Another ichnofauna comparable to that from the Tonganoxie Sandstone Member at Buildex Quarry consists of two assemblages, the Cincosaurus and Haplotichnus, from the Westphalian Pottsville Formation of Alabama (Rindsberg, 1990). The Cincosaurus assemblage consists of locomotion traces of fishes, xiphosurids, and amphibians. Surface grazing trails and trackways make up the Haplotichnus assemblage. Undichna, Haplotichnus, and Treptichnus also are present in the Pottsville ichnofauna. These deposits were interpreted as having accumulated in brackish water, alluvial-swamp, and tidal-flat settings (Demko in Rindsberg, 1990). The nonmarine nature of the ichnofauna and the absence of definitive marine indicators suggest a terrestrial to freshwater biota.
Kvale and Barnhill (1994) recorded an ichnofauna consisting of Treptichnus, Haplotichnus, small arthropod trackways, and possible fish-fin drag marks in tidal rhythmites from Lower Pennsylvanian strata of the Illinois Basin. These authors suggested that these strata were deposited on estuarine tidal flats under brackish to freshwater conditions. Both the trace fossils and sedimentary facies are similar to those in the Buildex strata documented in this paper.
The examples briefly discussed here yield clear evidence that a distinctive and recurrent trace-fossil assemblage (Buildex-type ichnofaunas) is widespread in Pennsylvanian tidal rhythmites of the Midcontinent. Identification of such ichnofaunas may be useful in the recognition of freshwater inner estuarine facies and may help to delineate fluvioestuarine transitions in incised valley systems.
Kansas Geological Survey
Web version March 19, 1998
http://www.kgs.ku.edu/Current/1998/buatois/buatois11.html
email:lbrosius@kgs.ku.edu