Ichnology

Abstract: Trace fossils such as Climactichnites offer rare insights into the palaeobiology of Cambrian soft-bodied animals, especially those that inhabited emergent sand flats and are not known from body fossils. Analysis of field and museum Climactichnites, together with experiments on the preservation of similar modern trails, indicates that the tracemaker was an elongate, bilaterally symmetrical, dorsoventrally flattened, soft-bodied animal with a muscular foot.

More than two hundred subcircular to crescent-shaped depressions, often with radiating markings, were discovered on a 120 m 2 bedding plane interpreted as base-of-slope carbonate deposits and belonging to the LutetianBartonian Peschici Formation at San Lorenzo (Vieste, Gargano Promontory, Italy). The area was mapped using a high-resolution aerial camera (mounted on a kite) and a terrestrial laser scanner. The survey allowed detailed morphologic analysis and topographic mapping of the traces, in order to analyze the very regular distribution pattern. The ichnological study, combined with sedimentologic and stratigraphic analyses, identifies the depressions as fish feeding traces. Although the tracemaker cannot be definitely identified, the comparison with modern and fossil fish excavations suggests a higher affinity with bony fishes (e.g., sturgeons) than with rays. The trace fossils are here attributed to the ichnogenus Piscichnus and constitute the first discovery of this ichnotaxon in the middle Eocene of the Apulia Carbonate Platform and of Italy.

The USGS estimates that the Powder River Basin contains as much as 1050 MMBO and 15,000 MCFG in unconventional, continuous reservoirs, making it one of the more prospective oil and gas basins in the Rocky Mountain region of the western United States. The Turner Sandstone has emerged as one of the "hottest" resource plays in the Powder River Basin. However, unlike its stratigraphically equivalent Wall Creek Member of the Frontier Formation, there is very little published data on the Turner Sandstone. This paper presents the workflow and preliminary results of a core facies, log facies, and sequence stratigraphic evaluation of the Turner Sandstone Member of the Carlile Shale in the Porcupine Field area of southeastern Campbell County. More than a dozen cores and hundreds of well logs were used in this evaluation.

The Turner Sandstone disconformably overlies the Pool Creek Member and is conformably overlain by the Sage Breaks Shale Member of the Carlile Shale. The lower Turner Sandstone consists of streaky, lenticular, and wavy bedded heterolithic strata and contains a low diversity, stressed, restricted, or brackish water trace fossil assemblage. The upper Turner Sandstone consists of upward coarsening vertical successions of bioturbated mudstone, bioturbated shaly sandstone, and bioturbated sandstone that are commonly "capped" by cross-stratified sandstone and structureless, "cryptically bioturbated" sandstone. The upper Turner Sandstone contains a high diversity, normal marine inner shelf trace fossil assemblage dominated by filter-feeding organisms. Most conventional production was from cross-stratified and structureless sandstone facies that accumulated in elongated, isolated sand bodies or sand ridges. Much of the remaining reserves are stored in low resistivity, pervasively bioturbated, shaly sandstone that represents less active parts of the inner and outer shelf system.

Systematic description of 25 gastropod species from the Khari Nadi Formation (Aquitanian) and Chhasra Formation (Burdigalian) from the Kachchh District, Gujarat, India is given. A checklist of 116 forms including those reported by earlier researchers, emending taxonomic identifications wherever necessary, is also provided. Vredenburg had referred these two formations together as ‘the Gaj Beds of Kachchh’. He noticed the affinity of molluscs among the Miocene deposits of Kachchh and Kathiawar regions of Gujarat, and Sind province of Pakistan. He also observed that molluscs from his ‘Lower Gaj’ and ‘Upper Gaj’ Formations showed relationship respectively with the Rembang (Aquitanian) and Njalindung (Burdigalian) series of the East Indies. Aquitanian and Burdigalian ages assigned by him were later substantiated by Raju on the basis of foraminifera. Present studies corroborated that the molluscan assemblage from the Miocene rocks of Kachchh is closely related to that from the Gaj Beds of Sind and the Ashapura Clay Member of Kathiawar; besides revealing that the fauna from these three formations taken together is essentially endemic. Discovery of certain species from the Quilon Beds in the Miocene of Kachchh evinces a close affinity between these two formations. The present fauna includes five extant forms, while 29 forms have related species in the Recent fauna.

"The modern benthic foraminiferal tests collected from a coastal area of south-western Sardinia (Portoscuso-Portovesme) that is heavily polluted by industrial activity reveal intense and widespread bioerosional structures induced by diversifi ed microborers. A large number of the foraminifera reveals microscopic round holes (1-60 μm in diameter) and roundish concavities (25x40 μm in external diameter) on their surface that belong, respectively, to the ichnospecies Oichnus simplex Bromley, 1981, and Fossichnus solus Nielsen et al., 2003. These traces just occur in the tests of the foraminifera which are heavily infested by microendolithic cyanobacteria, algae and fungi suggests comparable ethological behaviour between the ichnospecies Fossichnus and Oichnus and the microbial euendoliths that are ascribed to individual biological taxa. The greater occurrence of F. solus and O. simplex in the high-Mg foraminiferal porcelanaceous tests than in the low-Mg foraminiferal hyaline tests reveals that the bioerosional processes seem to be related to the Mg/Ca ratio, as well as to morphological structures of the taxa."

Graphoglyptids are a group of deep-sea trace fossils that exhibit ornate
burrow geometries. Feeding patterns represented by these burrows have
been interpreted as fodinichnial (mining), pascichnial (grazing), and/or
agrichnial (farming). In this study, several different graphoglyptid trace
fossils were analyzed quantitatively using fractal analysis to determine
which of these three feeding modes is most appropriate as an
interpretation. Graphoglyptid burrows lend themselves to fractal geometric
analysis, because they commonly exhibit the essential fractal
characteristics of scale invariance and self similarity. Fractal analysis is
presented as a tool for analyzing geometric configurations by combining
shape complexity and space usage into one number, the fractal dimension.
Fractal dimensions of such graphoglyptid burrows as Paleodictyon and
Spirorhaphe were compared with those of known fodinichnial burrows,
such as Zoophycos, and pascichnial trails, such as Scolicia, all from
Zumaia, Spain. Results indicate that the deposit-feeding burrows
(fodinichnia and pascichnia) illustrate a high fractal dimension, as would
be expected for a deposit-feeding–optimal foraging strategy. Graphoglyptids
illustrate a consistently lower fractal dimension than the depositfeeding
burrows, thus providing evidence against the suggestion that they
represent fodinichnial or pascichnial behaviors. This observation supports
the hypothesis that graphoglyptids represent agrichnial activity rather
than mining or grazing activities.

Animals produce a variety of structures to modify their environments adaptively. Such structures represent extended phenotypes whose developmental expression is rarely studied. To begin to rectify this, we used micro-CT scanning and time series experiments to obtain the first high-resolution dataset on the four-dimensional growth of ant nests. We show that extrinsic features within the environment, such as the presence of planes between layers of sediment, influence the architecture of Lasius flavus nests, with ants excavating horizontal tunnels along such planes. Intrinsically, the dimensions of the tunnels are associated with individual colonies, the dynamics of excavation can be explained by negative feedback, and the angular distribution of tunnels is probably a result of local competition among tunnels for miners. The architecture and dynamics of ant nest excavation therefore results from the local interactions of ants with one another and templates inherent in the environment. The influence of the environment on the form of structures has been documented across both biotic and abiotic domains. Our study opens up the utility of CT scanning as a technique for observing the morphogenesis of such structures.

ICHNOFAUNA OF MODERN COASTAL DEPOSITS FROM SOUTHERN BRAZIL. With the objective of establishing the relationship between coastal deposits and ichnofacies, an ichnofauna from modern coastal environments of the Rio Grande do Sul State, southern Brazil, is analyzed herein. The seaward area of the Peixe Lagoon was choosen due its proximity to the sea. Y- and J-shaped burrows made by the crabs Chasmagnatus granulata and Uca uruguayensis (the later occupied by the crab Metasesarma rubripes) dominated the ichnocoenosis, followed by bird and other vertebrate trackways on the lagoon margins. Insect trails and burrows also occur, as well as ant galleries. Horizontal and vertical burrows of polychaetes, and resting and escape traces of Callinectes spidus dominate the benthic ichnocoenosis of the lagoon. Analogies between the ichnocoenosis of the Peixe Lagoon and the Psilonichnus ichnofacies provide information on the processes related to faunal distribution in coastal environments.

A new tracksite located in the Mesozoic
autochthonous series covering the Aiguilles Rouges Massif,
circa 7 km to the NNE of the tracksite of the Vieux
Emosson, is briefly described. The trampled bed is most
likely coeval with the outcrop in the Vieux Emosson area.
Two poorly preserved quadrupedal trackways, almost
parallel, measure 9.8 and 8 m in length, respectively. They
are referred to the Chirotheriidae ABEL, 1835 form-family.
A short and well-preserved quadrupedal trackway,
composed of two manus-pes couples, is assigned to
Chirotherium cf. barthii KAUP, 1835. A reinterpretation of
the Vieux Emosson ichnotaxa reveals that most tracks, if
not all, belong to indeterminate chirotheriid and that no
clear evidence of dinosaur footprints is observed. The
trampled bed of the cover of the Aiguilles Rouges Massif
probably forms a megatracksite, which is Early or Middle
Triassic in age.

Ichnological study of Lower Pliocene rocky shores in several northwestern Mediterranean basins has revealed the existence of a recurrent trace fossil assemblage of borings. This assemblage is dominated by the ichnogenera Gastrochaenolites and Entobia, which often are accompanied by other borings, such as Maeandropolydora, Caulostrepsis, Trypanites, Circolites, Iramena, and unnamed U-shaped borings. The same Gastrochaenolites-Entobia assemblage has been described from Mesozoic and Cenozoic rocky shores around the world, and these observations validate the recently proposed Entobia ichnofacies as a recurrent ichnofacies for post-Paleozoic rocky shores

Bioerosion traces from six rocky shore localities in the Miocene Tarragona basin are described. The bioerosion affects Jurassic and Miocene carbonate substrates. The ichnotaxa include borings produced by bivalves (Gastrochaenolites and Phryxichnus), sponges (Entobia), annelids (Maeandropolydora) and sipunculids (Trypanites). Phryxichnus is recorded for the first time in the Miocene. Trace fossil assemblages, although slightly different among localities, can be tipified as a Gastrochaenolites-Entobia assemblage which is typical of Neogene rocky shores and belongs to the Entobia Ichnofacies which characterizes littoral rockground environments since the Jurassic. Borings affect both the rocky substrate and the associated conglomeratic deposits. The assemblages found on wave-cut platforms are composite assemblages resulting from the overprinting of successive ichnocenoses that replace each other during a transgression. The assemblages found in the conglomerates represent less mature communities due to clast instability produced by physical disturbance characteristic of a littoral environment. The rocky shores described in this paper were originated during a single transgressive event that took place during the Langhian-Serravalian (Middle Miocene) and the surface that can be drawn correlating the sites constitutes the base of the Tarragona Depositional Sequence.

The Pleistocene Chuí Formation at Osório (Rio Grande do Sul, Brazil) consists of coastal marine and eolian sands, the former containing abundant and well-preserved Ophiomorpha nodosa burrow systems. Detailed ichnological study has revealed interesting features associated with them. Small-sized Ophiomorpha, here assigned to a new ichnospecies, O. puerilis, are interpreted as possible burrows of juvenile thalassinidean crustaceans probably belonging to the same species as the producers of larger O. nodosa. Additionally, helicoidal burrows with thick, concentrically laminated linings are associated with the walls of O. nodosa. They are assigned to the new ichnospecies Cylindrichnus helix, and they are interpreted as dwellings of commensal annelid worms. The association of these three ichnospecies constitutes a fossil example of the role of thalassinideans as ecosystem engineers able to modify their environment and to create new space and resources usable by other organisms.

The ichnological study of fluvial fan and lacustrine Oligocene deposits in the NE Ebro Basin has allowed the recognition of three ichnoassemblages having a strong correlation with depositional facies associations. Lacustrine deposits lack bioturbation due to the hydrologically closed character of the lake that caused hypersalinity and made it inhospitable for benthic life. Terminal lobe deposits of the fluvial fan, which were sedimented in low wetland areas around the lake, bear a moderately diverse ichnoassemblage dominated by horizontal Taenidium barretti, Cochlichnus anguineus and bird footprints (Gruipeda  isp.). This assemblage can be assigned to the 'shorebird ichnofacies', a subset of the Scoyenia ichnofacies that characterizes the subaerial part of low-energy shore areas. Crevasse splay deposits in medial fluvial fan areas present a different assemblage also belonging to the Scoyenia ichnofacies. It includes most of the trace fossils found in the terminal lobes, except for the bird tracks, plus very abundant vertical burrows (Taenidium barretti and unnamed ornamented burrows). The presence of deep-tier traces of terrestrial invertebrates is consistent with the more proximal fan setting, having greater relief and consequently a lower mean groundwater position than lowland areas. Fluvial channels only bear irregularly clustered tunnel structures of unknown affinity formed after abandonment of the channel. Thus, trace fossil assemblages are mostly controlled by the position and fluctuations of water tables, which are the cause for their composite nature.

A specimen figured by Hitchcock (1858) and named Cochlea archimedea  presents interesting ichnotaxonomic and paleoecologic issues. The ichnogenus Cochlea is considered to be a preoccupied taxon and therefore invalid. The specimen in question is given its appropriate name, Undichna isp., based on its apparent morphology and is reinterpreted as a trail made by a fish. Two working hypotheses for the construction of the trail are: (A) as a single epichnial groove with side levees made by one fin in contact with the substrate and (B) as a hypichnial trail with two grooves made by two fins in contact with the substrate. A more specific approach cannot be taken without knowledge of the true toponomy of the trace fossil, as none is indicated on the original specimen. Regardless, the identification of the first trails made by fish in the Early Jurassic of the Newark Supergroup of Massachusetts indicates the need for more nondinosaurian trace fossil research in the Mesozoic rift basins of eastern North America. The most likely tracemaker, depending on the correct constructional hypothesis, is either a semionotid with a deeply set anal fin (hypothesis B) or Redfieldius  (hypothesis A). Considering the abundance of fish body fossils preserved in rocks of this age in eastern North America, it is likely that once recognized, more Undichna will be discovered in future field explorations.

Rosselia socialis: a dwelling structure of a probable ... LETHAIA Nara, M. 1995 10 30 Rosselia socialis: a dwelling structure of a probable terebellid polychaete. Lethaia, Vol. 28, pp. 171-178. Oslo. ISSN 0024-1164. The trace fossil Rosselia socialis Dahmer 1937 is a ...

Insects were the first animals to evolve powered flight and did so perhaps 90 million years before the first flight among vertebrates. However, the earliest fossil record of flying insect lineages (Pterygota) is poor, with scant indirect evidence from the Devonian and a nearly complete dearth of material from the Early Carboniferous. By the Late Carboniferous a diversity of flying lineages is known, mostly from isolated wings but without true insights into the paleoethology of these taxa. Here, we report evidence of a full-body impression of a flying insect from the Late Carboniferous Wamsutta Formation of Massachusetts, representing the oldest trace fossil of Pterygota. Through ethological and morphological analysis, the trace fossil provides evidence that its maker was a flying insect and probably was representative of a stem-group lineage of mayflies. The nature of this current full-body impression somewhat blurs distinctions between the systematics of traces and trace makers, thus adding to the debate surrounding ichnotaxonomy for traces with well-associated trace makers.