Cambrian Ichnofossils from the Zhoujieshan Formation(Quanji Group) Overlying Tillites in the Northern Margin of the Qaidam Basin, NW China

The Quanji Group is composed of siliciclastics and carbonates and was deposited on a relatively stable block, in the northern margin of the Qaidam Basin, NW China. It is one of the research hotspots in the Qilian-Qinling-Kunlun tectonic zones. However, it has long been argued whether the up- per Qnanji Group should be assigned to the Precambrian or the Cambrian for lack of convincing fossil evidence. The discovery of ichnofossils, including Rusophycus, Cruziana, Dimorphichnus, Treptichnus, Skolithos, Arenicolites, Palaeophycus, and Helminthopsis, indicates that the upper member of the Zhou- jieshan Formation （top Quanji Group） is Cambrian in age, and at least above the Treptichnus （Phycodes） pedum Biozone, the lowermost biozone in the Cambrian. The lower member of the Zhoujieshan Forma- tion should belong to the Cambrian. During the time when the upper member of the Zhoujieshan For- mation was deposited, the northern margin of the Qaidam Basin was dominated by the Cruziana Ichnofacies, characterizing a lower-energy shelf （shallow） sea environment with moderate-rich oxygen con- tents. In addition, the conglomerates in the Hongtiegou Formation of the Quanji Group underlying the Zhoujieshan Formation were generally regarded as tillites. However, the dolostones of the lower member of the Zhoujieshan Formation are, in lithology and geochemistry, different from the typical cap-dolostones of the Doushantuo Formation in South China, so it is necessary to further study the origins of the lower member of the Zhoujieshan Formation and the conglomerates of the Hongriegou Formarion.

Cambrian Stratigraphy and Faunal Elements Along the Kurgiakh-Surichun La Section(Kurgiakh Valley),Zanskar-Spiti Basin of Northwest Himalaya

The Cambrian rocks are well exposed along the Kurgiakh-Surichun La section,situated 78 km SE of the Padam Village along a track route at 33°03′787″N and 77°013′647″E in between the Kurgiakh and Surichun La,in Kurgiakh Valley(southeastern Zanskar).Around 715 m thick Cambrian succession was measured along the right and left banks of

A New Ichnogenus Kailidiscus Produced by Attachment from the Middle Cambrian Kaili Formation in Taijiang, Guizhou Province, China

Over 190 specimens of an attachment ichnofossil Kailidiscus （n. ichnogen.） have been found in the Kaili Bitoa, a Burgess Shale-type biota, from the middle Kaili Formation （early Middle Cambrian） in Taijiang County, Guizhou Province, southern China. Kailidiscus is an epichnia with a circular to oval attachment platform, on which there is a carbonaceous film probably formed by the body of the living organism. Structures such as a marginal furrow, an inner and outer marginal ride, many convex fold-ridges, and a large caved peripheral furrow on the attachment platform may be the result of basal tissues of a sessile organism that wrinkled to increase the attachment＇s surface area. The Kailidiscus organism may have been a sessile cnidarian attached to the muddy seafioor. Kailidiscus organisms lived in relatively quiet water, and were buried by a sudden influx of sediment.

Periodic anoxic shelf in the Early-Middle Ordovician transition:ichnosedimentologic evidence from west-central Utah,USA

Ichnosedimentologic evidence of periodic anoxic shelf in the Early-Middle Ordovician transition includes lower ichnodiversity, shallower bioturbation and burrowing depth (【4 cm), rare domichnia, tinyChondrites occupying shallower or shallowest tiering, widely distributed nodules of limonite pseudomorphs after pyrite, occurrence of trace fossils being closely associated with the storm event layers, and stratigraphic successions with orbital cyclostratigraphic architecture. It is suggested that lower atmospheric oxygen level during the Early Paleozoic, the Ordovician radiation, dramatic transgression and warmer temperatures would result in the periodic anoxia in the Early-Middle Ordovician transition. This episode began at the later Early Ordovician and lasted about 3.4 Ma on the basis of orbital cyclostratigraphy.

The new ichnotaxon Eubrontes nobitai ichnosp. nov. and other saurischian tracks from the Lower Cretaceous of Sichuan Province and a review of Chinese Eubrontes-type tracks

The Jiaguan Formation and the underlying Feitianshan Formation(Lower Cretaceous) in Sichuan Province yield multiple saurischian(theropod–sauropod) dominated ichnofaunas. To date, a moderate diversity of six theropod ichnogenera has been reported, but none of these have been identified at the ichnospecies level. Thus, many morphotypes have common "generic" labels such as Grallator, Eubrontes, cf. Eubrontes or even "EubrontesMegalosauripus" morphotype. These morphotypes are generally more typical of the Jurassic, whereas other more distinctive theropod tracks(Minisauripus and Velociraptorichnus) are restricted to the Cretaceous. The new ichnospecies Eubrontes nobitai ichnosp nov. is distinguished from Jurassic morphotypes based on a very wellpreserved trackway and represents the first-named Eubrontes ichnospecies from the Cretaceous of Asia.

Late Triassic sauropodomorph and Middle Jurassic theropod tracks from the Xichang Basin,Sichuan Province,southwestern China:First report of the ichnogenus Carmelopodus

Upper Triassic and Middle Jurassic strata of the Xichang Basin in Sichuan Province, southwestern China, yielded important dinosaur ichnofossils. From the Xujiahe Formation of the Yiguojiao tracksite, we report a Late Triassic footprint assemblage in China and the first discovery of diagnostic Triassic sauropodomorph tracks in this region. The tracks share a number of features in common with the ichnogenera Eosauropus(Late Triassic) and Liujianpus(Early Jurassic). The neighboring Bingtu tracksite is stratigraphically younger(Shaximiao Formation, Middle Jurassic) and preserves small tridactyl theropod tracks that represent the first occurrence of the ichnotaxon Carmelopodus in China and Asia. While these tracks are morphologically comparable to those from the Middle Jurassic type locality in North America, the specimens from China show the proximal margin of the digit IV impression in a more cranial position, which may indicate a trackmaker with a relatively short metatarsal IV. In addition to the skeletal record, the Carmelopodus footprints document the presence of small theropods in the dinosaur fauna of the Middle Jurassic Shaximiao Formation.