Trace Fossils

Bioerosional structures are well preserved in the Miocene Boka Bil Formation, exposed in the Kaiphundai section, Thangjing Hill Range of Manipur, India. Eleven ichnospecies representing the Trypanites Ichnofacies, viz., Entobia cateniformis, E. ovula, Gastrochaenolites anauchen, G. cluniformis, G. lapidicus, G. orbicularis, G. ornatus, G. torpedo, Maeandropolydora sulcans, Trypanites solitarius and T. weisei, are recorded from the two sections of the Boka Bil Formation. Two distinctive ichnoassemblages, Entobia-dominated and Gastrochaenolites-dominated are recognised. The Entobia-dominated assemblage suggests relatively deeper marine conditions in the deeper part of the back reef or fore reef while the Gastrochaenolites-dominated assemblage points shallower marine conditions, underwater depth of a few metres in the back reef to patch-reef zone of a back-reef lagoon.

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 crosssection, 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

Crab populations play a major role in net bioturbation of the coastal tracts of the Sagar Island, Hugli Estuary, India. The activities attest to scraping, churning, ingesting, burrowing substrate sediment for feeding, dwelling etc. Non-random distribution of bioturbated patches zone averaged for ten spatial zones indicates percent area bioturbation varying between 0.08% and 29.92%. No significant correlation exists between biological visa -vis geomorphological or sedimentological parameters as recorded under 12 chosen parameters varying in zones (Z1-Z10) and zone clusters (A, B and C). Bioturbated sediments, however, possess coarser mean size and better sorting than non-bioturbated sediments. We predict genetic link between biogenic coarsening of sediments and selective substrate aggradation as recorded in the zones (Z5 and Z6) of higher bioturbation (by percent area) over a decade (between 2008 and 2018). Onshore sediment transport in the study area appears to be influenced by the biogenic reworking and subsequent textural modifications of the substrate sediment. Fining landward trend is perceptible in the post-monsoon, non-bioturbated sediments that escaped seasonal storm reworking and biogenic reworking. Gradual inundation of the substrate is interpreted from the fining up sediment succession and the plant/animal traces preserved in them. This assay at Sagar Island predicts a constructive role of biogenic reworking by crab populations on sediment transport and substrate aggradation. Outcome of the present study may be applied to reconstruct sedimentation milieu in similar bioturbated and tidally influenced, retreating delta margin settings.

When nonlethal attempted predation breaks the aperture of a gastropod shell, the break is preserved as a scar which is frequently visible in the fossil record. Such scars are very frequently observed on fossil and living Turritellidae, a family of high-spired marine gastropods, but little is known about which predators make such scars or how they do so. If the form of these scars on fossil shells could be better interpreted biologically, a large data set of predation scars might become available for analysis. We experimented with live turritellids (Turritella banksi) and four species of crabs from the family Xanthidae (Panopeus sp., Eurypanopeus planus, Leptodius taboganus, and Xanthodius sternberghii) in Panama in order to investigate factors contributing to the breakage morphology resulting from crab predation on turritellid shells. Qualitative examination of scar morphology resulting from attacks by different crab species shows that particular crab species can cause distinctively-shaped scars, although some shapes of scars can be created by more than one crab species. Multivariate analysis of these scars reveals that scar morphologies arising from different crab species fall on overlapping continua in morphospace. Incorporating the shapes of fossil scars into these analyses reveals that fossil scars are similar to many of those created in the aquaria, and that scar shape can be accurately predicted by predator species. In particular, scars caused by Panopeus can be very similar to some fossil scars. Although the particular crab species used in the experiments probably do not prey on turritellids in the wild, the data on causes of break scar morphology and crab-turritellid predation behavior allow information of predation stored in the scars on fossil turritellids to be used to explore the history of predation on this important group of gastropods.

The Pleistocene dune field of Tufia, located on the east of Gran Canaria (Spain), contains different stratigraphic levels of indurated pillar-like structures that are interpreted as megarhizoliths. The megarhizoliths occur at the top of different aeolian sets and reach 31.5 cm in diameter and over 1 m in height. These scattered, free-standing, vertical, cylindrical-to-slightly conical columns usually appear as hollow cylinders, displaying elliptical cross-sections aligned with the prevailing wind. On the leeward side of some specimens the external wall shows a tail of rock matrix resembling a sort of "wind shadow". These tails and other remains of the associated rock matrix show a texture composed of long, horizontal, parallel cylinders orientated with the wind. Internally the most complete structures show five concentrically arranged zones: Zone (a), is a central pore corresponding to the cavity originally occupied by the root; Zones (b) and (c), which include alveolar and laminated carbonate textures indicating that carbonate precipitation was mostly induced by the roots and their associated microorganisms; and Zones (d) and (e), consisting mostly of aeolian sands. In (d) the sand grains show thin micritic coatings whereas in (e) vadose aragonite cements can be seen on the grain surface suggesting a less biogenic influence in their formation. The degree of cementation and the time of the precipitation of carbonate around the roots controlled the preservation of these zones. Thus, in some cases, Zones b, c and/or d are not preserved. Cylinders are up to 30× the diameter of the root that nucleated them. The presence of the megarhizoliths at the top of the aeolianite beds indicates that aeolian sedimentation halted several times, allowing soil formation and plant colonisation during slightly more humid periods. The occurrence of megarhizoliths is further proof of the alternation of arid and slightly more humid climates in the north Atlantic during the last glacial period. It is also noted that they may be misinterpreted as animal trace fossils or tree trunk casts, resulting in incorrect ichnological or palaeoenvironmental interpretations.

New information is provided on trace fossils from the Cambrian Series 2 to Miaolingian in the Upper Member of the Duolbagáisá Formation of northern Norway. This includes the first rich Cambrian material of Halimedides, a trace fossil with more or less regularly spaced swellings of different shapes connected by a median string. It is known principally from Mesozoic and younger deep-sea deposits, with a scarce Paleozoic record, making this one of the oldest occurrences of this ichnogenus. Other trace fossils occurring with Halimedides include the rare Bergaueria sucta, Palaeophycus imbricatus and Cruziana tenella. Psammichnites gigas and Syringomorpha nilssoni are documented photographically for the first time from this unit. The trace fossil association shows general similarity with that of the slightly older Mickwitzia Sandstone Member of southern Sweden and suggests a broad distribution of late early Cambrian trace-fossil producers across Baltica.

The extent and importance of trace fossils preserved in clastic beachrock from the southern section of the Yallahs Salt Ponds on the SE coast of Jamaica are described. The beachrock contains a seaward-dipping facies of cemented sandstones and conglomerates and a landward facies consisting of cemented sandstones packed with the trace fossil Psilonichnus, which is produced by the ghost crab Ocypode quadrata (Fabricius). The seaward-dipping bedded facies represents more than 95% of the beachrock at the Yallahs Salt Ponds and has an exposed height ranging from 6 to 50 cm and lateral continuity of 1 to 200 m. The bioturbated facies, which represents less than 5% of the beachrock at the Yallahs Salt Ponds, was only found at three localities. It has an exposed height of 40 to 60 cm, with outcrops traceable for 6 to 30 m along the beach. These bioturbated Psilonichnus-bearing units demonstrate that beachrock cementation occurred within the intertidal zone and the lower supratidal zone, where modern burrows of Ocypode are found. The high density of Psilonichnus burrows indicates multiple generations of Ocypode burrowing activity, demonstrating that the beach system was stable and was not affected by any tropical storms or hurricanes for an extended period before cementation. Psilonichnus burrows penetrate the entire thickness (up to 50 cm) of the beachrock at the three localities where they are preserved, and this indicates that a single episode of cementation was responsible for beachrock formation. A second episode of cementation is demonstrated by cobbles and blocks of broken beachrock cemented to the top of the exposed beachrock outcrop; this presumably occurred much later than the first phase of cementation.

The origin of motility in bilaterian animals represents an evolutionary innovation that transformed the Earth system. This innovation probably occurred in the late Ediacaran period-as evidenced by an abundance of trace fossils (ichnofossils) dating to this time, which include trails, trackways and burrows 1-3 . However, with few exceptions 4-8 , the producers of most of the late Ediacaran ichnofossils are unknown, which has resulted in a disconnection between the body-and trace-fossil records. Here we describe the fossil of a bilaterian of the terminal Ediacaran period (dating to 551-539 million years ago), which we name Yilingia spiciformis (gen. et sp. nov). This body fossil is preserved along with the trail that the animal produced during a death march. Yilingia is an elongate and segmented bilaterian with repetitive and trilobate body units, each of which consists of a central lobe and two posteriorly pointing lateral lobes, indicating body and segment polarity. Yilingia is possibly related to panarthropods or annelids, and sheds light on the origin of segmentation in bilaterians. As one of the few Ediacaran animals demonstrated to have produced long and continuous trails, Yilingia provides insights into the identity of the animals that were responsible for Ediacaran trace fossils. Molecular clock estimates predict that bilaterian animals diverged in the Cryogenian or Ediacaran period, and many bilaterian clades had diverged before the close of the Ediacaran period . If correct, these estimates mandate the existence of motile bilaterians in the Ediacaran period. In part, this prediction is met by trace fossils from the late Ediacaran period, which include many tracks, trails and burrows 1-3 . However, the phylogenetic importance of these ichnofossils is limited by the dearth of morphological details regarding the animals that produced them. To date, only a few Ediacaran taxa-Dickinsonia 4,5 , Kimberella 6,7 and Yorgia 8 -have been demonstrated to be capable of movement and producing trace fossils. For these genera, evidence for motility comes from trace fossils (known as mortichnia) that are produced shortly before death and are preserved together with the producers of the traces 11 . However, these Ediacaran organisms mostly produced discrete and isolated footprints or radula marks; so far, only Kimberella is known to be capable of producing continuous trails 12 . Thus, the identity of the producer(s) of most of the long and continuous trails that date to the Ediacaran period remains unknown. This limited knowledge about motile Ediacaran bilaterians greatly undermines our efforts to grasp the biological basis for a transformative evolutionary innovation that ultimately led to the Cambrian substrate and agronomic revolutions , which has had lasting effects on the evolution of the Earth surface system . Here we report Yilingia spiciformis (gen. et sp. nov), an animal fossil from the terminal Ediacaran Shibantan Member of the Dengying Formation (dated to 551-539 million years ago) (Extended Data Fig. ) of the Yangtze Gorges area (South China). Y. spiciformis is preserved with its locomotion traces, including a mortichnium. It is an elongate bilaterian animal that shows evidence of body segmentation, segment polarity and directional locomotion. Yilingia offers critical

The origin of motility in bilaterian animals represents an evolutionary innovation that transformed the Earth system. This innovation probably occurred in the late Ediacaran period-as evidenced by an abundance of trace fossils (ichnofossils) dating to this time, which include trails, trackways and burrows 1-3 . However, with few exceptions 4-8 , the producers of most of the late Ediacaran ichnofossils are unknown, which has resulted in a disconnection between the body-and trace-fossil records. Here we describe the fossil of a bilaterian of the terminal Ediacaran period (dating to 551-539 million years ago), which we name Yilingia spiciformis (gen. et sp. nov). This body fossil is preserved along with the trail that the animal produced during a death march. Yilingia is an elongate and segmented bilaterian with repetitive and trilobate body units, each of which consists of a central lobe and two posteriorly pointing lateral lobes, indicating body and segment polarity. Yilingia is possibly related to panarthropods or annelids, and sheds light on the origin of segmentation in bilaterians. As one of the few Ediacaran animals demonstrated to have produced long and continuous trails, Yilingia provides insights into the identity of the animals that were responsible for Ediacaran trace fossils. Molecular clock estimates predict that bilaterian animals diverged in the Cryogenian or Ediacaran period, and many bilaterian clades had diverged before the close of the Ediacaran period . If correct, these estimates mandate the existence of motile bilaterians in the Ediacaran period. In part, this prediction is met by trace fossils from the late Ediacaran period, which include many tracks, trails and burrows 1-3 . However, the phylogenetic importance of these ichnofossils is limited by the dearth of morphological details regarding the animals that produced them. To date, only a few Ediacaran taxa-Dickinsonia 4,5 , Kimberella 6,7 and Yorgia 8 -have been demonstrated to be capable of movement and producing trace fossils. For these genera, evidence for motility comes from trace fossils (known as mortichnia) that are produced shortly before death and are preserved together with the producers of the traces 11 . However, these Ediacaran organisms mostly produced discrete and isolated footprints or radula marks; so far, only Kimberella is known to be capable of producing continuous trails 12 . Thus, the identity of the producer(s) of most of the long and continuous trails that date to the Ediacaran period remains unknown. This limited knowledge about motile Ediacaran bilaterians greatly undermines our efforts to grasp the biological basis for a transformative evolutionary innovation that ultimately led to the Cambrian substrate and agronomic revolutions , which has had lasting effects on the evolution of the Earth surface system . Here we report Yilingia spiciformis (gen. et sp. nov), an animal fossil from the terminal Ediacaran Shibantan Member of the Dengying Formation (dated to 551-539 million years ago) (Extended Data Fig. ) of the Yangtze Gorges area (South China). Y. spiciformis is preserved with its locomotion traces, including a mortichnium. It is an elongate bilaterian animal that shows evidence of body segmentation, segment polarity and directional locomotion. Yilingia offers critical

The ichnogenus Psammichnites herein restricted to Psammichnites gigas is based on comparison of morphology, feeding behaviour, contrast between the burrows and the host rock and possible producers. The record of siphonal activity as a "snorkel device" is discussed. The diagnosis of the ichnogenus Olivellites now is amended and includes all the records of Psammichnites in the post-Cambrian. Olivellites is now documented in successions other than the classical tidal flat deposits facies of the Carboniferous of the USA. We propose

The sedimentary basins in the Continental Rift of Southeastern Brazil (CRSB) provide an opportunity for ichnological analyses due to its well-known facies relationships and paleoenvironmental interpretations. This study reports invertebrate trace fossils from the Neogene fluvial deposits (Floriano Formation) and applies integrated ichnological and facies analyses to reconstruct the environmental conditions recorded in this lithostratigraphic unit. Fieldworks revealed a rich ichnofauna in the Floriano Formation, whose facies associations have been interpreted as indicative of meandering river environments. Four sedimentary facies were identified, including bioturbated sandstone, horizontally stratified sandstone, laminated sandstone, and mudstone. Six ichnogenera were identified, Arenicolites, Beaconites, Camborygma, Palaeophycus, Skolithos, and Taenidium. Those ichnogenera occur as Skolithos, Taenidium, and Beaconites ichnocoenoses. The Skolithos ichnocoenosis is primarily represented within sand bar deposits, indicating arthropod colonization in abandoned channels. The Taenidium ichnocoenosis, which is observed within mudstone layers and presents Camborygma burrows, suggests transitional environments between aquatic and subaerial conditions, locally with high water table levels. The Beaconites ichnocoenosis indicates changes in substrate consistency associated with progressive desiccation and extended exposure time. Therefore, the identified ichnocoenoses, combined with the analysis of physical sedimentary structures, suggest generally humid conditions during colonization by invertebrates of the meandering river deposits of the Floriano Formation.

Trace fossils from a new locality in the Desejosa Formation, Freixo de Espada à Cinta area, northeast Portugal, are described, including Teichichnus rectus and the first Cambrian record from Iberia of the ichnogenus Rosselia, identified as R. cf. socialis. A literary review of the Cambrian record of Rosselia reveals no occurrences older than Cambrian Age 3. The occurrence of Rosselia in the Desejosa Formation therefore adds evidence to that of earlier reports on trilobite remains from the upper part of the Desejosa Formation for a Cambrian age of this unit. Both Rosselia and Teichichnus are zindicative of the Cruziana ichnofacies, which is representative of a shallow-marine depositional environment, consistent with earlier interpretations for the depositional conditions of the upper part of the Desejosa Formation in this sector, and in the equivalent Cambrian units in Spain.. Trace fossils. Rosselia socialis. Teichichnus rectus. Early Cambrian. Iberian Massif. Douro Group.

Understanding shale petrophysical parameters is of interest due to its direct implications as cap rocks for CO 2 or hydrogen storage, waste depositions, and as unconventional reservoirs. The generation and propagation of natural and induced fracture networks in such rocks is highly dependent on the mechanical behavior linked to several sedimentological parameters, as lithological discontinuities or bioturbation. This study is focused on a different sedimentological parameter that consists of trace fossils and their implication on the generation of fluid-assisted fractures, called bedding-parallel veins. In the Austral-Magallanes Basin, Southern Patagonia, Argentina, both geological features, Skolithos Ichnofacies (doomed pioneers trace fossils) and bedding-parallel veins, are numerous, especially at the top of the turbiditic bodies. The trace fossils exhibit U-shaped vertically oriented burrows composed of clean sandstone, partially cemented by calcite, and a spreite in the central part with heterogenous laminated siltstone. Bedding-parallel veins are composed of calcite fibers with some pyrite grains and bitumen. They are located on the top of the trace fossils along the lithological discontinuity between the turbiditic bodies and the impermeable shales. On their surfaces, a radial pattern starts growing from the trace fossils. Moreover, the number of bedding-parallel veins is dependent on the bioturbation intensity. With this study, we infer that trace fossils represent ichnological mechanical discontinuities (IMD) that have a key role in the generation and development of bedding-parallel veins. By correlation, we also suggest that these geological features must be thoroughly studied, especially regarding their potential for the development of induced fracturing networks.

A wide variety of biogenic structures mainly produced by in sect s , spiders, crustaceans , gastropods. bivalves. nematomorphs, nematodes and annelids has been reported from modero nonmarine environm ents. Although the preservarion potential ofthese structures is highly variable. the invertebratc trace fossil record of nonmarine seuings has shown to be richer than once believed. In eolian deposits, low density ichnofaun as are dominated by arthropod crawling traces commonIy associated with vertebrate track ways. Fluvial successions tend to be dominated by arthropod traces associated with vertebrate burrows and root structures. Low diversity ichnofaunas occur in channe l deposits. Low to moderate ichnodiversity assemblages of grazing trails and locomotion/feeding structures are common in floodplain sediments, particularly concentrated in pond deposits. CIosed-basin lake successions have a meagre trace fossil record, but open-basin lake deposits may host abundant ichnofossils. In alluvial-lacustrine transitional zones, meniscate burrows and arthropod trackways are common. whereas in low energy nearshore and offshore lake deposits. relatively high diversity feeding structure and grazing trail ichnof'aunas are present. Nonmarine ichnofossils evidence paleoenvironmental t rerids that are directly linked to progressive ecospace utilization, result ing in a significant increase of the ichnodiversity throughout the Paleozoic. Additionally, depth and extent of bioturbation also increased from t he Perrn ian into the Mesozoic and Cenozoic. At present, three nonmarine archetypical ichnofacies have been recognized. The Termitichnus ichnofacies typifies tcrrestrial deposit s; the Scoye nia ichnofacies characterizes transitional subaerial/aquatic environment s: and the Mermia ichnofacies occurs in permanent subaqucous lacustrine substrai es. However. potent ial add itional ichnofacies may be recognized in the future for other nonmarine environments, such as eolian dune s , dry interdunes, fluvial channels. and high energy lake shorelines.

Las perspectivas de Biocarbónsecuestro de carbono, ciclo de nutrientes y generación de energía Charcoal plays an important role in the global carbon cycle and the storage of carbon in charcoal was proposed by Seifritz in 1993. Seifritz proposed producing charcoal (biochar) and spread it on landfills. This proposal did not receive much attention until recent research on Terra Preta revealed the importance of charcoal to maintain soil fertility, particularly in the humid tropics. Simultaneously, the increasing interest in renewable energy raised the prospect to supply biochar from pyrolysis of waste biomass.

Analysis of conglomerates and sandstones of the Sperm Bluff Formation at the base of the Taylor Group (Devonian) between the Mackay Glacier and Bull Pass provides new insights into the nature of initial coarse-grained deposition on basement along the northern side of the McMurdo sedimentary basin. Six lithofacies are recognized in the Sperm Bluff Formation: conglomerate lithofacies, pebbly sandstone lithofacies, cross-bedded sandstone lithofacies, low-angle cross-stratified sandstone lithofacies, bioturbated sandstone lithofacies and interbedded siltstone/sandstone lithofacies. Sedimentary environments ranged from wave-dominated delta, estuary or lagoon to shoreface and inner shelf. The assemblage is thought to reflect changes in sea level. Rhyolite is the most abundant clast type in the coarse lithofacies, but is unknown in outcrop in southern Victoria Land. The rhyolites correlate in age and geochemistry with Cambrian granites in the basement. Coarse beds also contain numerous qua...

A bstract: A two step cluster analysis based on log-likelihood measures for categorial variables using 'Schwarz's Bayesian Criterion' for grouping allows the automatic detection of ichnofabric categories from a large data set. Preferred succes sions of these ichnofabrics were tested by 'Embedded Markov Chains'. This leads to the following ichnofacies interpreta tion: Alternating periods of higher/lower accumulation rates with higher/lower inputs of particulate food and higher/ lower oxygen contents in pore waters led to sequential colonization of the substrate. The trace fossils Phycosiphon and Nereites represent opportunistic colonization of oxygenated sediments rich in particulate organic matter (POM) by de posit-feeding animals, quickly after an increased sediment input. A further stage of colonization caused by the decrease of POM induced by consumption and oxidation forced the animals to search for food on sediment surfaces and from the water column. The open burrows Thalassinoides, Chondrites, Trichichnus and Zoophycos indicate stable-bottom conditions in periods of low accumulation rates. Zoophycos, Phycosiphon, Nereites and Teichichnus suggest the Zoophycos ichnofacies for the lower section of the core; a transition to the distal part of the Cruziana ichnofacies is suggested for the upper section of the core with the appearance of Thalassinoides. The changes between stable and unstable bottom conditions signifi cantly correlate with periods in magnetic susceptibility and calcium carbonate content, both forced by orbital cycles.

On the slabs surface located in the rural settlement Monjolinho (Fig. 1), in
Anastácio municipality, on the margins of the Engano River, a sub-tributary of the Taquarussu River, geologically belonging to the Botucatu Formation of Cretaceous Age in an interdune paleoenvironment, the engravings reproduce stylized forms, such as a calendar and representation of river channels. Associated with the petroglyphs, there are vertebrate ichnofossils, such as isolated footprints of Theropoda and an undetermined track.

The study of plant-insect interactions provides valuable information about the ecology of feeding behavior and the relationships between the host plant and the producer insect. Records of feeding traces are relatively rare for the Miocene of South America. Here, new records of plant-insect interactions on dicot leaves and fern fronds from the middle and late Miocene of Argentina are presented. In total, 1204 dicot and fern impressions were analyzed including 384 from the San José Formation and 856 from the Palo Pintado Formation. Traces of arthropod herbivory are found on 303 foliar impressions, 288 from the Palo Pintado Formation and just 15 from the San José Formation. Forty-four percent of all traces were found on Thelypteris interrupta (Willd.) Iwatsuki 1963 (Thelypteridaceae), followed by Cedrela fissiliformis Anzótegui and Horn 2011 (Meliaceae) (15.1%) and Schinus herbstii Anzótegui 1998 (Anacardiaceae) (11.3%). Thelypteris interrupta is associated with a low diversity of Damage Types, mainly hole and window feedings, indicating a monospecific relationship with the trace maker. On the other hand, the high abundance and diversity of damage types found on C. fissiliformis and S. herbstii denote that these plants were hosting a more diverse group of arthropods. Likewise, the lower number of traces identified in the San José Formation corresponds to the xeric conditions established during the middle Miocene in northwestern Argentina. These conditions changed in the late Miocene, at least in some regions, to a humid climate, promoting an increase in phytophagy that is evidenced by the abundance recorded in the Palo Pintado Formation.

The discovery of a paving slab with a number of prints suggestive of footprints oftetrapods led to a reinvestigation of a trace fossil, known from three localities, of which on! y two photographs had been published, each with only four prints. The slab was traced to a previously unrecorded site, De Puts, near Calvinia, located in the Tierberg Formation oftheEcca Group of the Karoo Supergroup. The prints from all the sites are referred to Broomichnium permianum Kuhn 1958, of which Quadrispinichna parvia of Anderson 1974 is a synonym.

Physics, materials sciences and mechanical engineering provide constraints that can be used to understand what infaunal animals do and did in the contexts of both making and destroying traces. As a primary example, on the temporal and spatial scales of burrow extension, many muds behave as linearly elastic solids that fail by cracking. These cracks are flattened, discoidal features that previously would not have been recognized as animal traces. Dominant guilds of deposit feeders in the oceans today are equipped with wedges, gills and feeding tentacles to make, breathe in and feed in cracks. As a second example, feeding in different orientations with respect to gravity poses different problems in mixing and transport of digesta, and the varied solutions may leave different fossil signatures. Evolution of vertical bioturbation in mud required innovations in both crack making and digesta handling, suggesting that burrowing innovations may have occurred first in sand, where burrowing at a shallow angle near the sediment-water interface is relatively easy.

ABSTRACT-The classic Early Jurassic age theropod footprints Eubrontes giganteus. Anchisauripus sillil1Ulni. and Grallator parallelus were established by Edward Hitchcock in 1836-1847 and are the type ichnospecies of their respective ichnogenera. We identify, describe, and figure the type specimens in detail for the first time since they were named. We also figure and describe the other elements of the type series as well as specimens mistakenly thought to be the types. All of the tracks corne from cyclical lacustrine and marginal lacustrine to fluvial strata from an interval spanning about one million years in the Early Jurassic age Meriden and Agawam groups of the Hartford and Deerfield basins of Connecticut and Massachusetts. Based on osteometric comparisons with skeletal material, these three ichnospecies were most likely made by theropod dinosaurs, as usually assumed. Although treated here as distinct ichnogenera, it is possible that their major proportional differences derive f...

The Upper Miocene-Lower Pliocene Río Negro Formation (Río Negro Province, Argentina) contains diverse and abundant continental trace fossils. The purpose of this contribution is to recognize distinctive trace fossil assemblages in interdune lakes as response to lake expansion and contraction. The interdune deposits host 23 invertebrate, vertebrate, and plant ichnotaxa that are linked to the hydrological dynamics of the lake. During lake expansion a highly diverse subaqueous trace fossil assemblage reflects an infaunal bivalve population living in a littoral zone with swampy vegetation and semiaquatic mammals. The trace fossil assemblage recorded during Lake Highstand is less diverse and mostly linked to bivalve-generated trace fossils reflecting resting, locomotion, and escape/equilibrium behaviour (comparable to the Mermia ichnofacies). The assemblage during lake contraction exhibits high ichnodiversity and is dominated by vertebrate trace fossils reflecting foraging activities of shorebirds, cursorial birds, and herding semiaquatic mammals and ground sloths frequenting water holes. Flat sandy areas with moist substrates marginal to the interdune lake displayed a moderate ichnodiversity and its distinctive components were armadillo meniscate burrows and footprints in cross-section, as well as subvertical calcareous root casts. Neogene interdune lacustrine deposits reflect a particular zonation of trace fossils in response to changing physical conditions.

This bibliographical and historical compilation pinpoints individual publications that pertain to, in whole or in part, these caves. There are numerous more caves in the region, of course, but these are the ones that have been mentioned in publicly available publications. The federally administered areas in which they are found are the Grand Canyon National Park and Grand Canyon–Parashant National Monument. Additionally, nearby Arizona Strip locales and a few extralimital areas of regional interest are noted. Most of the cave names are informal, their names taken from the publications.
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This is not a “guide” to Grand Canyon caves; it is a bibliographical and historical record of published materials that pertain specifically or partly to each named cave. Locations are not given for the caves due to concerns for resource management and cultural sensitivity, although a few of them are very well known even if they are not accessible by the general public.

for their suggestions and support relative to this research publication. I am indebted to Lindsay McClelland, the co-editor of this volume, for many contributions that helped to promote the management, protection and research of paleontological resources in the national parks. This volume is dedicated to Mike Soukup, Associate Director for Natural Resource Stewardship and Science in the National Park Service. His leadership in building support for science-based decisionmaking has strengthened the management and protection of all park natural resources. Fossils have been key beneficiaries of these policies, as parks increasingly recognize the importance of paleontological research and the value of paleontological resources. Finally, through the combined efforts of the women and men already mentioned, along with many others, the NPS Paleontological Resource Program continues to grow. Many research questions remain to be explored within the national parks and monuments. Likewise, the increasing numbers of paleontological inventories being initiated in the parks continue to uncover new evidence about the biological past. A holistic approach to managing paleontological resources, which includes research, is becoming the standard practice in national parks.

The reconstruction of palaeo-oxygenation levels in marine deposits from the Cretaceous has obtained a huge interest all around the world in recent years. This fascinating topic is here pointed out for the first time in the Austral Basin using the information provided by the black shales of the Río Mayer Formation, Patagonia, Argentina. The combination of sedimentology, ichnology and geochemistry (TOC, Ce anomaly and MnO content) allow the identification of three major intervals respecting the oxygen content. During the Berriasian and early Valanginian anoxic conditions prevail in the outer shelf. After that, between the late Valanginian and Hauterivian dysoxic palaeoenvironments were developed. Finally, a more oxygenated palaeoenvironment occurred since Aptian associated with a progradation of a proximal deltaic system. The identification of anoxic conditions is of much interest for the hydrocarbon research in this stratigraphical unit, which represents the most significant source rock of the Austral Basin.

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The upperm ost part of the Upper Bathonian Sponge Limestone member, Patcham Formation, of the Jhura Dome of Kachchh Mainland is a thickening-and shallowing-upward succession topped by medium-to thick-bedded humm ocky cross-stratified grainstones deposited by storm waves. Occasionally, thin, com monly lenticular, intraclastic-bioclastic silty marl intercalations between the grainstones are highly bioturbated, in contrast to the grainstones, in which, for the most part, trace fossils occur scattered. Large exposures of bedding planes o f the grainstones allow the detailed investigation of ichnological features, whereas the high density of traces in the soft marls precludes the identification of any ichnotaxa. Eighteen ichnotaxa have been recorded including Ophiomorpha, Thalassinoides, Taenidium, Gyrophyllites, Chondrites, Dactyloidites, Teichichnus, Bolonia, and Ancorichnus. Except for Ophiomorpha nodosa and Thalassinoides, which generally indicate m oderate to high energy conditions and are the dw elling burrows of suspension-feeding to omnivorous crustaceans, the ichnotaxa represent a deposit-feeding behaviour of their producers and thus are charac teristic of low-energy environments. The trace fossils form three ichnoassem blages characterized by (1) Ophiomorpha nodosa and Thalassinoides suevicus, (2) IThalassinoides isp. A, Taenidium, and Bolonia lata, and (3) Ancorichnus. The dom inance of traces of deposit-feeders in rocks indicative of high-energy events is counterintuitive and points to their non-contemporaneity. The sedim ents were deposited during brief highenergy events, whereas the trace fossils were produced when, after w aning of storm s low-energy condi tions prevailed. This tim e-averaging is particularly pronounced in trace fossils that extend vertically dow n wards and m ay reach strata deposited under distinctly different conditions. Thus, environmental interpretations based on trace fossils should refer to colonisation surfaces rather than to the sedim ent sur rounding the trace fossils. In the latter case, interpretations m ay be erroneous, especially when erosion * C o rre sp o n d in g author.

Based on detailed sedimentological analyses of cores, interpretation of well logs and a set of geochemical measurements performed on lacustrine sedimentary rocks, the palaeoenvironmental evolution
and the sedimentary architecture of the Paleogene continental Vistrenque Basin (SE France) have been reconstructed. The analysis of sedimentary archives revealed three main stages of basin infill evolution: (1) a
deep-lake basin (Priabonian-earliest Rupelian) whose sedimentation was dominated by terrigenous gravity driven deposits during a period of high subsidence rate and strike-slip fault activity and under a prevailing
humid climate; (2) an evaporative deep lake (early Rupelian) characterized by a drastic reduction in lake volume (forced-regression), terrigenous supplies and deposition of evaporites in disconnected sub-basins;
(3) an overall long-term normal regressive stage (middle Rupelian to earliest Chattian) of lake infill characterized by an increase in terrigenous supplies and a vertical upward transition from deep-lake gravitydriven
deposits to marginal lake and floodplain sedimentation. The onset of lake volume reduction and forced regression during the early Rupelian is associated with (1) the reworking of marginal lake carbonates
into the deep lake areas, (2) the deposition of organic-rich sediments (TOC > 10%) coupled with sulphatereduction processes in the deepest areas of the lake, (3) an important decrease in terrigenous supplies and (4) a long-term increase in d18O of matrix-supported carbonates. This early Rupelian forced regression of the Vistrenque lacustrine system is interpreted to result from a regional decrease in precipitation in response to global cooling during the Eocene-Oligocene Transition (EOT). The final infill of the Vistrenque lake system (late Rupelian-early Chattian) and the onset of a floodplain occurred in more humid conditions during a stage of decreased activity of the Nîmes Fault, prior to or during an early stage of the Liguro-Provençal rifting.

The ichnospecies Gastrochaneolites dijugus Kelly and Bromley 1984 and Teredolites longissimus Kelly and Bromley 1984, attributed to the boring activity of gastrochaenoid and pholadid bivalves, are described respectively from the Miocene Vilanova Basin and the Pliocene Almer ıa-N ıjar Basin. Miocene and Pliocene traces are preserved as positive casts associated to invertebrate shells and wood fragments, respectively; in both cases, the host substrate (shells and wood) has been lost almost entirely by different taphonomic processes (mainly dissolution). For the first time in the fossil record, the complete ichnogenetic sequence of these two ichnospecies is described and figured.

Modern fish are able to produce a plethora of different traces (both bioturbation and bioerosion structures) according to several behaviours, yet only five ichnotaxa have been interpreted as produced by the activity of fish in the fossil record. Many taphonomic factors may favour the non-fossilization of many of these traces and, even fossilized, they could have been misinterpreted. In this contribution, shallow and bilobed traces produced by the feeding activity of the perciform fish Diplodus vulgaris (Sparidae) in the estuary of the Piedras River (Lepe, Huelva, SW Spain) are described. Neoichnological study and comparison of these bioturbation structures with the fossil record allow associating them as Cruziana-and Rusophycus-like traces, i.e. traces with features very similar to those of such ichnogenera. Since these ichnotaxa have been commonly interpreted as the result of the locomotion and resting of different kinds of invertebrates, in order to get a better understanding of the marine and continental fossil record, we also propose taking into account fish as potential producers of these kind of traces in future paleoichnological studies.

Ein fragmentierter phyllocarider Krebs aus dem unteren Emsium von Reideschbaach bei Heiderscheid in Luxemburg wird kurz beschrieben und abgebildet. Basierend auf Merkmalen der Verzierung der Kutikula wird das Fossil vorläufig der Familie Rhinocarididae zugeordnet und mit einigem Vorbehalt zu der Gattung Nahecaris gestellt. Die starke Fragmentierung des Krebspanzers, die bereits vor der Einbettung stattgefunden hat, spricht dafür, dass es sich um einen möglichen Fraßrest handelt.

A fragmented phyllocarid crustacean from the lower Emsian of Reideschbaach near Heiderscheid/Luxembourg is briefly described and figured. Based on features of carapace ornamentation the fossil is tentatively placed in the family Rhinocarididae and assigned with reservations to the genus Nahecaris. The strong fragmentation of the carapace, which took part prior to burial, suggests that this specimen could represent a prey remain.

is an author of a recently published Open Access (free to read) article published in the journal Ecology and Evolution that draws attention to problems in estimating the sizes of extinct animals known only from incomplete remains. Paleontologists are often forced to make size estimates of extinct animals based on fragmentary remains, such as a tooth or a few bones. Often, such estimates are made by scaling up or down in size from living or extinct organisms known from complete or nearly complete remains, called `proxies.' Several potential problems were pointed out by the authors of the study. The organisms chosen as proxies might be only distantly related to the organism under study or otherwise unsuitable. Different dimensions of the body might scale differently with size rather than uniformly. The organism under study might be vastly greater in size than the proxy organisms. Four case studies, all of iconic, large marine animals, were discussed in detail. The taxa chosen for study were Dunkleosteus, Helicoprion, `Megalodon', and Perucetus. Dunkleosteus is a large, predatory, armored fish from the Devonian Period. It is known only from the bony skull and trunk armor. A cast of Dunkleosteus in the displays of the Denver Museum of Nature & Science is shown in Figure . Previous estimates of the body length range from 5 to 10 meters (i.e., up to 33 feet). However, recent studies conclude that the body was shorter and `chunkier', with a maximum length of about 4.1 meters (13.5 feet). The drawing in the background of Figure might need to be corrected.

Рассмотрены и проанализированы представления о так называемых ” карликовых”, малорослых и крупных колониях / рабдосомах граптолитов - давно вымершей группы очень мелких  морских колониальных животных, которые жили в далекую палеозойскую эру, в частности, на протяжении ордовикского, силурийского и девонского геологических Периодов.
В силуийском Периоде они стали доминирующей планктонной группой организмов, остатки которых имеют важнейшее значение для биостратиграфии пород осадочного происхождения.
В статье обсуждаются условия обитания  граптолитов в силурийском Периоде геологической истории Земли и некоторые возможные пути их эволюции и закономерности развития в пелагических зонах открытых морей, не блокированых от глобальных океанических водных просторов.
Вероятно именно с этим связано важнейшее значение остатков колоний граптолитов для биостратификации неритовых (глубоководных) осадочных горных пород.
До  окончания девонского периода граптолиты практически исчезли из геологической летописи, что, возможно, связано с глобальными изменениями климата и очередными регрессивными этапами в эволюции Земли, которые сильно сужали ареалы их обитания и снижали доступные для жизни граптолитов водные ресурсы.

Scratch circles are bedding-plane parallel sedimentary structures formed by the current-induced rotation of an organism attached to or partially inserted in the sediment, generating complete or partial circular impressions into the surrounding sediment (e.g. Allen 1982). Today they are most commonly observed in a sub-aerial setting due to wind-induced rotation of grass, or other plants (Fig. 1A, B). They also form sub-aqueously (e.g. Langerfeldt 1935, Ewing & Davis 1967) and this is the environment in which most fossil scratch circles formed. They are typically preserved as casts on bed soles (Fig. 1C) but are also found occasionally on bed tops (Fig. 1D). In a comprehensive text on sedimentary structures Allen (1982, pp. 521, 522) outlined the general characteristics and formation of scratch circles, including a single record of a scratch circle in the geological record, documented by Prentice (1962) from Cretaceous rocks of England. Although many additional occurrences are known, several of which were initially interpreted as body fossils or trace fossils (review in Jensen et al. 2002), they remain a relatively rare-or rarely reported-sedimentary structure. Possibly the earliest identification of a fossil scratch circle was made by Nathorst (1886) who compared 287

Fossil localities on the 80,000 year-old Bird Rock Terrace in coastal San Diego Co., Southern California yielded 5,160 specimens of the purple olivella shell, Callianax biplicata (Sowerby 1825), of which 749 (14.5%) had been drilled by octopods. However, in any one collection, the percentage of drilled Callianax specimens ranged between 2.4 percent and 26.4 percent. This suggests that a careful reexamination of existing museum fossil collections should reveal a rich, but previously overlooked, fossil record of octopod predation in the marginal eastern Pacific in the recent geologic past.