On An Old Beach

Years ago I was camping with a friend along the dissected edge of the Appalachian Plateau. That week we were experiencing some of the coldest weather in history for this part of the country. It was the second week of Jan. 1984 and the temp had dropped to -27°F (-33°C). On old guy that lived near our camp site smelled the smoke from our fire, and was amazed that anyone would be out in that kind of weather. So, he came along to investigate.

After setting around the fire and chit chatting for a while, he was impressed that we were cold weather enthusiasts and not just a bunch of silly kids out playing in the woods. He then took us on a tour of his land and showed us some of the sites that he thought were interesting.

One of those sites was along the base of a large cliff. In it, there was a fossil log of a lycopsid that was about 3 or 4 meters in length. One end of the log was nearly dislodged from the rest, so I ask if I could have the fossil. He knew of my enthusiasm for fossils from our earlier discussions, so he let me pry the small chunk from the rest of the log.

The base of the cliffs in the area are Mississippian limestones(Newman Fm.) capped by the sandstones and conglomerates of the Pennsylvanian Breathitt Fm. There is a nice disconformity between the two units; in some places with a few meters of relief within a relatively short distance.

I was already packing heavy due to the weather, and we were a couple of km back into the woods, but I wasn’t going to let nature reclaim this thing.

For scale, the board under the fossil is about 14 cm wide.

The other side.

Liesegang band along the edge.

Different view of the one above.

Isotelus Molts

Working an outcrop in the Clays Ferry Formation that is in the same bed, and close to, another outcrop that I have collected extensively(see here, here, and here), I came across some curious molts of an Isotelus gigas.

The Clays Ferry Fm was deposited in a relatively shallow subtidal environment, and throughout most of the area, the formation straddles the Mohawkian/Cincinnatian boundary(early Late Ordovician). Due to deposition below wave base in typical weather, most of the fossil are complete and a diverse assemblage can be found in the column.

The Bed form which this piece comes is composed primarily of orthoconic cephalopods, Isotelus, a few bivalves, and an occasion Flexicalymene trilobite.

What I find curious about the molts is found on pygidium and thorax of the smaller dorsal specimen. I have annotated it with a white line to highlight the area.

There is a crack and indentation that runs from the anterior posterior(Jeeez, I just caught that) margin through the pygidium, and from there it appears as if it continues on through the pleurons. As there is no suture along that area of the thorax, I would assume that the distal portions of the pleurons would be adjacent to the rest of the critter, but they are not there, So that has left me wondering if the structure is pre-molt, or if it is an artifact of lithification. Any Ideals?

Devonian Tabulate Coral

A few years ago, I was working a project in northern Jefferson Co. Ky. that was in the preliminary stages of development. As such, the area had been stripped of vegetation leaving a vast field of regolith that was a mud pit when it rained… sticky clayey mud. But, those rains also uncovered thousands of silicified fossils that littered the ground of the project.

One of the larger pieces that I picked up was a head of the tabulate coral Alveolites. It was fossilized as silica replacement that is common of many fossils in the Jeffersonville Limestone.

A view of the base of the colony

The top of the colony

The individual corallites are about 2mm diameter.

Another Ordovician Trepostomate

A while back, while working a rather new outcrop of the Millersburg member of the Lexington, I was having little luck finding anything worthy. So, on a whim, I decided to walk a few hundred meters down the road and about 10m down in the rock column to an outcrop of the Tanglewood member.

The Tanglewood was deposited near shore and above wave base, so the fossils(what few are there) are generally very abraded and of poor quality. But occasionally, I find a lens of mudstone within the Tanglewood that preserves some nice critters.

Unfortunately, this was not to be one of those days. Though, I did find a nice trepostomate bryzoan that I brought home.

I’m not much on the Bryzoa, but this one appears to be a Heterotrypa sp.

Here it is glued back together.

Micro-Bivalve

A quick post from something on the hard drive…

Often, when inspecting corals(Cnindaria) or sponges(Porifera) that I have found in the Millersburg mb. of the Lexington, I find micro-fossils at the base of the colonies. It could be coincidental, but I’m starting to think that the micros were juveniles and that their progenitor placed the off spring in a habitat that favored survival, or the ones placed there were more likely to survive… which seems more plausible.

Anyway, here is a small bivalve that was collected from just such an environment.

A little closer

Since the common bivalves from the Millersburg are modiomorphids or ambonychiids, These are probably ambonychiids… probably Bysonnychia sp. juveniles.

Enigmatic Critter

Hyolithids are a poorly understood group of critters. They first appeared in the Cambrian and became extinct during in the Great Dying(Permian-Triassic extinction) at the end of the Paleozoic. The Great Dying was the most severe crisis for the biosphere that the planet has ever experienced… about 95% of all species perished!

There are numerous hypothesis to explain the extinctions(google it), but it was probably a combination of several catastrophic changes that killed off most life.

A few hyolithids that were recovered from the Millersburg mb:

Someday, I will devote a post to the extinction event.

An Uncommon Lichid

Upon returning to Lexington, one of the first outcrops that I looked forward to collecting was a relatively small outcrop of the Millersburg member of the Lexington Limestone. I worked the outcrop for 8 years back in the 80s, and it produced some stunning fossils.

The Millersburg is a nodular unit of shales and limestones that was deposited on a shallow carbonate bank. The depositional environment was one of relatively high energy as evidenced by the broken and abraded fossils found within the member. For that reason, it is often overlooked by paleo geeks

But, I have found some spectacularly preserved inverts from the member. I pulled a well preserved example of coprophagious(poop eating) symbiosis among the gastropod Cyclonema varicosum and a crinoid from the member 25 years ago, but even better, I found an undescribed lichid trilobite from the same locality!

And, that is what bring me to this post.

That wonderful outcrop, with all of its rare fossils, is no more.

Yep, they paved paradise and put up a parking lot…

So, I moved on to an outcrop farther down the road. I found my first complete trilobite there! It too was gone- The outcrop, not the fossil( I thought that I had written a blog entry about evil civil engineers, but I guess that I didn’t; maybe in the future?)

I then moved on to the next outcrop that wasn’t destroyed, and it was a good one. Other than most of the Pychnocrinus that I have displayed on the blog, I also found a partial pygidium from a lichid trilobite.

Usually, I would pass on something as insignificant as a partial pygidium, but it was from a lichid. Too remember, I pulled an undescribed lichid up the road a bit.

The undescribed trilobite consists of 11 cephalons, two pygidia(is that the plural?), and one hypostome.

Anyway, here it is. It doesn’t look like much, but it sure got my heart racing.

The box is about 1cm

The Legend of Sleepy Lagoon

The “headless” trilobite:

An I. gigas that was found in the Clays Ferry Fm. in Anderson Co. Kentucky. When I found it, it was posterior-dorsal up. Wow, I was excited! Oh well…

Neat-none the less.

Ordovician Trepostomate

While visiting a friend’s(Herb) house, I noticed a stone that he had placed at the down spout of his gutter. Well, actually his father had placed it there many years ago in an attempt to inhibit erosion by allowing the energy from the falling water to dissipate at the surface of the stone.

The stone was placed in its location in the 50s or 60s, and the falling water, over the years, had exposed multiple “tips” of some kind of stony bryozoan. The bryozoan had been preserved as silica replacement in a bed of a muddy carbonate.

Herb knew of my enthusiasm for inverts, and when he noticed my pre-occupation with the “dissipation stone”, he ask if I wanted it!

Upon getting the rock home, I treated it with multiple baths of HCl^– to reveal the colony within… and a splendid colony, it was.

Trepostomate bryozoans can be particularly hard to ID without a thin section and intimate knowledge of the subject. And, I don’t have either, but the results are stunning.

It is probably some kind of calloporid.

Sorry, I don’t have a before pic and the finish is out of focus, but you get the ideal.

Since the rock was retrieved from the Kentucky River Valley near Frankfort, it is probably from the High Bridge Group; more than likely the Oregon Fm or Tyrone Fm.

EDIT:I am experiencing some kind of scripting error, so this is an off-site link.

EDIT: The scale is in inches(2.54cm/inch). Its a whopper!

Ouch!

Year ago while working an outcrop that has produced some stunning asasphids, I found this little Isotelus gigas. It appears that the little guy had a bite taken out of his cephalon, enrolled and died. I found it in a bed of the Clays Ferry Fm(early Late Ordovician) in Anderson Co. Kentucky. The bed is comprised of, almost entirely, I. gigas molts and orthocerid cephalopods.

EDIT: the bar at the bottom is 1 inch(2.54cm)