Trilobite In Tennessee

[Jomonn42]

Hello there,

I am still new here, and joined cause i found a small piece of trilobite in Middle Tennessee. I have kept up the search, and have something incredible... To me anyway... Ha.

So, I believe this to be ordovician rock, but it's hard to tell. I have added a pic of more fossils in the same strata, with in an inch vertically of where this was found. Ceraurus Pleurexanthemus is the closest thing I can find to it. The specimen is 3cm long and 2.5cm wide at the head...

What do you think?

Thanks

Jomonn

[PA Fossil Finder]

You actually have two trilobites, in your first picture there is trilobite "tail", or pygidium.

Very nice finds, I love trilobites

Those gastropods are cool too.

[Pumpkinhead]

Second pic looks like a calymene to me

My gut feeling is that your finds are Silurian

Edited August 16, 2015 by Pumpkinhead

[Jomonn42]

Thanks Pumpkinhead,

I have been coming up with Silurian also. The spiral gastropods are not Ordovician are they?

[Pumpkinhead]

There are a lot of high spired gastropods during and before the Ordovician, but for me the gastropods characteristic of that time period is stuff like Maclurites, which is not high spired. Fast forward to the mid Silurian which is where I have the most experience and two thirds of the gastropod species in my area are high spired, and to this day they are the dominant form of snail in marine environments. So you can find Ordovician gastropods like what you have, but I think that these ones are Silurian. Your trilobite I also think is a calymene, which are mostly represented in the Silurian.

Those are some great finds you've got there, and someone may come along who has a more informed opinion but it is because of the reasons listed above that I think your fossils are Silurian. Hope this helps you

[piranha]

It is indeed an Ordovician cheirurid. Key features of this group are quite apprent: the long genal spine and the flanges / furrows where the axis and pleural lobe intersect. The Tennessee ceraurids are currently classified as a couple of new species of: Gabriceraurus. Steve Westrop's grad student described these in his thesis and accordingly, species 1 & 2 are most similar to: G. gabrielsi and G. hirsuitus (Ludvigsen 1979).

 

 

Moss, D.K. (2012)

Trilobite faunas and facies of the Upper Ordovician (Sandbian) Lebanon Limestone, Nashville Dome, Tennessee.

MSc. Thesis, University of Oklahoma

 

Ludvigsen, R. (1979)

A trilobite zonation of Middle Ordovician rocks, southwestern District of Mackenzie.

Geological Survey of Canada Bulletin, 312:1-99

[Herb]

My .best guess on the gastropods are Homotoma sp. Internal and external casts, which would make it U.Ordovician. Those are wonderful gastropods by the way, I have never seen them before. If you find more of them would you be willing to trade some?

[FossilDAWG]

The gastropod immediately to the right of arrow in the first photo is a Hormotoma, possibly Hormotoma gracilis. The others to the right of that one are a species of Fusispira, possibly Fusispira subfusiformis. This is a typical middle/upper Ordovician assemblage, which agrees well with the Gabricerarus ID for the more complete trilobite. The pygidium may be a Bathyurus. Looks like you found a great site to collect.

Don

[Pumpkinhead]

Well, I was right about the "someone may come along with a more informed opinion part."

[piranha]

On 8/16/2015 at 0:27 PM, FossilDAWG said:

...The pygidium may be a Bathyurus...

 

 

According to this paper, the Nashville Dome bathyurid is: Raymondites

 

Patzkowsky, M.E., & Holland, S.M. (1999)

Biofacies Replacement in a Sequence Stratigraphic Framework: Middle and Upper Ordovician of the Nashville Dome, Tennessee, USA.

Palaios, 14(4):301-323

 

It's possible the missing piece from the pygidial axis was the point of attachment for the axial spine. In any event, Whittington said it's not significant for the genus whether or not the pygidia of all of the species in Raymondites bear the axial spine.

 

Whittington, H.B. (1953)

North American Bathyuridae and Leiostegiidae (Trilobita).

Journal of Paleontology, 27(5):647-678

 

 

 

[jpevahouse]

The trilobite is familar since I grew up hunting fossils in Middle Tennessee. The extensive limestone deposits are Ordovician and contain various coral, brachipod, cephalopod, gastropod and criniod as well the occasional trilobite. My brother and I were always hot in pursuit of a nice complete trilobite but usually we only found incomplete fossils. Eventually however we managed to find a nice example or two. Attached is a photo of our best find, about three inches long.

What I find more interesting in your picture are the fossils beside the trilobite which look like fish bones?

[Jomonn42]

I will make up a closer pic of the fossil next to it...

Honestly, I'm not sure what it is, I assumed a piece of coral.. Maybe?

[piranha]

Here's an update that Raymondites has recently been reassigned as a subgenus of Bathyurus.

 

Abstract:

 

The Upper Ordovician (Sandbian–Katian) bathyurid trilobite Raymondites Sinclair is revised using new collections from Missouri and Ontario, and archival material from Illinois, Wisconsin, New York, and Ontario. Phylogenetic analysis supports monophyly of Raymondites, but recognition of this genus renders Bathyurus Billings paraphyletic. We treat Raymondites as a subgenus of Bathyurus and label the paraphylum of species traditionally assigned to the latter as Bathyurus sensu lato. Bathyurus (Raymondites) is composed of five previously named species, B. (R.) spiniger (Hall), B. (R.) longispinus (Walcott), B. (R.) ingalli (Raymond), B. (R.) bandifer Sinclair, and B. (R.) trispinosus (Wilson), and two new species, B. (R.) clochensis, and B. (R.) missouriensis; an eighth species is placed in open nomenclature. All species share tuberculate sculpture on the glabella, a relatively short palpebral lobe whose length is less than half of preoccipital glabellar length, and a pygidial outline that is well rounded posteriorly. Aside from the most basal species, B. (R.) longispinus, they also possess occipital spines and, where the pygidium is known, axial pygidial spines.

 

Quote:

 

According to Patzkowsky and Holland (1999, p. 318, table 2), B. (Raymondites) is restricted to the M4 sequence boundary in the Nashville Dome region of Tennessee. Our revision shows that the youngest species of the genus range into the M5 and M6 sequences (i.e., well above the Millbrig K-Bentonite) outside of the Appalachian Foreland Basin in the Mississippi Valley of Missouri, Illinois, and Wisconsin, and over the Algonquin Arch of Ontario. Thus, the disappearance of B. (Raymondites) at the M4–M5 sequence boundary in Tennessee records regional extirpation rather than complete extinction.

 

 

Swisher, R.E. Westrop, S.R., & Amati, L. (2015)

The Upper Ordovician trilobite Raymondites Sinclair, 1944 in North America.

Journal of Paleontology, 89(1):110-134

 

 

 

[TNCollector]

From what county was it found? I have not seen any in my time here in East Tennessee, which is mostly Cambrian and Ordovician. The county locality might help narrow it down to the time period it is from.

[bethk]

Found lots of lovely gastropods that look just like the ones in the photos in the upper Ordovician at a quarry yesterday, So I'll echo the other more articulate posts that support Ordovician.

[Jomonn42]

Williamson county, Maury county area. Been working the numerous road cuts in the area

[TNCollector]

The East sides of both Williamson and Maury counties are all Ordovician, and the West sides are mostly Mississippian (Fort Payne formation dominant). I see these specimens as being Ordovician.

[Jomonn42]

Your right TNCollector, east maury county... Cool. I have looked further west, but haven't found much but a lot of bivalves...

[TNCollector]

I would keep looking, you might find a rare Paleozoic shark's tooth in the Mississippian formations. They look quite different than what you might expect (besides Cladodus), but are very interesting.