Hamilton Fossil-Lagerstatte (Upper Pennsylvanian, Greenwood County, Kansas): Internal Stratigraphy and Addition to the Microfossil Assemblage

Abstract

Three localized laminated limestones occurring near the top of the Hamilton paleochannel sequence (Virgilian) contain the well-known Hamilton fossil assemblage, a thanatocoenosis of terrestrial, marine, nonmarine, and euryhaline forms including plants, invertebrates, and vertebrates exhibiting skin preservation. Dissolution or disaggregation and sieving of the three limestones and associated limestone and mudstone units, the Hamilton Fossil-Lagerstitte proper, has produced the following additions to the Hamilton quarry (main quarry) assemblage: 1) the ostracodes Amphissites, Geisina, Gutschickia?, Pseudobythocypris, and Whipplella?, 2) two foraminiferids, an encrusting form and Globivalvulina, and 3) the shark Xenacanthus. Additional taxa are well-known fossils abundant in rocks of this age. As in the situation of previously identified taxa from the Hamilton Fossil-Lagerstaitte, the listed forms lived in a range of paleoenvironments from freshwater (Whipplella?) to marine (e.g., Globivalvulina), reflecting the coastal, and probably estuarine, setting of the Hamilton beds. The Hamilton quarry locality (SW 1/4, sec. 5, T. 24 S., R. 12 E., Greenwood County, Kansas) has attracted attention primarily because of the abundance of well-preserved fossils, mostly plants, arthropods, and vertebrates, which occur within three thin (<15 cm) finely laminated limestone beds. Fossil specimens have been collected at Hamilton quarry since the 1960's, and Kansas scientists have played an important role in the study of Hamilton fossils and geology as demonstrated by a series of publications beginning in the 1970's (e.g., Bridge, 1976; Leisman, 1976). The fossiliferous limestones at Hamilton quarry are part of a complex sequence of paleochannel deposits. The Hamilton depositional system is a low-sinuosity, north-south oriented paleochannel approximately six miles (9.7 km) long, one-sixth of a mile (0.3 km) wide (see Feldman et al., 1990), This content downloaded from 207.46.13.169 on Sat, 01 Oct 2016 06:02:11 UTC All use subject to http://about.jstor.org/terms 132 TRANSACTIONS OF THE KANSAS ACADEMY OF SCIENCE