Versailles State Park Pt 2 - Fun with Fossils

So as Allison mentioned in her last post, we spent a recent Saturday hiking around Versailles State Park looking for outcrops of the Waynesville and Liberty Formations (Katian; Richmondian). Many of the outcrops as you probably noticed and would have suspected, were covered in varying degrees of ice. It was also about 5 degrees C out, so we didn't feel like hiking through ice-cold streams was a wise idea. #JanuaryFieldWork As a result, most of our fossil hunting was restricted to the various cobble deposits along the stream's banks. There were plenty of goodies to be had there though!

This first image is of a rather sizable fossil that was seemingly randomly located along the trail approaching the stream. Not sure where it came from exactly BUT, it is rather neat! Here we have a large coral, likely a Tetradium (click the link for additional images of Tetradium from the Cincinnati Arch region).  

This image I am rather fond of. Here we have two different Ordovician bivalves, an Ambonychia  (link to the Ordovician Atlas page) on the right, and a Caritodens on the left.  Bivalved mollusks are typically aragonitic in composition which is why these clams are moldic (aragontie does not preserve as well as calcite) but what is notable about these critters is they are impressively large! My guess is these guys came from either the Wayensville or Liberty Formations.

This next image is from one of the outcrops Allison shared previously. To the immediate right of the scale bar is a jumble of brachiopods called Rafinesquina, very common to the Ordovician of the KY-IN-OH tristate. We often refer to these beds of jumbled Rafinesquina as 'cornflakes beds'. I imagine the name is self-explanatory!

This is another set of brachiopods from that same outcrop as the Rafinesquina, There are two primary brachs that you can see in this image, the one just right of center is an orthid brachiopod, likely a type of Hebertella.

Lastly a nice view of the iced lake as we were hiking back to our car.

All in all, it was a fun day hunting for outcrops and fossils and I look forward to getting out in the field more and sharing with you our discoveries!

Versailles State Park

This past weekend Christopher and I, with our friend Kyle of the Dry Dredgers, took advantage of the nice weather and head out into the field. We made our way to Indiana, lead by Kyle, with the objective of viewing some late Ordovician exposures. 

Waynesville/Liberty (Upper Ordovician) outcrop along the cut bank of the stream

A lot of ice on the stream and outcrops, but still some nice exposures. #JanuaryFieldWork

Notice the distinct blue color of the shale, common to shales of Waynesville and Liberty Formations

View from the top of the hill we hiked up after following streams in search of outcrops

Gumdrops

insitu Prasopora Lexington Formation, KY

Bryozoans are some of the most common fossils found in the Upper Ordovician deposits of the Kentucky Bluegrass. Prasopora falesi?,  closely related to P. simulatrix Ulrich, of the Monticuliporidae family is found only in Kentucky in rocks of  Kirkfieldian and Shermanian. Specimins have been found in the Grier Member (which spans the Kirkfieldian and Shermanian stage boundries), Brannon Member, Sulphur Well Member, Tanglewood Member, and through the Shermanian Stage portion of the Clays Ferry Formation.

Specimen has a 7cm diameter base

The hemispherical growth habit of P. falesi has lead to its more colloquial name the “gumdrop bryozoan” OR "chocolate drop" to local fossil collectors.

Another fun aspect of the growth habit of these bryozoans is when examining their underside you can often tell what they were living on... a bivalve perhaps? a silty muck? reworked clasts?

Specimens from left to right have a 5cm and 7cm 

diameter base.

In reading through Karklins, 2010 I am also entertaining the possibility that the specimens photographed above could also be Mesotrypa angularis Ulrich, 1893. I will be doing thin sections or acetate peel to investigate this further. If you have any thoughts or suggestions on the genus please comment below. Thanks for checking out Ordovician Weekly.

Reference: O. L. Karklins, U.S. Geological Survey professional paper, Issue 475, G.P.O, 1984, University of Michigan, Digitized Feb. 22, 2010.

Day of the Hypostome

Recently I was out in the field with members of our research group, studying the Lexington Limestone in Kentucky. It was one of those rare days in January where the sun was shining and temperatures were at a remarkable 12oC (~55oF)! Well we couldn't let a day like that past so we shook off the cobwebs and went out rid ourselves of some cabin fever.

It was at our first stop near the Rt 127/355 Junction in Kentucky, that one of the undergraduate students brought this slab over to me.

The obvious feature that stands out of course is the light brown 1/2 ring shape outlining the cephalon (head) of an Isotelus trilobite. Isotelus parts are pretty common in the Ordovician of the Cincinnati Arch, sort of the local weed organism which shows up everywhere.We marveled for a moment at the size of the beastie, Isotelus is known to be quite large (largest species is Isotelus rex at ~70cm long - see Palaeocast interview with Dr. Rudkin or the Original Paper) and I was about to hand it back when the real interesting part of the specimen popped out at me, part of the hypostome was present in situ.

The hypostome is the hard mouthpart of a trilobite believed to be used in feeding. It is located on the underside or ventral side of the trilobite. I have a wonderful GIF generated of one of my committee members demonstrating how these hypotstomes may have been used to scoop up worms, but he holds the fate of my future graduation partially in his hands so I will have to refrain from sharing!

Now finding a hypostome is not uncommon by any means, I had found one just a few minutes earlier that was in even better condition. (See my tweet highlighting another hypostome)

The interesting thing is to see the hypostome in situ with all of the cephalon (minus the margin) removed. 

Anyways I thought it was a cool little specimen and I will be certainly adding it to my future teaching collection. Please keep checking here for more posts on interesting fossils/strata we've found and for thoughts on equally interesting papers!