Trilobite Hunting, Crinoid Finding... Platteville Formation

[Caleb]

Due to accidently leaving a pile of fossils at a quarry last weekend, my father and I made the trip again down to Southwest Wisconsin to collect the Ordovician Platteville Formation. It was forcasted to be much warmer than last time, but cloudy all day with a chance of rain. Luckily this was wrong and it was an absolutely beautiful day to be collecting, sunny and the temp up to 70.

We decided to go to one of our new spots that has both the Mifflin and Grand Detour members of the Platteville Formation. We were looking primarily for a new species of Thaleops that seems to only come out of the Grand Detour member. We didn't have any luck with that, but what I did find was a very big shock and I must say I let out a hoot/cheer when I saw it. It was a slab of 6 rare crinoids that I have never collected myself. I think my father may have one or two, but these are much larger than anything he's found, and did I mention there were 6 of them!!?

Cremacrinus arctus

Crinoid

Pocket knife is 89.6mm/3.52" long

There's the cluster of 4 and then two more toward the lower right. They are mostly covered yet with matrix.

Here's a picture of me standing next to my prize of the day. Even from theis distance you can make the crinoids out... They're in front of my gut.

We continued our hunt in the large pile of Mifflin member, which lies directly below the Grand Detour member. Unfortunately I didn't find any complete trilobites, but I did find a nice example of a "once complete" Isotelus simplex with the hypostome exposed in place. The prize out of the Mifflin was a tiny Amphilichas sp. type 2 pygidium. Type 2 is the most rare of the Amphilichas out of the Mifflin. In the many years we have been collecting, my father has only found 3 specimens, and this was my first.

Amphilichas sp. type 2, right next to the Hypodicranotus sp. hypostome.

Isotelus simplex showing hypostome in place.

Our final stop was one of our classic collecting holes. I came away with a complete enrolled Isotelus simplex that made a fantastic close to a wonderful day. Pic coming soon.

[Bev]

Congrats Caleb! What a wonderful trip!

[squalicorax]

Good job buddy!!!

[PRK]

Wow, those are beauties! I'm from the west coast and never have encountered those kind of fossiliferous rocks. how does one go about removing something like that?

[evren]

Nice find!

[erose]

Don'tcha just love the Ordovician?

[Caleb]

Thanks all! With the cold weather creeping in fast, this was a good possible close to the collecting season. I may get out again if we get lucky like last year with a mild winter.

Wow, those are beauties! I'm from the west coast and never have encountered those kind of fossiliferous rocks. how does one go about removing something like that?

Collecting these bad boys is not going to be easy. Right now the crinoids are still in the field as we have not yet purchased a rock saw. It will not be an easy task to collect the crinoids as they are in a very large rock with no immediate signs of fractures. First off we will remove a layer below the crinoids to make sure there are no more/or to find there are more. Next we will use a 14" saw to square out the desired area and also weaken the massive slab. Next will be a lot of hammering and chisels to free the desired area. After that we will cut a line all around the specimen and try to make the slab thinner so it can be handled for prep. Finally we take it to somebody far more skilled than us and pay them to prep the crinoids making a fantastic display slab. As is, the crinoids look weathered, but the arms, calyx, and stems appear to be covered in a fine film. Once hit with an air abrasive, they should be beautiful.

A little diagram showing the desired collecting area and process

[PRK]

I was just curoius about that hugr solid rock. Yes I see that they are special and will prep just fine thanks!

[Crinoid Queen]

:drool: NIce Stuff Caleb!!! Those crinoids are yummy!

-CQ

Edited November 11, 2012 by Crinoid Queen

[Ludwigia]

Those crinoids are gonna be great, Caleb! Will you show them to us after prepping?

[Missourian]

I did a 'double take' when I saw the crinoids in the image thumbnail. Very nice. It looks like they were oriented by the currents before burial. I think I can speak for everyone wishing you all the luck with extraction and prep. We eagerly await the resulits.

[Caleb]

Those crinoids are gonna be great, Caleb! Will you show them to us after prepping?

Of course I will! Though it may be a while before that happens. I will probably drop them off to be prepped with a few other things at MAPS in April, and then get them back the following MAPS show. It's a long painful wait, but worth it to have them professionally prepped.

[trilobiteruss]

Excellent find Caleb, very exciting!

[Ludwigia]

Of course I will! Though it may be a while before that happens. I will probably drop them off to be prepped with a few other things at MAPS in April, and then get them back the following MAPS show. It's a long painful wait, but worth it to have them professionally prepped.

Well, I think it's well worth the wait if you don't have any other possibilities.