Limestone Member Research Articles

The Global Boundary Stratotype Section and Point for the base of the Turonian Stage of the Cretaceous: Pueblo, Colorado, U.S.A.

Following the recommendation of the International Commission on Stratigraphy (16 votes Yes [94%], 1 abstention, 2 votes not received), the Global boundary Stratotype Section and Point (GSSP) for the base of the Turonian Stage of the Cretaceous System is defined as the base of bed 86 of the Bridge Creek Limestone Member of the Greenhorn Limestone Formation at the western end of the Denver and Rio Grande Railroad cut near the north boundary of the Pueblo Reservoir State Park Recreation Area, west of Pueblo, Colorado, USA. This GSSP horizon is also exposed and protected in the adjacent state recreation area. It coincides with the first occurrence of the ammonite Watinoceras devonense, is in the middle of a global positive excursion in Carbon-13 isotopes, and is bracketed by widespread bentonites that have yield edages of 93 to 93.5 Ma.

The unusual sedimentary rock record of the Early Triassic: A case study from the southwestern United States

Sedimentary systems, as well as the earth's biota, changed dramatically following the end-Permian mass extinction. This global sedimentological transformation is reflected in the widespread occurrence of flat-pebble conglomerates, subtidal wrinkle structures, microbialites, and carbonate seafloor fans in various Lower Triassic sections. As a case study, a facies analysis of the Lower Triassic Virgin Limestone Member of the Moenkopi Formation and the Middle and Upper Members of the Union Wash Formation, southwestern United States was conducted and all unusual facies were documented within a palaeoenvironmental framework. The occurrence of the flat-pebble conglomerates and wrinkle structures is significant because these reflect a long-term reduction in vertical bioturbation. In the case of the subtidal microbialites and carbonate seafloor fans, their formation is linked to an increase in alkalinity. The presence of these facies in the uppermost Lower Triassic strata of the southwestern United States indicates that reduced levels of infaunal bioturbation as well as (and perhaps a consequence of) unusual ocean chemistry extended for 5–6 million years after the end-Permian mass extinction, suggesting that depositional environments as well as the biota were significantly affected by the extinction event.

Middle Anisian (Pelsonian) platform conodonts from the Triassic of the Mecsek Mts (South Hungary) - Their taxonomy and stratigraphic significance

Kovacs and Papsova (1986) described a Pelsonian conodont fauna from the base of the Misina Hill key geologic section (Mecsek Mts, South Hungary), extracted from the host-rock of a Schreyerites? binodosus specimen published by Detre (1973). In the present paper the conodont fauna of the entire key section is described on the basis of 26 samples (from No. Bh-1 to Bh-26). A detailed taxonomic review of Gondolella bulgarica, hanbulogi and bifurcata is given, which are distinguished at species level (following the detailed morphotaxonomic study by Germani 2000), although all morphological transitions between the three taxa are present. They are united into the G. bulgarica Group. Correlated with the Pelsonian type sections in the Balaton Highland (Aszofo, Felsoors), the entire exposed sections of the Bertalanhegy and Domorkapu Limestone Members belong to the upper part of the Pelsonian, e.g. to the Binodosus Zone. The Illyrian evaporitic Middle Muschelkalk event appears to be represented by a hiatus ...

Paleoecology of the Permian (Wolfcampian) Phylloid Alga Calcipatera from an In Situ Occurrence in Kansas, U.S.A.

In situ occurrences of the calcareous marine phylloid alga Calcipatera cottonwoodensis in the Permian Cottonwood Limestone Member (Beattie Limestone) occur in Greenwood County, Kansas, in association with platy algal packstones, which are the phylloid algal facies most commonly described in the literature. The in situ algal facies occurs in the upper 0.45 m of an exposure where it is overlain and underlain by algal packstones composed of transported and broken fragments of Calcipatera cottonwoodensis.
 Calcipatera cottonwoodensis colonized coarse carbonate sands or carbonate mud substrates. During growth, carbonate mud accumulated in the cup-shaped thalli, and death followed when the rate of sedimentation exceeded the rate of algal growth. The three lithologies--substrate, cup-filling, and smothering--are easily recognized on polished surfaces.
 Other members of the Calcipatera cottonwoodensis benthic community are Shamovella, encrusting and boring algae, foraminiferids, fenestrate and ramose bryozoans, brachiopods, bivalves, gastropods, trilobites, ostracodes, and echinoids. This occurrence and biotic association compares well with those described by Toomey (1976) and Wahlman (1988, 2002) from the Permian (Wolfcampian) of West Texas.

Paleoecology, Taphonomy, and Biogeography of a Coenothyris Community (Brachiopoda, Terebratulida) from the Triassic (Upper Anisian–Lower Ladinian) of Israel

Abstract A brachiopod community from the Fossiliferous Limestone Member (Upper Anisian–Lower Ladinian) of the Triassic Saharonim Formation at Har Gevanim, Makhtesh Ramon, southern Israel, is dominated by the terebratulid Coenothyris oweni Feldman. The community shows evidence of time-averaging and is largely composed of a single cohort of juvenile mortality of one spatfall. The Saharonim Formation was deposited under normal, calm, relatively shallow marine conditions as part of the global Anisian–Ladinian transgression. One horizon, varying in thickness between 1 and 1.5 cm, represents an autochthonous obrution deposit of juvenile Coenothyris brachiopods and 10 bivalve genera that were rapidly buried by pulses of clay in the form of flocculated mud. Other faunal constituents of the Saharonim Formation include conodonts, ostracodes, foraminiferans, bivalves, cephalopods, gastropods, echinoderms, and vertebrate remains that belong to the Sephardic Province and are diagnostic of the Middle Triassic series of...

Late Silurian pentameride brachiopods from Yass and Molong, New South Wales

The five known species of pentameride brachiopods from the Yass Syncline Ludlow (LateSilurian) succession, belonging to the superfamilies Pentameroidea, Gypiduloidea and Clorindoidea, are fully revised; no new species are recognised. The pentameroids Conchidium sp. cf. hospes and Aliconchidium yassi are confined to the Bowspring Limestone Member (Silverdale Formation). The gypiduloid Ascanigypa glabra and externally homeomorphic clorindoids Barrandina wilkinsoni and Clorinda minor replace them in the overlying Barrandella Shale Member, the last two extending into the Yarwood Siltstone Member (Black Bog Shale). Clorinda minor is also possibly present in the Rainbow Hill Member (Rosebank Shale). All except C. minor are uncommon to rare components of the Yass brachiopod fauna. Clorinda molongensis, a species of uncertain mid- to late Silurian age from the Molong Limestone, is also revised. Aliconchidium and Barrandina are known only from Yass, whereas Clorinda is cosmopolitan. Conchidium alsois widespread, but C. hospes is a species from the Prague Basin probably also known from the Urals and the Tien Shan. Ascanigypa is another Prague Basin taxon, recently recognised in Arctic Canada.

Early Triassic Trace Fossils of the Western United States and their Implications for Prolonged Environmental Stress from the End-Permian Mass Extinction

Abstract The end-Permian mass extinction left an indelible mark on trace-fossil assemblages. This is evident during the lag phase of the biotic-recovery interval that occurred in the Early Triassic. Research on the Spathian Virgin Limestone Member of the Moenkopi Formation, western United States, has yielded a mixed carbonate–siliciclastic trace fossil assemblage. The presence of such traces as Thalassinoides, Laevicyclus, and Gyrochorte indicate that previously unreported metazoan behaviors had reappeared in equatorial regions by the close of the Early Triassic. Whereas diversity of trace-fossil assemblages increased from earliest to late Early Triassic time, persistent small size, low average ichnofabric index, low bedding-plane coverage, and reduced tiering point to prolonged stressful environmental conditions following the end-Permian mass extinction—conditions for which there is an abundance of global sedimentological evidence. This trace-fossil assemblage provides a record of soft-bodied organisms t...

Late Early Triassic microbial reefs of the western United States: a description and model for their deposition in the aftermath of the end-Permian mass extinction

Research in the western United States to reinvestigate and characterize the previously reported stromatolites of the latest Early Triassic (Spathian) Virgin Limestone Member of the Moenkopi Formation has shown that these microbial build-ups formed patch reef mounds. Detailed field analysis of these reef mounds and the surrounding beds has established that they attained 1–2 m of topographic relief above the seafloor. A petrographic study of these microbial mounds illustrates that they consisted of microbial fabrics, as well as voids with early marine cements and formed in the absence of in situ metazoans. These reef mounds formed during the aftermath of the end-Permian mass extinction that spanned the Early Triassic. Due to the devastation of marine metazoans at this extinction, the Early Triassic has often been deemed a reef gap because no metazoan reefs are found at this time. Whereas colonial metazoan reefs are globally absent from Lower Triassic strata, microbial build-ups similar to these described from the western United States have been found in south China, Armenia, southern Turkey and Greenland. A regional Early Permian to late Early Triassic unconformity exists in the study region. However, analysis of these microbial reefs within a global context suggests that conditions favouring microbial reef development must have existed as long as 4–8 m.y. after the end-Permian mass extinction. A depositional model of these microbial mounds indicates that flooding of the shelf with anoxic and/or CO 2-rich deep waters may have fostered their occurrence.

Detection, quantification, and significance of hiatuses in pelagic and hemipelagic strata

Temporal gaps in the stratigraphic record have important implications for the interpretation of stratigraphically rapid geochemical and paleobiologic changes, for the development of high-resolution time scales (e.g., orbital time scales), and for deciphering the response of depositional systems to climatic change and basin evolution (e.g., accommodation space vs. sediment supply). In ancient pelagic and hemipelagic strata, the identification of relatively short hiatus (103–106 years) is commonly challenged by the resolution limits of geochronologic techniques. In this study, a quantitative method is developed to identify and quantify hiatuses in strata where Milankovitch orbital cycles are documented. The new method is based on the interpretation of evolutive harmonic analysis (EHA) results and permits estimation of minimum durations for the temporal gaps. Application of this technique to an optical densitometry data series derived from the Cenomanian/Turonian (C/T) Bridge Creek Limestone Member permits quantification of hiatus within the unit and addresses important questions about abrupt changes in biogeochemical proxy records across the boundary interval. Integration of the new method with stratigraphic data and geochemical burial flux estimates permits a detailed reconstruction of the controls on sediment delivery and hiatus generation, including a refined analysis of the orbital-scale linkages between climate and sedimentation.

Facies architecture and sequence development in a Neoproterozoic carbonate ramp: Lakheri Limestone Member, Vindhyan Supergroup, Central India

Outcrop-based study of high-resolution sequence stratigraphy (intra- and interfacies sedimentologic clues) in Neoproterozoic Lakheri Limestone, Central India, reveals definite signals for relative sea level variations and paleogeographic shifts between shallow beach-shoreface and distal-shelf. Depositional cycles in this carbonate formation are bound by unconformities or disconformities of ravinement origin. On outcrop scale the unconformities are sharp and irregular and marked by definite depletion in δ13C values of limestones. In the study area the entire Lakheri Limestone succession is divided into four depositional ‘sequences’ bound by type I unconformities. Different variants of system tracts (transgressive, highstand and lowstand), resulting from differences in paleogeographic locations, basin floor physiography and variable rates of relative sea level change, constitute the sequences developed on Lakheri carbonate ramp. A possible forcing of intrabasinal tectonics (both extension and compression) on meter to tens of meter thick Lakheri ‘sequences’ is inferred. Facies impersistence (both along and across depositional strike) of Lakheri Limestone is an additional complexity in depositional architecture of carbonate ramp sequence. This possibly resulted from formation of depositional slope breaks through tectonic or depositional factors. Three-dimensional reconstruction of lowstand wedge brings out the control of rugged physiography of the basin floor (imparted through patchy biohermal growth) on facies distribution in this Neoproterozoic ramp succession.

The Non-Actualistic Early Triassic Gastropod Fauna:A Case Study of the Lower Triassic SinbadLimestone Member

Abstract Through a detailed regional study of the Lower Triassic (Nammalian) Sinbad Limestone Member of the Moenkopi Formation in southeastern Utah, previously qualitative paleoecological observations on Early Triassic gastropods have been quantified. Paleocommunities of the Lower Triassic Sinbad Limestone Member are dominated by gastropod juveniles and small-size adult gastropods (99% of the gastropods are smaller than 1 cm) that form numerous microgastropod packstones and grainstones that were deposited subtidally. The results from this case study of the Sinbad Limestone Member reflect a global Early Triassic phenomenon of microgastropod-dominated open-shelf environments. These characteristics of the paleoecology of Early Triassic gastropod faunas are non-actualistic since, during Ecological Evolutionary Units (EEUs), larger gastropods and normal-marine communities are invariably common somewhere contemporaneous with the occurrence of microgastropod-dominated faunas. Early Triassic microgastropods behav...

NEW TRILOBITE TAXA FROM UPPER CAMBRIAN MICROBIAL REEFS IN THE CENTRAL APPALACHIANS

Previously undescribed trilobites associated with microbial patch reefs have been recovered from the Upper Cambrian (upper Steptoean Stage) Ore Hill Limestone Member of the Gatesburg Formation in south-central Pennsylvania. Reefs in the Imler Quarry and Drab-Beaverton measured sections yielded low-diversity assemblages of trilobites that we assign to the uppermost Cliffia lataegenae Subzone of the Elvinia Zone. The faunas are dominated by the catillicephalid Buttsia drabensis Wilson, 1951, and include several new taxa that are not known from coeval off-reef facies. Fine-scale correlation between the two sections reveals that the reefs in the Drab-Beavertown section are slightly younger than those at Imler Quarry and represent the youngest Steptoean fauna described from the Appalachian region.New taxa include Imlerella n. gen. (type species Imlerella praecipita n. sp.), Stittaspis n. gen. (type species Stittaspis loria n. sp.), and Dellea rogersi n. sp. Stigmacephalus? distorta Wilson, 1951, is reassigned to Stittaspis and is restricted to the type. Additional material of Buttsia drabensis illustrates features not discernible in previous treatments of this variable species.

Facies architecture and sequence development in a Neoproterozoic carbonate ramp: Lakheri Limestone Member, Vindhyan Supergroup, Central India

Outcrop-based study of high-resolution sequence stratigraphy (intra- and interfacies sedimentologic clues) in Neoproterozoic Lakheri Limestone, Central India, reveals definite signals for relative sea level variations and paleogeographic shifts between shallow beach-shoreface and distal-shelf. Depositional cycles in this carbonate formation are bound by unconformities or disconformities of ravinement origin. On outcrop scale the unconformities are sharp and irregular and marked by definite depletion in δ 13 C values of limestones. In the study area the entire Lakheri Limestone succession is divided into four depositional ‘sequences’ bound by type I unconformities. Different variants of system tracts (transgressive, highstand and lowstand), resulting from differences in paleogeographic locations, basin floor physiography and variable rates of relative sea level change, constitute the sequences developed on Lakheri carbonate ramp. A possible forcing of intrabasinal tectonics (both extension and compression) on meter to tens of meter thick Lakheri ‘sequences’ is inferred. Facies impersistence (both along and across depositional strike) of Lakheri Limestone is an additional complexity in depositional architecture of carbonate ramp sequence. This possibly resulted from formation of depositional slope breaks through tectonic or depositional factors. Three-dimensional reconstruction of lowstand wedge brings out the control of rugged physiography of the basin floor (imparted through patchy biohermal growth) on facies distribution in this Neoproterozoic ramp succession.

Stratigraphic architecture of the northern Oman continental margin - Mesozoic Hamrat Duru Group, Hawasina complex, Oman

ABSTRACT The Triassic to Late Cretaceous deep-marine sediments of the Hamrat Duru Group, Oman Mountains, represent a subunit of the Hawasina nappe-complex which was deposited in a deep marine basin. During the Late Cretaceous SSW-directed obduction of the Semail Ophiolite, the Hawasina complex was emplaced onto the autochthonous cover of the Arabian basement, while the original configuration of the basin was destroyed. New lithostratigraphic results and high-resolution radiolarian and conodont biostratigraphy lead to a revised stratigraphic scheme of the Hamrat Duru Group which conforms with the standard stratigraphical nomenclature. The Hamrat Duru Group is divided into six formations: (1) The Early Triassic (Olenekian) to Late Triassic (Upper Norian) Zulla Formation (Limestone and Shale Member, Sandstone and Shale Member, Radiolarian Chert Member and Halobia Limestone Member); (2) The Late Triassic (late Norian to Rhaetian) Al Ayn Formation; (3) The Early Jurassic (late Pliensbachian) to Middle Jurassic (early Callovian) Guwayza Formation (Tawi Sadh Member and Oolitic Limestone Member); (4) Middle Jurassic (Callovian) to Late Cretaceous (Cenomanian?) Sid’r Formation (Lower Member, Upper Member); (5) Late Cretaceous (Cenomanian? to Santonian?) Nayid Formation; and (6) Late Jurassic (early Callovian) to Early (Late?) Cretaceous Wahrah Formation. Most of the lithostratigraphic units (formations and members) show isochronous boundaries between the different outcrop areas. The stratigraphic architecture of the Hamrat Duru Group megasequence is controlled by alternating siliciclastic and carbonate sedimentation possibly related to the second-order sea-level variations. The sediments accumulated on the continental rise of the Arabian margin mostly by submarine sediment-gravity flows and hemipelagic to pelagic rainout. A close relationship of the evolution of the Arabian Platform and the adjoining slope and basinal environments is evident. Changes in carbonate supply, oceanographic circulation and/or variations in silica productivity resulted in two distinct phases of radiolarian sedimentation. The first phase corresponds to the Triassic late Anisian-early Norian time interval; the second started in the Early Jurassic late Pliensbachian and lasted, with some interruptions, up to the Late Cretaceous Coniacian. The litho- and biostratigraphic similarities between the Mesozoic Hamrat Duru Basin of the northern/central Oman Mountains and the Mesozoic Batain Basin of northeastern Oman are seen as related to Neo-Tethys-wide palaeoceanographic changes and suggest a strong interdependence of the two basins with the evolution of the Arabian Platform.

Lithostratigraphy of the Neoproterozoic Chattisgarh Sequence, its Bearing on the Tectonics and Palaeogeography

The Neoproterozoic Purana succession in the eastern part of Chattisgarh basin around Sarangarh has been classified into a conglomerate-sandstone-shale dominated proximal assemblage, and a lithographic limestone-shale dominated distal assemblage. The proximal assemblage constitutes the Chandarpur Group, and unconformably overlies the Archean crystalline basement complex. The Chandarpur succession has been classified into three formations that were deposited in fan-fan delta, deep water prodelta and storm- tide dominated prograding shelf environments. The distal assemblage, the Raipur Group, conformably overlies the Chandarpur Group, and may be subdivided into two shale-dominated formations separated by a limestone-dominated formation. The limestone sequence, the Sarangarh Limestone, comprises a lower member of mixed carbonate-siliciclastic succession deposited in a storm dominated shallow water platform, and an upper member of pelagic limestone that grades upward into a deep water shale, the Gunderdehi Shale. The rapid transition from shallow water platformal succession to deep-water pelagic limestone and shale points to abrupt deepening of the basin and drowning of the craton. The peak of transgression is represented by a persistent horizon of black limestone, a product of basin wide anoxia. Disposition of facies belts in proximal and distal assemblages and palaeocurrent directions measured from different facies belts point to a north-northwesterly palaeoslope of the basin. Signatures of intense storm and tidal currents in different litho-units collectively point to an open marine circulation condition. It has been inferred that the basin was connected to a major seaway that skirted the northern and north-western margin of the craton. Development of thick fan-delta sequence at the base of the succession, occurrence of felsic welded tuff within the Gunderdehi Shale, thick sandstone-mudstone cyclothems in the Chandarpur Group, and abrupt drowning of the carbonate platform leading to pelagic sedimentation collectively point to major tectonic control on basin evolution. The basin developed as a cratonic rift and evolved into a deeply subsiding one, without any major stratigraphic hiatus, through episodic tectonic pulses.

Proliferation of Early Triassic wrinkle structures: Implications for environmental stress following the end-Permian mass extinction

Lower Triassic strata in the western United States and northern Italy have yielded the first reported occurrence of microbially mediated wrinkle structures in shallow subtidal siliciclastic paleoenvironments since the Cambrian. We hypothesize that wrinkle structures formed under reduced infaunalization conditions during the aftermath of the end-Permian mass extinction. These wrinkle structures occur in siliciclastic sedimentary rocks in association with hummocky cross-stratification and, in some cases, trace fossils such as Asteriacites , Rhizocorallium , Planolites , and Gyrochorte that indicate a subtidal paleoenvironment. Wrinkle structures were found in the Campil Member in the Werfen Formation of northern Italy and in the Virgin Limestone Member of the Moenkopi Formation and the upper member of the Thaynes Formation exposed in the western United States. The presence of wrinkle structures is likely related to a unique taphonomic window that allowed for the preservation of these delicate features on storm-dominated siliciclastic shelves. Wrinkle structures commonly formed in a variety of subtidal paleoenvironments during the Proterozoic–Cambrian, but thereafter became restricted to intertidal-supratidal and deep-sea environments. This restriction has been attributed to the increase in infaunalization of metazoans following the Cambrian radiation. The proliferation of wrinkle structures in subtidal settings during the Early Triassic suggests that infaunal bioturbation was reduced after the end-Permian mass extinction and that this reduction lasted for millions of years.

Middle Ordovician (Darriwilian) conodonts from allochthonous limestones in the Oakdale Formation of central New South Wales

Twenty species of late Middle Ordovician conodonts including two new forms, Erraticodon bellevuensis sp. nov. and Ansella? haustra sp. nov., are described and illustrated from allochthonous limestone blocks in the Oakdale Formation of the Bell River Valley, N.S.W. The co-occurrence of Paroistodus horridus, Histiodella kristinae and Appalachignathus delicalulus in the fauna suggests the limestone was originally deposited in late Darriwilian (most likely early-mid Da3) time, providing a maximum age constraint on its inclusion in the Oakdale Formation. Some faunal similarities are apparent between this conodont fauna and that from (1) allochthonous limestone clasts within the Fairbridge Volcanics below the Wahringa Limestone Member and (2) contemporaneous deep-water cherts in basinal turbidite facies of the Adaminaby Group. The latter similarity suggests that prior to downslope displacement into the Oakdale Formation, the original depositional environment of the limestone was on an unstable outer shelf edge rather than in shallow water depths.

The Burgess Shale and associated Cambrian formations west of the Fossil Gully Fault Zone on Mount Stephen, British Columbia

West of the Fossil Gully Fault Zone on Mount Stephen, the three lowest members only of the Burgess Shale Formation are preserved: the Kicking Horse Shale, the Yoho River Limestone, and the Campsite Cliff Shale. The formation rests unconformably upon the Takakkaw Tongue Formation, whose dark basinal limestones conformably overlie paler shelf-like limestones of the Mount Whyte Formation. Mapping has resolved a long-standing problem and shown that the stratigraphical position of the famous Mount Stephen Trilobite Beds lies within the Campsite Cliff Shale. It has also revealed some of the complexities of the Fossil Gully Fault Zone, among which different periods and directions of component fault movements are indicated. Faunal evidence shows that the Plagiura–Kochaspis to Albertella and Albertella to Glossopleura zonal boundaries lie within the Takakkaw Tongue sequence. Within the Burgess Shale, three distinct soft-bodied communities occur at different stratigraphical levels on this mountain slope. The oldest, characterized by the arthropod Alalcomenaeus and chelicerate Sanctacaris, occurs low in the Kicking Horse Shale Member and is best known from Collins Quarry. The others lie within the Campsite Cliff Shale Member. The Trilobite Beds, characterized by claws of the dinocarid Anomalocaris and moults of the trilobite Ogygopsis klotzi, onlap the sloping top of a proximal bench facies of the Yoho River Limestone Member close to the Cathedral Escarpment. Slightly older and farther out in the basin are beds characterized by the dinocarid Laggania and a tulip-like animal related to Dinomischus, excavated about 12 m above the top of a thin distal wedge facies of the Yoho River Limestone at the S7 site. Among the illustrated trilobites, a new corynexochine from the Campsite Cliff Shale Member is figured.

MAPESITES, A NEW UPPER PENNSYLVANIAN (LOWER VIRGILIAN) AMMONOID FROM KANSAS

In recent years, the authors, along with colleagues, have documented the lower Virgilian ammonoid faunas of the Midcontinent and north-central Texas (Boardman et al., 1989, 1994a, 1994b; Work and Boardman, 1995, 1996). Generic diversity for this interval is the highest in any Upper Pennsylvanian succession: at least 18 genera (representing 15 families) have been recovered from the Colony Creek Shale in north-central Texas alone (Boardman et al., 1989). An additional, previously unrecognized ammonoid from the correlative Little Pawnee Shale in southeastern Kansas is described herein as Mapesites chautauquaensis new genus and species. It is a highly original taxon with no obvious close relatives. Representatives of Mapesites chautauquaensis n. gen. and sp. were recovered from the Little Pawnee Shale Member of the Cass Limestone from a roadcut exposure along US Highway 166, 1.4 km west of Peru, Chautauqua County, Kansas (NE NE sec. 20, T34S, R12E, Peru 7.5′ quadrangle). The Little Pawnee sequence at Peru consists of 2.6 m of dark gray fossiliferous shale with a 0.6-m black phosphatic zone 0.2 to 0.8 m above the base. Ammonoids occur as limonitic internal casts in the lower part of the shale sequence, 0 to 0.2 m above the base, and as calcitic casts in the middle part, 1.1 to 1.9 m above the base. The Little Pawnee Shale immediately overlies a thin, 0.1-m-thick dark skeletal packstone-wackestone unit, the Haskell Limestone Member, which contains the provisional Missourian-Virgilian Stage boundary (see Heckel et al., 1999, p. 50, 51 for additional details). The assemblage from the Little Pawnee Shale at this locality, in addition …

Ptychodus mammillaris (Elasmobranchii) and Enchodus cf. E. shumardi (Teleostei) from the Fort Hays Limestone Member of the Niobrara Chalk (Upper Cretaceous) in Ellis County, Kansas

Vertebrate fossils are rare components of the Fort Hays Limestone Member (uppermost Turonian - Lower Coniacian) of the Upper Cretaceous Niobrara Chalk. Herein, two fish taxa are described that are new to the unit: Ptychodus mammillaris Agassiz and Enchodus cf. E. shumardi Leidy. These additions increase the total number of documented vertebrate species to 11 for the Fort Hays Limestone and provide additional insights into the paleoecology (e.g. community structure) of the Western Interior Seaway during the deposition of the Fort Hays Limestone.