Pennsylvania rocks exposed in Knox, Peoria, Fulton, and Schuyler Qpunties in northwestern Illinois include 11 major marine units. The oldest marine unit is late Atokan and the youngest is early Missourian; the remainder are Desmoinesian in age. Each unit; has produced at least: some Conodonts, and the more than 300 samples produced an aggregate total in excess of 160,000 conodont specimens. These can be grouped into not fever than 78 kinds, considered species in disjunct element taxonomy. At least 10 multielement genera and 40 multielement species are represented. - Six new species: Diplognathodus illinoisensis, Neognathodus.metanodosus, N. polynodosus, N. oligonodus, N. anodosus and Gondolella pulchra are described.
Although ail marine beds were formed in hallow water,generally near shore, they represent the products of highly diverse environments.Conodont biofacies are sharply differentiated ind mirror this diversity. Ecologic.controls that effected conodont distribution are believed to have been salinity,energy, pH and possibly biologic antagonism.