Seasoned experts and first time fossil hunters alike visit Penn Dixie in the hopes of taking home a trilobite. Trilobites are extinct, marine arthropods, named for their three-lobed bodies. The majority of the trilobites found on site are Eldredgeops rana, although Greenops (uncommon), Bellacartrightia (rare), Pseudechenella (rare), Dipleura (very rare) have all been recorded at Penn Dixie.
On August 27th, 28th, and 29th, fossil hunters from all over the country flocked to Penn Dixie for Dig With The Experts 2021. Dig With The Experts is an annual event that allows fossil hunters to get their hands on freshly excavated material, with guidance provided by scientific experts who help locate and identify the site’s best fossils. Among this year’s dig participants was Theodore Gray, who unearthed one of Penn Dixie’s rarest trilobites – the coveted Pseudechenella rowi. Below is Theodore’s account of discovering and prepping this extraordinary find.
In The Field
I have been a member of Penn Dixie for years but living in California, I had been to the quarry only three times over the years. On each visit, I always found a few trilobites but never a nice prone one. In 2021, I had the good fortune to be in Western NY over the weekend of Dig With The Experts. I bought tickets for Saturday and Sunday with my goal of a nice prone Eldredgeops.
The execution of DWTE was new to me. I was aware that heavy equipment was involved but the sight of all those covered piles was amazing! The best part was no digging out the slabs by hand! Been there, done that.
I picked a pile and got to work. I met the young guy digging next to me, Cole from Kentucky, and we shared the joys of each find from our respective piles. I finished going through my pile by early afternoon and had a number of nice Eldredgeops in matrix but no “killer” prone examples. I spent the rest of the day snooping through the discards from Friday’s digs and found a few more Eldredgeops and even one nice complete prone 1 incher.
On Sunday, we returned in earnest and the same scenario ensued. I finished my pile by noon or so and then spent the afternoon banging on other peoples’ leftovers. I found another larger prone Eldredgeops that was split in the middle of the thorax but it certainly was big enough to fit the bill, if it was all there.
At some point, I had split a chunk of a slab and spotted a small pygidium, exposed by the split. The “skin” on the pygidium was damaged by the force of the split and crumbled away. Most of the bug was encased in the matrix but as I inspected it closer, I thought I saw traces of a genal spine. I suspected that it was something different but I did not know what.
Now, when you are digging at DWTE, you don’t waste time field prepping anything. When you find a “possible”, you put it on the keeper pile and keep moving! So, I shrugged, wrapped the trilobite in foil, put it on the keeper pile and moved on. By Sunday evening, my “keeper pile” was looking to be all that I could handle on the flight back to California and I guessed that I might need another suitcase.
On Monday, when I got back to my hotel, I revisited the little bug and it was clear that it had a genal spine. I texted “Cole from Kentucky” and sent him a photo of the mystery bug. He thought that the trilobite was an Eldredgeops, and that the “genal spine” could be a molt fragment. I told him that I thought there was a high probability that it was something else. Cole searched the PD website and found the description of the Pseudodechenella rowi.
Like Cole, having only been to PD on a few occasions, I was only aware of the presence of the Eldredgeops and Greenops genera. During DWTE, I heard chatter about the Bellacartwrightia and at some point, someone mentioned something about a rare Proteid. As a self taught preparator of trilobites, I know what a Proteid looks like. I “cut my teeth” as a hobby preparator working on dozens of Gerastos granulosus, a Moroccan proteid species that is so common that the Moroccans call them “flies”. Since the holochroal eyes were not visible on my specimen, only further preparation would confirm our conclusion.
Back At The Lab
As a preparator, one wants to “practice” on the rocks from a particular locality to establish a familiarity with the way that the matrix responds to the force of the air scribes. So, it was not until almost a month later, having prepared a dozen or more of my finds, that I started on the “little pygidium” bug.
In my lab, I use three primary air scribes, essentially “coarse, medium and fine”. The matrix of the Smoke Creek trilobite bed is actually quite soft so the majority of the prep work is done with the “fine” air scribe. The medium air scribe serves to “landscape” the matrix if needed. The final cleaning of crevices and such is done, by hand, with a pin vise.
As a preparator, one always should consider the final presentation of the specimen before starting. Since this bug was located on the edge of the rock fragment, I decided that it would look best if it was vertical on the face of the rock matrix. So, I used a tile saw to cut away the bulk of the rock fragment such that the remainder would stand up nicely with the bug presented on the face of the fragment.
In this case, there was a substantial thickness of matrix covering the bug so I used the medium scribe to remove most of the overlying matrix, creating a crescent shaped pattern around the bug. Then, I used the “fine” scribe to carefully expose the rest of the thoracic segments and the head.
The head was crushed and deformed so I stopped using the scribe when all of the main features were visible. At that point, I could clearly see that the genal spines were present on both sides and it has holochroal eyes. It was definitely a Pseudodechenella.
Given the rarity of the specimen and the damage to the pygidium, I opted to stop any further preparation and send it off to a professional preparator, Ben Cooper of Trilobites of America.
We would like to thank Theodore for sharing this discovery with us, and congratulate him on his rare find. If you’re interested in seeing more of Theodore’s lab and equipment, click here.