Bichordites monastiriensis from the Pleistocene of southeast Jamaica

Bichordites monastiriensis Plaziat and Mahmoudi 1988, produced by burrowing spatangoid echinoids, is figured and described from shallow marine siliciclastic strata of the Pleistocene Old Pera Beds (Coastal Group) of southeast Jamaica. Its occurrence there represents only the second formal recording of this monospecific ichno‐taxon and extends its geographic range from the Mediterranean region to the Caribbean. The spatangoid species that produced this trace fossil is unknown, but, unlike examples from other areas, it is unlikely to be Echinocardium.     

ECHINOID AND CRUSTACEAN BURROWS AND THEIR DIAGENETIC SIGNIFICANCE IN THE MAASTRICHTIAN-DANIAN OF STEVNS KLINT, DENMARK

The increase in species and specimens of fossils in the uppermost part of the Maastrichtian White Chalk is interpreted as a result of reduced depth. The absence of bryozoans, brachiopods, and regular echinoids in the Cerithium Limestone indicates sedimentation in tidal pools. After sedimentation of the Cerithium Limestone, burrowing activity followed. A burrow of Brissopneustes danicus similar to burrows of the recent Echinocardium cordatum is described. Callianassa and its burrows are found in the Upper Danian calcarenite but not in the Lower Danian or Maastrichtian of Denmark. The dominant type of burrows along the Maastrichtian-Danian boundary has presumably been formed by the crustacean Ctenocheles.
The early post-Maastrichtian burrowing activity was succeeded by (1) induration of the bottom sediment and a slight abrasion (2) dissolution of aragonite shells and siliceous sponges, (3) offshore sedimentation and filling of the burrows with Lower Danian chalk mud, bryozoan fragments and other fossil remains, and (4) settling in the deeper part of the soft chalk sediment and precipitation of flint in or around burrows near the surface of the sediment.     

湖北三峡地区埃迪卡拉系灯影组“蝌蚪状”遗迹化石*

遗迹化石是埃迪卡拉纪存在两侧对称动物最有力的证据。但多数埃迪卡拉纪遗迹化石为简单、水平的表面爬迹或潜穴。在湖北三峡地区灯影组石板滩段含典型埃迪卡拉软躯体化石的地层中新发现一类形态特别的化石,呈蝌蚪状,一端膨大,一端细管状。通过对化石形态、同位素分析以及沉积学特征的研究,说明该化石为遗迹化石,而不是实体化石。蝌蚪状化石为一种复合迹,垂向活动形成球状的膨大端,平行藻席层活动形成近于水平的潜穴,反映了造迹生物垂向切穿藻席层并沿藻席层进行觅食的行为。该发现说明了在埃迪卡拉纪晚期已有两侧对称动物开始形成较为复杂的潜穴。     

Specific status of Echinocardium cordatum, E. australe and E. zealandicum (Echinoidea: Spatangoida) around New Zealand, with comments on the relation of morphological variation to environment

The specific status of the heart-urchin Echinocardium cordatum (Pennant) around New Zealand is discussed in the context of the suggestion that the New Zealand form of this spatangoid is sufficiently distinct from E. cordatum to be regarded as a separate species, namely E. australe Gray or E. zealandicum Gray. A brief history of the problem is outlined and it is demonstrated that, from the beginning of the present century, specialist opinion has favoured the unitary species concept and been unenthusiastic about the validity of Gray's species. The pattern of variability revealed by a comparative morphological study of E. cordatum from the British Isles and E. australe/zealandicum from New Zealand did not support the specific separation of the Australasian species. Alternatively, it is proposed that the morphological structure of the test in E. cordatum may be considerably influenced by sediment texture and that the distinctiveness of some of the New Zealand specimens is related to their occupation of very fine deposits, which are not commonly exploited by E. cordatum around the British Isles.     

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.     

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.     

New Miocene scarabeid and hymenopterous nests and early miocene (santacrucian) paleoenvironments,patagonian Argentina

Three new trace fossils are described from Miocene paleosols of southern Argentina. Celliforma pinturensis, n. ichnosp. and Celliforma rosellii, n. ichnosp. are interpreted as cells of digging bees, possibly Anthophoridae, and Coprinisphaerafrenguellii, n. ichnosp. are brood balls of dung‐beetles. Both burrowing bees and dung‐beetles are common nesters in relatively open areas, confirming previous reconstructions of the paleoenvironment of the Pinturas Formation. A brief review of scarabeid and bee fossil nests from South America is presented, and we propose that constructed nests have a higher preservation potential than excavated nests. This fact explains their more common occurrences as trace fossils in paleosols. A new ethological category, calichnia, is proposed for hymenopterous and coleopterous traces, in which adult individuals make nests exclusively for larvae.     

Lower Cretaceous (Albian) shell-armoured and associated echinoid trace fossils from the Sácaras Formation, Serra Gelada area, southeast Spain

The Sácaras Formation (Albian, Lower Cretaceous) of the Serra Gelada succession (Prebetic of Alicante), southeast Spain, comprises carbonate‐rich, upwards thickening parasequences in which many types of trace fossils have been identified. The present study focuses on two types of tubular trace fossil characterized by features of their external coating. The first type is represented by a shell‐covered, structured trace fossil, up to 4?cm in diameter and 40?cm in length, built horizontally, from rectilinear (type 1) to gently curved (type 2), which envelopes an unstructured pipe of grey silty sediment. The coating is characterized by imbricated, flat particles, mainly orbitolinid foraminifers and other planar bioclasts, forming thin concentric layers; in cross section the bioclasts produce a typical plumed structure. This trace fossil represents a new ichnogenus and ichnospecies, here named Ereipichnus geladensis. Particle arrangement of the external coating is similar to that of terebelloid tubes, but Ereipichnus is a horizontal trace fossil, whereas structured worm tubes are vertical. The second type is a grain‐coated trace fossil, tubular in shape, with a simple internal structure. The coating is often reddish with respect to the neighbouring dark grey sediment and shows a slightly coarser‐grained texture, which envelopes the internal muddy pipe. This type, which yielded echinoids, was produced by irregular or heart‐shaped sea‐urchins (spatangoids) and is attributed to Scolicia or Cardioichnus. Facies analysis of the Serra Gelada succession with Ereipichnus and Scolicia or Cardioichnus locally shows other types of branched trace fossils (primarily represented by different forms of Thalassinoides) and bioturbation is developed in tiers, increasing upwards in abundance and diversity.     

Reassessment of sediments and trace fossils from old red sandstone (Lower devonian) of Dunure,Scotland, described by John Smith (1909)

In 1909 John Smith, a Scottish naturalist and geologist,described 23 «genera and 51 «species of trace fossils from small patches of sediment associated with andesite lava flows at Dunure, Ayrshire. He interpreted the traces as evidence of a diverse invertebrate fauna which inhabited small pools and fissures in the lava surface between eruptions. Smith's collection (c. 300 specimens) was presented to the British Geological Survey, Edinburgh but has remained largely unstudied.Re-examination of the Smith collection shows thatit came from 3 separate localities which differ in composition of the ichnofaunas, associated sediments and sedimentary structures. Arthropod trackways dominate the ichnofauna occurring in laminated siltstone frequently with ripple marks and foam marks suggesting formation in shallow lacustrine conditions. Preservational and behavioural analysis of trace fossils reveals about 10 valid ichnogenera of locomotion and swimming trackways, resting traces, feeding trails but few burrows. Presence of early terrestrial arthropod traces is uncertain. Palaeocological interpretation is of ephemeral lakes in distal braid-plain situation subject to subsurface invasion of andesite lava producing fluidization and deformation of wet sediment. The Dunure ichnocoenosis shows unique diversity of Devonian arthropod trace fossils.     

Lower Miocene bathyal and submarine canyon ichnocoenoses from Northland, New Zealand

Thalassinidean crustacean remains ( Callianassa ) are recorded from lower Miocene burrow networks belonging to the ichnogenus Thalassinoides . They were produced at mid bathyal depths of 1000–3000 m. Mid to lower bathyal basinal sediments and inferred outer neritic to upper bathyal submarine canyon sediments contain sparse ichnocoenoses composed entirely of feeding and dwelling structures, produced by burrowing polychaetes, echinoids and possibly sipunculoids and also by bivalves escaping burial during rapid sedimentation. These two ichnocoenoses are similar to those of proximal turbidite sequences, and this is considered a response to similar rates of sedimentation, water agitation and coarseness of sediment rather than a similarity in depth. An outer neritic to upper bathyal canyon wall ichnocoenosis was developed in semi-consolidated lutites and arenites by burrowing polychaetes, decapod Crustacea (shrimps and crabs) and possibly amphipods and other organisms. Inclined, but randomly oriented Rhizocorallium occur in the canyon wall, and their presence at these depths is explained by inferred abnormally high water turbulence and abundant suspended food matter as well as a favourable semi-consolidated lutite substrate.     

CLEPTOPARASITISM AND DETRITIVORY IN DUNG BEETLE FOSSIL BROOD BALLS FROM PATAGONIA, ARGENTINA

Abstract:  Traces within traces is a new ichnological field that is meant to shed light on significative palaeoecological aspects. Dung beetle fossil brood balls ( Coprinisphaera ispp.), from the Middle Eocene – Lower Miocene Sarmiento Formation of Patagonia, Argentina, show two different trace fossils excavated in its infillings and/or wall that reveal the presence and relationships among different components of past dung communities. Tombownichnus pepei n. isp. is represented by elongated pits, circular to elliptical in cross-section, occurring in the centre or beside ovoid mounds in the internal surface of the Coprinisphaera wall. These traces record the activity of cleptoparasites, such as other dung beetles or flies, whose larvae were probably carried passively with the dung for provisions. Tombownichnus pepei would represent the pupation chambers excavated by full grown larvae in the Coprinisphaera wall after completing their development inside provisioned dung. The other trace fossil, Lazaichnus fistulosus is represented by circular to subcircular borings occurring in Coprinisphaera walls, in connection with an internal gallery in their infillings. Its connection also with meniscate burrows and chambers in the surrounding palaeosol attributable to aestivation chambers of earthworms revealed that these organisms would have been active cleptoparasites or detritivores in dung beetle fossil brood balls.     

Distribution,substratum preference and burrowing behaviour of Lovenia elongata (Gray) (Echinoidea: Spatangoida) in the Gulf of Elat ('Aqaba), Red Sea

Lovenia elongata (Gray), the Indo-West Pacific spatangoid, was studied in the Gulf of Elat ('Aqaba) at the northern end of the Red Sea. The occurrence and local distribution of this macrobenthic burrowing species was determined and related to the particle size distribution of the substrata in which it was found. Its habitat preference is for clean, grassless, sandy bottoms in intertidal areas (beaches and sandbars), and on sublittoral level bottoms of protected bays and lagoons sheltered from heavy wave action. The preferred sediments were found to range from medium to fine sand. The population density, size frequency distribution, growth, reproduction, recruitment, and mortality of a sublittoral population of L. elongata (at Wadi Taba, Sinai) were studied.The mode of life of this burrowing heart urchin was observed in situ and in aquaria. Its burrowing and emergence behaviour are described. Experiments were carried out on the effect of particle size on burrowing behaviour. There are significant differences in the ability of L. elongata to manipulate substrata of varying grain size. The burrowing process was found to be most rapid in natural sand of medium-fine composition, corresponding to the normal sediment of the urchin's habitat. Such sediments were also found to be suitable for successful larval settlement; juveniles did not survive in coarser sand.Differences in population density and spatial distribution between various size groups are attributed to differences in their ability to manipulate the substratum. L. elongata is found to be morphologically suited to sand, particularly medium-fine sand; however, it is restricted by its morphology to shallow burrowing, since it lacks specialized mechanisms for deeper burrowing and funnel building.     

The trace fossil Thalassinoides from the Upper Ordovician of Tuva

Traces of Thalassinoides (the tunnels of unknown burrowing organisms) are described from carbonates of the Khondelensky layers of the Upper Ordovician of Tuva. Hitherto, this fossil was unknown in the Ordovician of the USSR. They demonstrate great similarity with Thalassinoides from coeval deposits of the Great Basin, USA. The traces are assumed to have been made in terrigenous-carbonate sediments deposited on the areas of a gently sloping shelf in quiet water, below wave base. □ Upper Ordovician, terrigenous-carbonate sediments, burrows.     

Observations on the morphology of Echinocardium cordatum (Echinoidea: Spatangoida) from diverse geographical areas

Various test features in six specimens of Echinocardium cordatum collected from South Africa, Trindade Island (South Atlantic), Australia, Japan and Ireland were compared with previously established data relating to British and New Zealand specimens. Morphological variations between the specimens were interpreted as infra-specific differences and no evidence was detected that the spatangoid conventionally defined as E. cordatum is more than a single species throughout its extensive geographical range.     

Trace fossils of animal‐plant interactions and “pseudointeractions” from maletín (Bohemian cretaceous basin,Czech Republic)

Old collections of the Upper Cretaceous flora at Maletín yield examples of trace fossils of plant‐arthropod interactions, comparable with recent insect galls. Grooves and ridges, often preserved on leaves at this locality, are (in contradiction to several previous authors) interpreted as traces of burrowing organisms, which originated in soft sediment adjacent to the plant remains lying on a lake floor or buried in the substrate. The leaves functioned in the sediment at the time of burrowing and/or during compaction of the substrate as distinctive laminar bodies with specific physical characteristics and therefore they enabled the preservation of some aspects of ichnofabric otherwise invisible in the surrounding strata.     

Strategies of burrowing in soft muddy sediments by diverse polychaetes

Muddy sediments are elastic solids through which morphologically diverse animals extend burrows by fracture. Muddy sediments inhabited by burrowing infauna vary considerably in mechanical properties, however, and at high enough porosities, muds can be fluidized. In this study, we examined burrowing behaviors and mechanisms of burrow extension for three morphologically diverse polychaete species inhabiting soft muddy sediments. Worms burrowed in gelatin, a transparent analog for muddy sediments, and in natural sediments in a novel viewing box enabling visualization of behaviors and sediment responses. Individuals of Scalibregma inflatum and Sternaspis scutata can extend burrows by fracture, but both also extended burrows by plastic deformation and by combinations of fracture and plastic deformation. Mechanical responses of sediments corresponded to different burrowing behaviors in Scalibregma; direct peristalsis was used to extend burrows by fracture or a combination of plastic deformation and fracture, whereas a retrograde expansive peristaltic wave extended burrows by plastic deformation. Burrowing speeds differed between behaviors and sediment mechanical responses, with slower burrowing associated with plastic deformation. Sternaspis exhibited less variability in behavior and burrowing speed but did extend burrows by different mechanisms consistent with observations of Scalibregma. Individuals of Ophelina acuminata did not extend burrows by fracture; rather individuals plastically deformed sediments similarly to individuals of the related Armandia brevis. Our results extend the range of natural sediments in which burrowing by fracture has been observed, but the dependence of burrow extension mechanism on species, burrowing behavior, and burrowing speed highlights the need for better understanding of mechanical responses of sediments to burrowers.     

Observations on the biology of Apatopygus recens (Echinoidea: Cassiduloida) around New Zealand

The biology of the New Zealand cassiduloid echinoid Apatopygus recens is reviewed in terms of its geographical distribution, sediment relationships, and associations with other echinoids. Observations were also made on the density and size-frequency distribution of an A. recens population at Croisilles* Harbour, Tasman Bay, and on the burrowing and feeding behaviour of specimens from this locality in an aquarium.
A. recens is a rapid and continuous deposit feeder which burrows completely beneath the surface of the coarse sediments with which it is characteristically associated. The construction of a respiratory burrow to the sediment surface was not observed and the species appears to rely entirely on an adequate interstitial water flow for its respiratory requirements. Two 24 mm long specimens each defaecated an average of 0·76 g dry wt of sediment/h which at the Croisilles Harbour habitat was equivalent to a population ingestion rate of about 7·6 g dry wt of sediment/m²/h.     

Modern and fossil traces in terrestrial lithic substrates

A number of biogenic processes leads to the formation of distinctive traces in terrestrial lithic substrates. These include: burrowing by vertebrates in moderately lithified rocks; scraping by mammals; smoothing and polishing of limestone surfaces by the locomotion of mammals; excavation by bees, wasps, and ants producing nesting and dwelling tunnels; dissolution of limestone surfaces by terrestrial snails; endolithic activity of fungi, algae, and lichens on subaerial rock surfaces; root corrosion; etc. Processes of biochemical weathering, biophysical erosion, and enlargement of cracks and fissures by the pressure of plant roots do not leave distinctive traces and therefore lie outside the ichnological realm. The fossil preservation of terrestrial bioerosional traces is expected to be uncommon. Nevertheless, various possible means of preservation must be considered, such as by rapid burial by volcanic material, by fluvial sediments, by travertine or tufa, by loess, “conservation”; in caves, case hardening of surfaces of porous rocks, and preservation of subsoil traces below fossil soils.     

Trace fossils and rhizoliths as a tool for sedimentological and palaeoenvironmental analysis of ancient continental evaporite successions

Recognition of evaporite formations from continental Tertiary basins of Spain provides evidence that trace fossils (including rhizoliths) can be abundant in some saline lake systems and their study helps in palaeoenvironmental interpretation of ancient continental evaporite sequences. Six main types of trace fossils have been distinguished and include: (1) networks of small rhizoliths; (2) large rhizoliths; (3) tangle-patterned small burrows; (4) isolated large burrows; (5) L-shaped traces; and (6) vertebrate tracks. Rhizoliths were related to both marginal areas of hypersaline lakes and lakes of moderately high saline waters. In these settings, pedoturbation resulted from colonization by grasses and bushes of distinct lake subenvironments. The activity of burrowing invertebrate faunas was especially intense in lakes of moderately concentrated brines from which gypsum was the main evaporite mineral deposited. A specific gypsum lithofacies (‘bioturbated gypsum deposits') forming thick, massive beds has a widespread occurrence in many of the basins. Tangle-patterned small burrows and minor isolated large burrows constitute the typical trace fossil types within the gypsum. The traces are interpreted as having been caused by burrowing insect larvae, probably chironomids, coleopterans and annelids. The behaviour of these organisms in recent lake environments yields information about the salinity range of lake waters from which gypsum precipitated. Concentration values averaging 100–150 g/l may be thus deduced though some organisms involved in the formation of the traces can tolerate higher salinities. The combined analysis of lithofacies and trace fossils from the lacustrine evaporite sequences contributes to the study of distinct saline lake subenvironments as well as changes in the sedimentary evolution of the lake systems. Consequently, trace fossils can provide valuable insight for palaeoenvironmental analysis of at least some evaporite formations that accumulated in continental settings.     

Scolicia and its producer in shallow-marine deposits of the Miocene Chenque Formation (Patagonia,Argentina): functional morphology and implications for understanding burrowing behavior

Abstract

Scolicia is one of the most conspicuous trace fossils in lower shoreface deposits of the Miocene Chenque Formation of Patagonia, Argentina. This ichnotaxon consists of horizontal, sinuous or meandering trace fossils with a laminated backfill and two parallel strings located at the base. Abundant body fossils attributed to Brisaster iheringi occur in close association to these trace fossils. The echinoids are very well preserved, and most of the specimens have some areas with their spines attached in life position. In particular, preservation of the subanal tufts of spines, associated to isopores (which are interpreted as being associated to funnel building tube feet), supports the interpretation that these organisms are the producers of Scolicia isp. A shaft connecting the burrow with the sediment-water interface was not observed in vertical sections of the excavations, although on bedding plane surfaces, some small circular tube outlets are recognized. However, the great diversity and abundance of ichnofossils co-occurring in these deposits may preclude adequate identification of vertical structures. These deposits provide an excellent opportunity to integrate trace fossil data, body fossil information and observations from modern analogues in order to perform a morpho-functional analysis of Scolicia.