Mazon Creek Fossils​

Collecting and Research
The Mazon Creek Biota of Illinois represents the most complete record known of a late Paleozoic community of animals and plants. As a Konservat-Lagerstätte (a deposit with exceptional fossil preservation), this extraordinary fossil assemblage ranks among other great fossil sites of the world, such as the Precambrian Ediacara of Australia, the Cambrian Burgess Shale of Canada, the Devonian Bundenbach and the Jurassic Solnhofen of Germany. Occurring in the 307 million-year-old Middle Pennsylvanian Francis Creek Shale, the Mazon Creek Biota comprises one of the most diverse fossil floras in North America - roughly 123 biological species - and also encompasses more than 500 animal species constituting 11 phyla and 23 classes. Many soft-bodied groups are represented among the fossil fauna specimens, as well as insects and complete vertebrate skeletons with soft parts. All were rapidly buried during a major flooding event. The stage was set by global warming and a change in tropical climate from consistently wet (with widespread equatorial coal swamps) to monsoonal. The latter alternating wet and dry seasons repressed plant growth and spawned intense upland erosion and delta progradation. Terrestrial, freshwater, estuarine, and a few marine organisms succumbed to the accumulation of river-borne silt and clays, and were then beautifully preserved in siderite (iron carbonate) concretions. Rising sea level caused by melting of the south polar icecap and compacting delta sediments assured their preservation in the geologic record. The site, located near Chicago, is accessible to hundreds of amateur collectors who are responsible for most of the rare animals and plants of the Mazon Creek area that are exhibited in museum collections. 
Click on titles or images to view galleries

​               Mazon Creek Fossil Flora

          Annularia inflata ancestral horsetail, R.M. Angkuw.
    Note: the above page is still under construction.

          Mazon Creek Fossil Fauna

   Elonichthys hypsilepus ​paleoniscoid fish, MPM VP-359230.

                                         Mazon Creek Area Paleontology
The slides contained on this page are excerpted from a presentation I gave at the Milwaukee Public Museum in 2016 entitled, Coal, Shale and Ironstone: The Geology and Paleontology of Mazon Creek. The remaining images from the talk are sprinkled into the galleries of Mazon Creek fossil plants and animals above.

                                                 Collecting in the Field

       Mazon River - private property.
    20th century coal strip mine spoils.
    19th century coal shaft mine spoils.
Header image: A detail of a Carboniferous coal swamp diorama from the The Field Museum of Natural History, Chicago. The paleontology image is of a generalized Pennsylvanian Period riverbank scene painted by Walter Myers (Figure viii.1 The Mazon Creek Fossil Fauna, ESCONI publication 2012).
Copyright © 2021 Andrew Young. Images on this page may be protected by copyright. They are presented here in ​accordance with fair use principles and are only being used for informational and educational purposes.