Tag: Pennsylvanian
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Mazon Monday #317: Pohlsepia Revisited — Not an Octopus After All
A new paper “Synchrotron data reveal nautiloid characters inPohlsepia mazonensis, refuting a Palaeozoic origin for octobrachians” in the journal Proceedings of the Royal Society B Biological Sciences refutes the classification of Pohlsepia mazonensis as an octopus and reclassifies it as a soft-bodied nautiloid as Paleocadmus pohli.
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Fossil Friday #312: Sublepidophloios protuberans with a spray of Cyperites bicarinatus
At first glance, today’s fossil might look like a cone. But, closer examination reveals it to be a nice specimen of Sublepidophloios protuberans with a spray of Cyperites bicarinatus at the top. Sublepidophloios protuberans is a species of lycopsid branch (see Mazon Monday #316) and Cyperites bicarinatus was the sterile leaves for the Lycopsida (see Mazon…
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Mazon Monday #316: Sublepidophloios protuberans
Today, we have Sublepidophloios protuberans, which is a species of lycopsid branch. It’s very common, actually the most common form of lycopsid bark in the Mazon Creek fossil flora.
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ESCONI Field Trip to Danville Shale Pile Fossils – Saturday, May 2nd, 2026
An ESCONI field trip to the Danville IL Shale Pile for Pennsylvanian fossils is scheduled for Saturday May 2nd, 2026 starting at 10 AM. This is on private property and there is an attendance limit of 25 people. The gate will be secured once we are in and locked when we leave. Plan on being…
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Mazon Monday #315: Another Langford Book Inscription
From time to time, we run across some old book inscriptions. Back in Mazon Monday #18, we highlighted a few… Well, here’s another interesting inscription.
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Fossil Friday #310: Mazon Creek Scallop
Another small concretion with a treasure inside… this one has a scallop (see Mazon Monday #35). This one is Aviculopecten mazonensis. There’s no information about where this concretion was collected, but Pit 11 is very likely. We ran across it while preparing for the 2026 ESCONI Show. Do you think these were as tasty as…
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Mazon Monday #314: Smithixerxes juliarum
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 have been amphibious, capable of venturing between water and land.
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2026 ESCONI Gem, Mineral, and Fossil Show – Preview #40: Mazon Creek Asterophyllites and a Sphenopterid in a Riker Mount
Last preview… a Riker Mount with a Mazon Creek Asterophyllites and a Sphenopterid… both are beautiful fossils. Today is the day… come out at 10 AM and see all the auction items for yourself!
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2026 ESCONI Gem, Mineral, and Fossil Show – Preview #38: Reticulopteris munsterii var. dawsonii from Mazon Creek
How about another Mazon Creek seed fern? This one is Neuropteris jacksonii (see Mazon Monday #250). If you are reading this… today is the day!
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2026 ESCONI Gem, Mineral, and Fossil Show – Preview #37: Alethopteris serlii from St. Clair, Pennsylvania
This preview is of a chunk of shale from St. Clair, PA. This piece contains numerous examples of Alethopteris serlii, a seed fern also found in Mazon Creek localities. We are getting very close now… inside 12 hours away!
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2026 ESCONI Gem, Mineral, and Fossil Show – Preview #33: Laveineopteris rarinervis from Mazon Creek
This is a beautiful specimen of Laveineopteris rarinervis (see Mazon Monday #81) a seed fern commonly found in the Mazon Creek fossil deposit. Come on out and check it out tomorrow!
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2026 ESCONI Gem, Mineral, and Fossil Show – Preview #30: Mazon Creek Achistrum, sp. Colony
Another Mazon Creek beauty… this is a nice Achistrum, sp. colony, which is a sea cucumber. You can see at least three mouths in the fossil. See Mazon Monday #29. Come on out and see for yourself, tomorrow, yes, tomorrow! Less than a day away!
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2026 ESCONI Gem, Mineral, and Fossil Show – Preview #28: Coelocanth Scale from Pit 11
Here’s beautiful example of a Coelocanth scale Mazon Creek’s Pit 11 locality. Look closely, the preservation is very detailed. Did we mention the tomorrow is the show… see you there!
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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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Fossil Friday #309: Acanthotelson stimpsoni
Today, we have a cute little Acanthotelson stimpsoni (see Mazon Monday #52) from the Mazon River. Acanthotelson stimpsoni is a syncarid shrimp. It’s the most common shrimp found in the Braidwood fauna.
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2026 ESCONI Gem, Mineral, and Fossil Show – Preview #23: Macroneuropteris scheuchzeri terminal pinnule
Preview 23 is a nice terminal end of a Macroneuropteris scheuchzeri from Mazon Creek. To learn more see Mazon Monday #39. Saturday will be here before you know it…
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2026 ESCONI Gem, Mineral, and Fossil Show – Preview #18: Lepidostrobus, sp. Cone
Here’s a beautiful Lepidostrobus, sp. cone (see Mazon Monday #202) from Mazon Creek. These cones were the reproductive organs of lepidodendron trees.
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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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2026 ESCONI Gem, Mineral, and Fossil Show – Preview #16: Calamostachys Cone
A the rarer side, we have a nice Calamostachys cone for preview #16. Calamostachys was one of the cones of Calamites (see Mazon Monday #99). Less than 6 days left until the show… how quickly time flies!
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2026 ESCONI Gem, Mineral, and Fossil Show – Preview #15: Macroneuropteris scheuchzeri
For this preview, we have a beautiful Macroneuropteris scheuchzeri (see Mazon Monday #39). This was collected from one of the Morris localities.
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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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2026 ESCONI Gem, Mineral, and Fossil Show – Preview #8: A Tully Monster on Pit 11’s Opening Day!
Today is opening day of fossil collecting season at the Mazonia-Braidwood State Park. So, it’s only fitting that the preview for today is a Tully Monster. Here it is… we hope you get out, enjoy some fresh air, and find a Tully today!
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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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Fossil Friday #303: Mounted Pecopteris notata
This is the “Fossil Friday” post #303. 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 one of the rarer forms, Pecopteris notata.…
