Search

Little is known regarding characteristics and evolution of radiolarian fossils in the early Cambrian due to its rarity and poor preservation. Here we report a new radiolarian fauna from the Cambrian Shuijingtuo Formation corresponding to the Chiungchussuan Stage (Cambrian Series 2) in western Hubei, China. It contains over 300 radiolarian tests and these fossils belong to 4 morphotypes, including Paraantygopora porosa gen.et sp. nov., Braunosphaera sinensis gen.et sp. nov., Tetrasphaera ? sp. and incertae spherical radiolarians. In taxonomy, Spumellaria predominates in the fauna and comprises 92% of the total. In shell structure, about 73% of all specimens are similar to the early Ordovician radiolarian fossils, with the shell walls characterized by perforated plate structures. The spherical radiolarians with latticed shells constitute another feature of the early Cambrian radiolarian fauna. The radiolarian fauna reported here contains many fossil specimens and covers different taxonomical taxa. These specimens usually consist of distinctive concentric multi-layers with complex structure. These characteristics indicate that Radiolaria had already thrived during the Cambrian Chiungchussuan Stage (Series 2, Stage 3), which may have occurred synchronously with the explosion and prosperity of macrobiota recorded in the strata deposited in shallower water condition.

A sequence of successive conodont datums and zones for the Cisuralian and Guadalupian series for the South China region of the Equatorial Warm Water Province is proposed based on the Shaiwa section, Ziyun, Guizhou. The seven conodont zones in ascending order are: Sweetognathus aff. whitei Zone of Artinskian Stage, a set of three new Kungurian zones of Sweetognathus guizhouensis Zone, Sweetognathus subsymmetricus Zone, Mesogondolella nashuiensis Zone; the Mesogondolella idahoensis lamberti Zone of uppermost Kungurian, the Guadalupian zones of Jinogondolella aserrata followed by Jinogondolella postserrata. The base of the Kungurian Stage is tentatively defined by the first occurrence of S. guizhouensis, 174.5 m above the base of the Sidazhai Formation. This suite of conodont datums and zones will help to improve the global correlations of Permian strata of the Kungurian Stage.

A highly diverse and well-preserved latest Permian radiolarian fauna was obtained from muddy siliceous rocks and siliceous mudstones of the Dalong Formation, southern Guangxi, China. Specimens of the Order Entactinaria were selected for taxonomic study. Thirty-four species, among which were nine new species and twelve unidentified species, are included in this investigation. The nine new species are Entactinia wangi, Entactinia minuta, Entactinia sashidai, Trilonche textiles, Triaenosphaera variabilis, Triaenosphaera megacantha, Provisocyntra densa, Provisocyntra ormistoni and Wuyia dongpanica. Permian species of the Family Spongentactiniidae Nazarov are reported first and the extinction pattern of the Order Entactinaria is discussed.

A very diverse ostracod fauna was discovered in the latest Permian strata of the Dongpan section, southwestern Guangxi, South China. Fifty-one species belonging to twenty-eight genera were identified and described, including two new species (Bairdia dongpanensis n. sp. and Spinomicrocheilinella anterocompressa n. sp). This type of assemblage, with nineteen palaeopsychrospheric species and four pelagic species, is the first world-wide deep-water ostracod fauna reported from the latest Permian strata and the first one recorded in the Permian of China. The palaeoenvironmental analysis allows one to propose an evaluation of the bathymetry variation along the Dongpan section. J. Micropalaeontol. 26(2): 169-191, October 2007.

A latest Changhsingian (latest Permian) foraminiferal fauna composed of 19 species (belonging to 10 genera) was recovered from the Daxiakou section in Xingshan County, Hubei Province, South China. Compared to contemporaneous faunas in South China, the Daxiakou fauna displays unique features: (1) nodosariids are the dominant forms in abundance and diversity; and (2) the most abundant forms have elongate and flattened tests, and include Geinitzina, Howchinella, and Ichthyolaria. The predominance of flattened elongate tests and their smaller size suggest that these foraminifers possibly lived in an oxygen-depleted, deep-water environment. Seven new species, Nodosaria quinquecostata n. sp., Howchinella inflata n. sp., H. hubeiensis n. sp., H. complanata n. sp., H. xiangxiensis n. sp., Ichthyolaria celsa n. sp., and Pseudotristix elongata n. sp. are described.

Diverse and abundant siliceous sponge spicules were found in the latest Permian beds, Dongpan and Ma’anying sections, South China, including 52 types and 85 forms. Further investigation on these spicules allows us to understand extinction patterns and processes of deep-water sponges. These sponge spicules rapidly decreased below the Permian/Triassic boundary (PTB), and the extinction rates reach up to 88%–90% for types and 88%–92% for forms. Their extinction pattern is a gradual one that consists of two stages: the first is characterized by a gentle and slow extinction speed and low extinction rate, and the second by sharp and fast extinction speed and high extinction rate. The morphological extinction process is involved in the disappearance first of the triaxons and tetraxons, then of the polyaxons and demas, and last of monaxons. In exterior structure extinction, the complex spicules with branches and spines became extinct more easily than did smooth spicules. After the end-Permian mass extinction, only five common and smooth forms survived: Oxeas A, Oxeas B, Strongles B, Oxy-orthpentactines and Oxy-orthohexactines A.

A bivalve fauna from the Permian—Triassic interval of the Dongpan section, Guangxi, South China is described herein. This bivalve fauna includes 16 species belonging to 10 genera. New taxa are Euchondria fusuiensis, Palaeoneilo qinzhouensis, and Claraia liuqiaoensis. Bed 12 of the interval (Talung Formation) contains the typical late Late Permian ammonoids: Huananoceras sp., Laibinoceras cf. L. compressum Yang, and Qiangjiangoceras sp. Bed 13 (Luolou Formation) contains typical Early Triassic bivalves Claraia dieneri Nakazawa, C. cf. C. wangi (Patte), and C. griesbachi (Bittner), which coexist with the earliest Triassic ammonoid Ophiceras sp. The bivalve and ammonoid distributions at the Dongpan section indicate that bed 12 should be assigned to the Late Permian, and bed 13 should be assigned to the Early Triassic. From the early Changhsingian to the Induan, the byssal notches of Claraia species tend to become progressively narrower, and change from being ventrally extended to being horizontally extended. The species level diversity of Claraia also increases through this interval.

Brachiopod miniaturization is both the reduction in size of individuals of a species over time, and where one brachiopod fauna dominated by larger individuals was replaced by a brachiopod fauna dominated by smaller individuals over time. This paper investigates this phenomenon prior to and during the end-Permian crisis in a deep water setting in South China, based on precise measurements of brachiopod body size and on the abundance and diversity of brachiopod species. The process of miniaturization near the Permian–Triassic boundary in deep water environments is characterized by: (1) Larger species, including Martinia sp., Costatumulus dongpanensis, and Anidanthus mucronata, reduced in average body size and abundance over time towards the end-Permian brachiopod extinction event. (2) Small species, including Attenuatella mengi and Spinomarginifera semicircridge, showed a mixed response with either no size change, or a reduction in average body size, while these species increased in abundance over time, indicating they were less sensitive to the stressed environmental setting. (3) Both the total abundance and the diversity of this brachiopod fauna decreased over time towards the end-Permian crisis. Regression, an increased input of terrestrial material and productivity decline are considered to all have contributed to brachiopod miniaturization, based on the biotic replacement and changes in sea-water chemistry. Among these factors, the fall in sea level is perhaps the primary factor, and led to a decline in productivity and an increased input of terrestrial material into the marine setting.

Investigations on the Upper Changhsingian radiolarian fauna in South China allow us to trace, in detail, extinction processes and to research relations between the Permian and Triassic radiolarian faunas. Evolution of the radiolarian fauna is divided into three stages: radiation, extinction and survival intervals. In the radiation interval (10.28–2.68 m below the PTB), the radiolarian fauna consists of 137 species belonging to 50 genera and includes 8 representative Triassic genera. Two crises are recognized in the extinction interval (2.68–0.77 m below the PTB). The first crisis is characterized by extinction at species level and the second crisis, by disappearance of many genera. In the survival interval (0.77 m below the PTB to lower Lower Triassic), the radiolarian fauna includes only Paleozoic-type taxa and its diversity and abundance are unusually low. The first crisis corresponds to the extinction located at the top of Bed 24d in Meishan Section D and the second crisis, to the extinction located at the top of Bed 24e of Meishan Section D.

A diverse and well-preserved latest Permian radiolarian fauna was obtained from bedded siliceous rocks and siliceous mudstones of the Dongpan Section, southwest Guangxi, China. All encountered specimens of the order Spumellaria and a few specimens of the order Entactinaria were selected for the taxonomic study of this paper. Thirty-three species, 15 of which are new species, were identified. They belong to 15 genera, three of which (Paracopicyntra, Copiconulus, and Yujingella) are new. The most interesting result of our study is that eight typical Middle Triassic spumellarian genera (Paroertlispongus Kozur and Mostler, Tetrapaurinella Kozur and Mostler, Paurinella Kozur and Mostler, Lithelius Haeckel, Archaeospongoprunum Pessagno, Tamonella Dumitrica, Kozur and Mostler, Bistarkum Yeh, and Tetraspongodiscus Kozur and Mostler) were discovered in the upper Changhsingian strata studied herein. Therefore, the most important and characteristic spumellarian families of the Middle Triassic were already present in the Late Permian of South China.

This paper describes a unique deepwater brachiopod fauna from the upper part of the Talung Formation at the Dongpan Section, southern Guangxi, South China. This brachiopod fauna includes 10 species belonging to 10 genera. New taxa are Anidanthus mucronata n. sp., Dongpanoproductus elegans n. gen. and sp., Costatumulus dongpanensis n. sp., and Spinomarginifera semicircridge n. sp. This fauna is characterized by small, thin-shelled species with high abundance and low diversity, and therefore is different in generic and species composition from the coeval faunas of the Late Permian limestone facies in South China. The brachiopod fauna can be safely assigned to the latest Changhsingian as indicated by the presence of abundant Paracrurithyris pigmaea, the immediately underlying radiolarian Neoalbaillella optima Zone of late Changhsingian age, and the overlying ammonoid Ophiceras sp. cf. O. tingi Tien of the lowest Triassic. This fauna is most likely to have lived in a deepwater environment as indicate...

A unique radiolarian fauna recovered from the top part of the Changxingian stage in south Guizhou, Southwest China, includes at least nineteen species one of which is new. The fauna is mainly composed of Permian species extensively distributed all over the world, such as Hegleria mammilla (Sheng and Wang, 1985); Ishigaum trifustis De Wever and Caridroit, 1984; Foremanhelena triangula De Wever and Caridroit, 1984; Triplanospongos dekkaensis (Noble and Renne, 1990); Nazarovella gracilis De Wever and Caridroit, 1984; and Nazarovella inflata Sashida and Tonishi, 1986, among others. Besides these species, a new radiolarian assemblage, represented by Copicyntra ziyunensis new species; Copiellintra fontainei (Sashida, 2000); Klaengspongus spinosus Sashida, 2000; and Paroertlispongus? sp., was discovered in South China. The assemblage only occurs in less than 10 m siliceous rock strata under the Permian-Triassic boundary at south Guizhou, Guangxi, and north Sichuan. Although only a few new species appeared during this period, they are very important for understanding both the radiolarian extinction at the end of the Permian and the relation between the Paleozoic and Mesozoic Radiolaria.

A new genus of the Corythoecidae (Albaillellaria, Radiolaria) was recovered from the Changhsingian (uppermost Permian) Dalong Formation in Guizhou Province, South China. Qiania Ito and Feng, gen. nov., containing Q. foremanae Ito and Feng, gen. et sp. nov. and Q. uncinata (Rudenko and Panasenko), is characterized by a conical shell consisting of an apical portion and an inflated region with a lateral foramen on the ventral side. The Corythoecidae were thought to range from the Late Devonian to Guadalupian (middle Permian). Therefore, this new find suggests the presence of this family until the latest Permian. Compilation of previous occurrences of corythoecids, in addition to those of Qiania, showed that most corythoecids including Qiania occurred in phosphate-rich facies, and that Qiania occurred in deeper facies than other corythoecids.

Four new species and one indeterminate species of radiolarians from the Changxiangian (Upper Permian) of southern Guangxi, South China are introduced. They all belong to one new genus: Megaporus n. gen. This new genus is characterized by two concentric spherical shells with pentagonal and hexagonal pore frames composed of thick but narrow bars, which is very similar in morphology to some genera within the Mesozoic subfamily Pantanelliinae PESSAGNO (1977), but differs from the latter in possessing initial spicules within medullary shell.