Use Of Trace Fossils Research Articles

Visualizing a process ichnology dataset, Lower Cretaceous McMurray Formation, NE Alberta, Canada

Abstract Process ichnology emphasizes the use of trace fossils as proxies for sedimentary processes and conditions. The advantage of this method is that depositional stresses can be identified based on several process-ichnological parameters. The purpose of this paper is to demonstrate the use of process-ichnology data, with a focus of establishing how process ichnology metrics can be visualized with geomodeling to aid spatial interpretation. For this study, process ichnology metrics (including bioturbation index and size diversity index), which is the product of interval ichnogenera diversity and interval maximum burrow diameter, are presented from a core dataset of the Cretaceous McMurray Formation. These data are modeled using standard geostastistical techniques for effective visualization of spatial trends. The modeled ichnology data are compared to sedimentary facies in order to interpret the dominant stresses occurring at the time of infaunal colonization. Several interpretations are made from the process ichnology model. The size diversity index and bioturbation index values from inclined heterolithic stratification show strong spatial variability related to variable depositional conditions across and along inclined heterolithic stratification bar forms. Facies interpreted to represent tidal flat deposition are distinguishable on the basis of relatively high bioturbation index values coupled with intermediate to low size diversity index values. Overall, we interpret variability in salinity and sedimentation rates to be the dominant infaunal stresses in the studied stratigraphic interval.

A historical perspective on applied ichnology in Western Canada

The study and application of ichnology, or trace fossils, have evolved substantially since trace fossils were first recognized (as such) in the late 19th century. Trace fossils were, in fact, initially interpreted as fossilized remains of marine algae (i.e. fucoids). This notion was not dispelled until A.G. Nathorst (1881) reinterpreted several fucoids — for example Chondrites , Zoophycos , and Palaeophycus — as the burrows of marine invertebrates. Both during the “age of fucoids” and for several decades thereafter, trace fossils were collected with the aim of determining diversities and temporal ranges of ichnofossil types, and the use of trace fossils as paleoecological indicators was not well developed. In the early part of the twentieth century, the ethologic and ecologic significance of ichnofossils was gradually recognized. In 1929, Rudolf Richter, an early leader in trace-fossil analysis, established the Senckenberg Vorschungstelle fur Meeresgeologie und Meerespalaontologie at Wilhelmshaven which was later known as “Senckenberg am Meer” (Senckenberg by the Sea). The purpose of this research station was to study animal-sediment relationships in modern depositional settings, in order to apply the actualistic concepts of Lyell to the ichnological record. An important abstraction needed to be embraced before trace fossils could be employed to aid in the identification of sedimentary environments. That is, a trace fossil represents a “behavior” employed by an animal to live in a sedimentary environment, and that the behavior is a physical response to chemical and physical depositional conditions. Conversely, ichnofossils can be used to interpret some sedimentary and chemical parameters of the depositional setting. …

Icehouse, cool-water carbonate ramps: the case of the Upper Pliocene Capodarso Fm (Sicily): role of trace fossils in the reconstruction of growth stages of prograding wedges

An integrated approach, based on the use of trace fossils combined with analysis of physical and biogenic structures, identification of key surfaces, and reconstruction of stratigraphic architecture, proved to be of critical value in defining the depositional environments, elucidating the dynamics of progradation, and characterizing the various systems tracts of Upper Pliocene progradational wedges (Capodarso area, Sicily) generated by cool-water carbonate ramps. The studied succession consists of a stack of six cycles, consisting of terrigenous mudstones passing upwards into biocalcarenite wedges with distinct clinoforms. The prograding biocalcarenite bodies show seaward-increasing height and steepness of the clinoformed front as a result of development into increasingly deeper water, and may be regarded as the record of distally steepened ramps, dominated by storm-induced downwelling flows. Evidence of forced-regressive progradation is provided by stratal geometries, physical structures, and trace fossil assemblages existing at the top of the bodies, which attest to a gradual increase in energy level at the top of the ramp, concurrently with the progression of seaward outbuilding of the bodies. Three trace-fossil suites (Thalassinoides/Piscichnus, Scolicia, Dactyloidites) are shown to be linked with the successive growth stages of individual prograding wedges, whereas abandonment stages, characterized by starvation of sediment input, are marked by the Ophiomorpha suite. The Capodarso ramps, like other Plio-Pleistocene equivalents of the Mediterranean area, are small, high-gradient ramps, with stratigraphical architecture controlled by high-amplitude, orbitally driven glacio-eustatic changes. An ecologically and bathymetrically based subdivision of the ramps into inner, mid and outer ramp environments is hardly applicable, as most of the wedge progradation occurs in highly dynamic conditions, dominated by physical processes of transport and resedimentation of skeletal material, which result in faunal composition dominated by allochthonous material. The use of trace fossils is of critical value in this context, due to the scarcity of ecological information provided by faunal elements.

Behavioral plasticity of modern and Cenozoic burrowing thalassinidean shrimp

The use of trace fossils as paleoenvironmental indicators is based on empirically-derived and tested links between environmental conditions, behavior, and trace fossil morphology. Four approaches were used to assess how faithfully and at what resolution trace fossils, as mirrors of behavior, reflect environmental change: (1) comparing the abundance and morphology of Ophiomorpha nodosa in tidal channel-margin and tidal channel-axis facies (Miocene, Delaware); (2) determining the range of morphology of O. nodosa produced under unchanging environmental conditions (within the channel-margin facies); (3) evaluating the behavioral response of the modern burrowing thalassinidean, Neotrypaea californiensis, in Mugu Lagoon, California to an environmental perturbation, namely the burial of layers of glass plates; and (4) assessing how ancient producers of Ophiomorpha dealt with obstacles presented by dense shell and coral accumulations (Miocene, Maryland; Pleistocene, Bahamas). Comparison of Ophiomorpha nodosa in channel-margin versus channel-axis facies indicated that O. nodosa was significantly more abundant in the channel-margin facies. However, there was no significant difference in burrow characteristics (exterior or interior diameter, wall thickness) between the facies. As recorded by O. nodosa, its thalassinidean producer did not modify its behavior in response to conditions in the tidal channel axis. Rather, the tracemakers tended to avoid the channel axis, as indicated by the reduced abundance of O. nodosa. In contrast, O. nodosa within the channel-margin facies was highly variable in degree of pelletization of the burrow wall, in burrow fill and definition of the burrow margin, and in architecture of the burrow system. Variation in O. nodosa found within the channel-margin facies reflected behavioral flexibility in the absence of environmental change. Modern burrowing shrimp adapt to barriers (layers of glass plates) implanted within the substrate. They alter the geometry and depth of their burrow systems; they may even share shafts that penetrate the barrier. Meters thick Miocene shell beds (Maryland) in which the shells are not densely packed contain Ophiomorpha and Thalassinoides; the producing thalassinideans were able to penetrate and move through the shell bed. Similarly, Pleistocene thalassinideans maneuvered around coral rubble in Bahamian fossil coral reefs. However, Miocene decimeter-thick shell beds that are densely packed and well sorted are not penetrated by thalassinidean burrows, implying that thalassinidean behavioral flexibility was not sufficient to penetrate densely packed shell beds. Likewise, in the Bahamian reefal settings, Ophiomorpha producers formed extensive maze systems immediately above impenetrable lithified surfaces in the reefal sequence. Behavior of thalassinidean shrimp is neither tightly constrained nor highly programmed, and there is no indication that this has changed since Miocene time. Small changes in morphology of traces produced by thalassinideans cannot be used to identify subtle changes in environmental conditions. Shrimp vary behavior apparently “whimsically”, as well as in response to environmental change. If this is true of animals other than thalassinideans, the challenge to the ichnologist is to distinguish between “background” and “environmentally triggered” behavioral variation as recorded in the trace fossil record.

GOLDRING, R. 1999. Field Palaeontology, 2nd ed. xv + 191 pp. Harlow: Longman (Pearson Education Ltd). Price £18.99 (paperback). ISBN 0 582 35625 3.

First published as Fossils in the Field in 1991, Goldring has re-published this useful book under its new title. The reasons behind the name change are unclear, but will presumably ensure re-purchase by institutional libraries! That said, there are notable differences between the two editions, in particular with reference to trace fossils. Goldring sets out to introduce the undergraduate or new research student to various techniques of studying fossils in the field. Chapters vary from suggestions of how to prepare for fieldwork, to identification of different body fossils, their use as environmental indicators, biostratigraphy and the recognition and use of trace fossils. The latter chapter in particular contains material not in the first edition. There are five appendices covering further suggestions for field preparation …

Use of trace fossils in delineating sequence stratigraphic surfaces (Tertiary Venetian Basin, northeastern Italy)

Abstract The lowermost third-order sequence of the Venetian Molasse Basin (Upper Chattian-Lower Aquitanian) in the Belluno syncline is composed of a transgressive systems tract, comprising a basal, condensed, glauconitic sand sheet deepening upwards into finer-grained offshore deposits, and a highstand systems tract mainly consisting of prograding, offshore mudstones capped by very fine sandstones representing offshore-transition deposits. An integrated sedimentological, ichnological and micropaleontological approach has allowed the recognition of the internal organization of the sequence, the subdivision into parasequences in absence of an obvious physical expression, and the characterization of significant discontinuity surfaces at both sequence and parasequence scales. The transgressive surface shows a complex geometry of bored and encrusted cavities produced by erosional undercutting and a system of neptunian dykes and sills, with hiatal shell concentrations as infill. Component parasequences in the texturally homogeneous transgressive sand sheet can be identified on the basis of the preservational state of trace fossil assemblages (softground versus firmground conditions) and subtle changes in grain-size and glauconite content. Omission surfaces bounding the parasequences are marked by increased glauconite content, and densely crowded, predominantly vertical or oblique, relatively large, very distinct, thin-walled or unwalled, and uncompacted burrows. The condensed section coincides with highest values in relative abundance of planktic foraminifers and in diversity of benthic foraminifers. Parasequence-bounding flooding surfaces in the muddy offshore portion of the highstand systems tract are recognized as firmground surfaces mantled by thin shell concentrations in a matrix of silty, highly burrowed, glauconitic sand.

Trace Fossils in Archaeozoology

In classical palaeontology, the subdiscipline of palaeoichnology has reached a spectacular development. In archaeozoology, the analysis of trace fossils or ichnofossils focuses most often on marks left by animals and people on animal bone, but many other trace fossils exist. The present paper provides a definition and a practical classification of trace fossils produced by animals, derived from the one used by most palaeontologists and a provisional inventory of archaeozoological ichnofossils. The use of trace fossils for archaeological reconstruction outside the much publicized realm of hominid food procurement is illustrated. Archaeozoology and palaeontology would both benefit from a more exhaustive treatment of ichnofossils from archaeological contexts.

Introduction to Trace Fossils and Dedication to Robert W. Frey

Over the years, we've participated in several different workshops and short courses on trace fossils. So why this one? Our intention in bringing together these papers for the Trace Fossil Short Course is to give an overview of how trace fossils can be used in paleontology. Historically, trace fossil research has centered on paleoenvironmental and depositional reconstructions—areas where trace fossils have much to tell. Indeed, the use of trace fossils by sedimentologists has flourished and is experiencing another burst of activity through the use of ichnofabrics in sequence stratigraphic studies. But trace fossils have paleontological stories to tell as well. Their use in uncovering the first occurrences of life in different parts of the stratigraphic column is well documented (e.g., the classic example of trace fossils occurring before body fossils in Precambrian/Cambrian transitional strata) as is their use in detailing different morphological details of unpreserved taxa or body parts.

Silurian Trace Fossils in Carbonate Turbidites from the Alexander Arc of Southeastern Alaska: ABSTRACT

Early to Late Silurian (Wenlock-Ludlow) body and trace fossils from the Heceta Formation are preserved in the oldest widespread carbonates in the Alexander terrane of southeastern Alaska. They represent the earliest shelly benthos to inhabit a diversity of marine environments and are important indicators of the early stages in benthic community development within this ancient island arc. The trace fossils are significant because they add to a small but growing body of knowledge about ichnofaunas in deep-water Paleozoic carbonates. Proximal to medial carbonate turbidites yield a low-diversity suite of trace fossils that comprises five distinct types of biogenic structures. Bedding planes reveal simple epichnial burrows (Planolites), cross-cutting burrows (Fucusopsis), and tiny cylindrical burrows. These and other casts, including chondrites( )-like burrow clusters, represent the feeding activities (fodinichnia) of preturbidite animals. Hypichnial burrows and rare endichnial traces reflect the activities of postturbidite animals. Broken and offset traces indicate that infaunal biota commenced burrowing before slumping and subsequent soft-sediment deformation. The abundance and density of trace fossils increases offshore in the medial turbidites associated with a decrease in the size and amount of coarse particles and with an increase in mud and preserved organic material. Although diversity levels are similar in themore » proximal and medial turbidite facies, they are much lower than in Paleozoic siliciclastic turbidites. This may reflect unfavorable environmental conditions for infaunal biota or paleobiogeographic isolation of the Alexander terrane during the Silurian. A greater use of trace fossils in terrane analysis will help to resolve this issue and should provide new data for reconstructing the paleogeography of circum-Pacific terranes.« less

Book reviews

Book reviews in this article: Memoirs of an Unrepentant Field Geologist, by F.J. Pettijohn. Ichnology: the Use of Trace Fossils in Sedimentology and Stratigraphy, by A. A. Ekdale, R. G. Bromley and S. G. Pemberton. Platform Margin and Deep Water Carbonates, by H. E. Cook, A. C. Hine and H. T. Mullins. Tills and Related Deposits: Genesis/Petrology/Application/Stratigraphy, ed. by E.B.Evenson. Atlas of Sedimentary Rocks under the Microscope, by A. E. Adams, W. S. Mackenzie and C. Guilford. Geomagnetism of Baked Clays and Recent Sediments, by K. M. Creer, P. Tucholka and C. E. Barton

Bioturbation in deep-sea fine-grained sediments: influence of sediment texture, turbidite frequency and rates of environmental change

Summary In the deep sea, burrowing infauna can adapt to variation in sediment texture within < 100–300 years. When there is continuous sedimentation, a continuous bioturbation process also takes place and the biogenic trace association found in the fossil record may be dominated by deeply penetrating burrows. A low-diversity trace fossil association ( Zoophycos ichnofacies) is typical. On the other hand, when turbidites interrupt the continuous bioturbation process, a highly diverse trace fossil association is often found in the fossil state that also contains highly organized near-surface traces ( Nereites ichnofacies). This biotope is usually controlled by the non-turbiditic sedimentation rate and the recurrence time of turbidites. Biogenic trace assemblages are mainly controlled by the nature of sedimentation and other environmental conditions rather than by water depth. Therefore, the widely accepted use of trace fossils as palaeobathymetric indicators in the deep sea may be restricted.

Trace Fossils as Environment Indicators in the Rocky Mountains: ABSTRACT

Ichnology is the study of the traces ancient organisms have left in or on the substrate. These traces, or lebensspuren, are in the form of tracks, burrows, trails, or borings, and are important clues in determining ancient rock environments. Throughout time, organisms have left various types of traces while engaged in different activities. The two major types of lebensspuren were made by suspension feeders found in turbulent water where organic matter is held in suspension, and by deposit feeders whose habitat is found in quiet, deeper waters where large quantities of organic matter settle from suspension. The different activities which occur in these two environments are the cause of the traces found in sediments. These include escape structures resulting from degradation or aggradation of sediments, feeding structures, dwelling structures, grazing traces, crawling traces, and resting traces. The use of trace fossils in hydrocarbon exploration is especially helpful in the Cretaceous sandstones of the Rocky Mountains because of the relative abundance of outcrops and the scarcity of body fossils. By combining the interpretation of physical processes with the biological traces, one more tool is made available in the determination of rock environments as an aid in hydrocarbon exploration. Materials exhibited include 8 × 10 color prints of different Cretaceous lebensspuren, hand-drawn cartoons of the six different trace activities, and a regional cross section of the Eagle sandstone illustrated by photographs of different traces near each location, as well as a variety of rock samples. End_of_Article - Last_Page 1355------------

Use of Trace Fossils for Interpretation of Triassic Depositional Environments, Northeast Border of French Massif, Central France: ABSTRACT

A variety of trace fossils occur in Triassic sediments of the northeast border area of the French massif as follows: 1. Vertebrate tracks: numerous species (approx. 30) that point to the existence of: (a) numerous large herbivorous reptiles (Isochirotherium) accompanied by small ones (Rhynchosauroides, Rotodactylus); rare carnivorous reptiles of relatively small size (Coelurosaurichnus, Sphingopus, Anchisauripus); common omnivorous or necrophagous reptiles (Brachychirotherium); (b) very small insectivorous or herbivorous reptiles or amphibians (small Rhynchosauroides, Prolophonichnium, Platipes, Furcapes). 2. Invertebrate trace fossils: Isopodichnus, Planolites, Cochlichnus. 3. Plant imprints: Voltzia sp. 4. Associated primary sedimentary structures: ripple End_Page 697------------------------------ marks, mud cracks, salt-pseudomorphs, and groove marks accompanied by vertebrate footprints on the same slab. The set of trace fossils and associated sedimentary structures indicates an origin at the fringes of aquatic areas and at the borders of vegetation zones. These large areas were used by the ruling reptiles as pathways between the water and the vegetation where they found resting, breeding, and feeding places. The smaller vertebrates were living in habitats near the vegetation or at the borders of small channels. The invertebrate traces point out the proximity of water and the fluctuation of water level. The primary sedimentary structures suggest variable water levels and the salt-pseudomorphs suggest marine water. The assemblage of traces suggests very large sandy areas between the sea or lagoons and zones of dense vegetation which favored proliferation of the mobile Archosaurs. End_of_Article - Last_Page 698------------

Changing Perspectives in Paleoecologic Use of Trace Fossils: ABSTRACT

Historically, trace fossils have been described as tricks of devil, plant or fucoid remains, or specific tracks of organisms, and more recently, as the behavioral responses of organisms to a particular substrate. Moreover, there are now many attempts to use trace fossils to model community structure, to interpret depth zonations, diversity, nutrient levels, etc. However, it stretches point to treat traces as pseudo-organisms. They can be excellent paleoindicators when accepted as complex structures they are--especially surface traces. Surface traces represent preservation of an ephemeral animal, combination of sediment, and fluid that can provide us with information about size, weight, style, and locomotory types of animals present; they can se limits for values of engineering or geotechnical properties of substrate (such as bearing capacity, water content, and shear strength); and they can indicate fluid regime (current velocities and directions) associated with site area. This information can be gleaned from fossil traces by treating them as structures created by organisms (nothing more), that to be preserved must respond to local, transitory conditions at seabed. End_of_Article - Last_Page 423------------

Ecological implications of possible enteropneust faecal casts in tertiary deposits near castlepoint, New Zealand

Summary Unusual “spiral” faecal casts from mid‐Tertiary beds of the Castlepoint area of North Island, New Zealand, are described and compared with modern enteropneust casts photographed at abyssal depths in the south‐west Pacific. Evidence suggests that the fossil casts originated in relatively shallow depths, and this discrepancy emphasises the caution required in the use of trace fossils for palaeoecological interpretations.