Names for trace fossils: a uniform approach

The taxonomic treatment of trace fossils needs a uniform approach, independent of the ethologic groups concerned. To this aim, trace fossils are rigorously defined with regard to biological taxa and physical sedimentary structures. Potential ichnotaxobases are evaluated, with morphology resulting as the most important criterion. For trace fossils related to bioerosion and herbivory, substrate plays a key role, as well as composition for coprolites. Size, producer, age, facies and preservation are rejected as ichnotaxobases. Separate names for undertracks and other poorly preserved material should gradually be replaced by ichnotaxa based on well-preserved specimens. Recent traces may be identified using established trace fossil taxa but new names can only be based on fossil material, even if the distinction between recent and fossil may frequently remain arbitrary. It is stressed that ichnotaxa must not be incorporated into biological taxa in systematics. Composite trace fossil structures (complex structures made by the combined activity of two or more species) have no ichnotaxonomic standing but compound traces (complex structures made by one individual tracemaker) may be named separately under certain provisions. The following emendations are proposed to the International Code of Zoological Nomenclature: The term 'work of an animal' should be deleted from the code, and ichnotaxa should be based solely on trace fossils as defined herein.     

A trace fossil assemblage from fluvial Old Red deposits (Wood Bay Formation; Lower to Middle Devonian) of NW-Spitsbergen, Svalbard

From the fluvial Old Red Sandstone (ORS) of the Lower to Middle Devonian Wood Bay Formation (NW-Spitsbergen), a diverse trace fossil assemblage, including two new ichnotaxa, is described: Svalbardichnus trilobus igen. n., isp. n. is interpreted as the three-lobed resting trace of an early phyllocarid crustacean (Rhinocarididae). Cruziana polaris isp. n. yields morphological details that point towards a trilobite origin. This occurence of presumably marine trace makers in a fluvial red bed sequence raises the question of whether we are dealing with marine ingressions that are not sedimentologically expressed, with homeomorphy, or with an adaptation of marine groups to non-marine environments.     

Intrastratal trace fossil zonation,Cretaceous flysch of northern California

Dissection of fine‐grained turbidites within the Franciscan complex at Trinidad Harbor reveals intrastratal zonation of biogenic structures. The pre‐depositional association comprises only three ichnotaxa (preserved in convex hyporelief) and is less diverse than the tiered post‐depositional association (comprised by at least seven ichnotaxa preserved in full relief). The latter association is dominated by Melatercichnus (n. ichnogen.). Post‐depositional trace‐makers exploited abundant plant detritus deposited with the turbidite sand. Temporal alternation of trace fossil associations resulted from the infrequent, but catastrophic, disturbance of pre‐turbidite communities and local replacement by assemblies of opportunistic organisms. Although probably short‐lived at specific sites, the post‐turbidite infauna was tiered, enabling a variety of deposit feeders to harvest phytodetritus of varied size or density simultaneously at different depths within newly deposited turbidite sand layers.     

Reappraisal of Schaubcylindrichnus: A probable dwelling/feeding structure of a solitary funnel feeder

The ichnogenus Schaubcylindrichnus has been considered as a cluster of multiple J-shaped tubes, all of which show congruency. Based on such a reconstruction, the trace fossil has commonly been regarded as dwelling tubes of gregarious, head-down deposit-feeding animals.

Well-preserved specimens of Schaubcylindrichnus are found in Miocene and Pleistocene strata of Japan. The trace fossil consists of a bundle of closely spaced, thickly lined tubes, each of which shows a gentle bow-like bend curving downward in a vertical to oblique plane. As individual tubes in a single bundle frequently show size-gradation of diameter, branching and/or cross-cutting, it is probable that the bundle was formed through successive burrowing by a solitary producer. In a longitudinal section of well-preserved specimens, a funnel-like, sediment-filled structure, which is attached to an upper end of a limb of the bow-shaped bundle, is observed. At the other end of the limb, there is a mound-like structure of sediment that is piled up from the bedding surface. The trace fossil was probably a burrow system of a solitary funnel-feeding animal, like an enteropneust.

According to comparisons with type specimens of the ichnospecies of Schaubcylindrichnus, namely, topotypes of Schaubcylindrichnus coronus and holotype and paratypes of S. freyi, S. freyi can be regarded as a junior synonym of S. coronus. As the topotype specimens of S. coronus have many common features with the traces in Japan, the latter should be included in the former. S. coronus therefore is concluded as the burrow system of a solitary funnel feeder.     

Paleoecology of the marine endobenthos

Endobenthic animals, which reside within the sea bottom, include stationary suspension feeders, mobile deposit feeders and both stationary and mobile carnivores. Their activities, especially with regard to dwelling, feeding, walking/crawling and resting/nesting, are recorded as trace fossils.Abundance, diversity and density of some kinds of trace fossils allow interpretation of the population strategies of the trace-makers in terms of opportunistic (r-selected) and equilibrium (K-selected) strategies. Opportunistic ichnotaxa tend to be faciesbreaking traces, which are highly localized in low-diversity, high-density trace fossil associations in rocks representing environmental extremes (e.g., variable salinities, harsh temperatures, low oxygen levels or shifting substrates). Equilibrium ichnotaxa usually are restricted to particular sedimentary facies and are characteristic of high-diversity, low-dominance trace fossil associations in sediments reflecting stable, predictable environmental conditions.The most important environmental factors influencing the composition of trace fossil assemblages in marine settings are bathymetry, substrate, oxygen and hydrodynamic energy. The four factors are closely interrelated, because as water depth increases, there is a general decrease in sediment grain size and hydrodynamic energy of the depositional environment. As depth below the water—sediment interface increases, the firmness of the sediment (due to compaction and dewatering) increases and the oxygen content of interstitial waters drops drastically.Marine ichnofacies are largely substrate-controlled. Soupgrounds are water-saturated, incompetent substrates typified by highly compressed and usually unidentifiable burrows. Softgrounds commonly contain numerous distinctive burrows and are zoned bathymetrically by the Skolithos, Cruziana, Zoophycos and Nereites Ichnofacies. Firmgrounds are characterized by stiff, compacted sediments, in which traces of the Glossifungites Ichnofacies are excavated. Hardgrounds are cemented substrates, in which bioerosion traces of the Trypanites Ichnofacies are bored. Woodgrounds are woody materials that have been exposed to the sea and bored by bivalves, which produce characteristic traces of the Teredolites Ichnofacies. Tiering of endobenthic communities is common and is related to substrate preference of the burrowers and oxygen stratification of interstitial waters.     

Three-dimensional morphology and palaeobiology of the trace fossil Dactyloidites jordii nov. isp. from the Carboniferous of England

The diverse ichnological assemblage from the outcrops near Howick (Northumberland, United Kingdom) is exceptionally well-preserved. Among these Carboniferous ichnotaxa is a new ichnospecies of Dactyloidites. Specimens were collected and processed using high-resolution serial grinding and photography to produce an accurate and precise three-dimensional model of these new burrows in full colour. The model produced in association with petrographic thin sections and field observations is used as the basis for comparison between Dactyloidites jordii nov. isp. and other ichnospecies of Dactyloidites. The current taxonomic status of the ichnogenus is examined and reviewed. D. jordii nov. isp. is a broadly bisymmetrical, stellate to palmate burrow composed of numerous long, narrow rays that exhibit three orders of branching arranged into tiered galleries radiating from a central shaft. The trace maker is suggested to be a vermiform organism with an adaptive burrowing strategy that facilitates alteration of its burrow construction to accommodate suboptimal sediment conditions. The adaptive nature of trace-making organisms and the inherent anisotropy of many burrowed media highlight the need for ichnologists to provide a type series rather than a single holotype, in order to capture the inherent range of common burrow morphologies.     

The oldest Mesozoic nearshore Zoophycos: evidence from the German Triassic

The trace fossil Zoophycos has been described from the Middle Triassic carbonates of the German Basin for the first time. It occurs in a calcilutite bed at the top of a shallowing-upward cycle (parasequence) in the transgressive systems tract of the Middle to Upper Muschelkalk sequence of Thuringia (Germany). Based on sedimentological and palaeontological features, the studied interval is interpreted as deposited in a marine nearshore environment with proximal storm deposits (tempestites). Zoophycos occurs in a very simple planar form with lobate spreiten, which were most likely produced by a worm-like animal by strip mining. The upper tier of the ichnofabric consists of Zoophycos, whereas the lower tier is occupied by cylindrical trace fossils of unknown taxonomic affiliation and with decreasing size towards the bottom. Associated trace fossils such as Rhizocorallium, Balanoglossites and Trypanites indicate a partly firm to hard substrate. No mixed layer is developed at the top of the trace fossil bearing succession. The ichnofabric together with the sedimentological features (disseminated pyrite, blue-grey colour) and palaeontological circumstances (poor benthic fauna, meiofauna with a small body size) support an interpretation of a dysaerobic environment. In the view of evolutionary change, Palaeozoic Zoophycos occurs in both deep and shallow marine deposits, whereas Mesozoic and Cenozoic Zoophycos is only common in shelfal and deeper-marine deposits. The new finding from the shallow-marine Middle Triassic represents the first reliable occurrence of Zoophycos after the end-Permian mass extinction and shows close similarities to its Palaeozoic precursors. It demonstrates that the producer survived the end-Permian mass extinction, became re-established in the nearshore realm and progressively colonized deeper-marine environments during the Mesozoic and Cenozoic.     

The insect trace fossil Tonganoxichnus from the middle Pennsylvanian of Indiana: Paleobiologic and paleoenvironmental implications

The ichnogenus Tonganoxichnus, produced by one or more monuran insect taxa, is now recorded from the Middle Pennsylvanian Mansfield Formation of Indiana. Tonganoxichnus is a resting trace that has three important implications. First, it represents a recurrent behavioral pattern in Upper Carboniferous to Lower Permian marginal marine environments of North America. Second, it provides finely resolved anatomical information for axial and appendicular body structures and behaviors that are difficult to determine from body‐fossil material alone. Third, integrated sedimentologic and ichnologic observations indicate that the Tonganoxichnus assemblage, inclusive of other ichnotaxa, is common in tidal rhythmites that were developed under freshwater conditions, probably in the innermost part of estuarine systems, close to or at the fluvioestuarine transition.     

Giant Paleodictyon in Eocene flysch

A giant Paleodictyon gomezi with a maximum mesh diameter of 13 cm and covering more than 0.5 m² occurs in the lower Eocene flysch near Zumaya. The giant Paleodictyon occurs with flute casts and, therefore, must have been produced deeply in the sediment. The lengthening of mesh cells parallel and perpendicular to the flute casts implies changing current directions during trace production. Rows of elongate and offset mesh cells reflect the row-by-row production of the trace; however, the base line followed by the trace fossil producer (meandering or spiral) cannot be reconstructed because of incomplete preservation. The extraordinary size of this giant Paleodictyon contradicts the evolutionary trend of deep-sea trace fossils toward optimization and miniaturization, since similar large Paleodictyon specimens occur in Silurian flysch.     

Temperate bioerosion: ichnodiversity and biodiversity from intertidal to bathyal depths (Azores)

In the temperate Azores carbonate factory, a substantial fraction of the calcareous skeletal components is recycled by a remarkable biodiversity of biota producing bioerosion traces (incipient trace fossils). To study this biodiversity, experimental carbonate substrates were exposed to colonisation by epilithic and endolithic organisms along a bathymetrical gradient from 0 to 500 m depth, during 1 and 2 years of exposure. The overall bioerosion ichnodiversity is very high and comprises 56 ichnotaxa and ichnoforms attributed to cyanobacteria, chlorophytes, fungi, other micro-chemotrophs, macroborers, grazers and epilithic attachment scars. In the intertidal, hydrodynamic force, partial emersion and strong temperature fluctuations lead to the lowest ichnospecies richness. This contrasts with the highest ichnodiversity found at 15 m under the most favourable environmental conditions. Towards aphotic depths, a gradual depletion in ichnodiversity is observed, most probably because of the restricted light availability and a slowdown in ichnocoenosis development. Analysis of similarity (ANOSIM), in combination with non-metrical multidimensional scaling (NMDS), was used to highlight variability in the relative abundance of traces among depths, substrate orientations and exposure times. Ichnodiversity and abundance of traces decrease significantly with depth and are higher on up-facing versus down-facing substrates, whereas differences between years were not as pronounced. This study demonstrates that statistical methods of biodiversity analysis are not per se restricted to biotaxa but may well be applied also to ichnotaxa. In the analysis of trace fossil assemblages, this approach supports the recognition of diversity patterns and their relation to environmental gradients.     

Trace fossils as paleoenvironmental indicators in the Taylor group (Devonian) of Antarctica

The Taylor Group of southern Victoria Land, Antarctica contains varied and abundant trace fossils, which have been interpreted by palaeontologists as indicating marine deposition. However, sedimentologists have largely favoured non-marine deposition on the basis of desiccation polygons, fining upward cycles, unidirectional paleocurrents, small channels, red beds and paleosols.

The debate is reconciled by a reinterpretation of the trace fossil assemblage. It is shown that widespread and well preserved Cruziana, Diplichnites, Rusophycus and Skolithos which have previously been used as marine indicators comprise an ichnofacies (Scoyenia) which is entirely typical of fresh water.     

Ichnology of Lower Jurassic beach deposits in the Shemshak Formation at Shahmirzad,southeastern Alborz Mountains,Iran

A 19 m thick package of well-sorted lowermost Jurassic (Hettangian-Lower Sinemurian?) sandstones within the Shemshak Formation of the southeastern Alborz Mountains displays features characteristic of foreshore to upper shoreface environments such as tabular bedding, low-angle lamination, trough cross-stratification, parting lineation, and oscillation ripples. In contrast to most other beach successions recorded in the literature the sandstones contain a trace fossil assemblage characterised by low abundance but comparatively high diversity. The assemblage, comprising 14 ichnotaxa, is dominated by Palaeophycus heberti, Rhizocorallium irregulare, Gyrochorte comosa, and Parahaentzschelinia surlyki. Contrary to predictions, which assume a dominance of suspension-feeders in such high-energy environments, the trace fossil assemblage represents a variety of ethological groups ranging from suspension-feeders to deposit-feeders, detritus-feeders, scavengers, and a possible trap constructor (Ctenopholeus), whereby deposit-feeders predominate. This anomaly is explained by a high amount of organic detritus in the sediment, indicated by abundant plant material, and a position of the beach in the vicinity of a river mouth.     

Borings in mobile clasts from Eocene conglomerates of Northern Dalmatia (Coastal Dinarides, Croatia)

Summary Bored clasts occur in Eocene conglomerates deposited in the upper shoreface and beachface settings of the Dinaric foreland basin. The trace fossil assemblage consists ofGastrochaenolites, Trypanites, and possibly some other ichnotaxa and may be compared to theTrypanites Ichnofacies. The preservation characteristics of the borings reflect many stages of colonisation/boring and abrasion. The removal of shells of the boring bivalves, the different depths of the abrasional truncation of borings, and the predominant preservation of the largest excavations (Gastrochaenolites) in the ichnocoenosis are related to repeated phases of abrasion, caused by the mobility of clasts. Coastal gravel is a specific variant of hard substrates, whose mobility controls the colonisation of borers, the type of assemblage and its preservation potential.     

The ichnofamily Celliformidae for Celliforma and allied ichnogenera

This contribution undertakes a comprehensive revision, lacking until now, of all the ichnotaxa attributed to fossil bee cells, one of the most common traces in paleosols. These ichnotaxa are morphologically related to Celliforma and consequently grouped herein in the new ichnofamily Celliformidae. Two new ichnogenera are formulated, Cellical‐ichnns igen. nov., for several ichnospecies previously included in Celliforma, and a new ichnospecies, C. chubutensis isp. nov., belonging to this ichnofamily, and Brownichnus igen. nov., for the ichnospecies favosites, which is not morphologically related to Celliforma. The ichnogenera included in this ichnofamily involve traces in which Celliforma, the most simple trace of the group, is part of their structure. Paltniraichnus is akin to Celliforma with antechambers and discrete walls. Uruguay, Corim‐batichnus and Rosellichnus are clusters composed of adjacent rows of Celliforma, or Palmiraichnus‐like cells. Ellipsoideichnus and Cellicalichnus are different arrangements of Celliforma‐like cells attached to tunnels.

Celliformidae are based on the morphology of the traces, all of them comprising cells, groups of cells and cells attached to tunnels. As such, its component ichnotaxa are based exclusively on morphological ichnotaxobases, which, in turn, were evaluated and selected with respect to the nest architecture of the trace makers, the bees. This paper analyzes some procedures and clues (i.e. behavioral homologies) that may be used to select the proper taxobases to erect ichnotaxa when the identity of the trace makers is known, as in this study case.     

How spatangoids produce their traces: relationship between burrowing mechanism and trace structure

Kanazawa, K. 1995 11 30 How spatangoids produce their traces: relationship between burrowing mechanism and trace structure.
Two spatangoid echinoids, Echinocardium cordatum and Lovenia elongata , were allowed to produce their traces in poorly and well-sorted sediments in aquaria. In poorly sorted sediments they formed distinct traces, comparable to fossil traces. Sorting of sediment occurred during transportation by the lateroventral spines and brought about characteristic patterns in grain size at the bottoms of the burrows and in redeposited sediment, which made the traces visible. Differences in the burrowing mechanism between E. cordatum and L. elongata are reflected in their trace structures. E. cordatum formed a laminated backlill structure which resulted from periodic accumulation of excavated sediment behind it, while L. elongata simply pushed excavated sediment by compression to the posterior sides of the test, so that their traces lack a distinct laminated structure and the width of the trace becomes larger than that of the animal. In well-sorted sediment, the echinoids burrowed in the same way as in poorly sorted sediment, but no visible trace was produced other than a drain tube. These observations reasonably explain some characteristic modes of occurrence of fossil spatangoid traces. Their different morphological expressions depend on sediment texture and the uneven lithification of traces. Spatangoids, trace, burrowing mechanism .     

Late Pleistocene freshwater fish (Cottidae) trackways from New England (USA) glacial lakes and a reinterpretation of the ichnogenus Broomichnium Kuhn

New trace fossil material from Late Pleistocene glaciolacustrine varves of the Connecticut River Valley, New England, USA represent the first evidence of freshwater sculpin in glacial Lake Hitchcock. Paleobiogeographic data constrain the timing of the last reinhabitation of freshwater cottids from a Wisconsinan glacial refugium. Freshwater sculpin were present in the area of study by ~ 13.7 ky BP, moving approximately 400 km in 5000 yr, and following the ice margin at distances as close as 35 km. The trace fossils warrant erection of a new ichnospecies, Broomichnium flirii isp. nov. Comparison of this new ichnospecies to Broomichnium permianum reveals distinct similarities, and it is possible that the Permian examples of B. permianum also were made by fish, which would reconcile a long-running controversy. Many groups of fish are demersal and make ventral body contact with the substrate and could potentially leave similar traces. Identifying new forms of trace fossils made by fish that use alternative modes of locomotion will prove useful in paleoenvironmental interpretations.     

Bioerosive structures from Miocene marine mobile‐substrate communities in southern Spain,and description of a new sponge boring

Abstract: Neogene palaeoshore sediments are abundantly represented along the Mediterranean coast of Iberia. An outcrop north of the Sierra Tejeda, named La Resinera, exposes concentrations of pebbles and boulders of marble, comprising an upper Miocene marine beach deposit. The high diversity of bioerosion trace fossils present in these boulders includes structures produced by polychaete annelids, demosponges, echinoids and endolithic bivalves, which indicate a shallow shoreface environment. The ichnotaxa represented are Maeandropolydora sulcans, Caulostrepsis taeniola, Entobia geometrica, Entobia ovula, Circolites kotoncensis, Gastrochaenolites torpedo, Gastrochaenolites lapidicus, Gastrochaenolites ornatus and Gastrochaenolites turbinatus. The borings are Tortonian (late Miocene) in age. Also present, and particularly abundant, are large sponge borings that have a single chamber from which radiating canals emerge. This trace fossil is designated as Entobia resinensis isp. nov.     

Plenasium xiei sp. nov. from the Cretaceous of Northeast China: Additional evidence for the longevity of osmundaceous ferns

A new species of the Osmundaceae, Plenasium xiei sp. nov., is herein described from the Cretaceous of Northeast China. The specimens examined here represent the earliest unequivocal record of the extant genus Plenasium in Eurasia based on fossil rhizomes. The rhizome consists of a central stem with a mantle of petiole bases and adventitious roots. The stem contains an ectophloic‐dictyoxylic siphonostele and a two‐layered cortex. The C‐shaped leaf trace bears two protoxylem bundles at the point of separation from the stele. The pith is heterogeneous. The parenchymatous inner cortex is thinner than the sclerenchymatous outer cortex. Lobed sclerenchyma bands occur at the adaxial sides of the stem xylem strands, in the concavity of the leaf trace, and along the adaxial side of the vascular bundles of the petiole base. In distal petiole portions, the sclerenchyma band splits into several groups in the transverse view. Sclerenchyma rings are heterogeneous with an abaxial sclerenchymatous arc of thick‐walled fibers. Numerous sclerenchyma strands of thick‐walled fibers appear in the petiolar inner cortex and the stipular wing. These fossils provide unambiguous evidence for the existence of subgenus Plenasium of modern Plenasium by at least the Late Cretaceous, demonstrating the longevity of this extant subgenus. Altogether the leaf and rhizome fossil records of Plenasium indicate that this genus was widely distributed across North America and Eurasia from the Early Cretaceous to the Early Cenozoic, followed by a range restriction to Eurasia in the Late Cenozoic. Extant Plenasium species are only known from East and Southeast Asia.     

Three-Dimensional Morphology of Beaconites capronus from Northeast England

Beaconites capronus is a winding meniscate backfilled trace fossil differentiated from comparable ichnotaxa Taenidium and Ancorichnus on the basis of its distinct and unornamented burrow lining. Typically, horizontal to subhorizontal B. capronus also includes vertical pipes, which serve as a point of entry for endobenthic deposit feeding activity. The burrows do not self-cross but often display secondary successive branching potentially indicating coprophagous feeding strategies in lower nutrient sediment. Beaconites capronus material is examined and discussed from the Carboniferous offshore transition zone deposits near Howick, United Kingdom. Samples were collected and analyzed using high-resolution serial grinding and modeling techniques documenting fine detail in three dimensions. As the burrows are actively backfilled and do not maintain a connection to the sediment water interface the trace making organism must have a method of coping with the low oxygen porewater conditions. Four methods are considered herein, as follows: 1) revisiting the sediment-water interface; 2) creating periodic shafts; or 3) employing the use of obligate anaerobic metabolism. Based on the material presented herein, an emended ichnospecific diagnosis is provided.     

Caedichnus,a New Ichnogenus Representing Predatory Attack on the Gastropod Shell Aperture

Predatory traces, in which the tracemaker has damaged the prey animal's skeleton to kill and consume it, have a deep fossil history and have received much scientific attention. Several types of predatory traces have been assigned to ichnotaxa, but one of the most studied predatory traces, the wedge-shaped excision produced as a result of attacks mainly by crustaceans on the apertures of gastropod shells, has yet to be described as an ichnotaxon. We propose the ichnogenus Caedichnus to describe the shell damage produced by aperture peeling behavior. Caedichnus is produced by predators that are unable to crush their prey's shells outright. Depending on the predator's peeling ability and the prey's withdrawal depth within the shell, the trace can extend through several whorls of the shell. Aperture peel attacks may fail, allowing such damage to be repaired by surviving gastropods. Thus, the types of attacks that produce Caedichnus may exert selective pressure on prey to evolve better-defended shells (in the case of gastropods) or to inhabit better-defended shells (in the case of hermit crabs). The identification of these trace fossils will enhance our understanding of how predation influences the morphological, and even behavioral, evolution of prey organisms.