Scolicia shirahamensis isp. nov.: a triple-corded scolicia and its ichnological implications

Abstract

Peculiar meniscate burrows with three sediment cords occur in early to middle Miocene tidal-flat deposits of southwestern Japan. Two of the cords are situated at the bottom and the other is at its center. Detailed observations of the burrow structures and comparative neoichnological studies of modern spatangoid burrows in a tidal flat revealed that the former two were true drainage tubes and the latter was fecal in origin. The trace fossil was thus assigned to the ichnogenus Scolicia. Based on these findings, a new ichnospecies Scolicia shirahamensis isp. nov. has been described here. The central sediment cord is seemingly identical to the drainage tube of the ichnogenus Bichordites, another ichnogenus that has been commonly ascribed to a fossil spatangoid burrow, similar to Scolicia. Careless ichnogeneric identification of a spatangoid burrow, based only on the central sediment cord, therefore, may produce an incorrect identification.     

Lunulichnus Tuberosus Ichnogen. and Ichnosp. Nov. from the Early Eocene Wasatch Formation,Fossil Butte National Monument,Wyoming: An Arthropod-Constructed Trace Fossil Associated with Alluvial Firmgrounds

A new trace fossil, Lunulichnus tuberosus, is described from fluvial deposits of the Wasatch Formation (early Eocene) at Fossil Butte National Monument, southwestern Wyoming, USA. L. tuberosus are straight, vertical to obliquely oriented, unlined cylindrical burrows with pronounced crescent-shaped wall sculptings. In situ examples of these trace fossils are most commonly preserved as sand-filled casts emanating from the erosional bases of fluvial channel sandstone bodies into underlying floodplain mudstone/siltstone beds. L. tuberosus is interpreted as the dwelling trace of a stream-dwelling decapod crustacean. Excellent preservation of fine detail, particularly their diagnostic crescent-shaped wall sculptings, support the hypothesis that L. tuberosus were excavated in firm substrata subjacent to fluvial erosional surfaces. As such, they are interpreted as constituents of alluvial Glossifungites trace fossil assemblages.     

Complex behavioural patterns and ethological analysis of the trace fossil Zoophycos: evidence from the Lower Devonian of South China

The trace fossil Zoophycos is abundant in the shallow‐marine deposits (tempestites) of the Lower Devonian (Emsian) Yangmaba Formation in Ganxi of Sichuan, South China. It often occurs as part of complex trace fossils that comprise different integrated elements: scratch traces, simple to complex spreiten structures with marginal tubes (Zoophycos) and vertical tunnels. The complex Zoophycos burrows consist of spreiten with a marginal tube, preserved as convex hyporeliefs on the sole of an erosion surface. The exquisite, complex spreiten are interpreted to have been formed by deposit‐feeding behaviour, where the animal constructed the trace upwards without leaving faeces in the spreiten. The width of the marginal tube in different whorls is almost constant. The scratches are observed on the wall of the marginal tubes. The Zoophycos intergrades with Spongeliomorpha and Chondrites and was later cut by vertical shafts. All these features together indicate that the Zoophycos‐maker might have been a vermiform polychaete instead of a predator such as a decapod crustacean (Spongeliomorpha producer). Based on stratigraphical and ichnological features, the complex trace fossils resulted from the complex activity of different opportunistic organisms (r‐strategist) that quickly occupied and thrived within the quiet, nutrient‐rich environment after storm events.     

Trace fossils in fluvial deposits of the uppermost Stockton Formation (Late Triassic), Newark Basin,New Jersey

Abstract

Fluvial deposits of the uppermost Stockton Formation (Late Triassic), Newark Basin, west-central New Jersey have yielded an assemblage of trace fossils. Dominated by burrows, specimens include Cochlichnus anguineus, Helminthoidichnites tenuis, Planolites beverleyensis, Scoyenia gracilis, Spongeliomorpha carlsbergi, Treptichnus bifurcus, Treptichnus pollardi, plant remains, and an undetermined vertebrate trace fossil. The assemblage belongs to the Scoyenia ichnofacies. On the basis of stratification and primary sedimentary structures, the beds are interpreted as deposits in a meandering stream environment. Larval insects, wormlike forms, and arthropods are probably responsible for most of the animal traces in wet or moist channel, floodplain, and point bar sediments subject to subaerial exposure.     

First Report: Trace Fossil Assemblage Ptychoplasma (P. excelsum,P. vagans), Dendroidichnites (D. irregulare), Ctenopholeus (?C. kutcheri) and Bergaueria (B. hemispherica) in the Cretaceous Rocks of Bagh Formation,Mainland Gujarat,India

Abstract

This report documents the discovery of repichnia trace fossils Ptychoplasma (P. excelsum and P. vagans) and Dendroidichnites (D. irregulare); the fodichnia traces ?Ctenopholeus (?C. kutcheri) and cubichnia traces Bergaueria (B. hemishperica) from silty limestones of the Cretaceous Bagh Formation. These trace fossils have significant implications for the depositional facies and the paleo-environmental interpretations of the Bagh Formation, which have long been debated. Previously identified traces of Protovirgularia were also found in association with the newly discovered trace fossils, indicating the coexistence of both wedge and cleft-foot bivalves. The western area of the mainland Gujarat is known for its abundance and diversity of trace fossils. The trace fossil bearing Cretaceous rocks in the region occur as thin irregular detached patches and linear outcrops. Previous studies documenting trace fossil assemblages from the Bagh Formation characterised them as a combination of dwelling, feeding and locomotion forms, with the stratigraphic unit becoming less fossiliferous westward. Trace fossils in this formation have been studied and described by many workers in the surrounding areas; however, ichnofossils described in this study are new to the Bagh Formation in this area. These trace fossils were observed on recently exposed outcrops along road cuts associated with new road construction from Khasra to Mogra village around Kadipani in Mainland Gujarat.     

Taxonomic reassessment ofBolonia Meunier, 1886 (trace fossil) based on new material from the type area in Boulonnais, northern France

The ichnospeciesBolonia lata Meunier, 1886 is a straight, bilobate trace fossil with a somewhat heart-shaped outline in cross-section. It has previously been reported from various localities mainly from the Jurassic by different authors under various names such asGyrochorte, Scolicia, orProtovirgularia. Because none of these previous determinations fully agrees with the trace fossils’ morphology, the ‘forgotten name’ is reintroduced, and due to a lack of type material a neotype from the type area of Boulonnais, France is proposed. The ichnogenus is currently represented only by one ichnospecies,B. lata Meunier, 1886. Diagnostic criteria ofBolonia and morphologically related trace fossils such asScolicia, Gyrochorte, Bichordites, “Taphrhelminthopsis nelsoni”, andProtovirgularia are discussed, the synonymy ofB. lata is provided and finally a discussion on the possible producer ofBolonia is given.      

Small shelly fossils and trace fossils near the Precambrian-Cambrian boundary in the Yukon Territory, Canada

In the past an ‘explosion’ in diversity and abundance of small shelly fossils and of trace fossils has served to mark the base of the Cambrian. However, no evidence has been presented to prove that the ‘explosions’ of the two groups were synchronous. We describe small shelly fossils and trace fossils from the same phosphatic limestone beds that indicate that the two events were separate in time. The small shelly fossils are Anabarites trisulcatus, Hyolithellus cf. H. isiticus, Microcornus? sp., Protohertzina anabarica, P. unguliformis, P. sp. A, Pseudorthotheca sp. A, Rushtonia? sp. A, four types of tuberculate plates and one type of reticulate plate. These fossils represent a restricted, ‘pre-explosion’ fauna and are assigned to the Anabarites-Circotheca-Protohertzina Assemblage Zone, an uppermost Precambrian zone in the Meishucun Stage, Yunnan Province, China. A point at the top of this zone has received strong international endorsement for future designation as the base of the Cambrian. Associated with the small shelly fossils are the trace fossils Cruziana sp. A, Cruziana? sp. B, Rusophycus sp. A, Palaeophycus rubdark and arthropod scratch marks. If found in isolation, this trace fossil assemblage would be considered as post-Precambrian because it includes large, highly organized arthropod traces that are traditionally accepted as occurring above the trace fossil ‘explosion’. We therefore conclude that the trace fossil ‘explosion’ predates the small shelly fossil ‘explosion’. If the proposed location of the base of the Cambrian in Yunnan is accepted, the small shelly fossil ‘explosion’ concept and its relationship to the boundary would not be greatly modified. The trace fossil ‘explosion’, however, would no longer indicate the base of the Cambrian and the ranges of some trace fossils would be extended into the Precambrian.     

The trace fossil Nummipera eocenica from the Tatra Mountains,Poland: morphology and palaeoenvironmental implications

Jach, R., Machaniec, E. & Uchman, A. 2011: The trace fossil Nummipera eocenica from the Tatra Mountains, Poland: morphology and palaeoenvironmental implications. Lethaia, Vol. 45, pp. 342–355. The tubular trace fossil Nummipera eocenica Hölder 1989 occurs in a single stratigraphical horizon in Eocene nummulitic limestones of the Tatra Mountains, Poland. The wall of N. eocenica is built of Discocyclina and Nummulities (larger foraminifera) tests, very rarely of the Ditrupa (Polychaeta) tube fragments, bivalve shell fragments, echinoid spines and coralline algae. Morphotype are distinguished on the basis of wall composition and structure. Morphotype A is dominated by fusiform Discocyclina tests, which were preferentially selected by the trace makers for construction of a well‐constructed and resistant wall. Morphotype B contains more robust tests of Nummulites, while morphotype C is dominated by saddle‐shaped tests of Discocyclina. Nummipera eocenica was produced during a period of seafloor stabilization caused by a deepening. The succession of the morphotypes B, A reflects diminishing energy and increasing water depth. Probably morphotype C represents even lower energy environment than morphotype A. The trace fossil is interpreted as a domichnion, which wall was constructed for protection. The trace maker can be considered between polychaetes and crustaceans; however, comparisons to the closest recent analogues, the polychaete Diopatra cuprea or alpheid shrimps, are not satisfactory. □Bartonian, burrow, Carpathians, large foraminifera, trace fossils.     

Ophiomorpha irregulaire, Mesozoic trace fossil that is either well understood but rare in outcrop or poorly understood but common in core

The distinctive trace fossil, Ophiomorpha irregulaire, differs from other ichnospecies of Ophiomorpha in the so-called “meander maze” configuration of its horizontal course, and by the possession of unevenly distributed, elongated, tapering wall-lining pellets. The ichnospecies has been described, without doubt, from only two outcrop localities, both Late Cretaceous in age and both lying within the Cretaceous Western Interior Seaway. Only a single, almost convincing example of the trace fossil has been reported elsewhere, in a Lower Jurassic outcrop in Italy. Apart from this last occurrence, the distribution of O. irregulaire in outcrop suggests that the trace fossil has a restricted time span and geographical range. In contrast, O. irregulaire is identified more commonly in cores, and these occurrences show no clear geographical restrictions and are reported in sediments of Jurassic as well as Cretaceous age. Outcrop exposures of Jurassic and Cretaceous sediments have been extensively studied by ichnologists and if the large, eye-catching O. irregulaire were as common as is suggested by core material, then the trace fossil would not have escaped notice in outcrop.Identification of the trace fossil in core is generally made on the basis of two-dimensional, vertical sections. The characteristic meander maze form cannot be seen in this view, and the identification is thus based almost entirely on the special shape of the lining pellets. As is well known, the identification of large trace fossils in the restricted format of core lacks the security of extensively exposed trace fossils in outcrop. The discrepancy between age and geographic distribution of O. irregulaire in outcrop and core suggests that some misidentification is occurring in core analysis.     

The Trace Fossil Paleodictyon within The Cruziana Ichnofacies: First Record from The Devonian in Pennsylvania

Offshore marine deposits of hemipelagic dark-gray shales comprising the Middle Devonian Mahantango Formation have yielded the first evidence of the trace fossil Paleodictyon from Pennsylvania. Paleodictyon occurs in conjunction with a diversity of largely deposit-feeding trace fossils belonging to the Cruziana ichnofacies, and documents another example of a shallower-water occurrence of this ichnofossil in Paleozoic rocks.     

Silurian trace fossils in carbonate turbidites from the Alexander arc of southeastern Alaska

Early to Late Silurian (Llandovery‐Ludlow) body and trace fossils from the Heceta Formation of southeastern Alaska are preserved in the oldest widespread carbonates in the Alexander terrane. These fossils represent the earliest benthos to inhabit diverse shallow and deep subtidal environments in the region and are important indicators of early stages in benthic community development within the evolving Alexander arc. The ichnofossils are particularly significant because they add to a small but growing body of knowledge about trace fossils in deep‐water carbonates of Paleozoic age.

Carbonate turbidites that originated along a deep marine slope within the arc yield a low‐diversity suite of trace fossils consisting of five distinct biogenic forms. Simple burrows (Planolites, two forms), ramifying tunnels (Chondrites), and tiny cylindrical burrows (?Chondrites) represent the feeding activities (fodinichnia) of pre‐turbidite animals that burrowed in the lime mud before the influx of coarser sediment deposited by turbidity currents. These trace fossils are associated locally with cross‐cutting burrows created as domichnia (Palaeophycus). Rarer hypichnial burrows and endichnial traces were created by post‐turbidite animals that fed soon after the deposition of coarse detritus from turbidity flows.

Trace fossils in these deposits reflect much lower diversity levels than in Paleozoic siliciclastic turbidites. This difference may represent unfavorable environmental conditions for infaunas, differential preservation, or significant paleogeographic isolation of the Alexander terrane during the Silurian. Greater utilization of trace fossils in terrane analysis may help to resolve this issue and provide new data for reconstructing the paleogeography of circum‐Pacific terranes.     

Evidence for targeted elasmobranch predation on thalassinidean shrimp in the Miocene Taliao Formation,NE Taiwan

Terrestrial and marine invertebrate organisms both leave records of their activities in the sediment in the form of trace fossils, at least during certain stages of their ontogeny. In contrast, trace fossils produced by vertebrate organisms are scarce, although terrestrial trace fossils provide exclusive insights into the social behaviour of their producers. In the marine realm, vertebrate trace fossils are relatively rare, difficult to identify and problematic to interpret. However, in certain settings, observations on serendipitously preserved and exposed trace fossils can shed light on the predatory behaviour of marine vertebrates. In Miocene outer shelf to nearshore sandstones of the Taliao Formation in NE Taiwan, large numbers of bowl‐shaped trace fossils can be observed. Morphology and size range (diameter typically 10–30 cm, average depth around 10 cm) of these trace fossils agree well with feeding traces of modern stingrays, and the trace fossil Piscichnus waitemata, which has been attributed to bottom feeding rays. Stingrays direct a jet of water from their mouths to excavate a bowl‐shaped pit to expose their prey. In the material filling the excavated bowl, broken pieces of two other common trace fossils, Ophiomorpha and Schaubcylindrichnus, are often found, and in a number of cases, vertical shafts of Ophiomorpha surrounded by dispersed pieces of wall material have been observed. In contrast, surrounding sediment rarely contains this kind of broken pieces of wall material. These observations clearly indicate that stingrays specifically targeted the producers of the trace fossils: thalassinoid crustaceans and worms, respectively. The targeted predation of these relatively deep burrowers furthermore suggests that the rays used their electroreceptive organs to locate the prey; as such, direct targeting of buried prey only based on olfactory senses has been shown to be ineffective in experiments with extant myliobatiform rays.     

Ordovician Bathyal Trace Fossils From Metasiliciclastics in Central Norway and Their Sedimentological and Paleogeographical Implications

Numerous trace fossils are recognized in metasiliciclastic rocks of the Lower-Middle Ordovician Lower Hovin Group, Upper Ordovician Ekne Group and on roofing slates from an unknown locality (probably Ordovician) from the Trondheim region, central Norway. The trace fossil assemblages are dominated by meandering pascichnial forms, i.e., Helminthoidichnites in the Lower Hovin Group and Helminthoidichnites and Nereites in the slates. Protovirgularia, Dictyodora, ?Planolites and ?Palaeophycus are less common. Alcyonidiopsis, ?Trichophycus, Chondrites, cf. Chondrites, Gordia, ?Phycodes, ?Helminthopsis, cf. Naviculichnium, Treptichnus, Saerichnites, Megagrapton and ?Paleodictyon (Squamodictyon) are rare. The trace fossils were collected or observed at 17 different localities and represent assemblages belonging to the Nereites ichnofacies (deep-sea flysch deposits with thinly bedded turbidites). They reflect a distal Nereites subfacies (fan-fringe or basin-plain deposits) transitional to a Nereites/Paleodictyon subfacies (proximal fan facies). The trace fossil assemblages indicate an opportunistic style of colonization related to fluctuations in food supply introduced by turbidity currents.     

Feeding traces of proarticulata—the Vendian metazoa

Three types of low-topography impressions are described from the Late Vendian, which are interpreted as the feeding traces of representatives of the phylum Proarticulata Fedonkin, 1985, which became extinct in the Precambrian. The producers of two types of trace were found. Impressions are usually large and arranged in groups; therefore their correct interpretation only became possible following large-scale excavation work that was carried out for the first time in the Late Vendian deposits of the Arkhangelsk Region in 1996–2001. The single trace (or trace platform) represents a copy of the whole ventral side of the body made by sandstone or only the part of it. Usually trace platforms are arranged in chains and orientated in one distinct direction. In spite of some superficial similarity, the fossils are neither body remains nor traces of post-mortem compression. The hypothesis of trace formation proposed suggests that the feeding strategy of Proarticulata was different from any feeding behavior known in large Phanerozoic animals. All types of imprints are identified as belonging to the genus Epibaion Ivantsov, 2002. It is proposed that the Australian fossil Phyllozoon Jenkins et Gehling, 1978 is also a feeding trace of Proarticulata.     

Trace fossils of the arthropod Camptophyllia from the Westphalian (Carboniferous) rocks of Lancashire, UK and their palaeoenvironmental context

Two arthropod trace fossils are described and analysed from the Carboniferous Lower Westphalian (C. communis and basal A. modiolaris chronozones) coal-bearing strata of Lancashire. The biserial trackway Diplichnites triassicus consists of five overlapping en echelon sets of 7–9 tracks preserved as epichnia and hypichnia in lacustrine siltstones. The trackway suggests subaqueous in-phase walking by a multi-segmented producer with a body length of 35–40 mm, width 17–22 mm, and 7–9 appendages. Curved, clustered, or laterally repeated, hypichnial lobes with transverse striations on the base of ripple cross-laminated sandstone are identified as Rusophycus versans. This trace fossil is interpreted as shallow resting or furrowing burrows of a homopodous arthropod, 30–60 mm long, 15–30 mm wide, and probably the same kind of arthropod as produced D. triassicus.A review of contemporary arthropod body fossils from Lagerstätten in Lancashire favours the onisciform, or Arthropleura like arthropod Camptophyllia as a potential producer of both of these trace fossils in a lacustrine palaeoenvironment.This study integrates the analysis of sediments, trace fossils and body fossils for reconstructing the arthropod biota and ecology in Westphalian lacustrine and crevasse splay fluvial palaeoenvironments.     

Ichnology of deep‐sea fan overbank deposits of the Ganei slates (Eocene,Switzerland)— a classical flysch trace fossil locality studied first by Oswald Heer

Ganei (Switzerland) is a classical locality for trace fossils. At this site, Heer (1877) described a large number of trace fossils, several of which were new taxa. The trace fossils occur in thin‐bedded turbidites in which the basal divisions of the Bouma sequence are typically absent; the turbidites are assigned to the Ganei Slates and are Eocene in age. They are interpreted to have been deposited in an overbank environment within an upper to middle fan area distal to a channel. Two trace‐fossil associations occur: the first (I) is characterized by bulldozing organisms producing biodeformational structures, Scolica, and Nereites irregularis; the second (II) association shows a distinct tiering pattern with near‐surface graphoglyptids and a mixed layer with simple tubes such as cf. Palaeophycus and Planolites, plus patterned tubes such as Nereites cirrinalis, and Chondrites. Deeper turbidite layers were colonized by Chondrites and Gyro‐phyllites. All trace fossils show a normal size spectrum compared to previously studied trace‐fossil associations, so the degree of oxygenation probably did not influence the composition of either trace‐fossil association. Seafloor sediment was probably soft and did not affect the trace‐fossil associations. Sedimentation rate and event frequency did not change and are estimated to have been in a range of 5–10 cm/1000 years and 2–5 events per 1000 years, respectively. The composition of trace‐fossil associations I and II is therefore interpreted to have been controlled by the benthic food content being higher for trace‐fossil association I than for II.     

Bivalve Wood Borings of the Ichnogenus Teredolites Leymerie from the Bohemian Cretaceous Basin (Upper Cretaceous,Czech Republic)

Finds of fossil wood with bivalve wood borings (Teredolites clavatus and T. longissimus) occur in various facies and presumed sedimentary settings of the platform, shallow-marine Bohemian Crectaceous Basin. The basin comprises areas with sandy-dominated sediments, with marl and clay-dominated sediments, areas with predominat sandy-marly rocks, and finally areas dominated by calcareous nearshore sediments. Teredolites clavatus is common in fossil wood of sandstones, originating in beach or deltaic settings; marl and clay-dominated rock frequently bear wood fragments densely bored by Teredolites longissimus. When accompanied by evidence of marine environments as body fossils, glauconite or typical trace fossils, most of the wood fragments are bored. The presence/absence of borings in wood fragments can be considered the most reliable and easily useable criterion of distinction of marine settings in sandy sediments of the margin of the Bohemian Cretaceous Basin.     

The Ichnofossils of the Triassic Hope Bay Formation,Trinity Peninsula Group,Antarctic Peninsula

The Triassic Hope Bay Formation (Trinity Peninsula Group) includes a diverse ichnocoenosis in the Puerto Moro succession (Hope Bay, Antarctic Peninsula). The Hope Bay Formation is a thick turbidite succession with a minimum vertical exposure of 533 meters along the Hope Bay coast. The rocks are locally affected by contact metamorphism related to later arc magmatism. The ichnofossils are found mainly in thick- and thin-bedded sandstone-mudstone facies composed of a monotonous repetition of sandstone-mudstone cycles. The sandstones are usually medium grained, massive or parallel laminated; the mudstones are massive and rarely laminated. In the fine-grained rocks, mainly the mudstones, there are distinct densities of bioturbation, and at least six patterns were observed. The following ichnogenera were recognized: Arenicolites Salter 1857, Lophoctenium Richter 1850, Taenidium Heer 1877, Palaeophycus Hall 1847, Phycosiphon von Fischer-Ooster 1858 and Rhizocorallium Zenker 1836. All appear to be feeding-traces. The trace fossil assemblages occur mainly in black mudstones rich in organic material that suggest a low oxygen environment. The stratigraphic interval in which they occur is interpreted as progradational supra-fan lobes with channel fill and levee deposits. The thin-bedded turbidite and mudstone lithofacies, where the ichnofossils are abundant, is interpreted as a distal fan turbidite or levee deposit related to a long-term channel fill. This study is the first significant report of trace fossils in the Hope Bay Formation.     

Ecological innovations in the Cambrian and the origins of the crown group phyla

Simulation studies of the early origins of the modern phyla in the fossil record, and the rapid diversification that led to them, show that these are inevitable outcomes of rapid and long-lasting radiations. Recent advances in Cambrian stratigraphy have revealed a more precise picture of the early bilaterian radiation taking place during the earliest Terreneuvian Series, although several ambiguities remain. The early period is dominated by various tubes and a moderately diverse trace fossil record, with the classical ‘Tommotian’ small shelly biota beginning to appear some millions of years after the base of the Cambrian at ca 541 Ma. The body fossil record of the earliest period contains a few representatives of known groups, but most of the record is of uncertain affinity. Early trace fossils can be assigned to ecdysozoans, but deuterostome and even spiralian trace and body fossils are less clearly represented. One way of explaining the relative lack of clear spiralian fossils until about 536 Ma is to assign the various lowest Cambrian tubes to various stem-group lophotrochozoans, with the implication that the groundplan of the lophotrochozoans included a U-shaped gut and a sessile habit. The implication of this view would be that the vagrant lifestyle of annelids, nemerteans and molluscs would be independently derived from such a sessile ancestor, with potentially important implications for the homology of their sensory and nervous systems.