The Global Stratotype Section and Point (GSSP) for the base of the Capitanian Stage was proposed in 1999 and defined by the first appearance datum (FAD) of the conodont Jinogondolella postserrata within the lineage J. aserrata -> J. postserrata -> J. shannoni at Nipple Hill in West Texas, USA. Despite its widespread recognition for more than two decades, the official GSSP paper was not published, nor have its index conodont fossils been properly documented. At Nipple Hill, only the uppermost 0.5 m of the Pinery Member belongs to the Capitanian Stage. J. postserrata first appears at 19.8 m above the base of the auxiliary Frijole section. Based on U-Pb CA-ID-TIMS geochronology of ash beds from the GSSP area, the base of the Capitanian Stage has been constrained at 264.28 +/- 0.16 Ma. Magnetostratigraphy suggests that the Illawarra Reversal is located slightly below the base of the Capitanian Stage. Strontium isotope chemostratigraphy generally shows a continuous decline in the Sr-87/Sr-86 ratio throughout the Capitanian in the GSSP area, but all ratios are higher than the Capitanian minimum of similar to 0.7068. delta(13)C(carb)profile shows no distinct excursion around the Wordian/Capitanian boundary interval. Detailed correlation suggests that the middle-upper part of the fusuline-based Midian Stage correlates with the Capitanian Stage.

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.

The Guadalupian Epoch was characterized by major changes in paleogeography, paleoclimate, and biodiversity. Yet, the paucity of precise and accurate radioisotopic dates from the Guadalupian stages in their type area, Guadalupe Mountains National Park in West Texas has rendered their calibration inadequate. In this study, we report high-precision U-Pb zircon geochronology by the CA-ID-TIMS method from three ash beds (2 sigma internal errors only) in the Rader Member of the Bell Canyon Formation at the Back Ridge Section (262.127 +/- 0.097 Ma, MSWD = 0.89, n = 3), the lower Pinery Member of the Bell Canyon Formation at the Frijole Section (264.23 +/- 0.13 Ma, MSWD = 0.89, n = 8) and the basal South Wells Member of the Cherry Canyon Formation at the Monolith Canyon Section (266.525 +/- 0.078 Ma, MSWD = 0.62, n = 5). The Bayesian interpolation statistics method is used to establish an age-stratigraphy model that estimates the base of the Capitanian to be 264.28 +/- 0.16 Ma, serving as the best age estimate for the Capitanian Stage at present. In addition, we review the existing geochronology from the Guadalupian Series in West Texas and seek to propose more precise temporal estimates of Guadalupian geological and biological events. These data constrain the high-frequency sequences of the Cherry Canyon and Bell Canyon formations in the Guadalupe Mountains National Park area. Accordingly, the base of the Wordian is estimated at 266.9 +/- 0.4 Ma and the Illawarra geomagnetic polarity reversal in West Texas at 267.4 +/- 0.4 Ma to 266.5 +/- 0.3 Ma. The global end-Guadalupian extinction began in the conodont zone of Jinogondolella altudaensis above the base of the Reef Trail Member of the Bell Canyon Formation and might continue to the Clarkin postbitteri postbitteri Zone in the earliest Wuchiapingian. The conodonts display a rapid evolutionary rate during this interval. This constrains the biotic crisis from ca. 260 Ma to 259 Ma based on our conodont age estimation. The emplacement of the Emeishan Large Igneous Province (ELIP) in South China has been constrained to ca. 260 Ma to 257.4 Ma based on zircon U-Pb geochronology by the CA-ID-TIMS method, overlapping with the end-Guadalupian extinction, which provides support for the temporal relationship between them. Additionally, the ELIP persisted into the early Wuchiapingian and may have hampered ecosystem restoration during the post-extinction interval.

Conodont assemblages from the Bashkirian-Moscovian boundary interval in the Naqing section, South China have been studied in detail. A landmark-based geometric morphometric analysis of the evolution of Diplognathodus ellesmerensis is presented. This analysis helps demonstrate that a distinct new species, D. benderi sp. nov., is the direct evolutionary ancestor of D. ellesmerensis. The potential of using the first appearance datum (FAD) of D. ellesmerensis as the Bashkirian-Moscovian boundary marker is re-evaluated via biostratigraphic correlations of conodonts and other fossil groups between different palaeogeographical basins. The FAD of D. ellesmerensis from within the D. benderi sp. nov.D. ellesmerensis lineage is an excellent potential marker to recognize a global Bashkirian-Moscovian boundary because of its global distribution, the abundance of supplementary marker species at similar stratigraphical levels, and the close stratigraphic proximity of the FAD to the traditional Bashkirian-Moscovian boundary, thus largely preserving the original concept of the base of the Moscovian Stage.

The Guadalupian Epoch is marked by the formation of the Pangean supercontinent, global sea-level change, rifting and drifting of the Cimmerian continents, formation of large igneous provinces and dramatic biotic changes. A high-resolution biostratigraphic, chemostratigraphic and high-precision geochronologic framework of this critical transition is fundamental to understanding these events. Extensive studies of the latest Cisuralian and Guadalupian Series in both South China and North America reveal the same conodont lineages, but the conodont interval zones based on Jinogondolella within the Guadalupian Series are slightly diachronous. High-precision U-Pb geochronological studies (CA-ID-TIMS method) calibrate the base of the Guadalupian Series (base Roadian) at 273.01 ± 0.14 Ma. A previously reported age from an ash bed overlying the Emeishan flood basalts, 259.51 ± 0.21 Ma, is adopted for the Guadalupian/Lopingian boundary (GLB). Based on recently published geochronology and Bayesian age modeling from the Guadalupian Series, the base of the Capitanian is constrained at 264.28 ± 0.16 Ma and the base of the Wordian is interpolated to be 266.9 ± 0.4 Ma. The Illawarra Reversal is of early-middle Wordian age. Both North America and South China possess a distinct negative δ13Ccarb excursion of 3-5‰ at the latest Kungurian and early Roadian (LK-ER CIE), which coincides with the early stages of a significant 3rd order sea-level rise. The large end-Guadalupian δ13Ccarb negative excursion may have been affected by post-depositional diagenesis or a warming event associated with the Emeishan volcanism. The 87Sr/86Sr ratios in both regions declined from the latest Kungurian to the late Capitanian, but have different ratios and reveal several fluctuations in the middle Guadalupian. Measured δ18Oapatite values suggest that the Delaware Basin was 3-4°C cooler than the eastern Yangtze Block. Analysis of a new high-resolution database of marine taxa indicates only a minor pre-Lopingian diversity drop from 261.04 Ma to 259.98 Ma, which coincides with the peak Emeishan volcanism. The widely-perceived “end-Guadalupian mass extinction” in North America is evidently masked by, and possibly an artefact of, a stratigraphic truncation effect due to rapid lithofacies changes from limestone to laminated evaporites with the closure of the west Texas basins.

The basal boundary of the Wordian Stage is defined by the First Appearance Datum (FAD) of the conodont species, Jinogondolella aserrata, at the Getaway Ledge section in the Guadalupe Mountains National Park, West Texas, USA. However, specimens of the conodont lineage from the GSSP section have never been illustrated. The complete stratigraphic interval is investigated and numerous conodont specimens are figured for the first time in this study. The conodont fauna includes the species Hindeodus wordensis, H. sp., Neostreptognathodus sp. A, Jinogondolella aserrata and J. aff. nankingensis. Only one conodont zone, the J. aserrata Zone, can be recognized at the section and the evolutionary lineage from J. nankingensis to I aserrata that defines the GS SP is incomplete in this section because the section is underlain by sandstone of the Cherry Canyon Formation with no conodonts. Large samples collected within the GSSP Bed lack conodonts, and the only microfossils found are abundant sponge spicules. A new measured section of the sub-Getaway unit near the Getaway Ledge section is reported here, which contains abundant fusulinids, but rare J. aserrata only. The marker species, J. aserrata, is reviewed to understand the boundary of the Wordian Stage. The previously documented two morphotypes of J. aserrata have different ranges, and first occurrences of both morphotypes A and B are lower than the currently-used GSSP level. Hindeodus wordensis is also found below the GSSP beds. Chemostratigraphic data, including carbon and strontium isotopes of rocks and oxygen isotopes of conodonts, are presented for the first time from the existing GSSP section. Carbon isotopic data and their pattern are difficult to explain, and some values are likely to be affected by diagenesis. The strontium isotopic data are also affected by diagenesis or the addition of more crustal materials based on relatively high Sr-87/Sr-86 ratios. The delta O-18 values of conodont apatite are slightly higher than those in this interval from South China.

From the perspective of Phanerozoic time, coal balls are rare, apparently limited to a 24 m.y. interval (323-299 Ma) in the Pennsylvanian and earliest Permian. Yet within this interval, coal balls occur in many coals. Approximately 82 transgressive-regressive sedimentary cycles have been described for the Midcontinent, Illinois and Appalachian basins of North America during the mid-to-late Pennsylvanian. One third (27/82) have coal balls, including 57% of major cycles, 36% of intermediate cycles and 16% of minor cycles. Coal-ball occurrence in the Donets Basin is similar: over an interval of about 4 m.y. (similar to 315-311 Ma, latest Bashkirian to mid-Moscovian), 39% (11/28) of transgressive-regressive cycles have coal balls. As North American paleoclimate became drier, tree ferns replaced lycopsids as the dominant plant in peat swamps at the Desmoinesian/Missourian boundary, and coal-ball occurrence declined. Overall, 47% of cycles (19/40) with lycopsid or cordaitean dominance have coal balls, whereas 19% (8/42) of cycles with tree fern dominance have coal balls (p < .004). While 32% (6/19) of minor cycles with lycopsid or cordaitean dominance have coal balls, no minor cycle with tree fern dominance has coal balls. This pattern may reflect the relative abundance of coal in the Late Pennsylvanian, with drier paleotropical climates in the Missourian-Virgilian leading to less paleotropical coal, fewer mines and a lower probability of discovering Missourian and Virgilian coal balls. However, average cycle duration decreased from 150 kyr in the Desmoinesian to similar to 100 kyr in the Missourian and Virgilian, and faster rates of relative sea-level rise could have affected coal-ball abundance, particularly if coal balls formed in marine swamps, with more rapid transgression leading to thinner coals, or to freshwater coals directly overlain by marine sediments. Rygel et al. (2008) suggested that Missourian-Virgilian cycles recorded more erosional relief than Desmoinesian cycles, consistent with increased amplitude and rates of sea-level rise during each glacial-eustatic cycle. Changes in Missourian-Virgilian cycles may have been augmented by stratigraphic attenuation as sediment filled the antecedent topography.

Systematic taxonomy of the ammonoid family Cyclolobidae is complicated due to the high degree of complexity and intraspecific variation in sutural patterns. Recently, the authors described a new collection of ammonoids from the Permian of West Texas, and these new data suggest that a taxonomic revision of Cyclolobidae is needed. Morphometric methods have historically been an effective tool in taxonomic analyses of ammonoids, although their application has primarily been restricted to the quantification of conch dimensions. We introduce several morphometric methods and indices to quantify sutural elements. These new methods involve angular measurements of various suture components in relation to the axial plane of planispiral forms, as well as linear measurements between specific suture components. Resultant data were compared to conch dimensions, and it was found that along ontogenetic progressions, some of these sutural indices correlate strongly with overall conch diameter. Therefore, these relationships can be used to reasonably estimate the total diameter of incomplete specimens at an ontogenetic stage concurrent with that of the measured suture. Additionally, some of these sutural indices correlate with one another through ontogenetic progression, and therefore only one of several combinations of sutural components is necessary to estimate some conch dimensions. We suggest that these new morphometric methods can provide a more accurate systematic taxonomy for ammonoids with complex sutures, and that more robust datasets may be produced from relatively incomplete specimens. We further suggest that these suture-based morphometrics can be useful for taxonomic studies of other ammonoid families characterized by complex suture patterns.

BACKGROUND:Paleozoic holocephalian tooth plates are rarely found articulated in their original positions. When they are found isolated, it is difficult to associate the small, anterior tooth plates with the larger, more posterior ones. Tooth plates are presumed to have evolved from fusion of tooth files. However, there is little fossil evidence for this hypothesis.RESULTS:We report a tooth plate having nearly perfect bilateral symmetry from the Mississippian (Chesterian Stage) Bangor Limestone of Franklin County, Alabama, USA. The high degree of symmetry suggests that it may have occupied a symphyseal or parasymphyseal position. The tooth plate resembles Deltodopsis? bialveatus St. John and Worthen, 1883, but differs in having a sharp ridge with multiple cusps arranged along the occlusal surface of the presumed labiolingual axis, rather than a relatively smooth occlusal surface. The multicusped shape is suggestive of a fused tooth file. The middle to latest Chesterian (Serpukhovian) age is determined by conodonts found in the same bed.CONCLUSION:The new tooth plate is interpreted as an anterior tooth plate of a chondrichthyan fish. It is referred to Arcuodus multicuspidatus Itano and Lambert, gen. et sp. nov. Deltodopsis? bialveatus is also referred to Arcuodus.

Three Pennsylvanian stratigraphic units in southwestern Missouri that have long been recognized as preceding the Cherokee Group (and as pre-Desmoinesian Stage) are compared on the basis of their conodont faunas: the Riverton Shale, the Ladden Branch Limestone Member of the Riverton Shale, and the type Burgner Formation from the subsurface. Shale at the base of the Riverton was sampled where it occurs above a well-developed underclay. It produced a conodont fauna that is mostly similar to that of the Ladden Branch Limestone Member, which occurs at the base of the Riverton Shale at other localities. Both units produced biostratigraphically important Neognathodus bothrops and N. colombiensis s.l.. A difference is that the Ladden Branch Limestone Member commonly produced specimens of Idiognathoides, whereas none were recovered from the basal Riverton shales. Both are assigned to the upper Atokan Neognathodus colombiensis Zone, and most likely are age-equivalent facies. Strata at the Republic coal pit, previously considered correlative with the type Burgner Formation, are now correlated with the Riverton Shale based on its N. colombiensis Zone conodonts and overall similarity to the basal Riverton. The core that represents the type Burgner Formation produced a conodont fauna somewhat different from the other sections, including specimens of an advanced morphotype of Neognathodus nataliae. The type Burgner Formation is, therefore, assigned to the upper part of the lower Atokan N. nataliae Zone.

Chaetetes , a hypercalcified sponge, formed expansive biostromes in Atokan strata of the Hueco Mountains, West Texas, where they grew in very shallow water on a broad shallow carbonate shelf. The Chaetetes there have tabular, columnar, compound-columnar, and branching shapes, and grew to heights of greater than 1 m. In most cases, they grew from a point source with an axial growth style. The laminar growth style occurs rarely, overlying growth interruption surfaces and where initial growth was on a hard surface such as solitary rugose corals. From the analysis of these fossils in the context of their inferred paleoenvironment, and integrating observations and available data from other localities, we conclude that the morphology of Chaetetes —their shape and growth style—was determined primarily by sedimentation parameters concurrent with their growth. These parameters were substrate character—texture and firmness—and both overall rate of sediment accumulation and variations in the rate relative to the rate of Chaetetes growth. Six species of Chaetetes were described previously in North America. Four of these are too incompletely known to be of taxonomic value. The other two, Chaetetes milleporaceus and Chaetetes favosus , form a continuum of morphotypes that is interpreted here to represent a single species, C. milleporaceus by priority.

Late Bashkirian and early Moscovian conodonts are abundant and diverse at the Naqing section, South China. All conodont genera known to have numerous species in the late Bashkirian early Moscovian are recorded here, including Declinognathodus, Diplognathodus, Gondolella, Idiognathodus, Idiognathoides, Mesogondolella, Neognathodus, and Neolochriea. At Naqing, many species of these genera provide a succession of conodont chronomorphoclines throughout the Bashkirian Moscovian boundary interval. They demonstrate that deposition was remarkably continuous through the boundary interval, a major criterion for selecting a Global Stratotype Section and Point (GSSP). This paper describes the current state of knowledge for several of these chronomorphoclines, and also provides an updated range chart of conodonts recovered from the Naqing section and their correlation with other regions.The taxon that best matches the current concept for the base of the Moscovian Stage in its type region is the phylogenetic first occurrence of Diplognathodus ellesmerensis. An ancestral form with most of the characteristics of D. ellesmerensis occurs at Naqing. More specimens are needed to completely document the chronomorphocline, but because D. ellesmerensis is found worldwide - including that close to the base of the type Moscovian - its evolutionary first occurrence would provide an almost ideal GSSP to define the base of the international Moscovian Stage. (C) 2015 Elsevier B.V. and Nanjing Institute of Geology and Palaeontology, CAS. All rights reserved.

Mid-Carboniferous strata of the Barnett Shale in the Sierra Diablo region are deep water, offshore sediments deposited in the Marathon Foreland Basin. These strata contain a remarkably complete ammonoid record spanning from the Late Viséan to the middle Atokan (Moscovian). Late Viséan strata are referred to as the "Folks Member" of the Barnett Shale and locally yield numerous ammonoids. Three assemblages can be recognized, which contain, from oldest to youngest, Goniatites eganensis and Girtyoceras hamiltonense (Goniatites eganensis Zone), Goniatites multiliratus and Girtyoceras meslerianum (Goniatites multiliratus Zone), and Choctawites cumminsi and Pachylyroceras cloudi (Choctawites cumminsi Zone). We erect the new genera Choctawites and Uralyroceras to accommodate, respectively, the North American species "Goniatites choctawensis Shumard, 1863", "G. kentuckiensis Miller, 1889" and "G. cumminsi Hyatt, 1893", and Uralian species formerly attributed to Pachylyroceras. For the material of "Pachylyroceras cloudi" of the South Urals, the new species name Uralyroceras arquatum is proposed.

Despite being recognized for many years, bentonites in the Guadalupian (Middle Permian Series) type area of West Texas and southeastern New Mexico have received little research attention. These important deposits offer opportunities for long distance stratigraphic correlation and high-precision radioisotopic age dating. In this study, apatite phenocryst chemistry is used to establish a tephrochronologic framework for the Manzanita Limestone Member of the Cherry Canyon Formation. Samples were collected from bentonites in one core and five field localities including Nipple Hill, which is the site of the Late Guadalupian (Capitanian Stage) GSSP and located in Guadalupe Mountains National Park. Apatite phenocrysts from these samples were analyzed for minor, trace, and rare earth element chemistry using electron microprobe techniques. Results indicate the presence of three patterns or trends of data that are repeated at multiple localities. These groups of data are interpreted to represent coeval deposits and are correlated among several localities to form a tephrochronologic framework. This framework links the strata on Nipple Hill with that of several other Guadalupian type area localities. Absolute age time control for the Guadalupian is poor, and the precise stratigraphic position of the existing radioisotopic date from Nipple Hill is uncertain. Based on a review of published reports and a new measured section of Nipple Hill presented herein, the most accurate position is in the Manzanita Member. That placement adjusts the only radioisotopic age constraint for the Capitanian GSSP lower in the Wordian Stage than previously reported. The bentonite correlations proposed herein constrain this position to the Mz-3 cycle of the Manzanita High Frequency Sequence and allow it to be traced to several outcrop localities, and across the Delaware Basin in the subsurface. Based on the correlation of a bentonite from its locus typicus near Casey’s Last Chance Well in Culberson County, Texas, the type specimen of the biostratigraphically significant ammonoid Newellites richardsoni is confirmed to have been recovered from the basal Manzanita Member (Wordian Stage), stratigraphically underlying the radioisotopic age date. The type locality of this ammonoid has been inconsistently reported in museum records and in the literature.

The Reef Trail Member, Bell Canyon Formation, represents the uppermost subdivision of the Guadalupian Series (Capitanian Stage) of theMiddle Permian in its type area. Previouswork in the PattersonHills and in other parts of theDelaware basin have produced conodonts (e. g., Clarkina hongshuiensis) that provide a direct biostratigraphic correlation to latest Capitanian age rocks in the Lengwuan Stage (=Capitanian, latest Guadalupian, Middle Permian) in China. The conodont species Clarkina postbitteri, whichmarks the basal part of the Lopingian Series (Upper Permian), has not been found in the Middle Permian of West Texas. For the first time we describe complete detailed sections of the Reef Trail Member in order to provide a lithostratigraphic framework on which to base further biostratigraphic studies.We designate and describe a formal primary reference section for the Reef Trail Member because of the absence of a complete section in the type area. We also describe another complete section and two other important but incomplete sections, all in the Patterson Hills. The strata of all of the sections described were deposited in a basinal setting near the toe-of-slope, and are dominated by carbonate materials. Nearby outcrops contain toe-of-slope debris that provide evidence of mass wasting of the Capitan reef immediately prior to onset of evaporite deposition of rocks of the Castile Formation in the basin. Biostratigraphic and lithostratigraphic evidence indicate that evaporate deposition occurred simultaneously throughout the Delaware basin.

Pennsylvanian phosphatic black shales are widely interpreted to have been deposited in waters deep enough to produce a pycnocline that would have developed as a consequence of increased riverine runoff into the largely landlocked North American Midcontinent Sea during the more humid interglacial intervals of the Late Palaeozoic Ice Age. We tested whether a gradient in surface water salinity existed in the North American Midcontinent Sea during times of maximum flooding by analyzing oxygen isotopes of conodont apatite from correlative Pennsylvanian black shales of the Midland, Midcontinent, Illinois and Appalachian basins. In the Midland and Midcontinent basins, average delta O-18 values for conodonts from the Oakley (middle Desmoinesian/upper Moscovian), Hushpuckney (lower Missourian, lower Kasimovian) and Heebner black shales (lower Virgilian/lower Gzehlian) are 18.8 +/- 0.3 parts per thousand, 19.1 +/- 0.2 parts per thousand, and 18.9 +/- 0.1 parts per thousand, respectively. Oxygen isotope ratios of conodonts from the Nuyaka Creek black shale (uppermost Desmoinesian/upper Moscovian) of the Midcontinent Basin are 19.8 +/- 0.3 parts per thousand, and thus significantly higher in comparison to the other black shales. These higher values support previous interpretations that the Lost Branch is a minor cyclothem, with south polar regions having been less deglaciated than during the interglacial phases of the more widespread major cyclothems. Conodonts from Oakley shale equivalents from Ohio and Pennsylvania are depleted in O-18 on average by 2.5 parts per thousand in comparison to conodonts from the Midcontinent Basin. This pattern is also evident for conodonts from the Heebner and Hushpuckney shales, although conodonts from the Appalachian Basin show only a 0.4-0.7 parts per thousand depletion in O-18 compared to conodonts from the Midcontinent Basin. The differences in delta O-18 are interpreted as reflecting primarily salinity, assuming that temperature was relatively constant across the palaeotropical Midcontinent Sea. Lower salinities in the Appalachian Basin and a significant salinity gradient in the Midcontinent Sea were reconstructed for the Desmoinesian Oakley shale, supporting the idea that freshwater discharge resulted in a salinity-stratified water column during times of "everwet" tropical palaeoclimate, at least in the eastern part of the epeiric sea. However, the salinity gradient is considerably reduced during the subsequent Missourian and Virgilian periodically dry interglacial periods (Hushpuckney and Heebner shales). This suggests that surface waters in the Midcontinent Sea were not significantly influenced by continental runoff and calls into question whether a halocline was necessary for the formation of phosphatic core shales. (C) 2015 Elsevier B.V. All rights reserved.