Trace Fossil Zoophycos Research Articles

Lower Jurassic trace fossil Zoophycos from the Ksour Mountains of northwestern Algeria and their palaeoecological and palaeoenvironmental significance

The Zoophycos ichnofacies is reported for the first time from the Lower Jurassic (Toarcian) deposits of Algeria. The trace fossil-bearing strata in the Ksour Mountains, northwestern Algeria, are an alternation of fine-grained limestones and marls. The assemblage is characterised by its low diversity, consisting of eight ichnospecies (Chondrites intricatus, C. targionii, Chondrites isp., Palaeophycus isp., Thalassinoides isp., Zoophycos brianteus, Z. cauda-galli, and Zoophycos isp.), representing the Zoophycos ichnofacies ethologically dominated by deposit-feeding behaviours of different producers. The abundance of Zoophycos and Chondrites within a low diversity assemblage suggest stressful conditions most likely indicating oxygen depletion within the sediment. Moreover, the presence of reworked burrows by Chondrites could indicate ecological succession. This is probably due to environmental conditions getting more stressful, and causing the need for exploiting the nutrient stored in the abandoned burrows after the death of the trace maker. This process is primarily associated with an oxygen-depleted environment, compelling the animal to engage in it as a means of obtaining energy, rather than actively searching for food within the sediment. On the other hand, the occurrence of Thalassinoides may indicate an improvement of palaeoecological conditions and short periods with partial increase of oxygenation. The ichnological, palaeontological and palaeoecological data of the studied succession indicate a relatively deep-water environment located well below the storm wave base at a deeper offshore setting.

CHARACTERIZATION OF BEHAVIORAL COMPLEXITY IN MARINE TRACE FOSSILS AND ITS PALEOENVIRONMENTAL SIGNIFICANCE: A CASE STUDY OF ZOOPHYCOS

The paleoenvironment influences trace-making behavior significantly, and progressively more evidence shows that this behavior follows scale-invariance properties. In this study, we focused on the definition of behavioral complexity in the trace fossil Zoophycos to explore its paleoenvironmental significance. Firstly, the fractal topography in Zoophycos was established by introducing virtual tertiary lamellae. Next, a fractal dimension ([Formula: see text]) model was proposed and the spatio-temporal evolution trend of the complexity of the trace-making behavior was established. In application, the correlation of [Formula: see text] to the paleo-water depth and substrate consistency of the paleoenvironment was analyzed with the aid of variations of [Formula: see text]C and lamellae deformations in Zoophycos from the Carboniferous-Permian Taiyuan Formation of North China. The results show that [Formula: see text] increases with paleo-water depth, although it decreases when the degree of substrate consistency increases. Our investigation indicates that fractal topography not only provides an essential explanation for the complexity of trace-making behavior but also plays a reliable and significant role in paleoenvironmental interpretation. Most importantly, this work may shed some light on the subject of fractal ichnology and provide a mathematical framework toward studies in quantitative ichnology.

Variations of the trace fossil Zoophycos with respect to paleoenvironment and sequence stratigraphy in the Mississippian Mobarak Formation, northern Iran

Zoophycos in the Mississippian Mobarak Formation (Central Alborz, Iran) shows its potential in interpreting depositional settings, ecological features and sequence stratigraphy. Zoophycos A (ZoA), Zoophycos B (ZoB), Zoophycos/Phycosiphon (Zo/Phy) and Phycosiphon (Phy) ichnocoenoses are identified in the middle and outer ramp facies of the Mobarak Formation on the basis of shape, ichnodensity, ichnocomplexity degree and size of Zoophycos and other trace fossils. Zoophycos portrays a proximal-to-distal trend in the storm-dominated ramp sequence. In deeper parts of the ramp with long-term stable conditions and organic enrichment, Zoophycos producers selected equilibrium strategies (K-selected), whereas into the shallower parts they opted for opportunistic behavior (r-selected) due to short-term stable conditions with low food flux. The feeding behavior proposed in this study is based on general morphology as well as mode of sediment exploiting, and includes deposit feeding and the caching model. Moreover, this study confirms that the distribution pattern of the Paleozoic Zoophycos producers within a sequence stratigraphic framework that was totally different from that of the Mesozoic and Cenozoic. During the late transgressive systems tract (TST) and early highstand systems tract (HST), the excess of benthic food and the environmental stability, together with the prevalence of dysaerobic conditions, caused intense burrowing by the Zoophycos producer in proximal outer ramp to distal middle ramp. Its ethology, paleoecologic strategies and taphonomic signatures suggest that erosionally-exhumed, dewatered muddy beds (firmground) were not able to provide appropriate conditions for deposit-feeding Zoophycos producers as a consequence of their lower environmental stability. Therefore, Zoophycos as a standard component of the resident fair-weather community cannot be a good representative of the distal expression of the Glossifungites ichnofacies.

Paleoenvironmental analysis of the ichnogenus Zoophycos in the Lower Devonian tempestite sediments of the Longmenshan area, Sichuan, China

The trace fossil Zoophycos is characteristic of the Lower Devonian in the Longmenshan area of southeastern China. Three distinct storm-generated or induced types of sedimentary sequences bearing Zoophycos have been identified in shallow marine deposits of the Bailiuping Formation and the Yangmaba Formation. The type A deposit is composed of siltstones with shell concentrations and wave ripples and small Zoophycos at the top. The type B deposit is characterized by fine-graded sandstone with long wavelength hummocky cross-stratification and black gray mudstone as well as the largest and densest Zoophycos at the top. The type C deposit has graded bioclastic limestone with short wavelength hummocky cross-stratification, muddy wackestone and large Zoophycos at the top. Based on the features of the types of Zoophycos, the distribution zone of the Zoophycos ichnogenus that preserved in tempestite sequence was built between the fair weather wave base and storm wave base in the Lower Devonian. This research suggests that the distribution patterns of Zoophycos formed in storm-induced deposits may not provide significant clues for the estimation of relative water depths.The hydrodynamic conditions and sedimentation rate are two important environmental factors of the development of the Zoophycos in the Lower Devonian shallow marine deposits where it was mainly affected by storms between the fair weather and storm wave bases. The abundance of Zoophycos at the top of locally frequent storm deposits could indicate a fairly opportunistic behavior and they were formed in the early HST deposit, which had a relatively stable environment with low energy and higher sedimentation rate.

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.

Testing ethological hypotheses of the trace fossil Zoophycos based on Quaternary material from the Greenland and Norwegian Seas

Despite the fact that the trace fossil Zoophycos has been found in rocks from most of the Phanerozoic, little consensus has been reached on how and why this intricate burrow was constructed. The Cenozoic morphotypes of Zoophycos typically include a helically coiled spreite arranged around a vertical shaft connected to the sediment surface. Morphological details and environmental preferences of the Zoophycos producer were studied using 156 cores from the Norwegian and Greenland Seas in order to test the different ethological hypothesis proposed for this trace fossil. The spreiten were constructed during interglacial or interstadial intervals and consist of a repeated alternation of lamellae consisting of fine-grained pelleted material, and coarse-grained unpelleted material, respectively. Spreiten were encountered in vigorously bioturbated sediment, in turbidite layers, and in layers dominated by coarse ice-rafted debris. This indifference to the composition of the substrate effectively rules out ethological models based on different forms of deposit-feeding, and the large size and wide spacing of the whorls of the spreiten also make the cesspit model unlikely. Rather, the observed features best agree with a cache behaviour, where the main purpose of the deep penetration was to store food and to prevent access by other burrowers, likely combined with some gardening of microbes. However, no indubitable evidence of a reworking of the cached material could be found, and probably the answer to how the cache was accessed by the producer is to be found in the marginal tube. The difference in diameter between marginal tube and spreiten lamellae, together with the presence of both open and filled marginal tubes indicate that the marginal tube is the result of a far more complex behaviour than simply a lateral shift through the sediment.

Cambrian Trace Fossil Zoophycos from the Czech Republic

Abstract Lobate and helical ichnofossils attributable to Zoophycos found in Middle Cambrian shales of the Palác Hill in the Železné Hory Mountains (eastern Bohemia) represent the oldest occurrence of this ichnogenus. Such a complex Zoophycos became frequent during the Mesozoic but has been never recorded in strata older than the Ordovician. As such, they represent the oldest occurrence of helical Zoophycos. Besides Zoophycos isp. there is also a 15 cm thick sandy siltstone layer which is strongly bioturbated by Planolites isp., which seems unusual in a Lower Cambrian ichno-association.

The trace fossil Zoophycos from the Silurian of Estonia

The trace fossil Zoophycos from the Silurian of Estonia

Trace fossil Zoophycos from the Aoshima Formation of the Neogene Miyazaki Group, southeastern Kyushu, Japan

Trace fossil Zoophycos from the Aoshima Formation of the Neogene Miyazaki Group, southeastern Kyushu, Japan

Changes in lifestyle and habitat of Z oophycos -producing animals related to evolution of phytoplankton during the Late Mesozoic: geological evidence for the ‘benthic-pelagic coupling model’

The trace fossil Zoophycos characterized by complex, three-dimensional morphology with systematic internal structures occurs throughout the Phanerozoic marine sediments. The specimens of Zoophycos examined herein consist of a downward and helical spreite and are a product of the excretory behaviour of endobenthic detritus feeders. They are divided into two basic types: pre-Jurassic and post-Cretaceous types on the basis of whorls of spreiten in a single specimen. The pre-Jurassic type has fewer than four whorls. In contrast, most of the post-Cretaceous specimens exhibit spreite with multiple coils more than ten whorls. The abrupt increase in whorl number during the Cretaceous suggests that the sedentary lifestyle of the producer should change from a short-term stay to long-term or permanent occupation of the same burrow. Timing of the lifestyle change the Zoophycos producers seems to be closely related to the deep-seaward migration of their habitats. The change in lifestyle and migration of Zoophycos-producing animals during the Cretaceous might be attributable to the establishment of eutrophic bottom conditions in the deep sea. These changes seem to be associated with the flux of large amounts of phytodetrital food produced by phytoplankton, which experienced an explosive increase in species diversity during the Late Jurassic to the Late Cretaceous. The series of changes in lifestyle and habitat of the Zoophycos animals during the Late Mesozoic can serve as one piece of geological evidence for the ‘benthic-pelagic coupling model’.

Ethological analysis of the trace fossil Zoophycos: hints from the Arctic Ocean

The distribution of the trace fossil Zoophycos in Quaternary marine sediments from the Arctic Ocean was studied in twelve piston and gravity cores retrieved during the Swedish icebreaker expedition ...

Zoophycos cyclicity during the last 425 ka in the northeastern South China Sea: Evidence for monsoon fluctuation at the Milankovitch scale

In a deep-sea piston core, covering the last 425 ka from the northeastern South China Sea, power spectrum analysis of several core data from sediment parameters has been conducted and compared with that obtained from time-series analysis of the distribution of the trace fossil Zoophycos through the core. Power spectra show a more or less well developed cyclical pattern, with similar cyclostratigraphic patterns for sand and carbonate content, oxygen isotopes and Zoophycos distribution, but different for carbon isotopes and total organic carbon content (TOC). Temporal calibration allows the recognition of Milankovitch orbital–scale cycles, with a duration of 111–100 ka for short-term eccentricity, 63–55 ka for the combined effect of both precession and obliquity, 42–40 ka for the obliquity cycle, and 28–21 ka for the precessional cycle band. The variable Milankovitch-scale cyclicity suggests the influence of a complex interaction of variable processes. East Asian monsoon variability at the Milankovitch orbital–scale cycles could determine variations in environmental conditions, including changes in the organic material reaching the sea floor, and in turn influencing the cyclical occurrence of the Zoophycos trace makers. The cyclicity of Zoophycos is of special interest to basin analysis, where Zoophycos has the potential of being used as a proxy for cyclical monsoon fluctuations at the Milankovitch scale.

Complex behavioural pattern as an aid to identify the producer ofZoophycosfrom the Middle Permian of Oman

The trace fossil Zoophycos is abundant in transgressive, shallow marine carbonates in the Middle Permian (Wordian) Khuff Formation of the Huqf-Haushi Uplift of Interior Oman. It often occurs as part of a complex (compound) trace fossil that comprises two integrated elements: (i) irregular galleries with straight to gently curved tunnels and interconnected shafts, and (ii) simple planar to complex spreiten structures with a marginal tube (Zoophycos). The galleries are characterized by irregularly winding, dichotomous branching, large variation in shape and size and circular to elliptical vertical cross-sections. Zoophycos consists of spreiten with a marginal tube, either originating as a simple lobe from the convex segment of a curved tunnel, or forming more complex, subcircular, spreiten systems parallel to bedding. The spreiten were formed by simple strip mining, where the animal defecated without producing faecal pellets. U-shaped marginal tubes indicate that the burrows were well aerated. The complex trace fossil points to combined dwelling and deposit-feeding behaviour, with irregular galleries in the firm substrate and Zoophycos spreiten in the softground below it. It can be assumed that the animal used the open tunnel system mainly for dwelling (domichnion) and possibly suspension feeding, but occasionally changed to deposit feeding while creating the spreiten (fodinichnion). The integration of the irregular galleries (tunnels and interconnected shafts) with the marginal tubes of Zoophycos suggests the same producer for this compound trace fossil. Many modern polychaetes produce very similar galleries within firm and soft substrates, and polychaetes are therefore interpreted as the most likely producers. Similarities between Permian and Triassic Zoophycos suggest comparable trace making behaviour before and after the end-Permian mass extinction.

2. Ethological interpretation of the trace fossil Zoophycos in the Hikoroichi Formation (Lower Carboniferous), southern Kitakami Mountains, Northeast Japan

2. Ethological interpretation of the trace fossil Zoophycos in the Hikoroichi Formation (Lower Carboniferous), southern Kitakami Mountains, Northeast Japan

Microbial and molecular fossils from the Permian Zoophycos in South China

The trace fossil Zoophycos was enriched in the lower part of the Guadalupian Maokou Formation of Permian in Laibin, Guangxi of South China, and characterized by observable lamellae within its spreiten. Associated with these lamellae are the prolific coccus- and spirillum-shaped microbe fossils. These microbes morphologically identified are 0.4–3.0 μm in diameter or length. Molecular fossils, including normal alkanes (dominated by C18, without an odd-over-even predominance), acyclic isoprenoids (such as pristane (Pr) and phytane (Ph)), extended tricyclic terpanes, pentacyclic triterpanes, steranes, alkylcyclohexanes, dibenzothiophenes, benzonaphthothiophenes, benzobisbenzothiophenes, were instrumentally identified in the wackestone characterized by the occurrence of abundant Zoophycos (composite ichnofabric indices are 4) and crowded microbial fossils. The value of the Pr/Ph ratio is less than 1, indicative of a dysoxic condition. The identification of abundant sulfur compounds (the thiophene series) related to the contribution of reductive sulfur favors the occurrence of sulphate-reducing bacteria. The association of abundant microbial colonies with microbial molecular fossils within the spreiten suggests that trace fossils Zoophycos would be a multifunctional garden carefully constructed by the Zoophycos-producer, where different microbial colonies were orderly and carefully planted and cultured in different minor lamellae within spreiten. Hence, it is proposed that the Zoophycos-producer symbiosed with microbial colonies on the mutual basis of food supply and the redox conditions.

Temporal variations of the trace fossil Zoophycos in a 425 ka long sediment record from the South China Sea: implications for the ethology of the Zoophycos producer

A 425 ka long record from piston core GIK17925-3 taken in the northeastern South China Sea was used to study the environmental conditions controlling the distribution of the Zoophycos trace fossil. The 12 m long core offers a unique opportunity to study the response of the Zoophycos-producing animal to environmental variations over four glacial–interglacial cycles. The trace fossils show a strong glacial to interglacial variation in their abundance with a special preference for intervals with low sedimentation rates. Additional X-ray radiograph studies of piston cores from the Southeast Asian Marginal Seas show that the trace fossil Zoophycos is widespread in slope and deep-marine sediments, with the highest abundances encountered in low sedimentation rate settings. The preference of the Zoophycos producer for low sedimentation rates in a setting with strong seasonal fluctuations in food supply due to the shift between winter and summer monsoons, is interpreted to be the result of a cache-model behaviour, where food is collected during rich times and squirrelled away for poor times. Core GIK17925-3 also offers an opportunity to assess the impact of Zoophycos bioturbation on various palaeoenvironmental proxies. In this core, more than 30 % of the measured data points were more or less strongly affected by Zoophycos bioturbation. Together with the widespread occurrence this percentage indicates that Zoophycos may pose a serious threat to palaeoclimatic reconstructions in cores from low to moderate sedimentation rate sites.

Gallery of Geology - The trace fossil Zoophycos in the Sandia Formation of north-central New Mexico

Gallery of Geology - The trace fossil Zoophycos in the Sandia Formation of north-central New Mexico

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.

Early Jurassic to Late Cretaceous evolution of Zoophycos in the French Subalpine Basin (southeastern France)

The complex and enigmatic trace fossil Zoophycos is recorded worldwide, from Cambrian to Holocene. The possible evolution of the ichnofossil has already been proposed by some authors, but their works concerned the very large group of trace fossils related to Zoophycos (structures that could be assigned potentially to several ichnogenera) recorded in several depositional basins. This paper focuses on the Subalpine Basin of southeastern France, where excellent outcrops facilitate the study of changes in Zoophycos that occurred between the Early Jurassic and Late Cretaceous. Thousands of specimens have been studied in detail. It appears that several trace fossils, classically related to Zoophycos, are so different that they could actually represent separate ichnogenera. But a group of them can be considered as belonging to a single ichnogenus, as they share the same morphological characters: a thin layer of bioturbated sediment (lamina), constituted by a network of primary and secondary lamellae and bordered by a marginal tube. The outline may be simple or lobate. The general architecture is a flattened cone, spirally coiled around a virtual central axis, without a vertical tunnel, and constructed upward, or, rarely, downward, in the sediment. One or several subsequent whorls are observed. The producers could have been specialized deposit feeders (sipunculans?), following a K-selected strategy. All these trace fossils are found in fine- to medium-grained limestones and marls. Inside this group, subtle differences make it possible to distinguish four morphotypes; they differ in size and how lobate they are, and they could be assigned to true ichnospecies. They succeed in time with slow and gradual changes and two trends are documented. These Zoophycos underwent evolutionary and environmental changes during the Jurassic–Cretaceous interval, becoming more lobate and larger, as they migrate to deeper and deeper environments. The four morphotypes share the same basic morphology, result from the same general activity, and are restricted to the same depositional basin. Therefore a unique clade of Mesozoic Zoophycos producers could be proposed. These animals have constructed structurally elaborate burrow systems that record complex and varied behavior. These trace fossils can also be regarded as extended phenotypes, that is adaptive projections of the organisms’ body and activity. The changes of the ichnofossils documented in the basin can thus reflect real changes in the organisms themselves and in their ethology: their phylogenetic history is mirrored to a certain extent in the succession of morphotypes. So, complex trace fossils, such as Zoophycos, are not only biosedimentary structures, but true mirrors of the evolutionary trends of their producers. This opens a new biological perspective for ichnological studies.

ニュージーランド古第三系アミュリ石灰岩産ZooPhycos(生痕化石)の形成メカニズムと形成者の古生態の再検討

ニュージーランド古第三系アミュリ石灰岩産ZooPhycos(生痕化石)の形成メカニズムと形成者の古生態の再検討