This is Mazon Monday post #15.
-----------------------------------------------------
The Field Museum has one of the most extensive collections of Mazon Creek specimens, both flora and fauna. The Field Museum has long been a big part of the study of this locality, with such historical giants as George Langford and Eugene Richardson working there. Currently, Jack Wittry works there.
In 1673, the first coal found in the New World was reported from along the Illinois River near Utica in LaSalle County (Ledvina, 1997). In the mid-19th century, another important find was made in the same area; Middle Pennsylvanian aged fossils were discovered along one of the tributaries of the Illinois River, the Mazon Creek (Shabica and Hay, 1997). Subsequent, extensive collecting of fossiliferous sideritic nodules across this area, by both amateurs and professionals, has led to large and important collections. Shortly after they were discovered, taxonomic review of this material commenced and has been ongoing since (e.g. Lesquereux, 1866, 1869, 1870, 1879-1884; Sellards, 1902a, 1902b, 1903, 1907; Noé, 1922, 1925a, 1925b; Arnold, and Steidtmann, 1937; Arnold, 1938; Janssen, 1940; Schopf, 1948; Abbott, 1954, 1958, Chaloner, 1956, 1958; Langford, 1958, 1963; Darrah, 1936, 1937, 1938, 1969; Taylor, 1967; Pfefferkorn et al., 1971; Pfefferkorn, 1973, 1976, 1979; DiMichele and Phillips, 1976; Pigg and Taylor, 1985; Drinnan et al., 1990; Drinnan and Crane, 1994; Wittry, 2006). As a result of these and other studies, in combination with intense collecting, the Mazon Creek floral assemblage has been recognized as highly diverse for its age (Pfefferkorn, 1979) and has gained recognition as a knoservat-lagerstätte (Feldman et al., 1993).
The vast majority of specimens held at the Field Museum are preserved within sideritic concretions, but plant fossils also occur as non-nodular carbonaceous compressions within the shale. All the specimens derive from the Middle Pennsylvanian (Desmoinesian) Francis Creek Shale Member of the Carbondale Formation in north eastern Illinois, from parts of Grundy, Kankakee, LaSalle, Livingston and Will counties (Baird, 1997a) and this is hereafter termed the Mazon Creek area. However, the majority of plant fossils were probably collected from spoil-piles associated with strip mines in Grundy, Will and Kankakee counties, Pits 1, 6 and mines near Morris being particularly important as well as to a lesser extent Pit 11. Francis Creek Shale deposits in Fulton County, Illinois and equivalent beds in Missouri and Oklahoma also contain fossil associations typical of the Mazon Creek associations (Baird, 1997a).
You can find a few pictures from their collection here.
Alethopteris serlii - FMNH P30098
Macroneuropteris scheuchzeri - FMNH PP46058
Laveineopteris rarinervis - FMNH - PP5606
Crenulopteris acadica - FMNH PP2648
Asterophyllites equisetiformis - FMNH P30919
Annularia sphenophylloides - FMNH PP29325
