Chaohusaurus is Oldest Known Ichthyopterygian

Ammonoid age control of the Early Triassic marine reptiles from Chaohu (South China)

Authors:

Ji et al

Abstract:

Here we described a series of ammonoid specimens from the Early Triassic of Chaohu, South China and recognized the occurrence of Procolumbites for the first time in this area. The Procolumbites layer is about one meter above the first appearance of Chaohusaurus, indicating that the oldest Chaohusaurus is within the Procolumbites Zone of middle Spathian age. This new age constrain is significantly older than the previously suggested Subcolumbites Zone assignment (early late Spathian). To date, Chaohusaurus is the oldest known ichthyopterygian.

Ediacaran Indian Acanthomorphic Acritarchs Give Hope to Global Biostratigraphic Correlation

Ediacaran acanthomorphic acritarchs from the Outer Krol Belt, Lesser Himalaya, India: Their significance for global correlation

Authors:

Shakla et al

Abstract:

Large acanthomorphic acritarchs have been previously reported from the Ediacaran successions of the Pachmunda and Krol Hill synclines in the Outer Krol Belt of Lesser Himalaya, India. Thin sections of chert from Krol ‘A’ Formation in Khanog and Rajgarh synclines, Outer Krol Belt, record an equally well developed and diversified assemblage of Ediacaran large acanthomorphic acritarchs. This assemblage contains specimens belonging to seven genera and ten species, identified as: Appendisphaera fragilis, A. grandis, Asterocapsoides sp. A, Asterocapsoides sp. B, Cavaspina acuminata, C. basiconica, Eotylotopalla dactylos, Knollisphaeridium sp., Papillomembrana sp., and Weissiella cf. grandistella. It also contains five unnamed forms, viz. A, B, C, D, and E. The Krol acritarch assemblage shows a close resemblance with the Upper Doushantuo or Tanarium anozos–Tanarium conoideum assemblage of China. However, the absence of biostratigraphically important markers such as Tanarium anozos and T. conoideum from the Krol assemblage, so far, makes it difficult to establish a definite biostratigraphic correlation between the two assemblages. The current observations from this new locality provide additional data for regional and global biostratigraphic correlation, and significantly increase the purview of Ediacaran sequences for global biostratigraphic zonation.

High-resolution Biostratigraphy and Chemostratigraphy From Ediacaran Neoproterozoic China

High-resolution biostratigraphic and chemostratigraphic data from the Chenjiayuanzi section of the Doushantuo Formation in the Yangtze Gorges area, South China: Implication for subdivision and global correlation of the Ediacaran System

Authors:

Liu et al

Abstract:

Intensive investigations on the Doushantuo Formation of South China have greatly advanced our understanding of the evolution of multicellular life and the atmospheric–oceanic system during the Ediacaran Period. Particularly, the well-established carbon isotope profile and rich acritarch microfossils from the composite carbonate and shale successions of the Yangtze Gorges area provide potential for chronostratigraphic subdivision and global correlation of the Ediacaran System. Here we present high-resolution biostratigraphic and carbon isotope data from a well exposed section: the Chenjiayuanzi section in the Yangtze Gorges area. The bio- and chemostratigraphic data confirm the presence of three distinct negative and two positive δ13C excursions, and two characteristic assemblages of acanthomorphic acritarchs: the lower Tianzhushania spinosa assemblage, and upper Hocosphaeridium scaberfacium – Hocosphaeridium anozos (=Tanarium conoideum Tanarium anozos in Liu et al., 2013) assemblage within the Doushantuo Formation. The results demonstrate the clear stratigraphic relationship between the acritarch assemblages and carbon isotope excursions of the Doushantuo Formation, and that the last occurrence of acanthomorphic acritarchs in the Chenjiayuanzi section represents the last occurrence datum found so far in the Yangtze Gorges of South China. Four stratigraphic markers are suggested here for defining chronostratigraphic boundaries of the Ediacaran System based on bio- and chemostratigraphy combined with intra- and interbasinal correlation. In particular, the base of the most significant and distinctive carbon isotope excursion (DOUNCE) at the top of the Doushantuo Formation, which is equivalent to the Shuram/Wonoka event elsewhere, shows potential to be a marker to define the series (Lower and Upper) boundary of the Ediacaran System, because it also marks the extinction of the Ediacaran acanthomorphic acritarchs.

Bioevents and Palaeoenvironmental Changes in Barremian Cretaceous France

Bioevents and palaeoenvironmental changes in carbonate platforms: The record of Barremian “Urgonian” limestones of SE France ☆

Authors:

Masse et al

Abstract:

Biostratigraphic studies of Barremian platform carbonates from SE France, and nearby regions indicate the Last Occurrence (LO) horizons of some common shallow water taxa. Firstly two dasycladale algae: Piriferella paucicalcarea and Salpingoporella genevensis, which have their first occurrence in the upper Hauterivian disappear in the lower Barremian, at the Nicklesia pulchella–Kotetishvilia compressissima transition. Secondly a rudist bivalve: the genus Agriopleura, which has its first occurrence in the upper Hauterivian has its LO in the lower upper Barremian, within the Gerardhtia sartousiana zone. The specific stratigraphic levels of the above bioevents recorded in platform carbonates may be used for dating corresponding ammonite free-successions. Stratigraphic implications are constrained by the biogeographical extent of the key species which is essentially the Western and Central European margin of the Mediterranean Tethys. The joint LO of P. paucicalcarea and S. genevensis are inferred to have been linked with oceanographic and climatic changes, i.e. a cooling event. Platform carbonates were interrupted by a drowning event represented by a Maximum Flooding Surface or Transgressive surface. Shallow water Orbitolinidae record significant extinctions and deep water ammonites show a significant turnover. Similarly, modifications in ammonite faunas, bottom currents, temperature changes, i.e. cooling, and a major extinction among the family Orbitolinidae coincided with the LO of Agriopleura. Platform perturbations, including exposure, possibly a sequence boundary, and basin margin instability, both with a tectonic background, were associated with this event. The foregoing events and the linkage of palaeobiogeographic changes, that is the migration of the key taxa towards southern latitudes, in correspondence with the LO bioevents indicate that thermal changes, including seasonality, appear to have been the prominent controlling factor.

Vase-shaped Microfossils From Cryogenian Neoproterozoic Yukon, Canada

740 Ma vase-shaped microfossils from Yukon, Canada: Implications for Neoproterozoic chronology and biostratigraphy

Authors:

Strauss et al

Abstract:

Biostratigraphy underpins the Phanerozoic time scale, but its application to pre-Ediacaran strata has remained limited because Proterozoic taxa commonly have long or unknown stratigraphic ranges, poorly understood taphonomic constraints, and/or inadequate geochronological context. Here we report the discovery of abundant vase-shaped microfossils from the Callison Lake dolostone of the Coal Creek inlier (Yukon, Canada) that highlight the potential for biostratigraphic correlation of Neoproterozoic successions using species-level assemblage zones of limited duration. The fossiliferous horizon, dated here by Re-Os geochronology at 739.9 ± 6.1 Ma, shares multiple species-level taxa with a well-characterized assemblage from the Chuar Group of the Grand Canyon (Arizona, USA), dated by U-Pb on zircon from an interbedded tuff at 742 ± 6 Ma. The overlapping age and species assemblages from these two deposits suggest biostratigraphic utility, at least within Neoproterozoic basins of Laurentia, and perhaps globally. The new Re-Os age also confirms the timing of the Islay δ13Ccarbonate anomaly in northwestern Canada, which predates the onset of the Sturtian glaciation by less than 15 m.y. Together these data provide global calibration of sedimentary, paleontological, and geochemical records on the eve of profound environmental and evolutionary change.

Geochronology of the Upper Cretaceous Tethys Deposits of Israel Established

Chronostratigraphy of the Upper Cretaceous high productivity sequence of the southern Tethys, Israel

Authors:

Meilijson et al

Abstract:

The Levantine high productivity sequence is a product of an extensive upwelling system that operated in the Late Cretaceous along the SE Tethyan margin. This system resulted in the deposition of a unique sequence of carbonate, chert, porcellanite, phosphorite and organic-rich (oil shale) sediments in a series of basins located proximally and marginally to the upwelling center. This study presents a detailed and updated chronostratigraphic framework for the high productivity sequence in Israel based on eight sections covering a N–S cross section of ∼90 km. The Shefela Basin (central Israel) represents the thickest and the most complete penetrated stratigraphic interval of the oil shale deposits in Israel. The newly drilled Aderet borehole in the Shefela Basin provided a continuous core record coupled with high quality geophysical well logs and was used in this study as a ‘type-section’ for the detailed chronostratigraphic scheme of the high productivity sequence. A total of 23 datum levels were recognized using planktic and benthic foraminiferal biostratigraphy, lithostratigraphy and gamma ray well log markers. The varying lithostratigraphic units (containing chert, phosphate, porcellanite and organic-rich carbonates) of the more proximal basins of southern Israel (Negev) were individually correlated to specific horizons within the monotonous organic-rich carbonates of the distal setting of the Shefela Basin.

The first occurrence of the Late Cretaceous organic-rich carbonates in Israel is documented in the Negev during the late Coniacian, within the upper Dicarinella concavata Zone, and corresponds chronologically to the upper part of the lower Menuha Formation. The regional unconformity around the Santonian/Campanian boundary was found to be less substantial at the distal localities in comparison to the proximal ones. The distinct appearance of the ‘Mishash Tongue’ chert in the Shefela was correlated to the massive Chert Member (Mishash Formation) in the Negev, and assigned to the middle Campanian. Deposition of the overlying phosphate series spans from the lower Contusotruncana plummerae to the base of the Pseudoguembelina palpebra Zones (78.3–71.7 Ma) and co-occurs in both proximal and deeper distal areas, although in a much lesser magnitude in the latter. The top of the phosphatic unit is marked by a regional unconformity. The oil shale deposits in southern Israel coincide with the 100 m richest TOC interval (average of 15.2 wt.% TOC) in the Shefela. The diminishing phase of organic-rich deposition occurred in a diachronous step-wise manner across Israel, from the top of the P. palpebra Zone to the upper part of the Abathomphalus mayaroensis Zone in southern and central Israel, respectively. This indicates that the full duration of the high productivity sequence in Israel spans approximately 19 myr.

Arabian Plate-wide maximum flooding surfaces (MFS) recorded during the Tectonic Mega-Sequence (TMS) AP9 timeframe (92–63 Ma) are identified here in the local sedimentary system of the Levant: K160 signifying the onset of organic-rich carbonates; K170 at the upper part of the massive and brecciated Chert Member; and K180 marking the diminishing phase of the high productivity sequence in Israel.

First Clarkforkian Equivalent Land Mammal Age Found in Paleocene Paleogene Europe

First Clarkforkian Equivalent Land Mammal Age in the Latest Paleocene Basal Sparnacian Facies of Europe: Fauna, Flora, Paleoenvironment and (Bio)stratigraphy

Authors:

Smith et al

Abstract:

The Paleocene-Eocene Thermal Maximum (PETM) is correlated with the first occurrences of earliest modern mammals in the Northern Hemisphere. The latest Paleocene Clarkforkian North American Land Mammal Age, that has yielded rodents and carnivorans, is the only exception to this rule. However, until now no pre-PETM localities have yielded modern mammals in Europe or Asia. We report the first Clarkforkian equivalent Land Mammal Age in the latest Paleocene deposits of the basal Sparnacian facies at Rivecourt, in the north-central part of the Paris Basin. The new terrestrial vertebrate and macroflora assemblages are analyzed through a multidisciplinary study including sedimentologic, stratigraphic, isotopic, and palynological aspects in order to reconstruct the paleoenvironment and to evaluate biochronologic and paleogeographic implications. The mammals are moderately diverse and not abundant, contrary to turtles and champsosaurs. The macroflora is exceptional in preservation and diversity with numerous angiosperms represented by flowers, fruits, seeds and wood preserved as lignite material, revealing an abundance of Arecaceae, Betulaceae, Icacinaceae, Menispermaceae, Vitaceae and probably Cornaceae. Results indicate a Late Paleocene age based on carbon isotope data, palynology and vertebrate occurrences such as the choristoderan Champsosaurus, the arctocyonid Arctocyon, and the plesiadapid Plesiadapis tricuspidens. However, several mammal species compare better with the earliest Eocene. Among these, the particular louisinid Teilhardimys musculus, also recorded from the latest Paleocene of the Spanish Pyrenees, suggests a younger age than the typical MP6 reference level. Nevertheless, the most important aspect of the Rivecourt fauna is the presence of dental remains of a rodent and a “miacid” carnivoran, attesting to the presence of two modern mammalian orders in the latest Paleocene of Europe. Interestingly, these two groups are also the only modern groups recorded from the latest Paleocene of North America, making Rivecourt the first direct equivalent to the Clarkforkian Land Mammal Age outside of North America.

Huaibei, Huainan, and Feishui Groups are Tonian Neoproterozoic (and may have an interesting vase shaped fossil)

Biostratigraphic and chemostratigraphic constraints on the age of early Neoproterozoic carbonate successions in North China

Authors:

Xiao et al

Abstract:

Thick carbonate successions of Proterozoic age were deposited in the Huaibei and Huainan regions along the southern margin of the North China Block. These successions, including the Huaibei Group in the Huaibei region and the Huainan and Feishui groups in the Huainan region, have been correlated with the Qingbaikou Group which outcrops in the Jixian area of North China and is the eponymous succession of the Qingbaikouan System (traditionally regarded as 1000–800 Ma). Recently, it has been shown that lower Qingbaikouan strata in the Jixian area may be as old as 1300–1400 Ma. By correlation, the Huaibei, Huainan, and Feishui groups may include Mesoproterozoic strata, but these units have also been interpreted as Tonian or Cryogenian–Ediacaran–Cambrian in age. These contradictory age interpretations hamper our ability to explore the rich paleontological and sedimentary records preserved in these rocks and to assess paleogeographic reconstructions. In this report, we describe new microfossils and stable isotope data (δ13Ccarb, δ18Ocarb, δ34SCAS) from the Huaibei, Huainan, and Feishui groups. Possible vase-shaped microfossils from the Jiayuan Formation of the lower Huaibei Group and characteristic early Neoproterozoic acritarchs (particularly Trachyhystrichosphaera aimika) from the Gouhou and Liulaobei formations are consistent with a Tonian age for the Huaibei and Huainan groups. Similarly, carbon isotope trends in the Huaibei, Huainan, and Feishui groups are comparable with Tonian δ13Ccarb patterns in South Australia and Laurentia, with a plateau of moderately positive (1–5‰) values followed by pronounced negative δ13Ccarb excursion in the Gouhou Formation, which may be equivalent to the Bitter Springs anomaly in South Australia. δ34SCAS values of the Huaibei Group are mostly 25–40‰, similar to values from the stratigraphically equivalent Jingeryu Formation in the Jixian area. Overall, the combination of biostratigraphic, chemostratigraphic, and available radiometric data suggests that the Huaibei, Huainan, and Feishui groups are early Neoproterozoic (Tonian) in age

Positive Carbon Isotope Excursion Recognized in Cambrian Tangwangzhai Section, North China

Integrated biostratigraphy and carbon isotopes from the Cambrian Tangwangzhai section, North China

Authors:

Bagnoli et al

Abstract:

The Tangwangzhai section, western Shandong Province, North China, the type section for the Cambrian Kushan and Chaomitian formations, yielded a diverse and relatively well-preserved conodont fauna, in which we recognize the Westergaardodina orygma, Westergaardodina matsushitai, Muellerodus? erectus, and Westergaardodina aff. fossa–Prooneotodus rotundatus zones of the North China conodont zonation. The Tangwangzhai conodont succession can be correlated not only with the polymerid trilobites occurring in the section but also with the conodont zones established for South China. The first occurrence of Furnishina longibasis and Furnishina quadrata in the upper part of the Westergaardodina matsushitai Zone allows the recognition of the base of the Paibian Stage and Furongian Series in the upper part of the Kushan Formation. The base of the Jiangshanian Stage, in the uppermost Muellerodus? erectus Zone, can be recognized by the presence of Westergaardodina cf. calix close to the base of the Chaomitian Formation. Chemostratigraphic analyses of the Tangwangzhai section show the onset of a positive carbon isotope excursion, referred to the SPICE event, in the upper part of the Kushan Formation at a level corresponding to the first occurrence of F. longibasis and F. quadrata. The base of the Jiangshanian Stage in the section is close to the demise of the SPICE positive excursion.

Presence of Diprotodontid Marsupial Neohelos davidridei in Jaw Junction Local Fauna, Australia Suggests Late Miocene Neogene Date

Revision in the diprotodontid marsupial genus Neohelos: Systematics and biostratigraphy

Authors:

Black et al

Abstract:

Neohelos is a geographically and temporally widespread genus of Cenozoic diprotodontid marsupials commonly used to biocorrelate otherwise undated Australian fossil deposits. Here, we revise the genus and describe two new species from the Riversleigh World Heritage Area of northwestern Queensland. Neohelos solus sp. nov. is a small, relatively abundant, plesiomorphic form, while the rarer, larger Neohelos davidridei sp. nov. is the most derived species of the genus with an upper premolar morphology that is structurally antecedant to members of the Late Miocene genus Kolopsis. Additional material of Neohelos tirarensis and Neohelos stirtoni is described. A chronological morphocline is evidenced by a gradual change in morphology accompanied by an increase in size from Ne. tirarensis through Ne. stirtoni to Ne. davidridei, and is generally consistent with the biostratigraphic distribution of Neohelos species throughout Riversleigh’s faunal zones A to D. Stage of evolution biocorrelation of Neohelos species confirms that some of Riversleigh’s Faunal Zone A deposits are Late Oligocene in age and predate the Wipajiri Formation of South Australia. Strong faunal correlations exist between Riversleigh’s topographically low to middle Faunal Zone C deposits and the Northern Territory’s Middle Miocene Bullock Creek Local Fauna. The presence of the highly derived N. davidridei in the Jaw Junction Local Fauna of Riversleigh’s Upper Faunal Zone C suggests a later Middle Miocene (post−Bullock Creek) age for this deposit.

Academic Bun Fight: Is There a Gap in the Middle Permian Strata?

Apparently back in 2005, Spencer Lucas argued there was a 2 to 3 million year gap in the known strata producing a hiatus.

Fossils of tetrapods (amphibians and reptiles) have long been used to correlate regionally Permian nonmarine strata (Lucas, 1998).
However, the development of a global Permian tetrapod biostratigraphy and biochronology has been hampered by several problems. The most serious may be the presence of a global gap (hiatus) in part of the Middle Permian record of tetrapods.

Michael Benton wrote in 2012 there is no gap in the Middle Permian Strata based on global evidence:

During the Permian, tetrapods showed a major transition from basal synapsid-dominated faunas in the first half to therapsid-dominated faunas in the second. The transition was significant in marking the beginning of richer and more complex communities, a precursor to modern terrestrial ecosystems. This changeover may have been gradual or abrupt, but its study has been complicated by the postulated occurrence of a substantial hiatus in the fossil record, termed “Olson's Gap”, which obscured the nature of the turnover. New evidence from redating of key tetrapod-bearing units of the American southwest and European Russia confirms that there is no gap in the fossil record of Permian tetrapods. Indeed, evidence for substantial sampling bias in the Permian tetrapod fossil record as a whole is queried.

Spencer Lucas replied in 2013:

Benton (2012) claims that there is no gap in the Middle Permian tetrapod fossil record, in contrast to my (2004) conclusion that a gap exists between the youngest pelycosaur-dominated tetrapod assemblages and the oldest therapsid-bearing tetrapod assemblages. I referred to this as Olson’s Gap and concluded that it is equivalent to most of the Roadian Stage. Instead, Benton (2012, his figure 1) correlates the youngest pelycosaur assemblages from Texas-Oklahoma with the oldest therapsid assemblages of Russia. However, in advocating this correlation, Benton does not address an extensive marine biostratigraphic database detailed by me (2004).

To which Benton replied in 2013:

In his comment, Lucas (2013) reiterates his earlier view that there was a marked gap in the tetrapod fossil record spanning the Roadian and Wordian of the Middle Permian, which I, and others (Reisz and Laurin 2001, 2002), have opposed. His arguments are far from certain, however. He says that the uppermost tetrapod-bearing terrestrial Permian beds in Oklahoma and Texas (United States) are Early Permian in age, and that the oldest Russian tetrapod-bearing beds are post-Roadian, so leaving a temporal gap of 2–3 m.y. On the first point, his view is not accepted by the majority of researchers, although the biostratigraphic evidence is far from watertight, and on the second, he is opposed by the majority of experts.

Exquisite Microfossils From Neoproterozoic China Contest Geochronoligical Placement of the Liulaobei Formation

Organic-walled microfossils from the early Neoproterozoic Liulaobei Formation in the Huainan region of North China and their biostratigraphic significance

Authors:

1. Qing Tang (a, b)
2. Ke Pang (a, b)
3. Shuhai Xiao (b)
4. Xunlai Yuan (a)
5. Zhiji Ou (a)
6. Bin Wan (a)

Affiliations:

a. State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, 210008, China

b. Department of Geosciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA

Abstract:

Biostratigraphic subdivision and correlation of early Neoproterozoic strata is hampered by the limited number of widely distributed and age diagnostic fossils. The acanthomorphic acritarch Trachyhystrichosphaera aimika, among a few other microfossil taxa, has emerged as a potential early Neoproterozoic index fossil, but its temporal and spatial ranges have not been thoroughly documented. To improve our knowledge about early Neoproterozoic biodiversity, we carried out a micropaleontological investigation of the early Neoproterozoic Liulaobei Formation in northern Anhui of North China. Our investigation using a low-manipulation maceration technique revealed a diverse assemblage of organic-walled microfossils dominated by sphaeromorphs and filaments, with relatively few acanthomorph taxa. A total of 23 taxa were recovered, including three new species (Eotylotopalla? grandis n. sp., Siphonophycus gigas n. sp., and Trachyhystrichosphaera botula n. sp.). Also present in the Liulaobei Formation are Trachyhystrichosphaera aimika (a species widely present in pre-Cryogenian Neoproterozoic and latest Mesoproterozoic rocks) and Pololeptus rugosus (a species characterized by an ellipsoidal vesicle with transverse annulations). The new data add to the growing diversity of early Neoproterozoic fossils and strengthen the basis for improved biostratigraphic correlation of early Neoproterozoic strata. Correlation with other geochronologically dated successions that contain Trachyhystrichosphaera confirms Trachyhystrichosphaera and T. aimika as promising index fossils to define and subdivide the pre-Cryogenian Neoproterozoic Era in terms of Global Boundary Stratotype Section and Point (GSSP), as opposed to current system using Global Standard Stratigraphic Age (GSSA). Available biostratigraphic data, including the occurrence of Trachyhystrichosphaera, Chuaria, Tawuia, and Sinosabellidites, suggest that the Liulaobei Formation is of pre-Cryogenian Neoproterozoic age, not Cryogenian–Ediacaran age as some have suggested in the past.