Abstract Six genera are treated .in this section They are arranged alphabetically: Cavusgnathus, Diploognathodus, Gondolella, Idiognathodus Neognathodus and Streptognathodus with their -species arranged phylogenctically. These are, by and large, considered to be -the “platform” genera most useful for biostratigraphy. Strictly speaking, Diplognathodus lacks a platform hut appears to be closely related to taxa that bear true platforms and aIso shows an evolutionary pattern much like that of platform-bearing genera. Three other genera are numerically important in these collections, but are not discussed in detail: Aethotaxis, Anahignathodus , and Idioprioniodus . Aethotaxis Baesemann, 1973, US a coomon and paleoecologically quite important conodont. It ranges through most orall of the, Pennsylvanian System and needs detailed monographic treatment considered to be beyond the scppe of this study. Anchignathodus Sweety 1970 (the Spathognathodus of authors), faces the same platform/nonplatform difficulty as Diplognathodus . The Pennsylvanian including Illinois basing species of Anchignatihodus have been studied in some detail by Merrill (1973a). Idioprioniodus Gunnell, 1933, is another nonplatforn conodont with great paleoecologic utility. Its apparatus composition has been, studied, based mostly on material from northwestern, Illinois, by Merrill and Merrill (1974), and studies about its spation are In process. Each of these genera is discussed briefly under the heading Multielement Taxonomy.

Abstract “Pennsylvanian rocks exposed in Knox, Peoria, Fulton, and Schuyler Counties in northwestern Illinois include 11 major marine units. The oldest marine unit is late Atokan and the youngest is early Missourian; the remainders are Desmoinesian in age. Each unit has produced at least some conodonts, and the more than 200 samples produced an aggregate total in excess of 160,000 conodont specimens. These can be grouped into not fewer 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. oligonodsus, N. anodus, and Gondolella pulchra are described. Although all marine beds were formed in shallow water, generally near shore, they represent the products of highly diverse environments. Conodont biofacies are sharply differentiated and mirror this diversity. Ecologic controls that effected conodont distribution are believed to have been salinity, energy, pH, and possibly biologic antagonism. Neognathodus is the most useful conodont genus for biostratigraphy in these rocks. Four zones and subzones are based on species of this genus and it has permitted relatively precise interregional correlations. Secondary zonations can be based on other genera that supplement the Neognathodus zonation and assist in identifying units. In decreasing importance these are Gondolella, the Idiognathodus-Streptognathodus plexus, and Diplognathodus.”

Abstract Late Pennsylvanian conodont faunas were dominated by idiognathodids historically assigned to Idiognathodus (flat P 1 ) or Streptognathodus (troughed P 1 ). Recent work suggests clades arose iteratively, through time, from unrelated ancestors in different geographical regions. The end-Desmoinesian extinction event terminated two major genera, Swadelina (troughed) and Neognathodus (long carina), and comparable new morphotypes developed from surviving Idiognathodus species in the early Kasimovian, especially in North America. True Streptognathodus (troughed) and Heckelina n. gen (asymmetric, eccentric groove) appeared in North America in the mid-Kasimovian. Another troughed clade arose in Eurasia (‘ S. ’ 2) and attained a global distribution by the late Kasimovian. A second, early Gzhelian, Eurasian radiation produced new troughed forms (‘ S. ’ 4) that dominated Gzhelian faunas globally. In South China, endemic clades of eccentrically grooved Idiognathodus ? and troughed forms (‘ S .’ 3) appeared in the late Kasimovian and persisted into the Gzhelian. Typical Idiognathodus species were uncommon by the late Kasimovian and disappeared in the mid-Gzhelian. After a low diversity interval in the mid-Gzhelian, a new major radiation of weakly troughed forms occurred (‘ S. ’ 5), which led to redevelopment of Idiognathodus -like elements in the Cisuralian. Other conodont genera from offshore ( Gondolella, Idioprioniodus ) and nearshore settings ( Hindeodus, Diplognathodus, Adetognathus, Ellisonia ) are poorly studied and show low diversity and little morphological change.

A quantitative analysis of conodont distributional patterns in the Middle Pennsylvanian (Atokan and Desmoinesian) Morgan Formation of northeastern Utah and northwestern Colorado supports previous empirically derived Pennsylvanian conodont biofacies models. R-mode factor analysis and stepwise discriminant analysis both demonstrate strong facies-dependence for the platform conodonts Adetognathus and Idiognathodus . The Adetognathus biofacies, which may also include Hindeodus and Diplognathodus , characterizes nearshore marine deposits in which salinity and/or temperature fluctuated considerably. The Idiognathodus biofacies, which also includes Neognathodus , characterizes slightly offshore, normal-marine deposits. The environmental significance of Idioprioniodus is uncertain because of its sporadic distribution; Gondolella , its normal faunal associate, was not observed, because its habitat is probably far offshore from those in which Morgan limestones were deposited. Even at the generic level, Pennsylvanian conodonts are environmentally sensitive; hence, they are useful for both sedimentologists and paleontologists. Sedimentologists can use conodont distributional data as an independent test of their paleoenvironmental interpretations. Paleontologists can identify conodonts that are strongly facies-dependent, and differentiate conodonts best suited for biostratigraphy.

Abstract 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.

Abstract A middle Pennsylvanian (Desmoinesian) conodont fauna was used to identify the interval represented by the Lower Kittanning cyclothem across the North American continent. The conodonts show both a succession through the cyclothem and a geographic variation that is related to the water mass and depositional environment. The faunas can be divided into normal-marine, high- and (or) variable-salinity, and high-productivity assemblages. Normal-marine faunas are dominated by Idiognathodus , which can be further divided into low-diversity and high-diversity faunas. The low-diversity Idiognathodus faunas characterize the marine deposits of the nearshore, marginal environments of the Appalachian Basin, and also the bulk of the black and gray shale and carbonate depositional environments of Midcontinent cyclothems. The high-diversity Idiognathodus faunas characterize fossiliferous limy shale and shaly limestone depositional environments typical of the shale–limestone transition in Midcontinent cyclothems and the richly fossiliferous limestone deposition in carbonate sequences in much of the western U.S., within the dolomite beds associated with sandstone deposition of the Tensleep Sandstone, and in fossiliferous limestones between sandstones and carbonate mudstones of the Paradox Basin. High-salinity and (or) variable-salinity faunas are dominated by Neognathodus and (or) Adetognathus , and characterize carbonate deposition in the Bird Spring–Ely platform, southwestern U.S., and shallow-water, typically algal facies within the Midcontinent cyclothems. High-productivity faunas are dominated by Gondolella , are extremely rare, and characterize horizons of surface substrate accumulation within black-shale and mud depositional environments. Maximum flooding within the cycle, as indicated by the highest diversity of normal-marine macrobiota and conodont fauna, does not occur in black shales but at the shale–limestone transition. Sixteen species of conodonts in eight genera are recognized in the cyclothem. The following four species are new: Idiognathodus crassadens, I. ignisitus, Neognathodus intrala , and Hindeodus calcarus. Two of these new species, N. intrala and I. crassadens , together with I. robustus , define an assemblage zone that allows correlation of the marine portion of the Lower Kittanning cyclothem across North America.

Abstract Late Moscovian–early Gzhelian conodonts occur abundantly in a newly discovered slope section, the Shanglong section, southern Guizhou, South China. The conodont fauna is dominated by P1 elements of Idiognathodus and associated with elements of Swadelina , Streptognathodus and Heckelina . A total of 62 species, including species in open nomenclature, were identified, which are assigned to eight genera. Index conodont species of Middle and Late Pennsylvanian, e.g. I. podolskensis Group, Sw. sp. A, Sw . subexcelsa , Sw . makhlinae , I . heckeli , I . magnificus , I . guizhouensis , H. eudoraensis , I . naraoensis , and H . simulator are all recovered, and their 10 conodont zones are recognized. The richness and abundance of the conodonts throughout the section are analysed. Conodont richness ranges from 1 to 14 and is positively related to conodont abundance (1–379). The composition of conodont elements, i.e. sinistral v. dextral, P1 v. non-P1 and adult v. subadult and juvenile, is presented. The numerical cluster technique is employed to identify four subbiofacies of the slope setting, namely the I . podolskensis , Swadelina , I. swadei–magnificus and Streptognathodus – Heckelina–Idiognathodus subbiofacies.