Relative abundances of conodonts stem from abiotic or biotic causes. High frequencies can result from: 1) biotic positive = high standing crop; 2) biotic negative = lethality (mass mortality); 3) abiotic positive = lag concentrates; 4) abiotic negative = starved sedimentation. Neither abiotic cause should substantially affect the taxonomic composition of the fauna, although either biotic cause—good or bad environmental responses—can and must. Pennsylvanian conodont biofacies are clearly established and evidence of their interrelationships and complexity has continued to mount. We currently recognize no fewer than five levels of conodont biofacies: Ia - Primary generic-level biofacies (examples: Cavusgnathus, Aethotaxis) Ib - Secondary generic-level (“nested”) biofacies (examples: Ellisonia with Cavusgnathus, Hindeodus with Aethotaxis) II - Species-level microbiofacies (examples: Idiognathodus delicatus with Missourian Idioprioniodus / Gondolella , Streptognathodus elegantulus with Missourian Aethotaxis ) III - Apparatus-level biofacies (examples: scottognathoid apparatuses least complete with Cavusgnathus, intermediate with Aethotaxis, most with Idioprioniodus in the Missourian) IV - Ecophenotype variant-level biofacies (examples: perhaps two “species” of Ellisonia with contrasting apparatus plans and morphologies in the Desmoinesian, possible Cavusgnathus morphotypes from the Cavusgnathus- to the Streptognathodus -biofacies).

Abstract Carboniferous conodont biostratigraphy comprises regional zonations that reflect the palaeogeographical distribution of taxa and distinct shallow-water and deep-water conodont biofacies. Some species have a global distribution and can effect high quality correlations. These taxa are incorporated into definitions of global Carboniferous chronostratigraphic units. A standard global Carboniferous zonation has not been developed. The lowermost Mississippian is zoned by Siphonodella species, excepet in shallow-water facies, where other polygnathids are used. Gnathodus species radiated during the Tournaisian and are used to define many Mississippian zones. A late Tournaisian maximum in diversity, characterized by short-lived genera, was followed by lower diversity faunas of Gnathodus species and carminate genera through the Visean and Serpukhovian. By the late Visean and Serpukhovian, Lochriea provides better biostratigraphic resolution. Shallow-water zonations based on Cavusgnathus and Mestognathus are difficult to correlate. An extinction event near the base of the Pennsylvanian was followed by the appearance of new gnathodid genera: Rhachistognathus , Declinognathodus , Neognathodus , Idiognathoides and Idiognathodus . By the middle of the Moscovian, few genera remained: Idiognathodus , Neognathodus and Swadelina. During the middle Kasimovian and Gzhelian, only Idiognathodus and Streptognathodus species were common. Near the end of the Gzhelian, a rediversification of Streptognathodus species extended into the Cisuralian.

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.

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.