First Mesozoic Scutigeromorph Centipede, from the Lower Cretaceous of Brazil

The first Mesozoic scutigeromorph centipede (Myriapoda: Chilopoda), Fulmenocursor tenax gen. et sp. nov., is described from the Lower Cretaceous (Aptian) Crato Formation of north-east Brazil. Previously described fossil Scutigeromorpha are known from Dominican and Baltic amber, the Carboniferous (Westphalian D) Francis Creek Shale of Mazon Creek, Illinois, the Silurian and Devonian of Britain, and the Devonian of New York State.     

Extinctions and migrations of Devonian rugose corals in the Eastern Americas Realm

Oliver, W. A., Jr. 1990 04 15: Extinctions and migrations of Devonian rugose corals in The Eastern Americas Realm. Lethaia , Vol. 23 , pp. 167–178. Oslo. ISSN 0024–1164.
Detailed plotting of the stratigraphic ranges of Devonian rugose coral genera within the Eastern Americas Realm reveals new information about the extinctions and migrations of this largely endemic fauna. There were significant faunal turnovers in the Lochkovian, middle Eifelian and late Givetian. as well as in the often discussed late Frasnian. The late Givetian turnover was nearly as great as the Frasnian one. Inward migration was principally from western North America, and the greatest influxes were during the carly Givetian and Frasnian. It seems likely that there were several separate incursions and that some genera were introduced to the east two, or even three times.     

A quantitative paleoecological approach to high-resolution cyclic and event stratigraphy: the Upper Ordovician Miamitown Shale in the type Cincinnatian

Stratigraphic cycles form an underlying high-resolution chronostratigraphic structure for much of the sedimentary record. However, before their chronostratigraphic utility can be realized they must be reliably correlated. A new integrated cyclic, quantitative lithologic and faunal method of correlating meter-scale cycles has been developed for a 12 m interval of the Miami-town Shale in the Upper Ordovician of the Cincinnati, Ohio area. First, using lithologic criteria alone, six flooding-surface-bound (shale-on-limestone) shoaling-upward (shale-to-limestone) cycles were delineated and correlated between seven outcrop sections within a 30 km radius; many correlations were ambiguous. Unusual fossil occurrences constrain correlations of cycles 3 and 4, and the limited presence of a dalmanellid, Heterorthina fairmountensis , shows that the flooding surface above cycle 3 lies 10 cm below the lithologic limestone-shale contact. Cluster analysis of faunal abundance data constrained correlations between all cycles and showed a major transition at the top of cycle 2, again below the lithologic limestone-shale contact. Finally, faunal depth gradient fluctuations interpreted from ordination of faunal abundance data confirmed and clarified the nature of cycle correlations; the major transition at the top of cycle 2 is a transgressive surface, and the middle part of cycle 3 includes the interval of maximum water depth. These features delineate a larger, 10-m-scale, cyclicity. The smaller, meter-scale cycles, interpreted as averaging 40–100 ka in duration, demonstrate the potential of a ten-to twenty-fold increase in the resolution of the type Cincinnatian stratigraphic record. Ecostratigraphy, faunal cyclicity, cyclic stratigraphy, event stratigraphy epiboles, benthic paleoecology, Upper Ordovician, Maysvillian, Caradocian, Ashgillian, Cincinnati.     

Shape analysis of two sympatric coral species: Implications for taxonomy and evolution

Fourier shape analysis of Pleurodictyum americanum and P. dividua , favositid tabulate corals, from the Middle Devonian Hamilton Group of New York State, indicates that colony growth form is variable within species between environments, but that the range of variability in growth form is static through time. Pleurpdictyum dividua displays a columnar morphotype; however, P. dividua and P. americanum cannot be discriminated from one another based on colony shape alone. A major prediction of the punctuated equilibrium model of evolution is morphological stasis throughout the duration of a species. Harmonic means of assemblages of P. americanum show no persistent temporal trends. The range of harmonic means present among the oldest assemblages (Centerfield Limestone) are comparable to those among the youngest assemblages (Windom Shale) and to those in the intervening intervals. Character stasis in colony growth form lasted throughout a 2.5-3.5 my interval. In tabulate corals, where reproductive modes such as fragmentation have not been demonstrated, growth form may be useful in interpreting ancient environments. In addition, the tempo of evolution of growth form can be analyzed when sufficient morphological data are available from a wide distribution of environments. Thus, Fourier shape analysis of growth form provides a powerful tool for paleontologists to interpret the ecology and evolution of colonial marine animals.     

Platinum group element enrichments and possible chondritic Ru:Ir across the Frasnian-Famennian boundary, western New York State

The Frasnian-Famennian boundary is recognized as the culmination of a global mass extinction in the Late Devonian. In western New York State the boundary is a distinct horizon within a pyritic black shale bed of the upper Hanover Shale defined by the first occurrence of Palmatolepis triangularis in the absence of Frasnian conodonts. The boundary is characterized by a minor disconformity marked by a lag concentration of conodonts. Iridium at the boundary is 0.11-0.24 ng/g, two to five times background levels of <0.05 ng/g; other Ir enrichments of 0.38 ng/g and 0.49 ng/g occur within 50 cm of the conodont-constrained boundary. Numerous Ir enrichments in the boundary interval suggest extraterrestrial accretion and platinum group element (PGE) concentration at disconformities, or mobilization and concentration in organic-rich/pyritic-rich laminations from cosmic or terrestrial sources. PGE ratios of Pt/Pd and Ku/Ir at the boundary horizon approximate chondritic ratios and are suggestive of an unaltered extraterrestrial source. These values do not conclusively establish a single extraterrestrial impact as the ultimate cause of the Frasnian-Famennian mass extinction, especially given the presence of similar Ir enrichments elsewhere in the section and the absence at the boundary of microtektites and shocked mineral grains.     

Fossil-Lagerstätten,palaeoecology and preservation of invertebrates and vertebrates from the Devonian in the eastern Anti-Atlas,Morocco

In some Devonian strata in the eastern Anti-Atlas, fossil invertebrates are abundant, display a high taxonomic diversity and indicate many shifts in palaeoecology. This is reflected in changes in faunal composition of invertebrates and vertebrates. Fossils of jawed vertebrates of late Lochkovian and younger age have been recorded and are relatively common with their abundance and diversity increasing towards the Late Devonian. Environmental changes in the Devonian also left their mark in the preservation of vertebrates and invertebrates from the Anti-Atlas, which varies strongly through time and regionally. This variation partially reflects environmental changes linked with the evolution of small marine basins during the disintegration of the continental shelf of Gondwana in this region, fluctuations of the regional sea level and other environmental changes. To improve our understanding of these ecological changes, of shifts in preservation through the succession and of the formation of Fossil-Lagerstätten, we analysed the mineral composition of some invertebrate and vertebrate samples of Devonian and Early Carboniferous age by Raman spectroscopy and X-ray diffraction. Additionally, we characterized some of these Fossil-Lagerstätten using palaeontological and sedimentological parameters. We examined eight Devonian Konzentrat-Lagerstätten and two Konservat-Lagerstätten with soft-tissue preservation (the Famennian Thylacocephalan Layer and the Hangenberg Black Shale of the southern Maïder). The last two are the first Konservat-Lagerstätten described from the Devonian of North Africa. The taphonomic and oceanic settings suggest that these Konservat-Lagerstätten are formed because of stagnation (related to vertical restriction of water exchange and water depth rather than limited spatial water exchange and a lateral restriction) in the relatively small Maïder Basin with limited water exchange with the neighbouring Tafilalt Basin. The temporally low oxygen levels in the Maïder Basin are a possible reason for the reduced chondrichthyan diversity (missing demersal and shallow water species) compared to the Tafilalt Platform.     

A stable and productive marine microbial community was sustained through the end‐Devonian Hangenberg Crisis within the Cleveland Shale of the Appalachian Basin,United States

The end‐Devonian Hangenberg Crisis constituted one of the greatest ecological and environmental perturbations of the Paleozoic Era. To date, however, it has been difficult to precisely constrain the occurrence of the Hangenberg Crisis in the Appalachian Basin of the United States and thus to directly assess the effects of this crisis on marine microbial communities and paleoenvironmental conditions. Here, we integrate organic and inorganic chemostratigraphic records compiled from two discrete outcrop locations to characterize the onset and paleoenvironmental transitions associated with the Hangenberg Crisis within the Cleveland Shale member of the Ohio Shale. The upper Cleveland Shale records both positive carbon (δ¹³C_org) and nitrogen (δ¹⁵N_total) isotopic excursions, and replenished trace metal inventories with links to eustatic rise. These dual but apparently temporally offset isotope excursions may be useful for stratigraphic correlation with other productive end‐Devonian epeiric marine locations. Deposition of the black shale succession occurred locally beneath a redox‐stratified water column with euxinic zones, with signs of strengthening denitrification during the Hangenberg Crisis interval, but with an otherwise stable and algal‐rich marine microbial community structure sustained in the surface mixed layer as ascertained by lipid biomarker assemblages. Discernible trace fossil signals in some horizons suggest, however, that bioturbation and seafloor oxygenation occurred episodically throughout this succession and highlight that geochemical proxies often fail to capture these rapid and sporadic redox fluctuations in ancient black shales. The paleoenvironmental conditions, source biota, and accumulations of black shale are consistent with expressions of the Hangenberg Crisis globally, suggesting this event is likely captured within the uppermost strata of the Cleveland Shale in North America.     

A POST‐SCRIPT TO THE ENIGMATIC PROTONYMPHA (DEVONIAN; NEW YORK): IS IT AN ARM OF THE ECHINODERMS?

Abstract:  A unique specimen of the supposed arm of the Middle Devonian (Givetian) starfish Foliaster transversus Blake, 1994[ Journal of Palaeontology , 68, 123–134] is shown to be closely comparable to the enigmatic organism Protonympha salicifolia , also of Devonian age, albeit slightly younger (Frasnian), and also from New York State. Similarities to starfish, or any other echinoderm, appear to be superficial. Differences from the type species of Protonympha are minor, but include the detailed structure of the transverse segments. For this reason a specific distinction is retained, and the taxon Protonympha transversa (Blake, 1994) now proposed. Enigmatic fossils such as Protonympha raised related questions of evolutionary affinity and the problems of pattern recognition. These questions may also touch on the interpretation of organic structures, such as might be returned from Mars (or further afield).     

Lipid biomarkers recording marine microbial community structure changes through the Frasnian-Famennian mass extinction event

Studying the response and recovery of marine microbial communities during mass extinction events provides an evolutionary window through which to understand the adaptation and resilience of the marine ecosystem in the face of significant environmental disturbances. The goal of this study is to reconstruct changes in the marine microbial community structure through the Late Devonian Frasnian-Famennian (F-F) transition. We performed a multiproxy investigation on a drill core of the Upper Devonian New Albany Shale from the Illinois Basin (western Kentucky, USA). Aryl isoprenoids show green sulfur bacteria expansion and associated photic zone euxinia (PZE) enhancement during the F-F interval. These changes can be attributed to augmented terrigenous influxes, as recorded collectively by the long-chain/short-chain normal alkane ratio, carbon preference index, C₃₀ moretane/C₃₀ hopane, and diahopane index. Hopane/sterane ratios reveal a more pronounced dominance of eukaryotic over prokaryotic production during the mass extinction interval. Sterane distributions indicate that the microalgal community was primarily composed of green algae clades, and their dominance became more pronounced during the F-F interval and continued to rise in the subsequent periods. The 2α-methylhopane index values do not show an evident shift during the mass extinction interval, whereas the 3β-methylhopane index values record a greater abundance of methanotrophic bacteria during the extinction interval, suggesting enhanced methane cycling due to intensified oxygen depletion. Overall, the Illinois Basin during the F-F extinction experienced heightened algal productivity due to intensified terrigenous influxes, exhibiting similarities to contemporary coastal oceans that are currently undergoing globalized cultural eutrophication. The observed microbial community shifts associated with the F-F environmental disturbances were largely restricted to the extinction interval, which suggests a relatively stable, resilient marine microbial ecosystem during the Late Devonian.     

Environmental distribution of colony growth form in the favositid Pleurodictyum americanum

Pandolfi, John M. & Burke, Collette D. 1989 01 15: Environmental distribution of colony growth form in the favositid Pleurodictyum americanum. Lethaia , Vol. 22, pp. 69–84. Oslo. ISSN 0024–1164.
Colony growth form is of fundamental importance to understanding the ecology of both modern and ancient marine sessile colonial animals. Fourier shape analysis of the coral Pleurodictyun americantum (Tabulata: Favositida) from the Middle Devonian Hamilton Group of New York State, indicates that colony growth form is variable between environments. Discriminate function analysis of harmonics 2–6 of 51 assemblages of Pleurodictyum americanum (N = 1900) shows that this species displays an onshore to offshore gradient in colony shape. Offshore environments characterized by low levels of turbidity, oxygen, and light contain more flattened, less hemispherical growth forms, whereas onshore environments characterized by high levels of turbidity, oxygen, and light contain more hemispherical, less flattened growth forms. Harmonic shape analysis detected subtle differences among samples of P. americanum from different environments, but also showed that distinctive morphotypes are distributed within horizons. as well as between them. In fact, no one-to-one correspondence in growth form to environment is apparent; growth forms are distributed within environments, suggesting that genetic factors may have had a greater influence over coral growth form than environment. In tabulate corals, patterns of within species variability must be determined before growth form may be useful in interpreting ancient environments. □ Tabulate coral, Fourier shape analysis, morphological variability, growth form, Devonian, Hamilton Group, New York .     

STENOKOLEOS BIFIDUS SP. N. IN THE UPPER DEVONIAN OF NEW YORK STATE

Stenokoleos is a genus for petrified axes from the Mississippian New Albany Shale to which an Upper Devonian occurrence in New York is added. Two orders of branching were known and the plant was thought to be related to coenopterid ferns. The new petrified axes from New York reveal three orders of branching. A pair of rachides emerges from one side of the stem at each node. Their position alternates at successive nodes (distichous). Each rachis bears alternately arranged pinnae. The shape of the xylem strand and the number of protoxylem areas are variable. Traces to the pairs of rachides arise either as two separate strands or as a single strand that is presumed to divide while still within the cortex of the stem. Traces to pinnae are ellipsoid or clepsydroid. Tracheids are scalariform and uni- or biseriate, circular-bordered pitted. Peripheral loops are present in all orders of branches. Protoxylem strands are numerous and maturation is mesarch. Cortex is parenchymatous where it is preserved but outer cortex is missing. Stenokoleos and Reimanniopsis are placed in a new family, Stenokoleaceae. This is classified as Incertae Sedis among Pterophytina in Tracheophyta. It is suggested that the plant is related more closely to the Mississippian pteridosperms Tristichia and Tetrastichia than to the coenopterid ferns.     

Fluctuations in a late devonian-early Mississippian phytoplankton flora of Ohio,U.S.A

Fossil diversity and abundance fluctuations of Late Devonian (Famennian)—Early Mississippian (Tournaisian) phytoplankton assemblages were determined in a stratigraphic sequence of samples in Barberton test core 3, from northeast Ohio. Both diversity and abundance were relatively high during deposition of the lower Chagrin Shale (Upper Devonian) and both decreased during deposition of the upper Chagrin Shale. The overlying Cleveland Shale (Upper Devonian) is characterized by sharply increased abundance with a corresponding (although less marked) increase in diversity; in contrast, both abundance and diversity were at relatively low levels during deposition of the Lower Mississippian Bedford Shale, the uppermost unit of the sequence. These trends agree with the phytoplankton periodicity model presented by Tappan, which indicates large-scale extinction at the end of the Devonian.Many of the acritarch and prasinophycean algal taxa have restricted stratigraphic occurrences within the section studied, making them useful for local and perhaps worldwide correlation. The stratigraphically restricted taxa provide a basis for the proposal of five biostratigraphic zones within the Upper Famennian (Upper Devonian) and a portion of the Lower Mississippian. In ascending order occur: the Gorgonisphaeridium ohioense Assemblage Zone, the Acriora petala Assemblage Zone, the Muraticavea enteichia Range Zone, the Cymatiosphaera labyrinthica Range Zone, and the Navifusa drosera Assemblage Zone.     

Quantitative conodont-based approaches for correlation of the Late Devonian Kellwasser anoxic events

We present the trends of absolute conodont abundance, relative genera abundance, and conodont morphometrics across the Late Devonian Kellwasser horizons at three northern Gondwanan epicontinental seaway locations.

At three contrasting depositional settings, the Kellwasser events are characterized by a decrease in conodont abundance, high percentage of the conodont genus Icriodus and morphological change of the conodont genus Palmatolepis. These changes can be identified in sections where the events are expressed as interbedded anoxic and oxic deposits as well as in settings characterized by continuous anoxic sediment accumulation. Hence, these changes are interpreted as global and synchronous and can be thus used for event correlation.

The paradox of these results is that despite quite similar isotopic signals, faunal change during the Lower Kellwasser event was less than during the Upper Kellwasser event. We interpret that this discrepancy is due to an unconformity (including topmost Frasnian to earliest Famennian) at several F/F sections which removed the record of peak paleoenvironmental change.     

Early Ordovician bathyurid province lithofacies, biofacies, and correlations -their relationship to a proto-Atlantic Ocean

The Early Ordovician bathyurid faunal province includes North America, Greenland, Spitsbergen, Scotland, and western Ireland and Norway. Dominant provincial lithofacies and biofacies include a Dolomite Suite with molluscan-stromatolite fossil content rimmed by Limestone Belts with dominantly trilobite-brachiopod faunas on a platform. Shale Belt rocks bearing graptolites, deposited on the platform slopes, rim the Limestone Belts. Volcanic rock-rich terrain partly borders the Shale Belts. Correlation between the lithofacies indicates that change from an expansion to contraction phase of a proto-Atlantic coincided with uplift of the carbonate platform and with tectonic activity in the Atlantic volcanic rock rich terrain. Brachiopods replaced trilobites as dominant faunal elements in more shallow platform waters at the same time. High trilobite diversity remained in deeper waters near platform margins. The changes took place in Earliest Mohawk-ian (Latest Arenig-Earliest Llanvirn).     

The ichnogenus Tremichnus in the Lower Silurian of western New York

Discovery of Tremichnus cysticus Brett on a crinoid pluricolumnal from the Willowvale Shale of western New York extends the range of this ichnogenus into the Lower Silurian. Pits attributable to Tremichnus apparently represent embedment sites of parasites or commensalistic, filter-feeding organisms of unknown affinities. Embedment of T. cysticus may have been accomplished by localized inhibition of stereom growth within the pits aided by secretion of substances that stimulated accretion of stereom by the host pelmatozoan in areas immediately surrounding the pits.     

SVALBARDIA BANKSII SP. NOV. FROM THE UPPER DEVONIAN (FRASNIAN) OF NEW YORK STATE

Svalbardia banksii sp. nov., is described from the Upper Devonian (Frasnian) Fish Cabin Creek locality near Pond Eddy, New York. The compression consists of ultimate branches bearing spirally arranged, unwebbed leaves. The unwebbed leaves are up to 3.2 cm long, are somewhat flexuous, and dichotomize in more than one plane. The new species is similar to the reconstruction of Actinoxylon banksii from the Middle Devonian (Givetian) of New York and strengthens the supposed relationship between Svalbardia polymorpha and Actinopodium nathorstii from Mimerdalen, Spitzbergen.     

Host-specific pit-forming epizoans on Silurian crinoids

Brett, Carlton E. 197807 15: Host-specific pit-forming epizoans on Silurian crinoids. Lethaia , Vol. 11. pp. 217–232. Oslo. ISSN 0024–1164.
Circular-parabolic pits occur commonly on the endoskeletal remains of certain Paleozoic crinoids. Detailed study of several hundred specimens, representing about 30 pelmatozoan species from the Upper Silurian Rochester Shale of New York and Ontario, reveals that such pits occur exclusively in seven species of crinoids. Furthermore, there are consistent differences in the morphology and orientation of holes occurring on the different crinoid species. This suggests that distinct epizoan species settled selectively on given hosts. The relationship between the hole-producing epizoans and crinoid hosts is inferred to have been a form of dependent commensalism. Preliminary surveys of other Paleozoic crinoid assemblages reveal similar host-selectivity by pit-producing epizoans. Crinoidepizoan pairs apparently co-evolved through considerable spans of geologic time as related genera and species of different ages, from Silurian to Pennsylvanian, exhibit similar pits.     

A new,high‐precision CA‐ID‐TIMS date for the ‘Kalkberg’ K‐bentonite (Judds Falls Bentonite)

The numerical calibration of the base of the Devonian is poorly constrained due to several factors. Few precise radioisotopic age determinations are available from the late Silurian and Early Devonian, and the limited published data carry large error bars from older analytical methodologies. Volcanic ashfalls suitable for dating occur in the Lower Devonian of the Appalachian Basin, but have not been precisely correlated into the global chronostratigraphical scheme because of limited bio‐ and lithostratigraphical information. Here, we report a new U‐Pb zircon radioisotopic age determination of 417.61 ± 0.12(0.23)[0.50] Ma and improved chronostratigraphical context, including revised biostratigraphy, for an ash bed in the New Scotland Formation, Helderberg Group, from the Lochkovian Stage that was previously identified as the Kalkberg K‐bentonite. This new information helps to integrate the classic New York Appalachian Basin succession into global Siluro‐Devonian stratigraphy, refine the calibration of the Silurian–Devonian boundary and more precisely estimate the duration of both time periods.     

Submarine erosion on a gentle paleoslope: a study of two discontinuities in the New York Devonian

Two diastems in the King Ferry Shale Member (Ludlowville Formation) are the result of local submarine erosion. These discontinuities, traceable from the Cayuga Valley to Seneca Lake, are marked by bioencrusted hiatus-concretions, and both diastems display westward erosional overstep of underlying beds. Hiatus-concretions show complex sequential histories of in situ formation, exhumation, and biodegradation. Activity of bottom organisms influenced erosion; substrate modification by infauna acted to trigger or accelerate sediment loss in a low energy setting. Both diasterns are developed along a depth related paleoenvironmental gradient; submarine erosion in this area is controlled, in part, by the presence of a gentle northwest dipping paleoslope. Juxtaposition of three conditions: bioturbation of surface muds, episodic wave or current impingement on these muds, and substrate inclination resulted in local sea floor erosion through a process of downslope sediment transport and dispersion. King Ferry diastems are termed stratomictic . Stratomictic discontinuities are erosional breaks which lack discrete hiatal surfaces due to vertical sediment mixing by infauna. They include several other examples from the New York Devonian and probably have analogs in numerous sedimentary sequences world-wide.