Dive Into an Ordovician Ocean—Trilobites—And a Rare Find

[FossilSniper]

          On July 1st, 2021, I went for the first time to a public, personal site and was very pleased with the results of my fossil excursion. The locale consists of several exposed formations, namely the Liberty formation I was hunting in. In my region of southwestern Ohio, that's known to be one of the best fossil-hunting formations due to its remarkable preservation of particularly fragile Ordovician life, even when compared to the excellent fossil preservation quality of other formations in the area.

         The thirty-three degrees Celsius heat was rather hot by itself, and as the sun's rays made me question my latitude, the rainwater in the ground from the rain several hours prior was evaporating and creating a blanket of humidity-saturated air which prevented my body from transpiring. That was lovely. On top of that, this was above a very tall cutaway, so there was this constant updraft of hot, humid air coming from the bottom. Needless to say, conditions were extremely hot and humid. A thermos filled to the brim with refreshing, ice-cold cranberry-grape juice was a lifesaver, as otherwise I would have certainly overheated and becoming a sizzling omelet atop a frying pan of Ordovician fossils under that laser of a sun! 

         With that being said, this is my first post regarding a fossil hunting trip in three years! While I have not been active on this forum, my paleontological trips have been ever more numerous. I remember you all, as I have been secretly watching in the meantime. I am a fossil sniper, after all.

          I should mention that I am an adult now, and I would prefer to have the "Youth Member" tag removed from my name.  I plan to conduct a full survey of my entire collection before attending university, so look out for that. My collection is considerably sizeable now, having nine years of fossil-hunting under my belt.

           Here are my finds! Best & rarest for last, though all of them are incredible in their own right. Every edge of a square on the grid is half a centimeter.

 

Assorted rugose corals. 

 

 

Gastropods.

 

 

Branching bryozoan.

 

 

The central branching bryozoan specimen in the prior figure under 200x microscope magnification. The skeletal cavity wherein individual zooids once resided 440 million years ago are evident, each 0.2 millimeters in diameter. The sheer level of detail in the preservation is as mind-blowing as this fossil's age. This photo is the product of using a computer to compile 140 photos focused at different layers of the specimen, as microscopes have a very narrow depth of field. I'm sure you all find as this fascinating as I do, so I compiled a photo for you guys.

 

 

Assorted brachiopods, with two bivalves on the top left. I collected some superb Rafinesquina alternata, which don't tend to come with both fragile and thin halves intact, together, and out of the matrix. There were also some Leptaena that I did not photograph, but were lovely and undulating. The rest are common genera here, except for the fourth one from the right in the bottom row and the partial one of the same species immediately northwest of it, which I would like help identifying. Expect to see it soon on the ID forum.  

 

 

Assorted associated, straight-shelled nautiloid cephalopod septa. 

 

 

A larger example of associated, straight-shelled nautiloid cephalopod septa and a partial living chamber.

 

 

Calcified straight-shelled nautiloid cephalopod. I always love the crystals on these. 

 

 

Flexicalymene meeki on the left and right. The left one is perfect, and is a very large example of what I generally find--my largest self-found complete trilobite, in fact--so I'm very happy with him. The right one is heavily weathered along its left and right, but the medial length of the pygidium, thorax, and cephalon are all present in some way, and the pleurae and glabella are resonant with Flexicalymene meeki, and I'm very happy with him, too. Adorable, curled little finger hugnuzzles of the ancient sea.

 

 

Drum roll please!

 

 

Figure 1

 

Figure 2

 

Figure 3

 

Figure 4

 

Figure 5

 

            This is a huge living chamber of a straight-shelled nautiloid cephalopod! Unlike the septal segments, the living chamber is very fragile with its thin, unsupported walls. This means it is very rarely preserved. Hence, in my near-decade of fossil hunting, I have never found a complete living chamber with its outer shell included until now. Let alone of this size!

           The only reason this one survived is because of the encrusting bryozoan that grew over its walls and thus strengthened them after the animal died--Figure 5 demonstrates the layers of the bryozoan well. This is also demonstrated on the side without bryozoan strengthening it in Figure 4, and how it simply crumpled due to the weight of sediments that accumulated on top of it after the animal died.

           Interestingly, one side has much more encrusting bryozoan than the other--this suggests that immediately after the animal died, part of the shell was resting on the silt of the ocean floor, preventing bryozoan from growing on it. The contrast in the thickness of walls of the living chamber & encrusting bryozoan growth on opposite sides of the fossil is evident between Figures 1 and 2, where in Figure 1 the walls of the living chamber are quite thin (one can tell from the thickness of the dark cracks on the bottom left), whereas in Figure 2 the walls are visibly significantly thicker (and layered from the encrusting bryozoan, upon zooming in). Deducing all of this is so cool.

          Additionally, Figure 3 zooms in on the bottom left fraction of the visible living chamber in Figure 2, and it actually shows the bryozoan growing around the edge of the living chamber walls and into the living chamber. This means that's the very outer rim of the living chamber! (In Figure 3, the white line is the living chamber wall, and the layers around it are the encrusting bryozoan. The light tan stone inside is just limestone.) On top of the sheer rarity of a fossilized living chamber, especially of this enormous size, having the edge of the living chamber preserved with enough detail to show the bryozoan that that grew into it over its rim—almost half a billion years ago—fascinates me. 

 

         To finish this post off, there really is a mystery in every fossil. With the encrusting bryozoan only growing one side of the living chamber in the final specimen, and the subtle, hard-to-spot detail of how it grew around the rim and into the living chamber, it's like every fossil is a murder mystery (literally) and we have to be Sherlock Holmes and figure out details about how the animal died. Considering this was 440 million years ago, we're all some pretty hardcore forensic scientists! 

 

 

 

 

 

Edited July 6, 2021 by FossilSniper

[Kane]

Good finds, and one never forgets finding their first complete trilobite.  

I'll ask one of the admins to formally usher you from youth to adult status here. @Fossildude19

[daves64]

5 minutes ago, Kane said:

I'll ask one of the admins to formally usher you from youth to adult status here. @Fossildude19

Which means he'll be expected to act like an adult (not really) & do all the "fun" adulting things... 

[Fossildude19]

17 hours ago, FossilSniper said:

  I should mention that I am an adult now, and I would prefer to have the "Youth Member" tag removed from my name.  

 

In 2018 you posted that you were 14. 

Are you 18 now?

[FossilSniper]

I am indeed. @Fossildude19 

On 7/5/2021 at 11:25 AM, Kane said:

Good finds, and one never forgets finding their first complete trilobite.

I have dozens of self-found trilobites, but I certainly do remember finding my first one. This one’s just my largest self-found specimen thus far.
 

Also, sorry for the double mention, Fossildude19; it was an accident. I can’t figure out how to remove the second one, so I’ll just leave it there. What’s done has been done.