This is Mazon Monday post #40. What's your favorite Mazon Creek fossil? Tell us at email:[email protected].
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Back in Mazon Monday #10, we posted about other siderite concretionary fossil localities from the Pennsylvanian Period. That list was worldwide. Here is an interesting paper from 1985 that discusses some of those Mazon Creek-type fossil localities in the central US. It's curious how many there are.
This map in the paper is proposing there is a certain type of coastal deposit that leads to fossil assemblages like Mazon Creek.
This excerpt touches on where they believe these deposits are found.
The principal aim of the present paper is to stress the recurrent nature of Mazon Creek-type biofacies in the context of Pennsylvanian facies cyclicity. Included herein are results of preliminary sampling of analogous Pennsylvanian concretion biotas elsewhere in the U.S. Midcontinent Region. Of particular importance is discovery of a new Essex fossil locality in western Missouri as well as additional occurrences of the Braidwood biota from other stratigraphic units within the Illinois and Midcontinent Interior Basins. The distinctive association of these fossils with estuarine—deltaic deposits juxtaposed on coals is discussed and a predictive model for recurrence of this facies is presented. Finally, we wish to emphasize that the Essex fauna was not an aberrant biota of limited temporal value but was, apparently, a stable faunal grouping which persisted through the late Palaeozoic and across the Permo-Triassic boundary.
Of course, the Braidwood and Essex faunas are mentioned. Additionally, there are discussions of Astoria, IL; Danville, IL; Windsor, MO (Knob Noster); Henryetta and Morris, OK; Sallisaw, OK; Georgetown, IL; and the localities around Terre Haute, IN.
Article
Mazon Creek-type fossil assemblages in the U.S. midcontinent Pennsylvanian: their recurrent character and palaeoenvironmental significance
Abstract
Terrestrial plants, the non-marine Braidwood Fauna, and the euryhaline Essex Fauna, best known from the Francis Creek Shale Member within the Mazon Creek area of northeastern Illinois, are found to recur in analogous deltaic lithofacies elsewhere both in Illinois and in adjacent states. An important new Essex-type fossil locality is reported from deposits coeval with the Francis Creek Member in Missouri, and occurrences of Braidwood animals from additional stratigraphic units are discussed. These assemblages occur in estuarine-deltaic deposits juxtaposed on coals; the significance of the association of these fossils with transgressive inundation of coastal peat swamps is discussed and a predictive model for the occurrence of Mazon Creek-type assemblages is presented. We believe that fossil associations comparable to those at Mazon Creek, occur in certain coastal deposits ranging in age from Pennsylvanian to, at least, the Triassic.
Footnotes
This text was harvested from a scanned image of the original document using optical character recognition (OCR) software. As such, it may contain errors. Please contact the Royal Society if you find an error you would like to see corrected. Mathematical notations produced through Infty OCR.
Description of plate 1
- Figure 2. Unidentified polychaete with everted proboscis. MCP 268; MCP, Northeastern Illinois University Mazon Creek palaeontology collection. Unnamed shale unit above Croweburg Coal Member, Windsor area, Henry Co., Missouri (magn. x 1.7).
- Figure 3. Eocarid shrimp Belotelson magister. MCP 253. Unnamed shale unit above Croweburg Coal Member, Windsor area, Henry Co., Missouri (magn. x 1.7).
- Figure 4. Bivalve Edmondia sp. MCP 249. Unnamed shale unit above Croweburg Coal Member, Windsor area, Henry Co., Missouri (magn. x 1.4).
- Figure 5. Polyplacophoran Pterochiton. MCP 263. Unnamed shale unit above Croweburg Coal Member, Windsor area, Henry Co., Missouri (magn. x 1.3).
- Figure 6. Protorthoptera (insect). Note branchiopod Leaia in upper right. PE 30369; PE, Field Museum invertebrate paleontology collection. Energy Shale Member. Little Vermilion River locality near Georgetown, Vermilion Co., Illinois (magn. x 2.5).
