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Found 368 results

  1. Mazon Creek: Best of the Best

    Our esteemed member @RCFossils has an impressive collection of fossils from the Mazon Creek deposits. Here, in this pinned topic, we will gather all of his "Best of the Best" topics, so that they may be easily found. Thanks, RCFossils , for making these wonderfully photographed and informative posts!
  2. Arthropleura is one of the most impressive animals that lived in the Pennsylvanian coal swamps. It is also the largest terrestrial animal known from the Mazon Creek deposit and largest terrestrial arthropod of all time. This giant millipede reach an enormous size estimated to be approximately 2 meters! Unfortunately we do not find complete body fossils. Tergites, limbs and an unusual joint structure that connected the leg to the body (rosette organ) have been found. Any Arthropleura material from Mazon is extremely rare. I would estimate there are only a few dozen specimens known to exist. The earliest reported find of Arthropleura in the Mazon Creek Came from George Langford and Eugene Richardson in 1952. They recovered 2 rosette organs. A few years later a complete leg was found. At first these finds were thought to be unusual shrimp. Richardson was the first to realize that they were indeed Arthropleura. This was the first reported find of Arthropleura in North America. Over the next 2 years a few other specimens were recovered. All were found in the same small area at Pit 1. Richardson formally described Arthropleura cristata in 1959. At the time there was some debate as to if Arthropleura lived its life in water or on land. Many trackways have been found at different sites proving that Arthropleura was terrestrial. Gut contents are known from more complete Arthropleura found at other sites showing that it fed on lycopsid spores. Lycopod cones have a similar appearance to a modern day pine cone. There are a few large coprolites that have been collected from the Mazon Creek deposit that consist of these cone bracts. These coprolites have been attributed to Arthropleura. I am very fortunate in having been able to accumulate several fantastic examples of the different body structures of this amazing animal. All specimens were collected from the actual Mazon Creek site. The leg shown is also pictured in The Mazon Creek Fossil Fauna book by Jack Wittry. This first specimen is tergite which would have been positioned on the outside edge of one of the body segments. Most specimens show preserve a bumpy texture. As you can see this one is smooth and might be showing the underside of this plate.
  3. This is a relatively rare member of the marine (Essex) portion of the Mazon Creek deposit. Hesslerella shermani looks to the casual observer to be some type of shrimp. It is actually a marine isopod related to modern day pill bugs. One of the main features that differentiate it from a shrimp is that it lacks a carapace. Other distinguishing characteristics are a rounded head with large eyes. The legs are also similar in length. Hesslerella is one of the smallest crustaceans found in the Mazon Creek deposit. They average around 2 centimeters or less in body length. At the time Hesslerella was described (Schram 1970), it was the earliest known isopod in the fossil record.
  4. I have been fortunate to hunt Mazon Creek fossils for nearly 40 years. I have collected Many tens of thousands of concretions. I have also purchased premium specimens from other collectors. In the past, I have posted many of these specimens on the forum. I have decided to start posting more in depth descriptions of some of the amazing animals that can be found in the MC deposit. All specimens that I will post are from my personal collection. The first animal that I will highlight is the holothurian or sea cucumber Achistrum sp. Sea cucumbers are a common animal in today’s oceans but quite rare in the fossil record. The Marine (Essex) portion of the Mazon Creek deposit is one of the few places in the world where complete body fossils of these animals can be collected. These worm like animals are actually a type of echinoderm and show 5 radial body elements that run the length of the animal. Well preserved specimens will show a sac like body and an oral ring preserving approximately 15 calcareous plates. Occasionally the intestinal tract and other internal features will be preserved. Just like modern sea cucumbers, Achistrum sp had a leathery body covered in “J” shaped sclerites or Sigmoid hooks. Often times, detecting these under a microscope is the best way to identity poorly preserved specimens. As the animal dried out, the skin would crack and these cracks were eventually replaced by calcite. This gives the body of Achistrum sp a septarian like appearance. While modern sea cucumbers have retractable tentacles surrounding the mouth, none have been observed in Achistrum sp. The animal can reach length of over 15 centimeters however most found average under 10 centimeters. Achistrum is relatively abundant and are occasionally found in masses of multiple individuals. Despite many thousands of specimens collected, Achistrum has never been formally described. At one time it was believed that there may be as many as a dozen different species of sea cucumber found in the Mazon Creek deposit. This has been reduced to one or possibly two different types. This first image shows an exquisite specimen that I collected at Pit 11 in 2017. it is a complete animal and preserves evidence of some unusual muscular structure in the esophagus area that I have not seen before.
  5. Mazon creek stuff

    Hi guys I have no locational info on the pits these were collected but some do have the layering typical of the actual creek specifically the Pecopteris but I was wondering if anyone could provide some accurate id’s thanks so much
  6. Jellyfish? Folded Annularia?

    I found this concretion already opened and heavily coated with dirt and minerals. The few parts I could see poking through gave me hope something was preserved. Now that I have cleaned it up, I am still trying to figure out whether or not the concretion contains a fossil. It can look very different depending on the way you position it. I see a jellyfish looking mantle but the tentacles look different from what I have seen before. Positioned vertically, I start to lose the jellyfish and wonder if it is a partial annularia. Or maybe it is just a lumpily split concretion.
  7. Carboniferous Terrificous

    Here are some fossils I found in the town of St.clair in Schuylkill county , Pennsylvania. Llewellyn formation. 300 Mya. preserved in black shale.
  8. Sphenophyllum?

    I have two different nodules from September that I think may be Sphenophyllum. Both nodules were found open, one had one half heavily covered in minerals. I did a short rinse in vinegar to clean that off.
  9. Unusually smooth nodule

    I found this half of an open nodule last September when I was hunting at Mazonia Braidwood. It was covered in dirt so I took it home to see if anything would show up when I cleaned it up. The dirt rinsed off easily and I was surprised to find a layered, smooth surface on the inner half. The feel and patterns of colors remind me of the inside of a shell. Has anyone seen this before or have any ideas about what this is?
  10. More unidentified MC fossils

    So we have yet another unidentified mazon creek fossil. I see two possible specimens here but I’m not convinced either are proper fossils or even what they could be. The larger one looks like wood to me, and the smaller one looks darker and oddly shaped. I first thought maybe a flat worn?
  11. Mazonia (Blob) fossils, please help ID

    I actually went to Mazon creek for once, however I’m quite new there so I need some help identifying what I found
  12. Mazon Creek Jellies?

    Hey guys! I’ve got some items here from Mazon Creek, IL, and I need a little help IDing them. The first one looks like a jellyfish to me, but I’m no expert. The second two... honestly I don’t even know if they’re fossils at all. The last one makes me think it might be because the center of the inside is dark and glossy and looks a little like a crunches up jelly, but I really can’t say. Any thoughts?
  13. Mazon Creek ID

    This tiny guy just popped in the freezer today. I apologize if the pictures aren’t the best – the nodule is barely a centimeter at its widest point, so my phone is having a tough time focusing. If they’re not good enough let me know and I’ll try again. Anyways, I have no idea what this is! Maybe some kind of bark?
  14. Mazon Creek fossil id

  15. Today was the 2nd day of the ESCONI Braceville Shaft Mine Trip to collect Mazon Creek concretions. I was not able to go yesterday since I did not arrive back from Puerto Rico until later that night. I did want to make it out today because I had a number of buckets of fossils (Mazon Creek flora and fauna, Indiana and Kentucky Ordovician has plates and loose horn Coral / bryozoan, Moroccan echinoids and Pleistocene/Pliocene shells) to dump out for the participants. I was not sure that the trip was going to go on due to rain, but I did receive a PM from @stats Rich advising me that it was on. I had contacted him before I left for vacation and advised him that I had some buckets that I wanted to dump. Rich and others also had fossils that were dumped yesterday and today. Even though there was quite a bit of rain in the morning, there were a number of ESCONI members who showed up for some fun in the mud, and it was muddy today. I did not stay to do any collecting due to the fact that my wife wanted me to go grocery shopping- lol. If you live in the area you should join ESCONI, you would love going on this trip that is held on two different weekends during the year. Here are a couple pictures that I took while I was at the site. The muddy walk in- Collectors on the hill- Participants going through the “dump pile” of fossils.
  16. Braceville fossil hunting

    Tomorrow I will be heading out on my first ESCONI trip. I will keep you guys updated on what we find!
  17. First Mazon Creek Fossil Hunt

    This weekend I made my first trip out to Mazon Creek! Sorry this is such a scroller, I'm going to try and have this post be informational since there is definitely some stuff I wished I'd known about in advance and some stuff I did that really aided my success. There are pictures at the bottom. The most important thing I did before my trip was print off a topographic map of the area that I pulled from ArcGIS online. It really came in handy. It was also necessary to have a permit to collect there, something I only discovered the night before. Here is a link to a PDF of the permit. I drove down with a fellow UChicago student. We parked at the first lot off of WN5000 road from the Kankakee road side. Our plan was to use the topo map to find the steepest erosional surfaces to collect on. Initially this strategy seemed like a bust. In our first forty minutes we only found three concretions between us. I think that was because the area near the parking lot and WN5000 road was just really picked over. As we moved deeper into the brush, our finding rate increased. At some points we literally found piles of concretions, this was usually because they had landed in the roots of trees or come up against some other impediment. Our best finds were usually midway and above on the hills. Finds near the bottom of the hills tended to be weathered more extensively and were often fragmented. The concretions themselves were reddish and mostly about the size of half dollars, but larger and smaller ones were also abundant. Concretions found in sunny areas tended to have oxidized to a rusty orange color. We found fragments of some very large concretions, so those are out there, but the largest intact ones we found were about the size of a tea saucer. Many were also pre-split from weathering. We collected a fair number of these since they were covered in mud and it was hard to tell whether there might be a fossil or not. By the end of the afternoon we each had about 1/3rd of a 5 gallon bucket filled with concretions. We could easily have filled the buckets with an additional hour or two of effort, but we were pretty tired and satisfied with our success, so we called it a day. In terms of the environment, the terrain was very rugged and filled with dense brush. Open spaces were filled with burr plants to the point of absurdity. By the end of the day we looked like we had ghillie suits from the sheer quantity of vegetable matter clinging to our clothing (picture below). I recommend wearing long sleeves and pants to protect the skin, and selecting fabrics that burrs will not easily cling to. Additionally, there were lots of biting insects, but a quick spray of DEET solved that problem. I'm prepping the concretions by throwing them in the freezer. However, I'd appreciate it if somebody could link me to a post on the proper treatment, or enlighten me below- both for my own knowledge and for other readers. Photo of two of my pre split finds- the rest are in the freezer right now. (I think a polychaete worm on the bottom, and I have absolutely no clue what the thing on the top is) Our overall route (roughly) Concretions/concretion fragments in situ Me covered in burrs and looking like a dork
  18. Hello everyone, I have noticed that I have almost no fossils from the Carboniferous period and would really love to add some to my collection. I have decided to start out with the Mazon creek as it had many fascinating inhabitants. I am interested in pretty much everything from there and am not looking for anything spectacular. For what I have, there are Thalassina anomala mud lobsters from Australia, Devonian fossils from New York such as trilos and brachiopods, Jurassic Ostracods from CT, a few echinoids and probably other things too.
  19. Mazon Creek Fossil

    To those of you who are serious collectors, this is probably not thought of as an outstanding specimen, but as I'm primarily a mineral collector, I was thrilled to find this piece! I believe it's a section of Calamites, with what I consider some amazing crystallization of calcite and sphalerite.
  20. Mazon ID Help

    I am thinking that this is a Drevotella proteana, with, but not necessarily attached to, a Palaeolima retifera.
  21. Mazon Creek

  22. Mazon ID Help

  23. Mazon Creek

    From a flat of specimens identified as from Pit 11. Three dimensional. Small leaf? Thanks! ~Paul
  24. Mazon Creek

    From a flat of specimens identified as from Pit 11. Mouth looks familiar as that of Achistrum, but no dessication cracks. Looking to confirm identification. Thanks! ~Paul
  25. Mazon Creek Unknown

    This is my first non-Essexella find so far. Or at least non-indistinguishable-blob find that is. That said, I have absolutely now idea what it is. It looks vaguely familiar but I can’t put my finger on it. I hope the pictures are decent enough, if not I can try again. I uploaded some with a contrast boost as some of the details are faint.