2023 Mazon Creek trips

[Anomotodon]

Hey everyone! Haven't posted here in a while, and thought I would come back with a trip report. Recently I became interested in Mazon Creek fossils - something unusual for me as a vertebrate person. I finally managed to get out in the field this spring and visit the Mazonia-Braidwood State Park and the Braceville spoil pile through an ESCONI trip. I have collected at quite a few Paleozoic sites before, but this was my first time hunting in the Carboniferous!

 

 

I went to Mazonia with a friend on a weekend in early April, when there was no foliage and it was sunny outside. I read a lot of threads about Mazon Creek on this forum and we decided to go straight through the bushes to search for the most inaccessible areas we could find.

 

 

Here are a few concretions. Sadly, both of these turned out to be empty

 

Also found a first Pennsylvanian garter snake 

 

Here is our total haul for ~4 hours.

 

 

The only non-Essexella thing we found already open was this coprolite (?). By the way - if you see any errors with identification in this thread please correct me, I'm still learning a lot about this awesome deposit.

 

Then came the freeze-thaw. I decided to cheat a little and use the -80C freezer in the lab I work in, which shortens the freezing part of the cycle to a few hours. At this point, most of the concretions from this trip have already opened:

 

 

My nicest and largest Essexella ascherae.

 

 

Another Essexella (after vinegar). When it opened, I first thought it was some arthropod segment, but I like it anyways.

 

 

This one is weird. Coprolite?

 

 

Probably nothing (?), but the pyrite is pretty.

 

 

A plant of some kind, probably not identifiable.

 

 

And my favorite find: I believe this is the apex of a Calamites sp. - segments are clearly visible. This concretion didn't want to open for over a month, so I got frustrated and dropped it from the 4th floor of my building as I didn't have a hammer with me... Don't do that.

 

 

 

Edited May 18, 2023 by Anomotodon

[Anomotodon]

Then I went on an ESCONI trip to the Braceville spoil pile on Saturday, May 6th. The weather was not particularly nice, but we found some good spots to dig in and returned with lots of concretions.

 

 

Here is the pile itself.

 

 

Digging through the mud while it was raining was fun.

 

 

The "fossil dump" was also really nice - I picked up a few plants and worms 

 

 

And then a 3 hour drive back to WI.

 

 

Came back with ~10L of concretions - probably not a lot for that site, but we only brought 1 small shovel and it's definitely enough to keep me busy for a few months. This time I split these concretions 50/50 between my home and lab freezers, and I alternated freezing and thawing for each of these fractions - so basically, I have a box of concretions to thaw every day for instant gratification!

 

 

So far, not a lot has opened. This one I think is a Mazonomya mazonensis.

 

 

Myalinella meeki or unidentifiable?

 

 

Some plant bit.

 

 

 

Two of the many Essexellas.

 

 

 

This one just opened up today, I can count 8 juvenile Essexellas. This concretion is very thin and the middle section seems to be on a different plane, so I will just leave it as it is.

 

There are still quite a few concretions left to crack, I will keep posting the updates!

Edited May 19, 2023 by Anomotodon

[Mark Kmiecik]

You did quite well for your first trip. The areas that are difficult to get to because of the vegetation have the most concretions. Keep adding photos to this thread as they open up. 

[Nimravis]

Nice finds- congrats.

[Runner64]

This one looks like it could be a shrimp maybe?

Edited May 19, 2023 by Runner64

[Anomotodon]

18 hours ago, Mark Kmiecik said:

You did quite well for your first trip. The areas that are difficult to get to because of the vegetation have the most concretions. Keep adding photos to this thread as they open up. 

 

17 hours ago, Nimravis said:

Nice finds- congrats.

 

Thanks! Next one that opens will be a complete shark, I am sure.

 

15 hours ago, Runner64 said:

This one looks like it could be a shrimp maybe?

 

Interesting, I haven't thought of that! I don't see any segmentation though?

[Runner64]

3 hours ago, Anomotodon said:

Interesting, I haven't thought of that! I don't see any segmentation though?

I think if you flip it this way, but it does look really worn:

 

It's difficult to say but if not a shrimp, I would lean toward coprolite

[Mark Kmiecik]

18 hours ago, Runner64 said:

I think if you flip it this way, but it does look really worn:

 

It's difficult to say but if not a shrimp, I would lean toward coprolite

 

I'm leaning toward sea cucumber.

[Anomotodon]

10 hours ago, Mark Kmiecik said:

 

I'm leaning toward sea cucumber.

 

Thanks! I was thinking about that too, but unfortunately I don't see any sclerites preserved  

[Anomotodon]

Also, a few more things have opened. At this point I think I am getting more bivalves than even Essexellas, although vast majority of them are really messed up.

 

 

Here is my favorite - Mazonomya in the death position! It cracked weirdly, but at least the shell is not crushed.

 

 

Here are a few of the broken up bivalves I found - a mix of Myalinella and Mazonomya, I think. So many of them just crumble into dust when you open the concretion - breaks my heart every time  

 

 

Not entirely sure on this one - a partial worm, like Didontogaster cordylina? It does look segmented, but the Y-shape is strange.

Edited May 21, 2023 by Anomotodon

[Mark Kmiecik]

The preservation of the bivalves is typical of that location. Only one in ten is "presentable". I can't tell on the worm. Not enough there. Not well preserved.

 

The bivalve in the first photo may pop the other side out with a couple more freeze/thaw cycles, but you might wait until you have a better specimen before you try.

[Anomotodon]

I think it's time for another update! First of all, a few more Essexellas. The more of them I find the more I like them - it is just incredible how many different shapes a blob can fold into.

 

 

For this one it looks like there are two anemones on different planes, folded in different shapes.

 

 

My nicest Myalinella meeki bivalve. The shell is on the side of the concretion, trying to escape, so it is difficult to take a good pic - but it is a complete valve. Also found quite a few really crushed ones.

 

 

My first identifiable worm! Pretty sure this is Esconites zelus, because jaws are visible (see the micropic).

 

 

Now this is a cautionary tale for why you should be careful when whacking concretions... This one broke in half, and only one of the halves split - the other one is still in the freezer. I think this is some worm, but I don't see any jaws or other diagnostic features - so let's hope it's just the tail.

 

 

Also found some neat plants! This is a Lepidostrobophyllum - a cone bract of an arboreal lycopod. I know nothing about plants, but after some research I am thinking this is L. majus? (or L. lancifolius?)

 

 

And another lycopod part - bark of Lepidodendron cf. aculeatum (although not sure if you can ID it to a species level)

 

 

A strange tiny thing. Seed of some kind? Or a really small and worn Cyclus americanus?

 

 

A few more concretions which I think had a fossil at some point but I doubt are identifiable. Leaving it here just in case anyone has any ideas.

 

Edited June 4, 2023 by Anomotodon

[deutscheben]

You’ve got some nice finds in there, congrats! 

[Anomotodon]

I still have quite a few Braceville concretions left, but sadly they are opening at a much, much slower rate now. So I decided to come back to pit 11 last weekend.

 

 

Me and my friend decided to check out the 'Tipple Hill' area that I found through various posts here, since it seemed more exposed - and it is the summer after all. We walked from the parking lot until we reached the rows of creek beds. That area is quite difficult to hunt because of the abundance of orange-red rocks that are not actually concretions and, unfortunately, in the first hour or so we found less than 10 concretions. But then we finally found a relatively rich area in the furthest creek bed.

 

 

A few concretions. The second one turned out to be a fish scale!

 

 

There was also a lot of pyritized wood in this area.

 

 

I finally found some neat stuff that was already opened - a nice Essexella and a coprolite (?).

 

 

About 2.5 hours into our adventure we realized that it was insanely hot and sunny and we 1) forgot sunscreen and 2) didn't bring enough water...  So after checking out as much of the last area as possible we headed back.

 

 

Overall, this trip was considerably less productive than my previous time at pit 11. Although I have hopes that concretions from that area are more likely to be fossilliferous - 2/2 open concretions we found had fossils after all. In the previous pit 11 location I visited this April, we only found a tiny coprolite open and overall I think only ~10% of the concretions had fossils.

 

 

First of all, here is what I think is a coprolite or some plant material (?). It is very 3D and has irregular texture, which is why I was leaning towards a coprolite.

 

 

The Essexella we found open after cleaning, it's definitely one of my favorites! Apologies for the scale on these pics, I somehow lost my ruler... 

 

 

My first vertebrate - a fish scale! I am thinking Ctenodus cristatus.

 

 

A small plant piece - maybe a Cyperites lycopod leaf.

 

 

Not entirely sure what this is - possibly shrimp molt? 

 

 

A bryozoan and some shell bits - I am assuming this is Silurian? The rock seems very different from the earlier Paleozoic dolomites I've seen in the area, and kind of looks like a concretion. 

 

 

 

[stats]

Nice finds!  Pit 11 is a challenging place in the summer!  Hopefully, you remembered your bug repellent...

 

Cheers,

Rich