Triassic trace fossils from lacustrine shoreline deposits of the Passaic formation,douglassville, pennsylvania

Lake‐margin deposits of the Late Triassic Passaic Formation, Douglassville, Pennsylvania, have yielded a moderate variety of trace fossils. The greatest diversity and abundance of trace fossils occurs on the sole of a thin gray claystone overlain and underlain by gray siltstones. Specimens of Cochlichnus anguineus, Helminthoidichnites tenuis, Helminthopsis hieroglyphica, Treptichnus pollardi, and paired trails reflect simple, unspecialized, horizontal grazing as well as feeding traces under very shallow water lacustrine conditions. The lack of commonly associated Scoyenia burrows in these deposits may possibly be related to the degree of maturation of the organic debris available. The traces, as well as a lack of meniscate burrows, compare favorably to the Mermia ichnofacies, except Passaic deposits exhibit evidence of subaerial exposure. This unit most likely records a lacustrine expansion whereby grazing trails were emplaced under fully subaqueous conditions. Subsequent shallowing and desiccation, followed by sediment influx during rainstorms, favored preservation of these traces.

In contrast, the Scoyenia ichnofacies consists of feeding burrows of Scoyenia gracilis and Spongeliomorpha milfordensis within reddish brown siltstones and mud‐stones (redbed sequence). The Scoyenia ichnofacies records limited exploitation, by opportunistic infaunal deposit feeders, of lake‐margin nutrients carried in during occasional rainstorms that punctuated otherwise extended periods of aridity.     

A Review of: “New Interpretations of Complex Trace Fossils”

Dinosaur Tracks and Traces, edited by David D. Gillette and Martin G. Lockley, 1989. Cambridge University Press, 110 Midland Avenue, Port Chester, New York 10573, USA. lvii + 454 pages. US$54.50.     

Taphonomic signatures,ichnofacies analysis and depositional dynamics of fossil macro-invertebrate assemblages of the San Juan Raya Formation,Zapotitlán Basin,Puebla, Mexico

In this paper, we describe the taphofacies and ichnofacies from Aptian strata of the San Juan Raya Formation in the Santa Ana Teloxtoc area, Puebla, Mexico. A composite stratigraphic section was analysed on a bed-by-bed scale up to a total thickness of 765.5 m. Our results show the presence of 10 taphofacies and 3 ichnofacies. The taphofacies and ichnofacies interpretation, and its correlation with the sedimentary lithofacies, enabled the determination of a palaeoenvironmental model for the study area that corresponds to a shallow marine, open-coast, clastic system with episodic sedimentation as a product of storm events. This system had several variations in sub-environments, from foreshore to offshore. Foreshore and shoreface environments are characterised by taphofacies Tf1, Tf2, Tf3 and Tf10 and PsI and SkI ichnofacies, representing lower faunal diversity moments (with the exception of Tf3 taphofacies). Meanwhile, taphofacies Tf4, Tf5, Tf6, Tf7, Tf8 and Tf9 were representative of shelf environments and are described as moments of medium-to-high faunal diversity (with the exception of Tf5 taphofacies).     

青海曲麻莱-治多地区巴颜喀拉山群(上三叠统)遗迹化石

首次对青海南部曲麻莱-治多地区巴颜喀拉山群上部(上三叠统)遗迹化石进行了系统采集,共采获遗迹化石33属54种。据遗迹化石的形态、习性、水深等环境成因特征,可划分为两类组合:一类以Cosmorhaphe,Helminthopsis,Helminthoida,Megagrapton,Paleodictyon等为主,产生于浊流事件前;另一类以Chondrites,Neo-nereites,Palaeophycus,Phycosiphon,Planolites,Zoophycos等为主,产生于浊流事件后,两者均为半深海-深海Nereites遗迹相的典型代表,反映晚三叠世研究区应为浊流沉积发育的复理石相沉积。     

Crocodile swim tracks from the latest Cretaceous of Europe

Recently discovered evidence of tracks in the continental beds of the Late Cretaceous Tremp Formation in the southern Pyrenees (NE Iberian Peninsula) has been identified as scratch marks made by buoyant crocodiles. The tracks are preserved in two distinct environments and substrates (marly limestones originating in a littoral mud flat and fine‐grained sandstones deposited in fluvial settings). Most of the crocodylian traces are ascribed to ichnogenus Characichnos, whereas a single plantigrade pes track is assigned to ichnogenus cf. Crocodylopodus. The crocodylian swim traces (Characichnos ichnofacies) found in the early and late Maastrichtian co‐occur with Brontopodus ichnofacies attributable to terrestrial tetrapods (titanosaur sauropods, cf. Brontopodus ichnogenus; and hadrosaurid ornithopods, Hadrosauropodus ichnogenus). Analysis of the tracks allows the interpretation of palaeoenvironmental settings and track production. Thus, in lagoonal environments, swim tracks of crocodylians were produced during the rise of the water level in successive tide cycles; in fluvial settings, the swim traces of crocodylians were produced within the channel at the low‐water stage. To date, there are no reports of Late Cretaceous crocodylian tracks in Europe, and the studied evidence represents the first and youngest track record of the group in the latest part of the Cretaceous (C29r) in this continent and probably in the world.     

Ichnology and sedimentology of a tide‐influenced delta in the Ordovician from the northeastern Alborz range of Iran (Kopet Dagh region)

The Middle–Late Ordovician Ghelli Formation in the Kopet Dagh region northeastern Alborz range of Iran is composed of siliciclastic rocks deposited in a variety of turbidite to marginal marine environments (deep marine clastic fan and related environments and prodelta, distal delta front, proximal delta front and distributary channels). The ichnology of the middle member of the Ghelli Formation is here reported. Combined sedimentological and ichnological analysis allows recognition of a tide‐influenced deltaic succession in the middle member of the Ghelli Formation consisting of three main facies associations: lower distributary channels, delta front and prodelta facies. Twenty‐two ichnogenera have been identified in this marginal marine succession: Arenicolites, Arthrophycus, Bergaueria, Chondrites, Conichnus, Cruziana, Cylindrichnus, Didymaulichnus, Diplichnites, Diplocraterion, Helminthopsis, Gyrochorte, Lockeia, Macaronichnus, Monomorphichnus, Palaeophycus, Planolites, Rosselia, Rusophcus, Skolithos, Teichichnus and ?Scolicia. Their distribution is clearly linked with lithofacies and depositional palaeoenvironments. The ichnological analysis reveals that the trace fossil suites developed in these environments indicate low diversity and low to moderate abundance of burrows, poor development of tiering and sporadic distribution. Low ichnodiversity and low bioturbation intensities with higher bioturbation clusters consist of facies‐crossing ichnogenera, and the impoverishment of suspension‐feeding trophic types indicates ‘stressed’, non‐archetypal expression of the Cruziana ichnofacies. The periodic higher intensities of bioturbation due to variations in hydrodynamic regimes of tidal currents reflect the archetypal of the Cruziana ichnofacies (and rare Skolithos ichnofacies).     

An integrative ichnological and taphonomic approach in a transgressive–regressive cycle: a case study from Devonian of Paraná Basin,Brazil

The palaeoenvironmental context of a section of the Devonian Ponta Grossa Formation (Paraná Basin) was examined using an integrated ichnological and taphonomic approach. Three taphofacies (T‐A, T‐B and T‐C) and six ichnofabrics are recognized. T‐A is mainly composed of disarticulated organisms and is associated with Chondrites, Planolites‐Palaeophycus, Asterosoma‐Zoophycos and Asterosoma‐Chondrites ichnofabrics, representing the Cruziana ichnofacies. The upward increase in diversity and abundance of body fossils for Taphofacies A can be explained by changes in sedimentation rates during aggradational to progradational phases. T‐B beds, represented by articulated brachiopods, occur in distal tempestites associated with the Skolithos ichnofabric (Skolithos ichnofacies) and represent higher hydrodynamic energy and oxygenation than in T‐A. Taphofacies C, characterized by a mix of articulated and disarticulated organisms, generally lacks bioturbation except for Chondrites ichnofabrics occurring only at the bed tops, suggesting low substrate oxygenation and low‐energy conditions. T‐C indicates the maximum transgression in the T‐R cycle, characterizing it as a good indicator of maximum flooding surfaces. The composite Asterosoma‐Teichichnus ichnofabric (bioturbation degree 5) occurs in layers without body fossils and represents suites of the Cruziana ichnofacies. This likely reflects intense intrastratal activity at all substrate levels, which facilitated the oxygenation of the substrate disallowing the preservation of organism remains. This observation indicates that the bioturbation is an important factor controlling the loss of taphonomic information within the TAZ, mainly when associated with detritus‐feeding trace fossils.     

Deep Endichnial Cruziana from the Lower-Middle Ordovician of Spain — A Unique Trace Fossil Record of Trilobitomorph Deep Burrowing Behavior

Full reliefs of Cruziana furcifera from the Lower-Middle Ordovician quartzite sandstone beds (Pochico Formation, southern Spain) points to deep, infaunal burrowing of trilobites. Some specimens show an unusual vertical extension with a wider lower part and a narrower upper part in cross section. They are referred to trilobites, which burrowed deeply in the sediment and were oriented obliquely head down and tail up. Deep burrowing seems to be common for other members of the Cruziana rugosa group, foremost C. rugosa and C. furcifera, less for C. goldfussi. The deep burrowing recorded in the discussed trace fossils can be referred to the earliest common infaunalization caused by trilobites and other arthropods during the Ordovician, probably in a response to a food competition on the sea floor, which promoted a behavioral plasticity within the same taxon or closely related taxa of trilobites.     

Controls on trace fossil diversity in an Early Cambrian epeiric sea: new perspectives from northwest Scotland

The Lower Cambrian Eriboll Formation of northwest Scotland is renowned for the high density, low diversity trace fossils (Skolithos ichnofacies) found in its upper Pipe Rock Member. Ichnofabric analysis of the member indicates that relatively small examples of Skolithos terminating at the same foreset boundary were formed during a brief colonization window after a single depositional event, that particularly long Skolithos specimens are equilibrichnia, and that palimpsests of Skolithos represent the marginal, slightly deeper water fringes of the Pipe Rock Member depositional environment. Nearest neighbour analysis, however, suggests that such palimpsests were uncommon. A much more diverse trace fossil assemblage is present in the overlying Fucoid Member (An t‐Sròn Formation), comprising Cruziana barbata, Dactylophycus, Didymaulichnus, Halopoa imbricata, ?Margaritichnus, Monocraterion, Monomorphichnus, Palaeophycus striatus, P. tubularis, ?Phycodes, Planolites montanus, ?Polarichnus, Rusophycus ramellensis, ?Psammichnites, Skolithos and various unidentified traces, and represents the Cruziana ichnofacies. Above the Fucoid Member, the Salterella Grit Member ichnofauna is more impoverished, yielding only Cruziana, Monocraterion, Rusophycus, Skolithos and ?Spirophyton. The ichnological variations between the Pipe Rock, Fucoid and Salterella Grit members are interpreted as being driven by changes in sea level. The low trace fossil diversity in the Pipe Rock Member indicates opportunistic colonization of laterally extensive, shoreface sediments deposited by regular influxes of terrigenous material, which were overlain by more distal, ichnologically diverse sediments (Fucoid Member) as sea level rose. A minor regression then caused an increase in terrigenous sediment input, producing an impoverished, proximal Cruziana ichnofacies (Salterella Grit Member).     

西藏南部堆纳地区上白垩统及下第三系遗迹化石及其环境意义

描述我国西藏南部堆纳地区宗山组下部及基堵拉组中的遗迹化石。宗山组中的遗迹化石组合可归属于Ｚｏｏｐｈｙｃｏｓ遗迹相,该遗迹相可进一步划分产于富氧条件下的Ｔｈａｌａｓｓｉｎｏｉｄｅｓ－Ｐｌａｎｏｌｉｔｅｓ遗迹及产于贫氧条件下Ｚｏｏｐｈｙｃｏｓ－Ｃｈｏｎｄｒｉｔｅｓ遗迹亚相。基堵拉组中的遗迹化石组可归属于在高能的潮下带的临滨和潮间带的前滨环境下产生的Ｓｋｏｌｉｔｈｏｓ遗迹相。