Category: Mazon Creek
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2026 ESCONI Gem, Mineral, and Fossil Show – Preview #25: Calomostachys Cone
We have a bunch of Mazon Creek fossils this year… here’s another nice cone – Calomostachys, sp. One day away from the show… are you coming?!?
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Mazon Monday #313: Mazon Creek Studies – the first 120 years
For this week, we have an article from the September 1978 edition of the Field Museum’s Bulletin. The full edition, which includes Jaunary thru December, is available on the Biodiversity Heritage Library (BHL) website.
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Fossil Friday #308: Beautiful things in small packages…
For this week, we have a nice and detailed orbicular pinnule from a Macroneuropteris scheuchzeri. The concretion is very small., but the “hairs” are there. Unfortunately, they may not show up in the photos. This concretion was collected from Pit 2 and opened via freeze/thaw. Check out the last photo to see the size and…
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Mazon Monday #312: Sigillaria tessellata
Sigillaria tessellata is an extinct species of spore bearing, arborescent (tree-like) lycophyte from the Mazon Creek fossil deposit. Arborescent lycophytes (or scale trees) belong to the group Lepidodendrales. Sigillaria is known from as early as the Middle Devonian. It went extinct during the Early Permian Period.
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Fossil Friday #307: Euphoberia sp. From Pit 11
For today, we have a very nice Mazon Creek millipede. Euphoberia is an extinct genus of millipede found in both Europe and North America. The genus was erected by Fielding Bradford Meek and Amos Henry Worthen when they described Euphoberia armigera as a centipede in 1868.
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Mazon Monday #311: Strip mining begins in Braidwood on May 23, 1928
Yesterday marked opening day for fossil collecting at the IDNR Mazonia–Braidwood State Fish and Wildlife Area. I hope you were able to make it out… or are planning a trip soon. This is prime season for collecting at Pit 11, the name many collectors still use for Mazonia–Braidwood.
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ESCONI Books and Items for Sale
ESCONI actively sells our Club’s new books on Mazon Creek fossils that were written by Jack Wittry (an Honorary Club member). We also sell other ESCONI-branded items such as T-shirts, hats, mugs, ornaments, memory sticks, etc., in addition to used books that are donated to the Club. These items are for sale at ESCONI’s annual…
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Fossil Friday #306: Cyclus obesus
Just earlier this week, Mazon Monday #310 was about Cyclus obesus. That post was triggered by Mike Monteith’s recent find. On one of the nice days last week, Mike was going through his freeze/thaw from this winter and found this very nice Cyclus obesus. Thanks for sharing, Mike!
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Mazon Monday #310: Cyclus obesus
This is Mazon Monday post #310. What’s your favorite Mazon Creek fossil? Tell us at email:esconi.info@gmail.com. Cyclus obesus is one of four species of Cycloidea found in Mazon Creek. It was described in the paper “Mazon Creek Cycloidea” by Frederick Schram. The paper was published in the Journal of Paleontology in 1997. In that paper,…
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Mazon Monday #309: Herbivory is Older Than We Thought!
This is Mazon Monday post #309. What’s your favorite Mazon Creek fossil? Tell us at email:esconi.info@gmail.com. The Mann Lab at the Field Museum has been very busy. Their new paper “Carboniferous recumbirostran elucidates the origins of terrestrial herbivory” published in the journal Nature Ecology & Evolution has significant implications for the Mazon Creek ecosystem. This…
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Fossil Friday #304: A Heartwarming Tully Reunion
This is the “Fossil Friday” post #304. Expect this to be a regular feature of the website. We will post fossil pictures you send in to esconi.info@gmail.com. Please include a short description or story. Check the #FossilFriday Bluesky/Twitter hash tag for contributions from around the world! For Valentines Day, we have a nice heartwarming Tullymonster reunion…
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Mazon Monday #308: Acitheca polymorpha
This is Mazon Monday post #308. What’s your favorite Mazon Creek fossil? Tell us at email:esconi.info@gmail.com. Acitheca polymorpha is an extinct species of the class Filcopsida. It is one of the rarer species of fern found in the Mazon Creek fossil localities. The classification of Acitheca polymorpha (Pecopteris polymorpha) has been problematic. Leo Lesquereux figured Pecopteris…
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Mazon Monday #307: Arjan Mann on Fossil Nerds
This is Mazon Monday post #307. What’s your favorite Mazon Creek fossil? Tell us at email:esconi.info@gmail.com. Episode #94 of the Fossil Nerds podcast is “The Marvelous Mini-Monsters of Mazon Creek with Arjan Mann”. Arjan is the Assistant Curator of Early Tetrapods at the Field Museum. He discusses his lab’s work, various ancient fish and tetrapods,…
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Fossil Friday #302: A Beautiful Macroneuropteris scheuchzeri from Braceville!
This is the “Fossil Friday” post #302. Expect this to be a regular feature of the website. We will post fossil pictures you send in to esconi.info@gmail.com. Please include a short description or story. Check the #FossilFriday Bluesky/Twitter hash tag for contributions from around the world! For this week, we have a beautiful pyritized Macroneuropteris sheuchzeri…
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Mazon Monday #306: Drevotella proteana
This is Mazon Monday post #306. What’s your favorite Mazon Creek fossil? Tell us at email:esconi.info@gmail.com. Drevotella proteana is believed to be a hydrozoan. It lived during the Pennsylvanian Period. Fossils of this soft-bodied animal are known only from the Mazon Creek fossil deposit, where exceptional preservation allows such delicate organisms to be recorded. Hydrozoans…
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Fossil Friday #301: French Palaeocaris
This is the “Fossil Friday” post #301. Expect this to be a regular feature of the website. We will post fossil pictures you send in to esconi.info@gmail.com. Please include a short description or story. Check the #FossilFriday Bluesky/Twitter hash tag for contributions from around the world! In Mazon Monday #294, we highlighted the fossil site at…
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Mazon Monday #305: Herdina mirificus
This is Mazon Monday post #305. What’s your favorite Mazon Creek fossil? Tell us at email:esconi.info@gmail.com. Herdina mirificus is an extinct species of short-winged insect, currently classified in the order Protorthoptera. Protorthoptera is an extinct lineage of insects that lived during the middle to late Pennsylvanian Period some 318 to 299 million years ago. The…
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Fossil Friday #300: Orthotarbus robustus from the River
This is the “Fossil Friday” post #300. Expect this to be a regular feature of the website. We will post fossil pictures you send in to esconi.info@gmail.com. Please include a short description or story. Check the #FossilFriday Bluesky/Twitter hash tag for contributions from around the world! Is there a better way to post our 300th Fossil…
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Mazon Monday #304: Field Museum… Illinois by the sea
This is Mazon Monday post #304. What’s your favorite Mazon Creek fossil? Tell us at email:esconi.info@gmail.com. In May 1970, the Field Museum opened an exhibit about Mazon Creek. It was called “Illinois by the sea: a coal age environment” and ran from May 25th until September 25th. It was a successful exhibit that featured Field…
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Fossil Friday #299: Annularia sphenophylloides
This is the “Fossil Friday” post #299. Expect this to be a regular feature of the website. We will post fossil pictures you send in to esconi.info@gmail.com. Please include a short description or story. Check the #FossilFriday Bluesky/Twitter hash tag for contributions from around the world! Today, we have another beautiful contribution from George Witaczek. This time…
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Mazon Monday #303: Smithixerxes juliarum
This is Mazon Monday post #303. What’s your favorite Mazon Creek fossil? Tell us at email:esconi.info@gmail.com. Smithixerxes juliarum is among the rarest animals found in the Mazon Creek fossil deposit. It belongs to an extinct group of arthropods known as the euthycarcinoids, which ranged from the Cambrian to the Triassic periods. Some researchers believe euthycarcinoids may…
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Fossil Friday #298: Seed Fern Fiddlehead – Spiropteris
This is the “Fossil Friday” post #298. Expect this to be a regular feature of the website. We will post fossil pictures you send in to esconi.info@gmail.com. Please include a short description or story. Check the #FossilFriday Bluesky/Twitter hash tag for contributions from around the world! This week’s Fossil Friday features a fiddlehead — the coiled…
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Mazon Monday #302: The Wreck of the 5560
This is Mazon Monday post #302. What’s your favorite Mazon Creek fossil? Tell us at email:esconi.info@gmail.com. The Marion Power Shovel Company was an American company that designed, manufactured, and built steam shovels, power shovels, blast hole drills, excavators, and dragline excavators. The company was headquartered in Marion, Ohio and operated from 1884 to 1997, when it…
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Fossil Friday #297: Alethopteris serlii
This is the “Fossil Friday” post #297. Expect this to be a regular feature of the website. We will post fossil pictures you send in to esconi.info@gmail.com. Please include a short description or story. Check the #FossilFriday Bluesky/Twitter hash tag for contributions from around the world! This week’s Fossil Friday is a favorite of many…
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Throwback Thursday #297: Season’s Greetings from the Langfords!
In 1939, their Christmas card included a photo of the “Fossil Gardens of Northern Illinois”. The picture is a view of the strip mines about 1 mile south of Wilmington, IL, at a place that was not far from where Cinder Ridge Golf Course is today.
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2026 ESCONI Gem, Mineral, and Fossil Show – Preview #1: Tully Monsters
This is the preview post #1 for the 2026 ESCONI Gem, Mineral, and Fossil Show Live Auction. The ESCONI Gem, Mineral, and Fossil Show for 2026 will be held on March 21th and 22nd at the DuPage Fairgrounds in Wheaton, IL, which is the same location as last year. All details can be found here.…
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Mazon Monday #301: Cordaianthus ovatus
This is Mazon Monday post #301. What’s your favorite Mazon Creek fossil? Tell us at email:esconi.info@gmail.com. Cordaianthus ovatus is thought to be the fertile structure for Cordaites borassifolius (see Mazon Monday #299), an extinct genus of early gymnosperms. Cordaites probably grew to more than 100 feet tall in swampy conditions, forming forests similar to modern day mangroves. Cordaianthus…
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Fossil Friday #296: Roachoid Wing from the Creek
This is the “Fossil Friday” post #296. Expect this to be a regular feature of the website. We will post fossil pictures you send in to esconi.info@gmail.com. Please include a short description or story. Check the #FossilFriday Bluesky/Twitter hash tag for contributions from around the world! This beautiful roachoid wing was collected from the Mazon…
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Mazon Monday #300: Mazon Creek horseshoe crab fossil shows evidence of ancient algal or parasitic infestation
This is Mazon Monday post #300. What’s your favorite Mazon Creek fossil? Tell us at email:esconi.info@gmail.com. The Lauer Foundation just won’t let the Mazon Creek horseshoe crabs alone… first it was Euproops danae remains in bromalites (see Mazon Monday #283), now they’ve found evidence of ancient algal or parasitic infestation in another Euproops danae fossil from the…
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Fossil Friday #295: Juvenile Dvinosaur From Mazon Creek
This is the “Fossil Friday” post #295. Expect this to be a regular feature of the website. We will post fossil pictures you send in to esconi.info@gmail.com. Please include a short description or story. Check the #FossilFriday Bluesky/Twitter hash tag for contributions from around the world! We have a particularly special Mazon Creek fossil to share…
