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There are two contrasting opinions on the stratigraphic and palaeogeographic distribution of the relatively rare trace fossil Ophiomorpha irregulaire: 1) the trace is mostly restricted to the Upper Cretaceous of the Western Interior Seaway, or 2) it has a post-Palaeozoic record and a worldwide geographic distribution. In this study we document the finding of O. irregulaire in Upper Cretaceous turbidites of the Alta Vista Formation, southern Patagonia, providing additional evidence on the morphology and composition of its pelletal masses, the ethology of its producer and the palaeogeographical and palaeoenvironmental distribution of the trace fossil. The burrow walls are lined with dark mud and their elongate, spiky pellets are formed by a sand core that is also lined with mud. The association with typical fodinichnia, such as Halopoa, Spirophyton, and Zoophycos and the common presence of O. irregulaire in sediments with abundant plant detritus, suggest that the producer was a deposit feeder. Crosscutting relationships and occurrences at several levels within thick-bedded turbidites, suggest a relatively deep tier emplacement of the trace. The finding of the trace in the Southern Hemisphere supports its envisaged worldwide palaeogeographic distribution

Chalk reservoirs are commonly modelled as dual-porosity systems, in which a very porous but low permeable matrix is intersected by highly permeable vugs and fractures from which oil and gas can be produced. The Gullfaks Field in the Norwegian North Sea contains such a reservoir, which is producing from Maastrichtian chalk in addition to the conventional Triassic and Jurassic siliciclastic reservoirs. However, in comparison to the prolific chalk fields in the southern North Sea (e.g. Ekofisk, Valhall), chalk reservoirs in the northern part (e.g. Oseberg and Gullfaks fields) experience challenged production due to reservoir presence and quality related to depositional facies and structural conditions. Analyses of cores from three wells in the Maastrichtian Shetland Group of the Gullfaks Field reveal that this interval is completely bioturbated during several stages, e.g. mottling with diffuse bioturbated texture in an early softground stage that became subsequently overprinted by more discrete burrows with active and passive fill and different rock properties during the stiffground and firmground stages of the ooze. A rich and moderately diverse trace-fossil assemblage consists of abundant Zoophycos, common Chondrites, Taenidium, Thalassinoides and Virgaichnus, and rare Nereites, Planolites, Spirophyton and Teichichnus. Ichnological features allow the differentiation of five recurrent ichnofabrics (Thalassinoides, Zoophycos, Chondrites, Nereites and Zoophycos-Taenidium ichnofabrics) with variable influence on porosity and permeability. The Thalassinoides ichnofabric in chalk has the highest impact on improving reservoir quality, whereas Zoophycos and partly Chondrites ichnofabrics, in marly chalk and chalky marlstone respectively, contribute to creating potential reservoir zones if burrow density is high enough. Thin-section analysis of the different ichnofabrics illustrates the negative or positive effect of burrows on porosity distribution, whereas microCT imaging reveals an intriguing system of partly open micro-burrows (e.g. Virgaichnus) within the matrix, which serves as source for porosity. This burrow porosity provides a connection in the matrix that hosts open vugs and fractures, thus improving oil production.

Integrative research including facies characterization, ichnological composition and foraminifer analysis has been conducted on cores from Site U1385 of the IODP Expedition 339 to evaluate the incidence of Marine Isotope Stage (MIS) 12 and MIS 11 on deep-sea environmental changes. Four color facies groups have been differentiated, showing variable transitions between them (bioturbated, gradual and sharp contacts). Trace fossil assemblage, assigned to the Zoophycos ichnofacies, consists of light and dark filled structures, with Alcyonidiopsis, Chondrites, Nereites, Planolites, Spirophyton, Thalassinoides, Thalassinoides-like structures, and Zoophycos. A deep-sea multi-tiered trace fossil community is interpreted, revealing predominance of well-oxygenated bottom and pore-waters, as well as abundance of food in the sediment for macrobenthic tracemaker community. Changes in environmental parameters are interpreted to be associated with significant variations in trace fossil distribution according to the differentiated intervals (A to M). Benthic foraminifer concentration in the sediments and variations of the planktonic foraminifer assemblages suggest significant changes in surface productivity and food supply to the sea floor since the ending of MIS 13 to the end of MIS 11 that could be correlated with the registered changes in facies and trace fossil assemblages. At the end of MIS 13 values of annual export productivity were very low, that together with the presence of light-color sediments and the continuous presence of light Planolites and Thalassinoides, reveal lower organic carbon flux to the bottom and high oxygen conditions (interval A). Afterwards the organic matter supply increased rapidly and remained very high until Termination V, determining an eutrophic environment, expressed by high benthic foraminifer accumulation rates, and reduced availability of oxygen, that correlate with the record of Spirophyton and Zoophycos, and the presence of Chondrites, observed in intervals B and D. Lower benthic foraminifer accumulation rates during MIS 11 suggest an oligotrophic environment at the bottom consistent with lower inputs of organic carbon, associated with high oxygen content of bottom waters that agrees with the lighter color of the sediments as well as by the continuous presence of light Planolites and Thalassinoides in the differentiated interval M. The evolution of the macrobenthic tracemaker community during MIS 12 and MIS 11 responds to major changes in bottom water ventilation probably linked to variations in deep water (North Atlantic) thermohaline circulation, determining variations in oxygen and food availability.

Ichnofossils content of Paleocene source rock sediment were examined based on two wells cores from Bintuni Basin, West Papua, Indonesia. The cores are from Paleocene interval of Waripi - Daram Formations and known as the potential source rock sediment interval. This study aims to determine the sea level changes during the depositional of the Waripi - Daram Formations. Representative of 18 ichnogeneras including: Arenicolites, Asterosoma, Chondrites, cryptic bioturbation, Glossifungites, Helminthoida, Nereites, Ophiomorpha rudis, Palaeophycus, Phycosiphon, Planolites, Rosselia, Scolicia, Skolithos, Spirophyton, Teichicnus, Thalassinoides, and Zoophycos. The sea level curve generated from both wells based on ichnofossils association, suggest that there were at least three deepening – shallowing cycles. The cycles generally begins by inner to middle neritic interval that sign by appearance of Ophiomorpha and Chondrites with few Phycosiphon, while the deeper interval of outer neritic, upper bathyal into abyssal usually indicated by Zoophycos, Helminthoida, Nereites, Spirophyton and abundant of Phycosiphon. Sea level curve reconstructions based on the depositional environment suggest that during Paleocene Well-2 was located closer to the land compared to Well-1. Rapid shift in the depositional environment could indicate an initiation of regional uplift in the area caused by a new subduction system to the north of the Basin.

At least four styles of complex behavior are recorded in trace fossils: (1) Intricate, programmed behavior that is recorded in complex trace fossils, such as Spirophyton and Zoophycos. (2) Behavior that is complex in consisting of multiple simple behaviors performed by a single organism, as indicated by one trace fossil merging into another (compound trace fossils). (3) Behavior in which an animal constructs both complex and simple structures, as demonstrated by direct connection between the two structures. (4) Two scales of complex behavior reflected in multiple specimens of one trace fossil arranged in a pattern to produce a distinctive, larger-scale structure. Until recently complex trace fossils (e.g. Zoophycos) alone have served as proxies for complex behavior. Recognition and reconstruction of diverse modes of behavioral complexity allow more biological information to be gleaned from the trace fossil record.

Leperditiid and beyrichiid ostracodes in marine margin deposits of the Devonian Catskill magnafacies of New York State document brackish conditions in what were previously considered freshwater floodplain deposits. The very low diversity ostracode fauna (two species) includes an abundance of anomalously thin-shelled individuals that belong to the genera Leperditia ? and Welleria . This ostracode fauna is one of the oldest reported from brackish water in the stratigraphic record, and it documents the early ecological radiation of ostracodes into waters of reduced salinity. Associated fossils, including the bivalve Archanodon and the conchostracan Euestheria , have been considered to be freshwater forms, partly because of their occurrence in these rocks that were assumed to be fluvial in origin. Nearly everywhere, however, the ostracodes are associated with cosmine-bearing fish fragments, lingulid brachiopods, and the feeding trace Spirophyton , which have a marine or brackish-water affiliation. The presence of open carapaces on bedding planes as well as adults and several instar stages of each ostracode species indicate lack of postmortem transport. At least one ostracode-bearing mudstone contains the mineral amesite; associated calcareous mudrocks interbedded with these units contain symmetrical ripple marks, mudcracks, and locally intense manganese-oxide staining. Collectively, these features indicate extreme environmental conditions and suggest highly variable salinities in shallow pools or embayments along the paleoshoreline. The presence of brackish-water faunas, perhaps estuarine in origin, indicates an aspect of the diversity of Devonian paleoenvironments along this portion of the Catskill deltaic complex not previously recognized. The deposits are widespread, although not ubiquitous, within thick sequences of fine-grained flood-basin deposits. Because most previous paleoecological studies of fossils from these rocks assumed the sediments to be of freshwater origin, the new interpretation of brackish-water communities presented here could have important implications for understanding the evolution of early terrestrial organisms. For example, some animals may have evolved in brackish estuarine environments rather than in freshwater rivers as assumed in previous studies. Recognition of this brackish facies elsewhere in the Catskill succession will not only aid future identification of paleoshoreline position but may also help clarify whether early terrestrial organisms made the transition to land via brackish or freshwater environments.

The aim of this work is to describe and interpret well preserved Lower Carboniferous Zoophycos from Belgium. They are compared to other similar Zoophycos studied by the same authors from Jurassic and Lower Cretaceous from France. Finally, some general conclusions are proposed which are also supported by data from the literature. Lower Carboniferous deposits in the Tournai area (Belgium) are characterized by the abundance of well preserved Zoophycos previously described as Spirophyton. The upper unit of the Tournai Limestones, the Antoing Formation (Ivorian), was studied here. It is usually made of fine-grained carbonate mudstones or wackestones, occasionally passing to packstones. The paleoenvironmental setting is typical of the deep part of a carbonate ramp, with occasional storm deposition. The general organization of Tournaisian Zoophycos is the same as that seen in Jurassic and Lower Cretaceous specimens of southeastern France: a single open tube and a lamina with an upward helicoidal growth. This similar organization suggests a similar ethology for the corresponding tracemaker considered as a deep sediment feeder with an efficient mining program. The more simple morphology of the Tournaisian burrow system suggests that this program is less complex than for the Mesozoic equivalents. Zoophycos is best developed in fine-grained sediments. In opposition to the Jurassic examples of southeastern France, this sediment must have still been soft, never slightly firm, when colonized. In addition, the abundance of Zoophycos at the top of locally frequent storm deposits could indicate a fairly opportunistic behavior. Considering the above mentioned assumption, the increasing complexity of the morphology and the modification of the related ethology, a possible evolution from an r-strategy to a K-strategy is suggested for the Zoophycos-creating organism during geologic time.

Lochkovian redbeds in the Dnester formation in Podolia, Ukraine, record an upward transition from marginal-marine to fluvial conditions. A 60-m-thick section through transitional strata reveals a regressive stack of three facies associations laid down in: offshore lagoon, inshore lagoon or bay, and a fluvial-estuarine plain. The offshore lagoonal association shows green to variegated alternation of fossiliferous, bioturbated limestones, quartz arenites and shales. Numerous coquinas contain schizohaline ostracods, vermiform gastropods, Lingula, charophyte gyrogonites, all mixed with fragments of marine forms such as articulate brachiopods, tabulates, goniatites and leiospheres. Trace fossil assemblages contain abundant Skolithos, Spirophyton, Teichichnus and simple tubular forms. The inshore lagoon or bay association is a largely non-fossiliferous, locally bioturbated, red succession of interbedded mudstones and sandstones, which are arranged in coarsening-up units capped by thin, channelized sandstones. The presence of Lockeia, Monomorphichnus, Rusophycus and Skolithos suggests that the coarsening-up units could have originated as small bayhead deltas and washover fan-channel complexes. A new ichnospecies, Monomorphichnus podolicus, described here, occurs also in these deposits. In the overlying fluvial-estuarine association, the only trace fossil recorded is Skolithos, which occurs in dense clusters along upper levels of cross-bedded ribbon-shaped channel fills. Until now, piperock has been considered as an ichnofabric of the Skolithos ichnofacies that is typical of sandy beaches, bars and spits, whereas the findings presented here expand landwards the environmental range of Skolithos piperocks into more intracoastal marine-influenced settings.

Spirophyton producers inhabiting ephemeral ponds on estuarine floodplains marginal to the (Devonian) Catskill sea covering present-day southern New York were subjected to salinity fluctuations and desiccation, whereas Zoophycos producers living farther offshore were buried by storm deposits. Producers of Zoophycos living in interdistributary bays on Pennsylvanian lower delta plains (Tennessee) contended with fluctuations in salinity and oxygen conditions and variations in sediment grain size and in rate of sedimentation. In each case the producer was an r-selected opportunistic species, as shown by the distribution of the Spirophyton or Zoophycos and the paucity of co-occurring trace fossils. Morphologic analysis indicates that the Paleozoic producers of these Zoophycos and Spirophyton: (1) transported sediment downward from overlying layers or the sediment surface, and (2) were capable of a variety of behavioral patterns, only some of which resulted in complex 3-dimensional structures.

Spiral or planar radiate imprints, described as Zoophycos, Taonurus, Spirophyton, Physophycus, Cancellophycus, and Glossophycus are regarded as fossil prostomia of sedentary marine worms of the Sabellidae. Methods for the study and description of these fossils, consistent with this mode of origin, are described.

The most familiar markings known to the Scottish geologists may be said to be the Spirophyton, Cauda-galli, which is supposed to be the impression of a marine Alga, and which always indicates a position near the Main Limestone and the Hosie. The impressions here exhibited were found very near the same position, and I have found similar impressions on the shores at St. Monans; Kirkcaldy; North Berwick; and Charleston, all occupying practically the same geological position. The rocks at Charleston are well adapted for the preservation of impressions of this kind, composed as the exposure is of layers of mudstone and sandstone alternating. Worms crawling on the mud left the track of their bodies, and the sand coming on top has taken sharp casts of the tracks. Worms that bored through the mud to sand lying below have left well-defined burrows due to the fine parting of mud carried down on their bodies. In these impressions there are represented at least two subkingdoms, the worms and the gasteropods, besides the algae: what the others represent it would be difficult to say. In a paper by Sir J. William Dawson, of Montreal, read to the Geological Society of London, 1890, some impressions are described very similar to those at Charleston, but Dawson’s specimens are Silurian, while mine are Carboniferous. Mr. John Smith, in a privately printed paper in 1909, described in his Upland Fauna of the Carrick Old Red Sandstone many trails and tracks of unknown creatures, and, now that we This 250-word extract was created in the absence of an abstract

IN the Czechoslovak Carpathians I have found imprints, described in the literature from many localities throughout the world as Zoophycos, Taonurus, Spirophyton, etc. The occurrence of these imprints in numerous localities in the Czechoslovak Carpathians is closely related to fine-grained sandstone strata, and sometimes to the marlstones (Cretaceous, Palaeogene). After a detailed investigation I concluded that these imprints were formed by abandoned prostomial parts (gill organs) of sedentary marine worms (Annelida, Polychaeta) from the family Sabellidae1. The imprints are closely similar to the recent genus Spirographis Viviani 1805. As in that genus, the gill rays of the fossil worms are spirally wound around an asymmetrical gill lobe either to the left or to the right side, in the ratio of about 1:1. In sedimentary rocks the gill organs are either perpendicular to the bedding plane or they form flat coinciding accumulations.