A preliminary study of palynomorphs and other plant fossils from Mississippian clastic sediments in the Antler basin, Nevada and Utah, suggests that much of the Upper Mississippian sediments were deposited in a transitional environment rather than a marine environment, as previously thought. The Antler basin received most of its clastic sediments from the east flank of the north-south-trending Antler orogenic belt in central Nevada. The clastic sediments generally become finer and thinner eastward until they interfinger with a carbonate platform in central Utah.

Numerous fossil plant taxa have been found in these clastic sediments from central Nevada to central Utah. Assemblages of terrestrial palynomorphs associated with lycopod bark impressions (Lepidodendron), leaf impressions (Lepidophyllum), fruiting body impressions (Lepidocarpon), and, most importantly, impressions and casts of rootlike rhizomes (Stigmaria) suggest that the plants grew in place during periods of nonmarine deposition.

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