Limestone Member Research Articles

A new Placoderm fish (Acanthothoraci) from the Early Devonian Jauf Formation (Saudi Arabia)

An exceptionally well-preserved new acanthothoracid (placoderm fish) presenting complete endocranium and skull roof, from Saudi Arabia (Qasr Limestone Member, Jauf Formation), Early Devonian in age, is described as Arabosteus variabilis n. gen., n. sp. Compared to other Acanthothoraci, the new taxon exhibits a skull roof variable in its dermal plate distribution (e.g., a supernumerary plate: the posterior central plate) and sensory line pattern. Even the different specimens of this taxon show such variability between them. Arabosteus variabilis n. gen., n. sp. enlarges the scope of our knowledge of Acanthothoraci and Placodermi in general. Traditionally, the Arthrodira, one of the historically earliest described groups, provide the standard reference model for the placoderm skull roof pattern. The interpretation of the acanthothoracid skull roof pattern of the Saudi taxon from an arthrodiran model and the establishment of homologies is impossible to resolve unless based on prior assumptions (e.g., hypothesis of fragmentation or fusion for the paranuchal plate complex). The lateral line system of A. variabilis n. gen., n. sp. is unstable (e.g., presence or absence of the postmarginal sensory line canal) making it ambiguous to define bone homology and terminology. Consequently spatial distribution of skull roof plates has been retained for such a task with a minimal reference to the instable features of the sensory line groove distribution.

Discontinuity surfaces and event stratigraphy of Okha Shell Limestone Member: Implications for Holocene sea level changes, western India

The Okha Shell Limestone Member of Chaya Formation is the coarse grained, shell rich deposit commonly recognized as the beach rocks. It has been age bracketed between Late Pleistocene and Holocene. Late Quaternary sea level changes have been studied with beach rocks along the Saurashtra coastal region. The present study has been carried out in the Okhamandal area of the Saurashtra peninsula especially on the Okha Shell Limestone Member as exposed at various locations along the coast from north to south. Temporal and spatial correlations of the observations have revealed three events in the Okha Shell Limestone Member of Chaya Formation that are correlated laterally. The events show depositional breaks represented by discontinuity surfaces, the taphofacies varieties and ichnological variations. The present study in the context of available geochrnological data of the region suggests a prominent depositional break representing low sea level stand (regression) during an Early Holocene during the deposition of Okha Shell Limestone Member.

Geomorphology and genesis of the remarkable Araras Ridge tufa deposit, Western Brazil

The Araras Ridge tufa extends for over 30km along a c. 100m high fault scarp, probably representing one of the most extensive tufa deposits in South America. The deposit comprises massive crystalline calcite occurring both as in situ tufa deposited along the vertical face of the scarp or as extensive debris deposits resulting from erosional disaggregation of the scarp. Although minor active tufa precipitation can be observed in streams, the deposit is not active at present, except for volumetrically limited reprecipitation of calcite as subaerial stalactites or surface flowstone. 230Th dating confirms that the bulk of the deposit is considerably old, basal ages being beyond the dating limit of the method (>600kaB.P.) and most ages being older than 250kaB.P. Field and remote sensing observations demonstrate that the upper limit of the deposit parallels the fault scarp, being associated with the contact between the upper dolomitic and the lower limestone members of the Araras Formation. Carbonate beds are arranged in a regional scale synclinal structure that allows water infiltration and storage at the top of the more impure limestone, favouring discharge at the ascending limb of the syncline, close to the scarp. Genesis of the deposit thus probably involved a series of palaeo perched springs aligned along the top of the scarp. Current climatic and geomorphic conditions are not conductive to major tufa development, suggesting a distinct palaeoenvironment during former depositional phases.

A preliminary investigation into calcareous dinoflagellate cysts and problematic microfossils from an expanded Cretaceous/Paleogene boundary section at Kulstirenden, Stevns Klint, Denmark

Located to the north of the Stevns Klint Peninsula (Denmark), Kulstirenden shows the transition from Cretaceous chalks to Danian carbonates across the Cretaceous – Paleogene (K/Pg) boundary. The K/Pg boundary at Kulstirenden is represented by the Fiskeler Member (Fish Clay), a streaked marl interval with a smectite rich, red oxidised layer at its base marking the boundary. The Fiskeler Member is important as it includes the iridium concentration linked to the bolide impact which may have caused the end-Cretaceous mass extinction and is at its maximum thickness at Kulstirenden (c.45 cm). Calcareous dinoflagellate cysts (Calciodinelloideae) have been investigated from within the fine fraction (45–125 μm) at Kulstirenden in order to understand the ecological implications of these enigmatic microfossils. Several species were found within the Fiskeler Member, including Orthopithonella collaris Wendler et al. (2001, Rev. Palaeobot. Palynol. 115, 69–77). This species is of particular interest as it demonstrates reduced paratabulation and may indicate a transgressive period immediately after the K/Pg boundary event. O. collaris has been described as a morphotype formed under post-K/Pg environmental conditions and is, therefore, described as a “disaster” taxon that marks the K/Pg boundary at Stevns Klint. The distribution of this taxon is more extensive than previously documented, disappearing as carbonate sedimentation returned in the Cerithium Limestone Member of the Danian. Several calcareous microfossil specimens that were found cannot be associated with the dinoflagellates and display Bolboforma-like features. While the origins of Bolboforma are enigmatic, the current finding expands their stratigraphic range and suggests an appearance of this group of organisms found at Stevns Klint may give an insight into the inception of this group into the earliest Danian.

Conodont biostratigraphy and lithostratigraphy across the Permian-Triassic boundary at the Lukač section in Western Slovenia

Detailed conodont biostratigraphy and lithostratigraphy of the Late Permian and Early Triassic were studied at the LukaC section in western Slovenia. The analyzed section is composed of the Bellerophon Formation (evaporite-dolomite member) and the newly introduced Lukae Formation (transitional beds, streaky limestone member and carbonate-clastic member). The Permian-Triassic boundary interval is represented by transitional beds of carbonate facies deposited in shallow restricted marine conditions. The presence of H. parvus in sample L1 in the transitional beds marks the systemic boundary between Permian and Triassic. The studied interval is characterized by a diverse microfauna that contain conodonts, foraminifers, ostracods and gastropods. Six conodont zones have been recognized, in ascending order, the latest Changhsingian (uppermost Permian) praeparvus Zone, and the Griesbachian (lowermost Triassic) parvus, lobata, staeschei- isarcica , postparvus and anceps zones. This faunal succession represents the first known and the most complete conodont biozonation across the Permian-Triassic interval from the entire Dinaric region. The recognized conodont biozones can be correlated with the biozonation of the Southern Alps and of the GSSP Meishan D section.

PALEOHYDROGRAPHIC INFLUENCES ON PERMIAN RADIOLARIANS IN THE LAMAR LIMESTONE, GUADALUPE MOUNTAINS, WEST TEXAS, ELUCIDATED BY ORGANIC BIOMARKER AND STABLE ISOTOPE GEOCHEMISTRY

Abstract The late Guadalupian Lamar Limestone Member of the Bell Canyon Formation, Delaware Basin, west Texas, records dramatic fluctuations in radiolarian faunal composition that are interpreted to record basin-scale changes in hydrography. Samples taken across one of these intervals of fluctuation show a change from a sparse, nearly monospecific fauna dominated by Follicucullus ventricosus to a more radiolarian-rich interval dominated by spongy spumellarians of the Copicyntrinae and Spongodiscidae. Carbonate stable isotope and organic biomarker geochemical data from this same interval support a strong terrestrial-freshwater influence on the spumellarian-dominated beds. Specifically, biomarker data show lower C22/C27 ratios and n-alkane distributions indicative of terrestrial organic matter sources in the spumellarian-dominated beds. In the whole-rock carbonate fraction, δ18O and δ13C show a shift to more negative values, consistent with increased meteoric water influence in the spumellarian-dominated in...

Comparison of 87Sr/86Sr isotope and biostratigraphic ages of uplifted fossil reefs in the Indo-Pacific: Indonesia, Papua New Guinea and Fiji

The lithology of limestone from seven Neogene sites from the Indo-Pacific region, from the Salayar Limestone in South Sulawesi, Indonesia, the Yalam Limestone in East New Britain, Papua New Guinea (P.N.G.) and the Daliconi and Futuna Limestone members of the Tokelau Limestone Group on Vanua Balevu in the Lau Group, Fiji, is described. The ages of foraminiferal assemblages collected at all sites are compared with 87Sr/86Sr isotope ages of samples from the same locations. Combined geochemical and biostratigraphic dating indicates a late Miocene to Pliocene/Pleistocene age for sections in Indonesia, a middle Miocene age for sections in P.N.G., and middle to late Miocene ages for sections in Fiji.

Foraminifera from the Permian-Triassic transition in western Slovenia

Foraminifers from the Upper Permian Bellerophon Formation, Permian-Triassic "transitional beds" and lowermost Triassic "streaky limestone member" of the Luka Formation in the Luka dection, western Slovenia are described and illustrated. Four new species of foraminifers are described: Multidiscus zhiriensis, M. dinaridicus and Globivalvulina lukachiensis from the Upper Permian, and Lingulonodosaria slovenica from the lowermost Triassic. The assemblage of Late Permian foraminifers consists of species characteristic of the Changhsingian of many regions in the Tethys: northwestern Caucasus, Transcaucasia, Iran, Turkey, northern Italy, northwestern Serbia, northeastern Hungary, and South China. Unfortunately, the uppermost part of the Bellerophon Formation in the Luka section is represented by dolomite and does not contain foraminifers. The Permian-Triassic boundary interval is represented by carbonate "transitional beds" deposited in a shallow restricted marine environment that contains foraminifers and conodonts. The species "Cornuspira" mahajeri, "Earlandia" gracilis, and "E." tintinniformis, marking the lower boundary of the Triassic worldwide based on foraminifers, are found both below and above the first appearance of the conodont species Hindeodus parvus in the Luka section. These species appear to be ecological species and their appearance coincideswith a stressful shallowwater environment. The first intervalwith nodosariid foraminifers appears 2mabove the P/T boundary and a second one is approximately 5m above the boundary. Both of these intervals with nodosariids are within the range of the conodont species H. parvus and within the I. staeschei – I. isarcica conodont Range Zone.

Ntegrated stratigraphy of St. Peter's Pool section (Malta): New age for the Upper Globigerina Limestone member and progress towards the Langhian GSSP

The St. Peter’s Pool section, that outcrops at Delimara Peninsula (south-eastern part of Malta Island), belongs to the Upper Globigerina Limestone, the youngest member of the Globigerina Limestone formation. The high resolution integrated study performed on it revealed the great potentiality of this section for a further development of the Mediterranean Langhian biostratigraphy and for a better understanding of the geology of the Maltese Archipelago. Calcareous plankton quantitative analyses allowed the definition of several bioevents with a great potential for biostratigraphic studies. Some of them are already well-known, such as the Helicosphera ampliaperta LCO (Last Common Occurrence), the paracme interval of Sphenolithus heteromorphus and the Acmea interval of Paragloborotalia siakensis, while the potential of Paragloborotalia bella LCO and the P. siakensis Acme0 are documented for the first time in the Mediterranean area. Other bioevents were recognized through qualitative analyses, such as the Paragloborotalia acrostoma LO (Last Occurrence), the Globigerinoides sicanus FO (First Occurrence), the Paragloborotalia birnageae LO, the Globorotalia mariae mariae FO and the P. bella LO. The St. Peter’s Pool section is characterized by a continuous sedimentation from the upper part of MMi3 Zone to the lower part of MMi4c Subzone of planktonic foraminiferal zonation of Di Stefano et al. (2008) and from the uppermost part of MNN4a Zone to the lower part of MNN5a Zone of calcareous nannofossil zonation (Di Stefano et al. 2008). The magnetostratigraphic interpretation, though rather uncertain, enabled us to identify the C5Cn–C5Br interval. On the basis of the bio-magnetostratigraphic events recognized in the St. Peter’s Pools section, we were able: i) to date the base of the Upper Globigerina Limestone member outcropping in the Delimara Peninsula; ii) to obtain the Burdigalian age for the Upper Globigerina Limestone member, that is the oldest ever recognized in the Maltese Archipelago and iii) to propose this section as potential candidate for the definition of the Langhian GSSP (Global Stratotype Section and Point), thanks to the high quality of calcareous plankton content, the deep paleoenvironmental setting, the suitability for future cyclostratigraphic studies and, finally, the easy accessibility to the outcrops.

First record ofTelephina(Trilobita) from the Ordovician of northeastern Estonia and its stratigraphical implications

For the first time a telephinid trilobite was recorded from the shallow-water rocks of the North Estonian Confacies Belt in the oil-shale mining area of northeast Estonia. A cranidium of Telephina (Telephops) biseriata (Asklund) was collected from a loose boulder of the kerogenous limestone of the Viivikonna Formation, Kukruse Stage, together with a rich assemblage of other trilobites, bryozoans, ostracods and rare graptolites. In its type area Jamtland, Sweden, T. biseriata occurs together with Pygodus anserinus and Hustedograptus teretiusculus in the Staltorp Limestone Member of the Anderso Shale Formation, marking the latest Darriwilian. The occurrence in the North Estonian Confacies Belt of Telephina, known as a pelagic trilobite inhabiting deeper-water areas, probably reflects a transgression event at this time. Together with T. biseriata, other trilobite taxa such as Remopleurides and Lonchodomas, common in the Hustedograptus teretiusculus Biozone in deeper-water areas, arrive in the North Estonian Confacies Belt. Graptolites from the other loose boulders at the same locality have been identified as Hustedograptus cf. uplandicus, which occur together with a few dendroids.

Origin of Lower Triassic microbialites in mixed carbonate-siliciclastic successions: Ichnology, applied stratigraphy, and the end-Permian mass extinction

Studies aimed at understanding the recovery from the end-Permian mass extinction have focused on the distribution of faunas, trace fossils, and microbialites across depositional environments, but few have examined how these individual ecologic components relate to one another, especially the latter relationship between microbialites and trace fossils, which appear to be mutually exclusive. Microbialites occur throughout Lower Triassic strata primarily in two different forms depending on the depositional system in which they were preserved in. In carbonate-dominated settings, microbialites can commonly take the form of large stromatolitic patch reefs, while in siliciclastic settings microbialites are found primarily as wrinkle structures. This study focuses on the palaeoenvironmental distribution of microbial structures and trace fossils from an uppermost Lower Triassic deposit, the Virgin Limestone Member of the Triassic Moenkopi Formation, which is comprised of mixed carbonate-siliciclastic sedimentary rocks, and is known to contain both stromatolites and wrinkle structures, in addition to trace fossils.Results show that the highest trace fossil diversities are found in lower shoreface environments, while offshore environments contain the lowest diversity. Strata deposited in the offshore transition, separating lower shoreface and offshore environments, contain moderate diversity trace fossil assemblages. Microbialites, in the form of either stromatolites or wrinkle structures, appear to emerge only following transgression, and are commonly found across and following marine flooding surfaces. Wrinkle structures appear to have formed as low-oxygen waters encroached upon nearshore settings, suppressing bioturbation and allowing for microbial mat development. Stromatolites likely formed due to the upwelling of anoxic alkaline waters during transgression, which may have generated a firm substrate for colonization, as well as fostering cementation of the microbialite. While most studies examining the aftermath of the end-Permian mass extinction focus on either carbonate- or siliciclastic-dominated settings, this study reports the environmental distribution of microbialites in both carbonate and siliciclastic facies, and unites them into a single depositional model that accounts for stratigraphic distribution, relation to trace fossils, and the unique environmental conditions present during the aftermath of the end-Permian mass extinction.

Fusulinids from the Howe Limestone Member (Red Eagle Limestone, Council Grove Group) in Northeastern Kansas and Their Significance to the North American Carboniferous (Pennsylvanian)-Permian Boundary

Fusulinids from the Howe Limestone Member (upper part of the Red Eagle Limestone, lower part of the Council Grove Group) are described here for the first time. The Howe fauna is particularly significant because it represents the earliest fusulinids known to occur above the new conodont-based Carboniferous (Pennsylvanian)-Permian boundary at the Glenrock Limestone Member-Bennett Shale Member contact (Red Eagle Limestone) in northeastern Kansas. The Howe fusulinid assemblage is composed entirely of species of the genus Leptotriticites. The species L. hughesensis and L. glenensis were originally described from just beneath the new systemic boundary horizon in the Hughes Creek Shale Member and Glenrock Limestone Member, respectively. L. wetherensis is a species from the Stockwether Limestone Member of north-central Texas, which is thought to directly overlie the new systemic boundary in that region. L. gracilitatus is a species reported from below and above the boundary in west Texas and New Mexico. Therefore, the Howe Limestone Member fusulinid fauna is quite transitional in character. The first typical and diagnostic early Permian (Wolfcampian Series) fusulinids in the midcontinent section appear in steps through the stratigraphically higher Neva Limestone Member of the Grenola Limestone (Paraschwagerina kansasensis), and the Cottonwood and Morrill Limestone Members of the overlying Beattie Limestone (Schwagerina jewetti, S. vervillei). This offset of conodont and fusulinid faunal changes should be taken into account in regional and interregional biostratigraphic correlations of the new systemic boundary.

Left behind – delayed extinction and a relict trilobite fauna in the Cambrian–Ordovician boundary succession (east Laurentian platform, New York)

AbstractTwo completely dissimilar faunal changes occur between the Sunwaptan and Skullrockian Stages (Ptychaspid and Symphysurid ‘Biomeres’) in the uppermost Cambrian on the east Laurentian craton. An undolomitized section in the Little Falls Formation in Washington County, New York, shows a typical ‘biomere’ extinction, with highest Sunwaptan trilobites followed by the abrupt appearance ofCordylodus proavusZone conodonts and the lowest post-extinction trilobites (ParakoldinioidiaEndo) 5.0 m higher. This stage boundary interval is very condensed by comparison with coeval Great Basin and Texas sections. Approximately 70 km southwest, typical pre-extinction taxa (the catillicephalidAcheilopsUlrich and several dikelocephalid species) are shown for the first time to persist well beyond the extinction as they occur with middleC. proavusZone conodonts (Clavohamulus elongatusor, more likely,Hirsutodontus simplexSubzone). The Ritchie Limestone member of the uppermost Little Falls Formation yields a succession of conodont faunas that spans theC. elongatus–H. simplex–Clavohamulus hintzeiSubzones (middle–upperC. proavusZone). These data prove that the trilobites are a relict fauna that persisted into theSymphysurinaZone of the Skullrockian Stage. The massive (burrow-churned), mollusc-dominated Ritchie Limestone, with the second Upper Cambrian cephalopod locality in east Laurentia, represents an inner-shelf refugium for Sunwaptan trilobites that has not been previously encountered. Final extinction of typical Sunwaptan clades is at least locally diachronous, and a simple, genus-based approach to trilobite biostratigraphy in the Cambrian–Ordovician boundary interval is untenable. The relict fauna appears to be distinct at the species level, so it is likely that a viable, species-based biostratigraphy can be developed.Teridontus gallicusSerpagliet al. 2008 is a synonym ofT. nakamurai(Nogami, 1967), andT.?francisiLanding sp. nov., with a large base and tiny cusp, is a lowerC. proavusZone form. New trilobites areAcheilops olbermanniWestrop sp. nov. andParakoldinioidia maddowaeWestrop sp. nov. The lowest Ordovician ‘Gailor Dolomite’ is a junior synonym of the Tribes Hill Formation, and the Ritchie Limestone is assigned to the top of the terminal Cambrian Little Falls Formation.

Slides, soft-sediment deformations, and mass flows from Proterozoic Lakheri Limestone Formation, Vindhyan Supergroup, central India, and their implications towards basin tectonics

The Neoproterozoic Lakheri Limestone (LL) Member of Vindhyan Supergroup, central India, interpreted as a low-gradient homoclinal ramp, contains a wide range of signatures indicating syn-sedimentary basinal extension and compression. Whereas features like intraformational truncation (slide) surfaces of varying geometry, creep and bedding translation manifest the phases of extension, the compressional events are registered in bed-confined thrusts and outcrop-scale folds. A wide range of outcrop and microscopic deformational features are associated with the sliding events, the expressions of which vary based on their relative position with respect to the slide surface (over- or underlying) and the degree of built-up pore water pressure. The detached sediment mass often evolved in the form of mass flows with rheology varying between cohesive debris flow and low-density turbidity current. In particular, operation of reflected turbiditic flows is suggestive of irregular depositional substrate, induced by curvilinear syn-sedimentary slides in otherwise low-gradient distal shelf platformal setting. The present study intends to relate the observed extensional and compressional features of LL succession with the flexural response of early rifted Vindhyan basement under reversing in-plane stress in its post-rift depositional history. Bipolar NE–SW orientation of the slide planes is well consistent with the proposed rifted configuration of Vindhyan basement. Centimeter- to decimeter-deep slide detachments and equally thick mass-flow beds are indicative of relatively deeper level of necking during the early syn-rift phase of Vindhyan history.

Solar variance recorded in lacustrine deposits from the Devonian and Proterozoic of Scotland

Abstract: Continental lacustrine laminites deposited in low latitudes have been examined from the Devonian and Torridonian (Mesoproterozoic) strata of northern Scotland to investigate the consistency of sunspot periodicity through geological time. The thicknesses of 2448 annual laminae were measured from the Middle Devonian ( c . 388 Ma) Achanarras Limestone Member, Lower Caithness Flagstone Group, and of 2821 laminae from the Mesoproterozoic (1.2 Ga) Poll a'Mhuilt Member of the Stoer Group. Time-series analysis resolved periodicities of 13.8 and 13.9 years in the complete Devonian and Mesoproterozoic datasets respectively. When sedimentological variance was considered and the data were examined as evolutive spectra those sections consisting of the most robust data consistently yielded periodicities between 8.6 and 13.7 years for the Devonian section and 9.2 and 10.6 years for the Mesoproterozoic section. These correspond well to Schwabe cycles. Evidence for the presence of the longer Hale cycles (20 years) was also recognized in the Devonian time series. The sunspot periodicities identified within the Devonian and Mesoproterozoic show little variance from published examples from the Quaternary and Eocene and therefore provide evidence for the consistency of solar processes and solar–atmospheric interactions for the past 1.2 Ga.

Origin of cone-in-cone calcite veins during calcitization of dolomites and their subsequent diagenesis: A case study from the Gogolin Formation (Middle Triassic), SW Poland

Although bedding-parallel cone-in-cone structure calcite veins are present in the Middle Triassic Gogolin Formation in Opole Silesia, their occurrence is limited to the Emilówka Cellular Limestone Member. Marly limestones (dedolomites) consisting of calcite pseudospar are the host rocks. The veins, which are up to 3 mm high and 30 cm long, are built of densely packed cone columns, with individual cones up to 0.7 mm high and 0.6 mm wide at their bases, and with vertex angle values ranging from 30° to 50°. The cones are microfractured, and the adjacent cones are vertically shifted in oblique planes. The exceptionally small veins consist of calcite fibres up to 0.15 mm high. The veins are built of low-magnesium and non-ferroan calcite, characterized by low δ 18O values ranging from − 6.8‰ to − 7.4‰, and low δ 13C values ranging from − 2.9‰ to − 4.5‰ vs. PDB. These isotopic values are similar to those obtained from the host rocks (δ 18O from − 6.8‰ to − 7.4‰, and δ 13C from − 3.2‰ to − 3.6‰ vs. PDB) and they are strongly depleted in comparison with the isotopic values of other carbonate particles from the Gogolin Formation. The veins only formed in one lithostratigraphic member, suggesting that their origin is related to processes which acted only locally. There are two unique processes that the Emilówka Cellular Limestone Member alone in the Gogolin Formation underwent: early diagenetic evaporitic dolomitization of lime mud in the sabkha environment, and subsequent calcitization of dolomite. Dolomitization led to sediment cohesion loss, porosity increase and initial horizontal laminae separation as a result of the transformation of calcium carbonate to dolomite within anisotropic deposits. Similar values of geochemical parameters obtained from the vein calcite and the host rock calcite are evidence that vein-filling precipitation was contemporary with dedolomitization. Geochemical data combined with sedimentological research and burial history show meteoric-derived waters saturated with respect to calcite as a source of the vein calcite. Dedolomitization and vein precipitation may have taken place from the Norian/Early Jurassic to the Late Jurassic when the study area became eroded land, and the Emilówka Cellular Limestone Member may have acted as a local paleoaquifer conducting the meteoric-derived waters. Solid inclusions in the veins, detached from the host rock and the calcitized nodules, show that the force of calcite crystallization was the main factor responsible for vein widening. Vertical shifts of adjacent cones, remnants of primary fibrous calcite crystals, as well as the burial history justify the application of Tarr's theory in interpreting the origin of the secondary cone-in-cone structure within the fibrous structure veins. The timing and the particular conditions required for the cones to develop are uncertain.

Radiolarians from the Lamar Limestone, Guadalupe Mountains, West Texas

Well-preserved radiolarians are described from a road-cut of the upper Lamar Limestone Member of the Bell Canyon Formation along Highway 62/180 in the Delaware basin of West Texas. The upper part of the Lamar Limestone contains early Capitanian (late Guadalupian) conodonts and fusulinaceans and is assigned to the Reichelina lamarensis and the Jinogondolella postserrata zones, respectively. A total of 31 species were recovered from 17 samples in a ~6m section of micritic laminated limestone. Twenty species are reported from this locality for the first time, including 6 new species; Copiellintra ferula, Copiellintra laurelae, Hegleria agnusiforma, Hegleria globosa, Rectotormentum fengi, and Stigmosphaerostylus wildei. Sectioning and transmitted light microscopy of the spongy taxa reveals internal structures and allows for a more natural grouping of genera and species based on aspects of wall structure, rather than external geometry or presumed internal structure. All of the spongy taxa lack an entactinarian spicule and the genera Copicyntra, Copiellintra, Copicyntroides and Hegleria are reassigned to families within the Spumellaria. Lamar radiolarian assemblages show fluctuations in their faunal composition, alternating between albaillellarian-dominated assemblages composed mostly of Follicucullus spp. and spumellarian-dominated assemblages composed largely of spongy taxa of spherical, oblate, to discoidal shape (Copicyntra, Copiellintra, Copicyntroides, Klaengspongus, Tetrapaurinella, and Hegleria). By far the most common radiolarians are spongy spumellarians and albaillellarians, but latentifistularians also occur sporadically in samples, and entactinarians are rare and occur throughout the section. These marked faunal fluctuations are interpreted to be environmentally driven and is the subject of ongoing investigations using geochemical proxies to reveal paleoecological controls.

Three Jinogondolella apparatuses from a single bed of the Bell Canyon Formation in the Apache Mountains, West Texas

Complete apparatuses are described for Jinogondolella aserrata, J. errata (new species), and J. postserrata (transitional from J. aserrata) from a single bed in a section of the Bell Canyon Formation exposed in the Apache Mountains, West Texas. The conodont assemblage precisely equates this bed in age to the upper part of the Pinery Limestone Member of the Bell Canyon Formation and the base of the Capitanian in its type locality in the Guadalupe Mountains. The apparatus of Jinogondolella is different from most other gondolellid genera in that it has dimorphic to polymorphic elements in the S2 position and three pairs of platform elements.

A new skeletal remain of the durophagous shark, Ptychodus mortoni, from the Upper Cretaceous of North America: an indication of gigantic body size

Ptychodus mortoni Mantell is a Late Cretaceous shark that possessed pavement-like tooth plates that were used to feed on hard-shelled macroinvertebrates (durophagy). Here, we describe a new specimen of P. mortoni from the Fort Hays Limestone Member of the Niobrara Chalk in Kansas, USA, that consists of associated teeth, placoid scales, and a portion of the right upper jaw. Although the specimen is fragmentary, this fossil supports the previously proposed contention that P. mortoni was a gigantic animal that likely reached at least 10 m in total body length with an estimated jaw length of nearly 1 m.

Study of Echinoids of Gurpi formation, Iran

AbstractIn order to detailed study of Echinoids, some samples are collected from Brown limestone member of Seimare from Gurpi Formation with 213 meter thickness which located in the vicinity of Ilam province; settling over Ilam Formation continuously. Paleontological results indicated Campanian - maastrichtian age at this section. Detailed analysis of the 300 samples led to recognition of Bivalve especially Bivalve of Lofa, Brachiopods and five species of Echinoids such as: Salenia nutrix, Globator bleicheri, Orthopsis miliarisi, Goniopygus superbus, and Conulus douville