My Mazon Creek Finds

[deutscheben]

I will be using this thread to post what I have found fossil hunting in the Mazon Creek area, including the ESCONI Braceville pile, Mazonia/Braidwood, and any other sites I get a chance to explore. Although I had been to Mazonia a few times previously with virtually no luck, my first successful trip was with ESCONI last September at the private spoil pile they have access to. These first fossils are all from there.

I have tried to give the best IDs I can- please jump in if you think I have anything wrong. I also forgot to put something in for scale on this first batch of photos, my apologies.

First are three that I believe to be Essexella asherae, all very different looking though. The first is quite large, 7.5 cm across, and I love the red color.

Next are two Achistrum sp., the first is my favorite fossil I have found from Mazon Creek thus far- curled up neatly in the nodule and nearly complete. The second is partially pyritized- I couldn't find any similar examples online, so it seems fairly unusual.

Here are a few Mazonomya mazonensis, the top one is adorably petite- the shell is less than 1 cm across.

This is small impression fossil of some bark- I'm still learning to ID the Pennsylanian flora, so I'm not sure exactly what this would be called.

This appears to be a trace fossil, possibly a tunnel of some sort?

I believe this is a coprolite.

Finally, a few incomplete worms. The first I have identified at the tail end of Didontogaster, while the second nodule seems to have a few thin worm-like fossils preserved- perhaps Flabelligeridae sp.?

[deutscheben]

I returned to Mazonia/Braidwood last weekend and collected quite a few nodules. Here are two that split in the field- a small Pecopteris sp. fern frond and a very partial Neuropteris sp. As more split, I will post them in this thread!

Edited March 13, 2016 by deutscheben

[CBOB]

Nice stuff!

[Rob Russell]

Very nice! Thanks for sharing!

[lissa318]

Nice finds!!!

[deutscheben]

After dozens of duds from my Mazonia trip in March (looks like all the nodules from one spot where I found a bunch only had pyrite in the middle, no fossils), I finally had a few split with recognizable fossils in the middle.

The first is a blobby Essexella similar to the one in my first post:

The second was very exciting, my first Mazon shrimp! Since it is not complete and preserves only the ventral surface, I'm not sure exactly what type it is- perhaps Belotelson? The carapace has a really neat blue-green color that contrasts with the orange outline.

For those with experience dealing with Mazon Creek fossils- would it be worth it trying to prep any more of the shrimp out?

Edited May 8, 2016 by deutscheben

[TheRocksWillShoutHisGlory]

That's a cool shrimp!

[deutscheben]

Over the last few months I've gone through almost all of the nodules from my March trip to Mazonia. The result has been Essexella a plenty (and nothing else)! Here they are, in a variety of different sizes, preservation types and colors.

A fairly faint one.

This one is quite clear in outline, and my first of this non-"blobby" preservation type.

My biggest by far, and interesting details in the folds.

This one is my favorite of the bunch.

Edited July 17, 2016 by deutscheben

[deutscheben]

In late May I also had a chance to collect a small number of nodules from a site in Morris, IL. Here are the identifiable fossils I have found in that batch- there are a couple more I am unsure about that I will be posting in the ID forum.

Another Essexella! And yet again, a slightly different form of preservation.

Aviculopecten mazonensis, a new species for me, so I was excited to find this one.

These Mazonomya were already open in the field and are pretty weathered.

This one is good condition though- I love the fine intricacy of the growth lines.

[Rob Russell]

Beauties! Thanks for sharing! . Is the scale in one inch increments?

[deutscheben]

Oops yes, the grid is one inch squares.

[doushantuo]

Great finds,all of them.

[deutscheben]

Thanks guys! I had two more concretions split last week. I finally started the freeze and thaw with my finds from the May ESCONI trip to Braceville and the first is from that batch. Another Essexella, but it's a great one, with a very distinct bell and nice coloration.

The second is my smallest Mazon fossil so far. This one is from the Morris site. The nodule contains some plant debris, but near the edge (in the middle of the picture) is the tiny shell of what I believe is the branchiopod Pemphilimnadiopsis ortoni.

Edited July 24, 2016 by deutscheben

[Wrangellian]

Love those Essexellas... I wouldn't mind if I kept finding them - they're jellyfish for godsakes! How many people can collect jellyfish (or any softbodied) fossils?

[Lori LuvsFossils]

Nice!

I've got 40 in rotation. I thawed again this afternoon, but for some reason this has been a pesky bunch. Usually I have a popper or 2 in the first couple of freezes so I'm willing to say even the freezer isn't cool enough this extra hot summer. lol

[CraigHyatt]

Nice!I've got 40 in rotation. I thawed again this afternoon, but for some reason this has been a pesky bunch. Usually I have a popper or 2 in the first couple of freezes so I'm willing to say even the freezer isn't cool enough this extra hot summer. lol

I am *so* going to start doing this. I see so many nodules and never bother picking them up. Can't wait to see what kind of goodies are in there. :-)

Edit: Give me the rundown on freeze thaw. Do you soak them in water before freezing? How long do you freeze them? Do you let them warm up naturally or hit them with a heat gun, hot water, etc.? Do you need to tap them with a hammer to pop them or do they crack by themselves?

Edited July 27, 2016 by CraigHyatt

[Lori LuvsFossils]

I spread them out in a single layer then cover them with water. Freeze solid, then run under HOT tap water. Sometimes you'll hear a little "pop", sometimes it comes minutes later. I let them sit at least 10 minutes before putting them back in the freezer.

NO HAMMERS, no matter how irritated you get. Some of them go in & out of the freezer 30+ times. I've got 2 from 2 years ago that still haven't popped. THOSE, I threaten to hit, but haven't yet. lol

[CraigHyatt]

I spread them out in a single layer then cover them with water. Freeze solid, then run under HOT tap water. Sometimes you'll hear a little "pop", sometimes it comes minutes later. I let them sit at least 10 minutes before putting them back in the freezer.NO HAMMERS, no matter how irritated you get. Some of them go in & out of the freezer 30+ times. I've got 2 from 2 years ago that still haven't popped. THOSE, I threaten to hit, but haven't yet. lol

Thanks so much. Heard other members talking about this, but never really considered trying it. Not sure what mama's going to say about finding rocks in the freezer. ;-)

[CraigHyatt]

I don't know a round rock from a concretion, so I'm going to pick up a sample of 10 rocks of different sizes and materials. You pays your money, and you takes your chances. It's not like there's a global rock shortage. :-)

[ynot]

I don't know a round rock from a concretion, so I'm going to pick up a sample of 10 rocks of different sizes and materials. You pays your money, and you takes your chances. It's not like there's a global rock shortage. :-)

image.jpegimage.jpeg

Most concretions have a high iron content and tend to be reddish brown (rust ) colored. There are some that have a gun metal gray color. Very few are light tan or buff colored.

Tony

[deutscheben]

Most concretions have a high iron content and tend to be reddish brown (rust ) colored. There are some that have a gun metal gray color. Very few are light tan or buff colored.

Tony

And the concretions of the type in this thread can only be found in the Mazon Creek deposits in Illinois- although there are certainly many different types of fossil-bearing concretions that can be found across the country.

[Wrangellian]

I don't know a round rock from a concretion, so I'm going to pick up a sample of 10 rocks of different sizes and materials. You pays your money, and you takes your chances. It's not like there's a global rock shortage. :-)

image.jpegimage.jpeg

I'm not sure what those are, but to be sure I was collecting concretions I would look in an area where sedimentary concretion-bearing rock was exposed, to avoid picking up any old rock that has been rounded by abrasion in a stream.

Myself, I have not even been bothering with the concretions I find in my local shale though they do sometimes contain fossils, they're often just too tough to break open with a hammer and when they break they don't break cleanly - usually thru the fossil rather than around it, but I doubt freeze-thaw would work any better on these. Or maybe it would - I should try a few someday...

I tried freeze-thaw on a batch of Mazon conc's and most of them just crumbled. Only one ended up having a small fossil and its outer 'rind' was all flaked off by the freeze-thaw, not very attractive. All those ones I see online and for sale on ebay have nice intact rinds and I wonder if they weren't opened with the careful tap of a hammer.

Edited July 28, 2016 by Wrangellian

[deutscheben]

Love those Essexellas... I wouldn't mind if I kept finding them - they're jellyfish for godsakes! How many people can collect jellyfish (or any softbodied) fossils?

I missed your comment somehow, Wrangellian. I definitely agree; although they may be common Mazon Creek fossils, finding a 300 mya jellyfish preserved in such detail amazes me every time!

[deutscheben]

Speaking of jellyfish, here is my latest batch of Essexella that have split, a good grouping to show the diverse ways they can be preserved. These are all from the Braceville site.

[deutscheben]

Two more decent finds from my last few freeze/thaw cycles. Both of these are from the Braceville dig.

The first is my best preserved and most complete Mazonomya- it has some neat coloration too, with a light "stripe" running across both valves.

The second is poorly preserved, but appears to be a polychaete worm of some sort. The nodule actually split on an additional plane on the opposite side too, revealing a sliver of another worm, but I'm using all of my willpower to avoid hammering it to bits to expose it. It's hard to resist sometimes!