane is busy in general, that can be an indication, but again not always: at times it is busy with just tiny fragments. Or filled with vermiculating tube coral. Or just branching bryozoans.
If the rock has even a single trilobite fragment showing, such as a free cheek, a genal spine, or a pygidium, it is marked for excavation and splitting. Again, there are no guarantees that the rest of the rock will be as generous.
This is an example of the process. I've wrestled even larger, armour stones, from these piles, so this is not the most challenging example:
As this rock showed some promise, I cleared away some of the overlying rock to the upper left so as to have a closer look at its layers. Compounding the difficulty was that this was early morning, and the mud is frozen, as are some of even the smaller rocks that need to be tapped with the hammer before removing. In this image, I've already done some exploratory slicing of the top and was intrigued with what I was seeing enough to continue.
Clearing away more debris around the rock. At this point, I'm unsure just how deep this runs. The small pry bar is not budging this, and I usually stop trying when the bar starts bending. What I would learn later is that this rock was running under the even larger rock to the upper right. Sometimes it is a game of unlocking rocks whereby you need to unlock the rock by removing those around it, but then you find those other rocks are also locked in by other rocks, and so on. I try to limit those instances as sometimes it seems never-ending, and I will encounter a rock that weighs over 600 pounds that I just can't budge.
By this point, it has been nearly an hour. I've done some exploratory chiseling, but the rock is too thick and dense to get clean slices. Instead, it tends to fracture upwards, which is useless as it creates rounded concavities that make splitting impossible. So why not use the sledge and swing it against the exposed upper left? No dice. All that smashing achieves is a mashing and denting. How about a chisel? Can't go too deep down on this as I'll just end up driving the chisel in about an inch and creating tons of powder and no break. What about coming from the lower right? A sensible approach...but this is a game of angles at times and what this picture does not show well is that the rocks on the lower right are on an incline while the main rock is on a slight inverted incline, which means the chisel won't go in straight.
When all else fails, and no measure of even the most awkward angles of hammer and chisel will work, or pry bar will budge for clean extraction, it is time for brute force. In this case, I exploit any visible weakness in the rock and go for a vertical split. It's not ideal as it might cleave through fossils, but sometimes you need to break eggs to make an omelette. Having exposed a chert area with a hairline fracture, in goes the chisel and down comes the sledge hammer. It isn't a big chunk, but it may help going forward. This is the beginning of the momentum in removing this one. Sometimes those cracks are superficial, and sometimes I have to repeat this chunk-split approach a few times if the rock is even larger than this one.
Hundreds of hammer blows later and some artful chisel-action, I'm able to split the top off this one. The pry bar was needed to remove it as it was partially stuck under the bigger rock, and that meant gradual push/pull in a game of inches to slide and wrestle it off. That leaves just the lower half, which is still deeply lodged in the dirt and debris.
Inspection time. Let's have a look at the upper portion. Apart from a big brach and a few big bryozoan pieces from about an hour earlier when slicing the uppermost part, this seems to have a bit of promise. I set it aside for splitting later.
Both pieces are out! The one on the left is actually quite thick (about a foot on its widest edge). A Crassiproetus pygidium is showing at the top of this one, and you can make out its impression on the rock right next to it. I'll still need the sledge to split these into more manageable pieces for the rock hammer. From observation, I note that this entire rock has just two active bedding planes. Sometimes even the bigger rocks may only have one thin plane, and these are very tightly packed. The rest of the layers tend to be sparse, broken bits or entirely blank.
So, the result of about 90 minutes of hard work and frustration? A 3 mm wide pygidium of what I suspect to be Mystrocephala. Yes, all that work and splitting for a 3 mm fragment. If I specialized in collecting non-trilobite fossils, this rock would have been more gainful. As disappointing as the ROI is on this bloc, at least it was something! Other instances have led to zip, or sometimes the rock that just keeps on giving. There's never really much certainty until you excavate and split them.
Six hours of scouting and pounding through mostly blanks and bits didn't net me much more today other than this fragment of an Acanthopyge pygidium, with some kind bryozoanal growth on its left side. I've had better days! But, the viable rocks are getting much harder to come by, and I'm having to default to the B- and C-piles.
I'm not going to say the season is done yet. There looks to be a few more good days in the forecast for one more go. I've marked two so-so potential blocs for splitting that I'll get to first so as to save time on scouting.
Xmas Eve: Totally skunked. It seemed what few potentially viable rocks I could find were just loaded with corals and uninteresting fragments, so I came home with nothing despite putting in a good six hours. I had queued up a few larger rocks two days earlier for splitting, but those were a bust. However, no sense in complaining, and this might have been only the second or third time I've ever come back with absolutely nothing to show for the effort.
Boxing Day: A much better outing than the last one. Although I can't say I came back swimming in riches, I did have much more luck.
On the left is the impression of another Echinolichas eriopis. The positive side is only one half of the pygidium, and seems resistant to good photography which would otherwise show its nice pygidial rib annulations. On the right is a lichid genal spine / free cheek that is still attached to the glabella (which itself is under a bit of matrix for me to remove). This would be a first in finding an attached cheek to this lichid (possibly Acanthopyge, but I'll have to uncover the glabella to be certain).
The new trick is not to turn my nose up at a certain B-pile type of rock that is largely blank, but of the right strata (not grey, but the light tan colour). What is blank can quite surprisingly display a sudden busy layer, but it is not obvious when reading the rock's vertical record. It means persistent trial and error splitting. I've now queued up over ten metric tons of this type material for my next return, which likely won't be until tomorrow (Saturday, December 28) as I'm due to hang out with some of my fossil buddies on a trip to Arkona today.
So just when I come to desperation (yet again) that I've exhausted my site's possibilities, a bit of itinerant, exploratory splitting has opened up new possibilities. Granted, the rock is perversely dense, frustrating in many places, and some of the rocks marked for breaking down are the size of a trunk, but I'm nothing if not determined.
I'll likely have tomorrow and Monday to get at them in search of more lichids. After that, it is likely that winter will bury and freeze all hunting trips until spring. Still, this welcome and unexpected extension of the season means I have to make the most of it!
Today was a gorgeous day, and it is somewhat fitting that the last day of the collecting season be sunny and warm. Yes, this was the last day... I mean it this time! As there are only 11 days left until vacation, a mountain of essays to read and grade, and the fact that winter weather is going to return and stay in earnest, today was it.
The rocks were heavy and hard as always. I didn't come away with as much material as some of them were absolute duds. Like last time, most of the gains were made from a single rock. Let's lead off with the usual suspects:
Left: I think I found this one on a previous trip, but it was in my bag when I was emptying it. Likely a Mystrocephala stummi with mineralized goop on the posterior border of the shell. Right: the ever-present and readily available Crassiproetus crassimarginatus. I am impressed with just how large these ones can get in this material.
There were plenty of Pseudodechenella pygidia (and free cheeks galore), but all of them were on the small side and situated in the middle of larger rocks, so not really worth the effort to reduce and bring home.
When tubercles are showing, that means lichids are in the house. I'll need to clean this one up.
I also found (not pictured) the thorax of a Pseudodechenella that needs to be glued, and a very well defined cranidial fragment (median lobe) with exquisitely detailed tubercles.
This one is pretty tricky to photograph as it seems that my devices try to overly blend the specimen and its matrix. The left is the positive, which still has some parts concealed under matrix. On the right is the negative. Yes, another candidate for Echinolichas eriopis.
A few more attempts to photograph the positive from different lighting angles. What are the chances of finding a new lichid twice in as many days? This one is as large as the one I found Sunday. Whereas the former one has a bit better detail on the pygidial ribs, this one has evident pygidial spines (with tubercles!). There is still an opportunity to reveal more on the right side.
It was nice to end the season on a high note. Although I never quite seemed to find an absolute complete trilobite in this material, these last three months have been filled with surprises. Trilobites in the Amherstburg are very much a faunal minority compared to the thickets of coral and bryozoans, but I made out okay for the effort. The site will now be waiting for me in spring.
Down tools. For real this time!
At this point, I'm just about ready to summarize some key findings, pulled from my field notes, about this imported material. As stated in previous posts, it is reasonable to assume judging by the lithology and presented fauna that this is material from the Amherstburg/Lucas Fms. The nearest and cheapest source of this material for the purposes of a drainage area riprap would likely trace this material to a quarry or quarries in Ingersoll. As it is unsuitable material for cement, this material is generally stripped off.
The fauna is suggestive of a minor reef community. Apart from the thickets of toppled rugose coral (likely due to wave action) and some colonial rugose as well as tabulate (Favosites) communities that have considerable in-fill suggestive of rapid sedimentation burial, the common presence of bryozoans as binders does point to reef development. Bafflers such as crinoids are more scarce in these sediments, possibly suggesting a lack of cohesion and maturity of these minor reef complexes. In some of the materials, thin black layers may suggest a shallowing sequence and possible subaerial exposure in shallow, possibly peritidal conditions. Deeper waters are reflected by the appearance of some packstone pulses with larger grain-size limestones. The upper portion of the material with black stained shale partings or a higher appearance of chert nodules (indicative of siliceous sponges) may contain stromatoporoids, branching bryozoans, and rostroconchs (?Conocardium cuneus). Likely presence of algal mats.
What is known is that this environment would have been situated in the Appalachian basin, southeast of the Findlay arch (by current orientation). It is not unreasonable to expect shared faunal elements with equivalent strata found in New York, such as the Onandaga Fm, and more particularly with the Edgecliff, Nedrow, and possibly Moorehouse Members.
Trilobite fauna are generally represented as a minority fauna in these relatively small coral bioherms. When present, disarticulated moults are suggestive of higher energy conditions, likely swept into gaps and pockets in the biohermal mass. Of note is the complete absence of phacopids, suggesting the environment was not well suited for their spread into this particular biohermal region. Instead, burrowing proetids are relatively abundant, including the illaenimorph Crassiproetus crassimarginatus that appears most commonly in these sediments, followed by Pseudodechenella sp..
Here is a comparative table of trilobites of equivalent geologic age appearing in three locations. A-SITE = the area under study; A-ON-FR = Formosa Reef, Ontario (Michigan basin); O-NY = Onandaga of New York.
As is evident from the table above, only two species of trilobite are shared between the three locations. My location shares three trilobite species from the Formosa Reef, and five with equivalent strata of New York. Two species (in bold) are shared across all three strata.
The seasonal highs for the year have been sticking around after our initial arctic bursts. So, on a sunny Sunday I was back out to my Amherstburg/Lucas Fm spot.
Some rocks I had written off as not as viable have turned out to be much more productive than I thought. Case in point would be another larger piece of armour stone to break down. It seems that, for each trip, there is usually that one rock that gives up the most goodies. So the focus here is on a single rock this trip.
No doubt about this rock being from the Amherstburg Fm, as here is a Mystrocephala stummi (albeit in a rather poor state). Several fragments of the proetids Crassiproetus and Pseudodechenella appear as well, as is usual with this material.
This looks to be another genal spine (possibly belonging to Acanthopyge contusa), but it seems to be curving up and out. The two tubercles on the right appear to be on some kind of axial ring? Huh? I'll need to clean this one up a bit more to figure out where this fits. I initially picked it up thinking it might be a thoracic segment. But the spiny processes seem identical in their orientation to previous genal spine fragments.
A closeup and greyscale image of a fairly mashed lichid cranidium, likely Acanthopyge contusa with the tell-tale scattering of tubercles.
This was the trip-maker. Positive and negative. As is usual in these rocks, the preservation is not ideal. Also, the amount of force needed to split these rocks sometimes results in unavoidable damage in the field where parts of the rock are pulverized forever with no chance of retrieving much more than dust and flakes. The state of the positive (left) had me utter an expletive, but let's focus on what this is and not fixate on its aesthetics. This is not like the many small (~1-1.5 cm wide) Acanthopyge contusa pygidia. This whopper measures 3.5 cm wide.
Notice the middle of the pygidial axis and that it has a kind of prominent "bit" that looks like an oversized tubercle. That is actually the base of a spinal process.
I've grey-scaled and boosted the impression side to better show the pygidial outline. So what is it? We can likely rule out Acanthopyge contusa on account of a few factors (the robust width of the ovoid pygidium, the additional number of pygidial spines --three on each side plus two smaller ones on the postaxial border, the presence of pygidial rib annulations). The pygidial morphology seems very similar to that of Terataspis grandis, with the exception of the short, backward curving spines.
So it's not quite a match for either Acanthopyge or Terataspis -- and yet those are the only two Devonian lichids reported in Ontario. So I tapped the expertise of our Fossil Forum trilobite master to assist in finding the right fit for this oddball. According to him, it may be a match with Echinolichas eriopis, listed as Lichas (Conolichas) eriopis in Hall and Clarke (1888):
(Image from: 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.
The spinal process, if complete, would have been quite long. Hall & Clarke report it as being in the "corniferous limestones," which was later revised to the Onandaga Fm. The equivalent strata in southwestern Ontario would be the Amherstburg/Lucas Fms so it fits the geologic age of the material. J.A. Fagerstrom draws from E. eriopis as the type specimen from which he distinguishes E. parallelobatus in the Formosa Reef (Amherstburg Fm), but Rolf Ludvigsen (1987) distinguishes the Formosa Reef lichid as being Acanthopyge contusa. It is not unreasonable to consider E. eriopis as appearing in strata equivalent rocks in Ontario given a shared cratonic basin with New York, but it is not yet reported in the literature, making this perhaps the first of its kind on this side of the border as far as I know, and according to the literature.
So, once again a lichid fragment has me all excited. It means there are still hidden surprises in these rocks after three months of diligent field work. As it looks like tomorrow will be warm and sunny -- perhaps the very last warm and sunny day left in 2019 -- I plan to return to the site and continue my exploration in the hopes of finding more.
Completely unexpected, but the last few days have been about 4-5 degrees above freezing, which has allowed the snow to melt. A partly sunny, snow-free day at 5 Celsius happily coincided with my day off, so I went out back to my Amherstburg/Lucas Fms fill.
I spent most of my time with one very large piece of armour stone that weighed north of a ton. Persistent sledgehammer + chisel + pry bar meant I could reduce it to chips. It was a generous rock, too, with abundant trilobite pieces from top to bottom. In fact, it had numerous representatives of 4 out of the 5 species that appear in this material.
My best find was this Acanthopyge contusa pygidium. Although the rock split was unfortunate, the preservation is actually quite good for this material as I can make out the pustules and pygidial ribs fairly clearly:
I also picked up interesting brachiopods and gastropods (not pictured) that will be going into a gift box. Here are some other trilo fragments from the rock that kept on giving. I am trying to perform relative due diligence in collecting these as I may need to consult with some earth science colleagues to unravel a few mysteries about this material.
Not a bad haul on a cooler day.
So is this finally it for the season? Perhaps, but pending how steady my final essay grading goes, it looks like there will be another potential dig day next week.
And to close out this post, my fossil comrade Malcolm sent me pics of the Eldredgeops iowenesis southerworthi cephalon I found back in the summer. It very much needed stabilization, so I entrusted the prep-master himself. This is stabilized with paraloid as the whole thing was crumbling apart (as is common with Hungry Hollow material).
There's been snow on the ground fairly consistently since the beginning of the month, but I did manage an encore visit to my local spot on November 4, and may have another opportunity for the same this week when the temperature "soars" to about 6 Celsius. When we've seen a few days of arctic blasts that make it feel more like January, you take what you can get!
I've been scratching the fossil itch in a number of ways. I'm reading a few fascinating dissertations and journal articles on isotopic analysis of the Hungry Hollow Member, another on the deposition conditions of the Kettle Point Formation shale, and one on measuring coral ridges as paleoenvironmental indicators of the Widder Formation. And at least one classic by Brett and Landing on the Givetian disconformity in Southwestern Ontario. Some ask why I don't just go and earn an earth sciences degree as (as one postdoc told me) I seem to be far more capable and knowledgeable than most recent BSc grads. Flattering, yes, but I suppose I haven't been presented with that option being a true crime of opportunity. Besides, the one advantage I have in being a well-versed amateur is that I don't have to split my time between the field and the lab (+teaching and grant-chasing); it can be all field fun for me! Besides, if I wanted to pursue a degree in everything I am interested in, I'd need a few lifetimes. The happy medium is to read voraciously and talk shop with the professionals.
This past weekend I went to the annual London Rock/Mineral show. It was great to talk shop with diggers, knowledgeable vendors, and some geo-scholars. It was more a social visit of several hours, as there are not that many fossils at shows like these -- mostly minerals and jewellery. Most of the fossils on offer were the usual common stuff, like polished Madagascar ammonites, Utah trilobites (i.e., endless Elrathia kingii), etc. But I did buy something from a French vendor who was a geology teacher in Morocco and knows all the big paleo names that have done research there.
Fairly common Moroccan bugs that I got as a package deal. Not the best prep, either, but passable (and not butchered). The vendor was up front about some areas that have light restoration, although I could pretty much tell upon having the specimens in hand. To my collecting shame, I didn't yet have a complete Reedops cephalotes, which is fairly common. My first one is missing half of its back end, so it was nice to have one complete and prone. It is about 80 mm. The one at the top of the picture is the classic Paralejurus rehamnanus and measures about 70 mm.
The other fossil-y thing I did this weekend was get back to some drawing that had been put on hold due to teaching/grading duties (and so is again back on hold as I navigate what remains of the semester!).
Calling the season's time of death today on November 1. And so it is down field tools for 2019, and taking up the prep tools for winter (may it be short and merciful). Unless there is a miraculous change in weather to permit an encore, this is it. The next two weeks look like pre-winter is setting in, and the last two weeks of November are a bit of a write-off as the end of semester grading will suck up all my available time.
In retrospect, it is tough to pin a qualifier on this collecting season; neither was it the best nor the worst. Like life itself, there were incredible moments/finds that punctuated a series of disappointments. Not that many new trilobite species were added to the collection this year, but the few added were nothing short of exciting. I ranged from the Ordovician to the Devonian.
I’ll kick things off with this year’s disappointments first to get that out of the way.
1. My local honey hole that had pretty much ran dry the previous year had not produced anything new from weathering; in fact, it has been steadily overgrown since I first collected there in 2013. A few desultory visits during the spring mean splitting shards from my own previous trips. Tapped out.
2. Our upper Widder spot was quickly made off limits by mid-April. Fortunately, I did find a really nice and large placoderm dorsal plate before the window of opportunity slammed shut. As that spot was the regular go-to for our out-of-town crew (and fossil comrades who visit once a year), that put a major dent in options this year. This would be the first year since I started that there would not be a season to develop the site and extract Widder goodies. Also, extensive work at that location for so many years has pretty much made it unsafe and not so viable for excavation. We had to fall back on prospecting new areas, and defaulting to the Hungry Hollow Member, which is not exactly the easiest stuff to work with -- it's muddy, chunky, coral-infested, fragile or shattery.
3. The annual trip to NY at the end of April was brutally cold with sleet and snow. I also came up empty-handed from my trip to Deep Springs Road (apart from field comrade gifts, of course!). So no full Dipleura found.
4. A second trip in August to Penn Dixie did net a few buckets of material, but the exposed area for excavation was brutally hard, unweathered, and likely a point where the trilobites were pinching out laterally. It meant twice the work for half the haul.
5. A road cut in the Cobourg Fm that I prospected in July turned out to be a bust when exploring it in more detail in late September.
6. A second trip to Bowmanville, which is usually the capstone of the collecting year in autumn, was preempted by car trouble.
6. Plans to visit some very coveted private spots did not materialize for one reason or another.
But it wasn’t all a bust, strikeouts, and skunked trips. I can count a few victories this season:
1. Finding one of the largest placoderm dorsal plates found in the Widder.
2. Plenty of improvement at the prep bench, in addition to new tools (PT Aro and ME-9100), new higher capacity compressor, and a top shelf camera.
3. Finding a perfect Flexicalymene croneisi prone specimen during the June Bowmanville trip. Finding them prone is rare as opposed to enrolled.
4. Prospecting that new spot near Nottawasaga Bay — even if it turned out to be an unproductive dud later on in the season.
5. Any and all time spent with field comrades from near and far: Malcolm, Greg, Kevin, Roger, Don, Paleo Joe, Tim, Jeffrey, Jay, James, and everyone else I broke rocks with this year.
6. Finding a nice, large cephalon of Eldredgeops southworthi in the Hungry Hollow coral-tangled muck-rock. We sourced the layers from a new, untouched spot (now pretty much tapped out).
7. Finding a new local honey hole on August 22 that was a real game changer that truly turned the season around. It is there that I pulled out my first Terataspis grandis fragments, and two nearly complete Pseudodechenella sp., in addition to a healthy number of Acanthopyge contusa, and a two examples of Mystrocephala stummi.
8. A fascinating trip to the type locality of the Formosa Reef member of the Amherstburg Formation, focusing on the windward flank netted plenty of goodies.
9. Not collecting-related, but I took to drawing trilobites seriously this year with substantial improvement — enough to have a few of them featured in The Trilobite Papers.
10. Compiling a master list of Ontario trilobites has become its own archivist’s passion.
So, on balance, 2019 had its ups and downs with the “ups” cancelling out a lot of the “downs.” With more site closures and stuff tapping out, this was a year to forge ahead and explore new possibilities as opposed to being resigned in not letting the hammers ring. I didn’t buy many trilobites this year, which can account for the decline in species-adds this year. That being said, costs were still a bit high given new equipment and a few sunk costs on accommodations.
Trip Totals (days):
Local honey hole (old spot): 4
Local honey hole (new spot): 25+
Penn Dixie: 5
(~50 days) (last year ~34)
I was able to get out there more this year than last year despite a narrowing of site options. Now on to what I consider to be this season’s top finds:
New species to the trilobite collection that were a result of my fieldwork include Pseudodechenella sp. (from the upper edge of the lower Devonian; not yet clear on which species, but they are distinct from other examples of the genus found later in the Hungry Hollow Member), Terataspis grandis, Acanthopyge contusa, Mystrocephala stummi. So that makes two new proetids and two lichids. So, like 2018, my self-collected tally for new species was 4. There may be more than that, but I would need to spend time with Lieberman’s text on proetids of Eastern North America to determine if I have any species variants of the many Crassiproetus pygidia I’ve collected from my Bois Blanc / Amherstburg material.
This is a good time as any to feature all the Acanthopyge contusa heads and tails from my new local spot:
As I also found genal spines (but no determinate thoracic segments), I sketched a quick reconstruction that perhaps I'll try to formalize as a better illustration in winter:
In my dogged pursuit of long dead things, I shared my collecting spots with living things, too:
And, O! the messes we will make. Some snaps of sites and fossil comrades breaking rock together.
Now that fieldwork is at an end for 2019, it is time to start planning for 2020. Last year I didn’t plan as well as I could, which meant kind of starting off on the back foot. That, and a delayed spring and taking a few sites for granted, meant not optimizing on the time I usually have off once the academic year is over. So now begins a sitting down with the maps and to carve out the areas throughout Ontario that could use some pioneering work in exploration and prospecting, if not also visiting now forgotten spots.
I also received a lot of of great gifts from other collectors this year, and performed a lot of prep, but this end of year report is already fairly picture-heavy as it is.
Although I don’t have a massive amount of material to prep for winter, I still have some work I can do. Perhaps it is just as well since in terms of time: I’ll be teaching a heavier load in winter in addition to taking a sunny holiday in February. There will be more blog posts in the off-season as I tend to get caught up in some fossil thing or another.
On a warm Sunday, I made it up north to the Formosa reef road cut. It was likely my last major trip of the season, and it certainly did not disappoint. I had read and re-read the research papers on this site, which is the type locality for this massive biohermal feature situated in the Amherstburg Formation. The two main sources would be these:
Fagerstrom J.A. (1961) The Fauna of the Middle Devonian Formosa Reef Limestone of Southwestern Ontario. Journal of Paleontology 35.1: 1-48.
Ludvigsen, R. (1987) Reef trilobites from the Formosa Limestone (Lower Devonian) of southern Ontario. Can. J. Earth Sci 24
The road cut itself is quite sizeable, and represents a massive knoll. My focus was on the windward side of the reef where skeletal debris would have been swept in by currents. The wackestones and stromatoporoidal boundstones contain a staggering amount of faunal diversity. There were certainly corals, both tabulate and rugose, but just about everything else including gastropods, brachiopods, bivalves, crinoids, and a profusion of different kinds of nautiloid. Of course, there are trilobites as well, but none have been reported complete.
The cut runs along both sides of the road, with additional access from behind the reef as well.
And it is fairly tall, too. There really is an abundance of material, much of it more fossil than matrix. What we collected in 2.5 hours is hardly representative of what this material has to offer.
This was the main focus of the visit: the windward side of the reef. Every single rock was full of fossils -- and not just coral. The weathering and oxidation made for some interesting steinkerns.
Although the material looks quite dense as it weathers a dark grey (inside is a creamy off-white with orange oxidation), it breaks apart easily. Unlike a shale that will split in sheets, this material breaks apart in angular chunks, a little like the material at Hungry Hollow (but much clearer to see what's inside). Pictured above are some usual surface features including a nautiloid cast and a chunk of tabulate coral. The material was quite easy to work with.
It took just a matter of minutes to start piling up stuff to bring home. Every rock and every split had something new and interesting. Of course, I wasn't too picky about what I was collecting as this was my first visit. It is a little like someone's first visit to Arkona when the tendency is to fill buckets with horn coral!
Nautiloids were abundant.
Weathering made for some very neat looking cross-sections, as pictured here with the exposed siphuncle.
This would be my first cyrticonic nautiloid. Quite neat!
I found a number of these small rostroconchs, too. Of course, I'm pretty full up on rostroconchs from my local imported fill site.
Plenty of gastropod steinkerns, some flat and others high-spired. Some also contained large crystals inside. There were also plenty of brachiopods of varying types, but I didn't manage to collect them this round.
Deb found this large, double-valved bivalve that popped free of the matrix. I had found a smaller more beat up one, so this example was the clear winner to be taken home.
Corals, corals, everywhere. Some had very nice crystallized cross-sections among the rugose variety, but we left those in the field. Despite this being a reef, the corals were less "in the way" compared to the Hungry Hollow Member at Arkona; many more types of fossils were given equal billing. Also not pictured were the crinoidal hash.
So what about the mud bugs? Ludvigsen reported that trilobites were rare in this material, and that is not something I could confirm from experience; just about every rock had some kind of trilobite fragment, be it a pygidium, cranidium, or librigena. By far the most abundant species would be Crassiproetus crassimarginatus (subspecies brevispinosus). Pictured above is just one (exfoliated) example of about ten or more I brought home, leaving about as many or more in the field! Ludvigsen's text reports 222 fragments found over a matter of a few years; I could probably acquire that many in a full day there. Of course, no complete example has ever been reported, and it is unlikely due to the nature of the depositional environment. One has to be content with partials.
If Crassiproetus is the most abundant trilobite represented there, the second most would be Mannopyge halli. Pictured here is a rather beat up version, and it was odd I only found the one -- but then I may have missed a few in the haste to make the most of our short time at the site. You can see the pygidial nodes like a necklace along the right edge.
In third place for relative abundance would be Mystrocephala stummi. I was pleased to find this fairly nice example which looks a bit more well articulated and robust than the more flattened examples I've found at my local spot (yes, I found a second fragment a day before this trip!). No traces of the other two most rare trilobites in this material (Acanthopyge contusa, and Harpidella sp. of which the literature reports a single cranidia).
Overall, this was an incredible trip filled with new surprises. Although I had to miss out on Bowmanville this autumn, this certainly was a significant event of the season. I do plan on returning there again, either later this year or more likely in the spring. I hardly did this site justice as there is still so much to explore.
The long October weekend is here, and despite it raining this morning, I was able to get out yesterday and have plans to make a few visits to my Bois Blanc Formation rubble between bouts of turkey and getting caught up with essay grading.
The number of rocks that are highly fossiliferous is dwindling, but I'll have enough to see out the rest of this year. This small haul of trilobite partials would be considered a fairly good outing: three fragments of Acanthopyge contusa and two fairly preserved pygidia of Crassiproetus crassimarginata. That brings my total Acanthopyge fragment count to about 9, and 13 lichids overall. If I could only find a complete example, I could stop collecting the fragments.
As the material is very rostroconch-dominant, I only pick up the odd one on occasion if they look nice.
I hope to get out a few more times in the next while and update this post if more neat finds are made. So, to be continued...
So another four hours out back, and I didn't do too poorly. It took me a bit longer of trial and error to find the right productive rock, and it was this one rock -- and only this rock -- that produced the days finds.
I suspect this to be another lichid genal spine (possibly Acanthopyge contusa). Left: negative and positive. Right: closeup.
Just missing its cheeks, an otherwise complete Pseudodechenella sp. None too shabby! This would be the day's best. Perhaps I'll have another go tomorrow.
Well, it was a challenge to find more productive rocks to split. Four hours, and not much to show for it. In fact, it was the first visit in some while where I didn't even find a trace of a lichid. But sometimes a small find can be just as rewarding.
This looks very much like a Mystrocephala stummi to me (compare with the image from Ludvigsen on the right). If so, that would make a new species find for me. Although the pygidium axial width is not 1/3 or more of the entire pygidial width, I can make out the little nodules along the heavily incised pygidial ribs. Of course, the fact that it is only reported in the Formosa reef (Amherstburg Fm) possibly problematizes the assigning of this rock to the Bois Blanc, but so did the appearance of Acanthopyge contusa. There's trilobites from both formations here, sometimes on the same bedding plane. Perhaps another visit tomorrow? For now, round 1 of turkey.
Five hours and I've pretty much managed to tap out a section of much of the viable rock. It wasn't until the last half hour that I was able to find anything at all, with much of the time spent splitting duds, blanks, bits, and other false leads. If the fourth of four sections has any viable rocks left, they are massive armour stone boulders that even I can't either move or do more than splinter/fracture the edges. So on I moved to section two.
As with a lot of the lichids in this material, the preservation is generally poor, but this Acanthopyge contusa positive and negative is still fairly articulated with the course tubercles and delineated goblet-like pygidium axis. That brings me to 15 lichid fragments, with eleven of those from this species. I probably have more examples of this species than any museum.
Once more into the breach before I give the site a rest for a bit. My focus tomorrow will be a return to section two. There's still some source rock to go through from where I obtained this pygidium. If time and energy permit, I might poke around section one (fairly tapped out) and section three (mostly blank or lenticular coral limestone + domes). I've put in 16 hours in 4 days.
And another five hours in the proverbial hole, and that will be all for now as I need to get back to much-neglected work. But on to the finds that close out these five days of persistence.
Yes, it's yet another Acanthopyge contusa. Although the photo doesn't do it much justice, this is a very nicely preserved cranidium despite missing a lobe on the right. The tubercles are nice and clearly defined.
The trip-maker? What appears to be a cranidium that compares favourably to Terataspis grandis. Image on the right is from Ludvigsen's text. But, sadly, it is just another Acanthopyge.
Here is the same specimen in sunlight, and the negative below.
So, the final tally:
5 days (21 hours)
12 Trilobites (7 lichids, 4 proetids) = 7 Acanthopyge contusa, 2 Pseudodechenella sp. (one almost complete), 2 Crassiproetus crassimarginatus, 1 Mystrocephala stummi
Not bad at all. Spending all this time out there has forced me to revise assumptions about this material, and it may be a blend of Bois Blanc, Amherstburg, and Lucas Fms. Not sure when I'll be going back, but my hammering arm needs a break!