Tag: MazonMonday
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Mazon Monday #332: Tom Testa Winter Freeze/Thaw
Sorry, this is a bit of a repeat… But, Tom Testa has been on our minds lately and we’ve all been enduring a stretch of hot weather, so here’s a post that will cool you off!
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Mazon Monday #331: Recap of Tom Testa Day at the Carbon Hill School Museum
Back in Mazon Tuesday #328, we did a post about Tom Testa and his amazing Mazon Creek fossil collection. There was a great turnout at the Carbon Hill School Museum special event “The Legacy of Tom Testa” on June 25th, 2026.
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Mazon Monday #329: Danville Spoil Pile May 2026
Saturday, May 2nd, 2026 was a fairly nice day. It was partly cloudy with some wind. It was a little cooler than previous trips.
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Mazon Tuesday #328: The Legacy of Tom Testa
Michele Micetich, curator of the Carbon Hill School Museum, will host a special event on Saturday, June 27, 2026, celebrating the life and legacy of Tom Testa. A lifelong fossil collector with a passion for Mazon Creek fossils, Tom assembled one of the finest private collections of its kind. In 2015, he gave his collection…
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Mazon Monday #327: Direct development of stem tetrapods across the fin-to-limb transition
A significant paper on tetrapod development was published last week, and Mazon Creek fossils played a central role. “Direct Development of Stem Tetrapods Across the Fin-to-Limb Transition” by Jason Pardo and Arjan Mann of the Field Museum appeared in the journal Science. Lauer Foundation for Paleontology, Science, and Education also contributed to the study. The…
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Mazon Monday #326: More Mazon Creek at the 2026 CGMA Show
This is Mazon Monday post #326. What’s your favorite Mazon Creek fossil? Tell us at email:esconi.info@gmail.com. Long-time ESCONI member Rich Rock had an amazing display of Mazon Creek fossils at the CGMA show. There’s a little a bit of everything here, from clams to ferns to spiders to an absolutely breathtaking Alethopteris serlii. Enjoy!
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Mazon Monday #325: Braceville Spring 2026 Field Trip Report
We held our spring Braceville field trip a few weeks ago. The weather was nearly perfect… partly cloudy with temperatures in the high 70’s and low 80’s each day.
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Mazon Monday #324: Stepwise loss of complexity in hagfish eyes prior to deep sea colonization
Mazon Creek hagfish made headlines again last week. New research led by Victoria McCoy, Assistant Professor in the Department of Geosciences at the University of Wisconsin–Milwaukee, was published in the journal Biology Letters. In the paper, “Stepwise Loss of Complexity in Hagfish Eyes Prior to Deep-Sea Colonization,” McCoy collaborated with several familiar names… Arjan Mann…
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Mazon Monday #323: Mazon Creek at the 2026 CGMA Show
Jack Wittry had a breathtaking display at the 2026 CGMA Show at the Kane County Fairgrounds this past weekend. It featured Mazon Creek fossils named for ESCONI members.
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Mazon Monday #322: Asterophyllites longifolius
Asterophyllites longifolius like its sister taxon Asterophyllites equisetiformis (see Mazon Monday #103), formed part of the foliage of the giant horsetail-like plant Calamites. Both species are known from Mazon Creek, but while A. equisetiformis is common, A. longifolius is a very rare. One distinguishing characteristic of A. longifolius is that the leaves are longer than…
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Mazon Monday #321: So, where’s the shrimp?!?
Andy Jansen wrote this article for the December 2007 edition of the ESCONI newsletter. Andy has been an ESCONI board member for many years. He’s currently our Treasurer and Librarian. If you attended our show in March, he was in his usually position at the book display and sale tables.
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Mazon Monday #320: A shoot at the root? Unique development and evolution of the stigmarian apical meristem
Our friends at the Field Museum have been busy… this time it’s paleobotany. The paper “A shoot at the root? Unique development and evolution of the stigmarian apical meristem” was published in the journal Proceedings of the Royal Society B a few days ago. The authors should be familiar… Michael P. D’Antonio, C. Kevin Boyce,…
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Mazon Monday #319: ESCONI Braceville Trip Spring 2005
Our spring trip to Braceville Spoil Pile is coming up in May. The sign-up will kick off very soon. We have been going there for many years. For the spring trip in 2005, Barbara Brotman, a reporter for the Chicago Tribune was there to talk to a few ESCONI members and talk about ESCONI.
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Mazon Monday #318: Eusphenopteris neuropteroides
Eusphenopteris neuropteroides is an extinct seed fern species that is relatively uncommon, though it is primarily known from the terrestrial deposits of Mazon Creek. It was originally described as Pseudopecopteris anceps by Leo Lesquereux, but its classification has shifted over time as its relationships to other taxa became better understood. Over the years, it has…
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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 with the new name Paleocadmus pohli.
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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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Mazon Monday #315: Another Langford Book Inscription
From time to time, we run across interesting old book inscriptions. Back in Mazon Monday #18, we highlighted a few… Well, here’s another interesting inscription.
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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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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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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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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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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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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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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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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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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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Mazon Monday #303: Happy 60th Birthday, Tully Monster!
Happy 60th Birthday to the Tully Monster! Well, actually tomorrow is the day. And, I guess technically it’s really been 307 – 309 million years, but who’s really counting. Eugene Richardson, Jr., who first called it “Mr. Tully’s monster”, described the animal in the paper “Pennsylvanian invertebrates of the Mazon Creek Area, Illinois: the morphology…
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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…
