云南武定下奥陶统Cruziana遗迹化石群落及其地层和地理分布

本世纪三十年代初,我国古生物学家尹赞勋先生曾详细研究采自滇东和川西南的一些 Cruziana 遗迹化石(尹赞勋,1933)。他首次在我国介绍了二叶石(Bilobites)这一名称同遗迹属名 Cruziana 的关系;讨论了三叶虫可能是 Cruziana 的遗迹动物;并系统描述了上述 Cruziana A,B,C 三种类型。这篇著作对研究我国三叶虫遗迹化石开创了方向,奠定了基础。     

An Important Ornithischian Tracksite in the Early Jurassic of the Shenmu Region,Shaanxi, China

A large track site with multiple,well-preserved trackways of an Early Jurassic quadrupedal ornithischian dinosaur is the first report of Moyenisauripus-like trackways from Asia,herein named Shenmuichnu...     

Trilobite trace fossils and their stratigraphical significance in the Cambrian sequence of the Holy Cross Mountains,Poland

Abundant and varied trilobite trace fossils are recognized and described in the Cambrian sequence of the Holy Cross Mountains. Cruziana and Rusophycus are stratigraphically significant and some of the described traces may be used as local index fossils. The first recognition of the Cruziana barbata ichnozone in Poland is made and it occurs in the uppermost Middle Cambrian. A new position for the Middle/Upper Cambrian boundary is established. Three new ichnospecies are described: Cruziana magna, C. regularis and Rusophycus crebus.     

Cambro‐Ordovician trace fossils from the SW‐Norwegian Caledonides

A diverse trace fossil association is described for the first time from low‐grade metamorphic rocks of the SW‐Norwegian Caledonides. The investigated cliff sections with autochthonous to parautochthonous metasediments comprise a coarsening‐ and thickening‐upward succession interpreted as prograding delta deposits. Sedimentary features indicate a tide‐influenced environment. Twenty‐one ichnospecies have been identified and assigned to the Cruziana and Skolithos ichnofacies, including the oldest record of Beaconites capronus and Macaronichnus segregatis. Cruziana ichnostratigraphy (sensu lato), previously rarely used in other palaeocontinents than Gondwana, allows an age determination for these metasediments of Middle Cambrian to Lower Ordovician as indicated by the presence of Cruziana barbata, C. furcifera, C. rugosa, C. semiplicata, Didymaulichnus rouaulti and Rusophycus ramellensis. Baltica was geographically the most isolated from the other three large continents (Gondwana, Laurentia and Siberia) during Cambro‐Ordovician time, and provinciality of faunal assemblages (e.g. brachiopods, conodonts) has been proved and is also supposed for trilobites by some authors. However, although the Cruziana ichnospecies result from a high specialization of their tracemakers, and therefore only a small group of trilobite species is eligible for its origin, the ichnospecies reported from Baltica occur also on other palaeocontinents and do not support the assumption of trilobite provincialism. Copyright © 2004 John Wiley & Sons, Ltd.     

New arthropod traces from the Lower Triassic Kockatea Shale Formation,northern Perth Basin,Western Australia: ichnology,taphonomy and palaeoecology

Abundant scratching traces are described from the Early Triassic Kockatea Shale Formation in the Northampton area of the northern Perth Basin, Western Australia. Except for the Radichnus trace that represents grazing of a possible decapod mecochirids, Scalpoichnus minchinensis igen. and isp. nov. is established to accommodate other scratching sculptures, which might have been produced by arthropods that share similar feeding behaviours to those of decapods. These arthropod traces occurred on a mat‐bound substratum defined by wrinkle structures. Microbial mats may have served as food resources for trace‐makers feeding on the substratum. Furthermore, microbial envelopes functioning as a sole veneer in early diagenesis acted as a crucial role for the preservation of those shallow‐tiered engraving traces. Abundant arthropod traces indicate frequent grazing activities probably by decapods or organisms having similar feeding habits upon microbial mat‐bound substratum, implying that the deposit‐feeders or omnivores survived on the matgrounds in the aftermath of the end‐Permian mass extinction in Gondwanaland. Copyright © 2013 John Wiley & Sons, Ltd.     

The longest theropod trackway from East Asia,and a diverse sauropod-, theropod-, and ornithopod-track assemblage from the Lower Cretaceous Jiaguan Formation,southwest China

Here we report a large dinosaur tracksite from an extensive fluvial sandstone surface in the Lower Cretaceous Jiaguan Formation of Sichuan Province, China. The site contains over 250 individual tracks comprising at least 18 recognizable trackways, including the longest theropod trackway (cf. Eubrontes) known from China. This exceptional theropod trackway consists of 81 successive footprints covering a distance of 69 m. The tracks are well-preserved and are expressed both as true tracks on the main “upper” surface and as transmitted undertracks on a locally exposed “lower” bed. Also recorded are six other theropod trackways, including small Grallator-like ichnites, eight sauropod trackways (cf. Brontopodus), and three small ornithopod (cf. Ornithopodichnus) trackways with a parallel orientation, which may indicate gregarious behavior. Several trackways of a larger theropod trackmaker show pes imprints with elongated traces of the metatarsals, suggesting extramorphological (substrate-controlled) variation and/or plantigrade posture, which is here interpreted as indicating a change in gait assumed in response to deep and soft sediment. The assemblage indicates a diverse dinosaur fauna in the Lower Cretaceous Sichuan Basin with variously sized theropods, sauropods, and ornithopods. The late occurrence of footprints of the Grallator-Eubrontes plexus in Lower Cretaceous strata is further evidence of the extended stratigraphic range of this morphotype and the distinct palaeobiogeographic distribution of these trackmakers in East Asia.     

Integrated ichnological and sedimentological studies of the Parahio Formation (Cambrian) of the Zanskar region (Zanskar-Spiti Basin), Northwest Himalaya

Lower-Middle Cambrian (Lungwangmiaoan-Hsuchuangian stage) Parahio Formation (Kunzam La Formation) exposed at Purni Village, Niri-Tsarap Chu Valley of Zanskar region of Tethyan Himalaya has yielded a high diversity and abundant ichnofossils with myriapod trackways. It includes Cruziana isp., Phycodes palmatum, Diplocraterion isp., Diplichnites isp., Dimorphichnus isp., Tapherhelminthopsis cf. circularis, Teichichnus isp., Monomorphicnus isp., Lockeia isp., Skolithos isp., Planolites isp., Palaeophycus isp., Isopodichnus isp., and arthropod appendage marks. Integration of ichnological and sedimentological studies for measured part of the Parahio Formation (Cambrian) reveals that alternating energy conditions due to recurring storm events were superimposed on low energy fair-weather sediments. The post-depositional Arenicolites ichnofacies, preserved within the high-energy storm beds of shoreface deposits, commonly overlies the fair-weather assemblage of pre-depositional Cruziana ichnofacies of relatively more offshore deposits, which contains more diverse and varied behavioral signatures of various deposit feeders. The traces of the Cruziana ichnofacies are abruptly replaced by traces of Arenicolites ichnofacies and show reiteration throughout the measured part of the Parahio Formation. The ichnofabric indices in these deposits range from ii3–ii5. No discrete sets of tiers are observed; perhaps there were two coeval communities. Ichnologically, an idealized wave-dominated progradational cycle in the Parahio Formation is characterized, from base to top, by a Cruziana ichnofacies (lower-upper offshore to offshore transition) and storm related Arenicolites ichnofacies (shoreface). Each progradational cycle reflects a progressive increase in sand content, degree of oxygenation, hydrodynamic energy and dearth of food. These environmental factors controlled the vertical distribution of trace fossils in Parahio Formation. The occurrence of Cruziana ichnoassociation much below the Middle Cambrian trilobite horizon in the Parahio Formation restricts the age of this part of the formation to the pre-Middle Cambrian, probably series 2 of Cambrian system.     

Trilobite biostratigraphy in the Middle and Upper Ordovician of western Leningrad Region

Biostatigraphical significance of trilobites of the Middle and Upper Ordovician in the eastern Baltic area is discussed, based on a new material from numerous outcrops from Leningrad Region. The study of the Middle and Upper Ordovician trilobites in the Mednikovo, Viivikonna, Gryazno, Khrevitsa and Elizavetino formations allows establishing two trilobite interval-zones. The zone of Chasmops odini in the upper part of the Uhaku and Kukruse stages, and the zone of Chasmops marginatus in the lower part of the Haljala Stage (the Idavere Substage). The upper part of the Haljala Stage (J~ohvi Substage) is characterized by the occurrence of Rollmops wenjukowi. Distribution and biostratigraphical significance of some trilobite taxa (Asaphus (Neoasaphus) lepidus, Illaenus intermedius, Toxochasmops maximus) is discussed.     

A new deep‐water Upper Ordovician (Caradocian) trilobite fauna from south‐west Wales

A deep‐water trilobite fauna has been discovered in the otherwise graptolitic Mydrim Formation near Clarbeston Road, Pembrokeshire, south‐west Wales. Associated graptolites indicate an early Caradocian age. The trilobites comprise three species with eyes reduced or absent, representing an atheloptic assemblage with benthic life habits, which appeared during a short period of relative oxygenation of the Welsh Basin. The trilobite Platycalymene dilatata (Tullberg) is redescribed from the type material from Sweden, and new material from Wales is assigned to this species. Two new species are described in addition. Rorringtonia multisegmentata sp. nov. possesses twelve thoracic segments, which has implications for the classification of the Rorringtoniidae within the Aulacopleuroidea. Trinucleus conollyi sp. nov. differs from T. fimbriatus in the proliferation of the radial sulci. Copyright © 2006 John Wiley & Sons, Ltd.     

New Early Cretaceous Pterosaur-Bird Track Assemblage from Xinjiang, China: Palaeoethology and Palaeoenvironment

A pterosaur-bird track assemblage from a sandstone-siltstone-mudstone sequence of the Lower Cretaceous Tugulu Group of Xinjiang comprises the first pterosaur track record from this province and the largest specimen thus far known from China.The pterosaur tracks are assigned to the ichnogenus Pteraichnus based on the triangular overall-shape,the four elongate digit traces and the robust manual digit trace Ⅲ.Supposed trackmakers were dsungaripterid pterodactyloids whose skeletal remains are well known from the Tugulu Group.The bird tracks that occur on the same surface,are those of typical shorebirds,known from different other localities in southeast Asia.The congruence with Koreanaornis dodsoni described from the same stratigraphic level justifies an assignment to this ichnospecies.This is a further evidence of the co-occurrence of pterosaurs and birds in a typical iakeshore environment with possible seasonal alteration of water supply and aerial exposure indicated by wave ripples,mudcracks and repeated cycles of coarse to fine sediment.Pterosaurs and birds frequented the shoreline and may have fed also on the numerous invertebrates such as the Scoyenia tracemaker that left abundant burrows.     

Trace fossils of precambrian metazoans “Vendobionta” and “Mollusks”

Metazoan trace fossils from the Upper Vendian are preserved together with remains of corresponding organisms. The traces belong to “Vendobionta”, representing the Precambrian phylum Proarticulata and to a presumably trochophoran animal Kimberella quadrata. These organisms fed on microbial mats, which preserved fossil traces. Impressions of the mat surface structures, traces, and bodies of animals are preserved in marine terrigenous sediments on the basal surfaces of sandstone beds. Proarticulata grazing traces are represented by groups and chains of impressions left by the ventral side of a body or its central and posterior parts. Kimberella traces are represented by long ridges united into bundles, fans, and chains of fans. All these traces were largely formed mechanically, i.e., by mat scratching with cilia (Proarticulata) or teeth (Kimberella). Proarticulata representatives destroyed only a thin upper layer of the mat, while Kimberella could possibly scratch the mat through its entire thickness or even tear off pieces from it.     

Stratigraphic significance of the Cambrian ichnofauna of the Zanskar region,Ladakh Himalaya,India

The Cambrian succession in the Zanskar Basin of Tethys Himalaya contains an abundant ichnofossils like in the other Tethyan Himalayan successions. The ichnofossils are stratigraphically important as they occur below the trilobite body fossils and are useful to define the basal part of the Cambrian. The ichnofossil assemblage reported from the Zanskar Basin of Ladakh Himalaya is significant to demarcate the Early Cambrian age due to lack of other faunal elements so far. The body fossils of trilobites recorded from the overlying beds indicates the earliest part of the Middle Cambrian age. Sixteen ichnogenera identified include: Bifungites, Cruziana, Diplichnites, Dimorphichnus, Isopodichnus, Lockeia, Merostomichnites; Monomorphichnus, Psammichnites, Palaeophycus, Planolites, Rhizocorallium, Skolithos, Taphrhelminthopsis, Teichichnus, Trepitichnus and trilobite scratch marks etc. The ichnogenera reported so far from this part of the Tethyan Himalayan region belongs mostly to the traces of arthropod origin. The ichnofauna ranges in age from Lower Cambrian to late part of the Middle Cambrian. The ichnofaunal assemblage can be assigned to repichnial, cubichinial, pascichnial, to fodinichnial behaviour. The distribution of ichnofossils in the studied sections shows that the ichnofossils are predominately less in occurrence in the sections were trilobites dominates and higher in the successions the abundance of ichnofossils decreases.     

Paleobiogeography,paleoecology and paleoenvironmental significance of the Cambrian trilobites from the Zanskar region (Zanskar-Spiti-Kinnaur Basin), Northwest Himalaya

In present study the newly recorded latest Middle Cambrian trilobite fauna from the Cambrian succession of the Zanskar region of Zanskar-Spiti-Kinnaur Basin (Tethyan Himalaya) is analyzed critically to assess relationships with other Cambrian faunal elements of equatorial peri-Gondwanaland. The identification of genus Neoanomocarella, Parablackwelderia, Kunmingaspis, Fuchouia, Damesella and Dorypyge from the Cambrian of the Zanskar region and their comparison with those of South China and Australia is significant. It constitutes the basis for assessing the paleobiogeographic affinities during the Cambrian. The latest Middle Cambrian trilobite fauna from Zanskar shows proximity of Indian margin with that of southwest China “outboard” micro-continent. The recovery of analogous Middle Cambrian species i.e., Dorypyge perconvexlis, Fuchouia bulba, Fuchouia cf. oratolimba, Parablackwelderia sp. and Damesella sp. from the Zanskar region (Tethyan Himalaya) suggests a contiguous close proximity with south China and Australia during the latest Middle Cambrian, which supports the model of Meert and Van der Voo (1997) for assembly of Gondwanaland. The presence of Kunmingaspis in Zanskar and similar reports from northwestern Yunnan-Tibetan region, northern Henan, central and southeastern Hubei, north China, western Xinjiang and Yangtze platform reveal a close affinity between the Indian margin and the Yangtze platform during the Middle Cambrian. The trilobite fauna indicates the deeper shelf-shallow slope environment of deposition under fluctuating conditions of relative sea-level. The faunal elements of the Lejopyge acantha and Proagnostus bulbus zones indicate that the sea inundated the northern margin of Zanskar region during the latest Middle Cambrian time (Teta transgression) which is synchronous with globally recognized eustatic events during Lejopyge laevigata Zone.     

杭州湾庵东浅滩现代沉积物中的生物遗迹

杭州湾庵东浅滩沉积物中发现有多种造迹生物,主要有蝼蛄、泥甲虫、宁波泥蟹、珠带拟蟹守螺、泥螺、弹涂鱼、蚂蚁和鸟类等,营造的生物遗迹主要为觅食迹、居住迹和爬行迹(爬迹、拖迹和鸟足迹)等。分析表明,浅滩不同亚环境的造迹生物及其遗迹的主要类型和分布特征具有明显的差异性: (1)在潮上带植被茂密的草滩环境中,以层面上的生物觅食迹、居住迹和鸟足迹为主,造迹生物主要有蝼蛄、泥甲虫、蚂蚁和鸟类等,其中以蝼蛄的潜穴最为丰富。(2)在高潮滩的积水泥沼环境中,有大量近海喜盐植物,生物遗迹主要有宁波泥蟹的“J”形、“W”形和“Y”形潜穴、弹涂鱼的羽状爬迹、珠带拟蟹守螺在层面上营造的弧形、圆圈状的觅食迹和“C”形的条带状生殖迹。(3)在中、低潮间带的粉砂质环境中,以层面上珠带拟蟹守螺不规则的觅食迹为主。生物遗迹的分布与浅滩沉积底质沉积物粒度与含水量等特征密切相关。本研究不仅丰富了杭州湾浅滩沉积的新遗迹学研究,而且对古代潮汐沉积及其环境研究有重要的借鉴意义。     

The oldest trilobites in Cambria: Early Cambrian trilobite faunas from the Llanberis Slates Formation,Gwynedd, North Wales

Historical published works on the fossil fauna of the Llanberis Slates Formation in Gwynedd, North Wales, concentrated on the endemic trilobite Pseudatops viola (Woodward, 1888), and placed the formation towards the top of Stage 3 (Series 2) of the Cambrian chronostratigraphy.The impression given was that the fauna is not particularly diverse and fossils are rare. However, recent collecting has produced a comprehensive fauna of sponges, hyolithids and diverse arthropods including over 250 trilobite specimens from two localities of the uppermost Green Slate horizon. Among them are examples of the endemic trilobite Pseudatops viola, sufficiently well preserved to enable a reappraisal of its status. The most abundant trilobite is a form of Strenuella (cf. strenua), but the collection includes previously unrecorded eodiscoid trilobites and specimens representing unrecorded and potentially new taxa. These additions result in the most comprehensive lower Cambrian trilobite assemblage yet described from Wales, and place it in the lower part of Stage 4, Series 2 in standard global terms.     

The ecological,significance of variation in the generic composition of Rawtheyan (late Ordovician) trilobite faunas from North Wales,U.K.

Contemporaneous trilobite faunas from Rawtheyan rocks forming the local base to the Ashgill Series change in their generic composition along the outcrop between Bala and Corris. The change, although overall a very marked one, is progressive and is held to reflect original ecological control along a depth gradient between a locally elevated area around Bala and the deeper central part of the Welsh Basin. Along this intrabasinal slope three distinctive trilobite generic associations–the Ceraurinella-Encrinuroides Association, the Nankinolithus-Opsimasaphus Association and the Novaspis-cyclopygid Association–succeeded each other in gradually deeper water. Faunas of all three associations differ markedly from contemporaneous faunas of shallower shelf environments.     

Trace fossils from the Upper Ordovician (Caradoc) of the Berwyn Hills,Central Wales

A suite of Caradocian trace fossils from the Berwyn Hills, Central Wales, are examined. They include forms produced by trilobites (Cruziana, Rusophycus, Trichophycus, Monomorphichnus), pelecypods (Lockeia), ?gastropods (?Imponoglyphus) and traces of debatable affinity probably produced by oligochaete and polychaete annelids, amphipods and crustaceans (Skolithos, Planotites, Teichichnus, Diplocraterion, Arenicolites, ?Gyrochorte, ?Palaeophycus, Vermiforichnus). Representatives of the Skolithos and Cruziana communities coexist in this assemblage and no subdivision into discrete ichnofacies is therefore possible. The trace fossils are examined in terms of their relationship to the structure and composition of Upper Ordovician communities and it is concluded that substrate and ecological controls were more important limiting environmental parameters than depth.     

Microbial signatures in peritidal siliciclastic sediments: a catalogue

A catalogue of microbial structural signatures is presented, based upon the coupling of fundamental biogeochemical–microbial processes and local morphogenetic determinants. It summarizes a collection of sedimentary structures obtained from two modern siliciclastic peritidal environments in different climatic zones (temperate humid: Mellum Island, southern North Sea; subtropical arid: coast of southern Tunisia). Textural geometries reveal a high structural diversity, but their determinants are primarily based upon six major parameters: (1) intrinsic biofactors: structural diversification of sedimentary microbial films and mats inherent in the organisms, i.e. their construction morphology, growth, taxis and behaviour, and local abundance of specific morphotypes. Most prominent are the ensheathed filamentous cyanobacteria Microcoleus chthonoplastes and Lyngbya aestuarii, and the sheathless filamentous cyanobacterium Oscillatoria limosa. (2) Biological response to physical disturbances: sediment supply, erosion and fracturing of surface layers resulting from desiccation cause growth responses of biofilms and microbial mats. (3) Trapping/binding effects: physicobiological processes give rise to grain orientations and wavy to lenticular lamina, lamina‐specific grain arrangements and ‘sucrose’ calcium carbonate accumulations. (4) Secondary physical deformation of biogenic build‐ups: mechanical stresses acting upon sediments overgrown and biostabilized by biofilms and mats produce erosional and overthrust structures. (5) Post‐burial processes: textural fabrics that evolve from mechanical effects of gas formation from decaying mats, and features related to the formation of authigenic minerals (calcium carbonates, calcium sulphates, pyrite). (6) Bioturbation and grazing: post‐depositional structures, such as Skolithos‐type dwellings, traces of burrowing insects, gastropod grazing traces and faecal pellets. In synopsis, the catalogue firstly comprises a sound set of ubiquitous signatures. This uniformity in architectural characteristics is attributed to the presence and local dominance of certain microbes throughout the different settings. The catalogue secondly documents signatures that are extremely sensitive to tidal position, hydrodynamic regime and overall climatic conditions. These kinds of signature indicate narrow facies zones, which often coincide with the activity or dominance zones of certain organisms. An overview of structures of microbial origin from the fossil record underlines the potential of many of the signatures included in this catalogue to become fossilized and provide strong indicators of former siliciclastic tidal settings.     

New dinosaur tracks from Korea, Ornithopodichnus masanensis ichnogen. et ichnosp. nov. (Jindong Formation, Lower Cretaceous): implications for polarities in ornithopod foot morphology

Twelve trackways of ornithopods from Lower Cretaceous lacustrine margin deposits of the Jindong Formation represent new dinosaur trackways described from Korea. The site, discovered during highway construction, was rescued by removing the most important trackways to the Korean Natural Heritage Center in Daejeon, where they are on permanent display. The new ichnotaxon Ornithopodichnus masanensis ichnogen. et ichnosp. nov. is recognized as a distinctive robust tridactyl track, slightly wider than long (l/w ratio = 0.91), with positive (inward) rotation. The toe prints are very thick, broad and U-shaped, resulting in a trefoil outline with a smoothly rounded hind margin. Digit III is short and projects anteriorly much less than digit II and IV (= weak mesaxony). Divarication of digits II-IV is about 70° with interdigital angle II-III larger than III-IV. Trackway width is narrow and the stride length/track length ratio is about 4.2–4.6. The Ornithopodichnus trackways evidently represent gregarious blunt-toed Iguanodon-like bipedal ornithopods, although poorly preserved manus traces are discerned in a few trackways. Ornithopodichnus is distinct from other well known iguanodontid tracks that display much stronger mesaxony and indicates a polarity in ornithopod foot morphology that can be verified by reference to known foot skeletons.     

Peri-Gondwana Late Early–Middle Cambrian trilobites from the Kuhbanan Formation in Dahu section,Kerman Province,Iran

Outcropped of the Kuhbanan Formation at Dahu, near Zarand, about 63 km north of Kerman, Iran contains peri-Gondwana trilobites. In this study, 185 trilobite samples including six species and genera were identified and described from Dahu section. This trilobite’s assemblage including Redlichia noetlingi, Redlichia sp., Kermanella kuhbananensis, Kermanella lata lata, Kermanella lata minuta, Iranoleesia pisiformis, and Iranaspis sp. based on occurrence of the trilobite fauna a late Early to Middle Cambrian (Series 2–3) is suggested for this strata. These trilobite fauna help confirm conclusions from recent geological studies that place the Kerman Basin of Iran during the Cambrian.