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Late Ordovician Trilobites


Guest solius symbiosus

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Guest solius symbiosus

I stopped by the outcrop today that I was on my way to visit a couple of weeks ago when I got side tracked by another outcrop(see my last thread in this section). This is the first time I have collected this outcrop since the 80s???; back then it produced decent trilobites on occasion.

The bed is about 10cm thick, and located in the Claysferry Fm. It is early Late Ordovician. I have collected from this bed at several outcrops in about a 20km² area. It appears to be continuous through the immediate area. The strange thing about the bed is that it is composed, almost entirely, of fragments from Isotelus gigas.

Over the years I have pulled some nice I. gigas from the bed. A bed that is a couple meters lower in the column produces some nice Trinucleus sp. cephalons and pygidiums, but at this locality, it was not exposed.

On the way to this outcrop, I stopped by an outcrop that is the same horizon(and about 2km from) a bed that I hunted years ago. That bed produced several pieces of an un-described trilobite, but it has since been destroyed by construction. I picked up a few things, but I'll save those pics for another day.

A big slab of flow stone on the face of the outcrop.

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Close up of the base of the flow stone.

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Lots of trepostomates above, and below, the "trilobite zone".

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A ramose colony(height of pic about 12cm).

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Lots of I. gigas partials.

A nice sized pygidium

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A glabella and pleuron.

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Pygidium, librigena, pleuron, ... ect.

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A little bit of everything.

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It was only a matter of searching before some better ones came along.

This one appears to be nearly complete. The side of the stone shows more of the pleurons where is is enrolled.

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Bingo! Usually when these thing molt, they split along the glabellar suture and the cephalons are rarely complete. This one should prep out nice. The stone that this one is on also has a nice Gravicalymene cephalon, but I didn't notice it until after the pic was taken.

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It would have been nice to find the rest of this one.

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This one is weathered. Most of the cephalon and pygidium is gone. The axial lobe aligns with, and is closest to, the scale.

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The outcrop is about 40 miles from the house, so it is a pain to drive to, but I'm going to try to hit it again one day next week.

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Where else but the Forum can you read a line like "I got side tracked by another outcrop"?

I wish I lived 40 miles where I could pick-up trilobites like bmore picks-up sharks teeth!

BTW, the flowstone is very cool.

"There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant

“Try to learn something about everything and everything about something.” - Thomas Henry Huxley

>Paleontology is an evolving science.

>May your wonders never cease!

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Guest solius symbiosus

^^From the looks of it, I'm pretty sure the whole thing is there. I have a ton of stuff to prep... one of these days.

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Nice trilos. When I lived there, I was always searching for them, with not much success (other than the complete Gravicalymene you have seen). Your pics confirm that I was finding pieces of them at the time and never even knew it (young and dumb back then). I knew they were broken pieces of something and usually just threw them aside. Sometime this year....

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Guest solius symbiosus
Nice trilos. When I lived there, I was always searching for them, with not much success (other than the complete Gravicalymene you have seen). Your pics confirm that I was finding pieces of them at the time and never even knew it (young and dumb back then). I knew they were broken pieces of something and usually just threw them aside. Sometime this year....

These were found out off US 44 in Anderson Co, but I have also located the same bed in several areas off 62. Back in the 80s, I pulled several nice ones from this same bed... one measuring about 25cm; however, it is weathered. If I make a trip to my warehouse, I'll post some of the pics. Here are a couple that I have laying around from the same bed.

I also have the negative of this one. I was trying to chop a pygidium out of a piece of matrix, looked down, and this one was laying at my feet. It was on the bottom of the stone that I was chopping, and fell out from the hammer blows on the upper surface.

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Unfortunately, the cephalon is missing

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It looks like something took a bite out of this one. (scale is about 2.5 cm)

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Guest solius symbiosus

While chopping out this "orthoceras"(note the preservation of the original hatched pattern of the shell).

mag x30

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I found this thorax in a piece that had broken off. The whole thing is probably there, but the stone is in about 20 pieces, so it will be a puzzle.

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I started working on the one trilobite.

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Guest solius symbiosus

I had a couple of hours to kill today, so I took the drive and visited an outcrop a couple of miles from the one visited Sunday. It is the same "trilobite bed". I saw a pygidium from a calyminid(Flexi???), but I forgot to photograph the thing. This does give me hope that a phacopid will be found there eventually.

Acicular crystals in a vug(celestite???)

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It would have been nice to find the rest of this one, but no luck.

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This thing would have been a monster.

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Holochroal eye facets from the above pic(mag about x20 and x40). As this type of preservation often preserves nice detail, I might try to grind a few thin sections from the eye.

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Another monster. Ventral pygidium

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Check out the size of this hypostome. I bet these things predated on the orthocerids. :P

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I think most of this one is preserved.

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As this one was in a large slab, and I didn't have a sledge or saw, I had to leave this one behind. But it was a big one.

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sweet trilos! by the way, i love your avatar!

I arise in the morning torn between a desire to improve the world and a desire to enjoy the world. This makes it hard to plan the day. ~ E. B. White

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