Biostratigraphy and palaeobiogeography of Lower Permian (lower Kungurian) conodonts from the Tak Fa Formation (Saraburi Limestone), Thailand

Lower Permian (lower Kungurian) conodonts are reported from the Indochina Block of Southeast Asia. The fauna from the Tak Fa Formation of the Saraburi Limestone Group exposed in limestone hills NNW of Khok Samrong, Thailand, includes Sweetognathus subsymmetricus Wang, Ritter and Clark (early forms) and Pseudosweetognathus costatus Wang, Ritter and Clark. The co-occurrence of these species indicates a Lower Permian age (upper half of the lower Kungurian) for the sampled limestones representative of the Mesogondolella siciliensis–S. subsymmetricus Zone of South China. Sweetognathus and Pseudosweetognathus are for the first time reported from the Indochina terrane located in the palaeoequatorial belt in the Kungurian. Pseudosweetognathus appears restricted to the Kungurian of the South China and Indochina terranes thus supporting palaeogeographic reconstructions that isolate these terranes within the Palaeo-Tethys during the Kungurian.     

Permian and Triassic Radiolaria from Northwest Thailand: paleogeographical implications

Well-preserved radiolarians were recovered from seven sections in the Mae Hong Son-Mae Sariang area, northwestern Thailand. 51 species assigned to 34 genera are identified, including 1 new species (Triassospongosphaera erici Feng sp. nov.) and 19 unidentified species. They are divided into the Late Permian, late Ladinian and middle Carnian radiolarian assemblages. Newly identified radiolarian assemblages, together with the published radiolarian biostratigraphic data from this region, indicate that there was a pelagic basin during the Late Paleozoic and Triassic. This basin was joined to the Chiang Dao and Changning-Menglian oceanic basins, and they represent the main oceanic basin of the Paleotethyan Archipelago Ocean. This main oceanic basin was situated in the traditional “Shan-Thai Block”. Therefore, “the Shan-Thai Block” was not a single block during that stage, but composed of the Paleotethyan Ocean and two continental terranes that were affiliated with the Gondwana and Cathaysian domains, respectively.     

Diversity and paleoenvironmental significance of Middle Triassic ostracods (Crustacea) from northern Thailand: Pha Kan Formation (Anisian,Lampang Group)

The Pha Kan Formation that crops out at the Phra That Muang Kham section, south of Lampang city, was measured and sampled for ostracod analysis. We here report the occurrence of 29 species distributed among 14 genera. Four new species are described: Triassocypris phakanella Forel nov. sp., Leviella lampangensis Forel nov. sp., Bektasia yawella Forel nov. sp. and Hungarella poli Chitnarin nov. sp. The present data represent the first detailed report of Middle Triassic (Anisian) ostracods from the Sukhothai terrane and the first insight into diversity dynamics following the end-Permian extinction in this area. The ostracod assemblages of the Phra That Muang Kham section are discussed and document an important shift from siliciclastic to carbonate conditions, from a protected to an open marine environment, followed by a slight regressive trend up-section associated with repeated salinity fluctuations. This fauna illustrates the post-crisis recovery during the Middle Triassic and some hypothesis are issued on the distribution pathways of several taxa.     

Early Permian radiolarians from Southern Thailand,the deglaciation of Gondwana and the age of the basal Ratburi Group

The first radiolarian fauna obtained from Permian carbonates in Thailand is of late Kungurian age and is present in the basal beds of the carbonate–mudstone–chert Phap Pha Formation, Ratburi Group. This succession contains several species of the radiolarian Pseudoalbaillella, and some sponge spicules. The radiolarian fauna consists of abundant Pseudoalbaillella aidensis and P. elegans together with P. fusiformis, P. longtanensis, P. m. rhombothoracata and P. sp. A. Other species include P. cf. aidensis, P. cf. elongata, P. cf. fusiformis, P. cf. ishigai, P. cf. lomentaria, P. cf. longicornis, P. cf. longtanensis, P. cf. ornata, P. cf. simplex, P. cf. m. scalprata, P. cf. m. postscalprata, P. cf. u–forma m. I, P. cf. u–forma m. II, and P. spp. The radiolarian assemblage suggests its correlation to the P. longtanensis Zone which, in turn, is correlated to the P. ishigai Zone of late Kungurian age. The occurrence of an abundant but generically low–diversity radiolarian fauna suggests restricted physical conditions and, with other evidence, suggests deposition along a cool deglaciating or deglaciated continental margin with an abundance of silica possibly provided by glacial meltwaters. The abundant chert in the Phap Pha Formation is part of the widespread Permian Chert Event.     

Permian and Triassic radiolarians from chert breccia in the Nong Prue area,western Thailand: its origin and depositional setting in the Paleotethys

Bedded chert and siliceous shale successions previously regarded as the Silurian–Devonian rock units, distributed in the Nong Prue area, northwest of Kanchanaburi, western Thailand, yielded Lopingian (upper Permian) and Lower–Middle Triassic radiolarians. We found chert breccia layers in northern Nong Prue area, mainly consisting of angular to sub-angular chert clasts with matrices of silt-sized chert grains and clay minerals. We discriminated uppermost Pennsylvanian–Lopingian (upper Carboniferous–upper Permian) and Middle Triassic radiolarian-bearing chert clasts from four different levels of the chert breccia; 28 species of 15 genera with one radiolarian gen. et sp. indet. are identified. On the basis of sedimentary characteristics of the chert breccia, we suggest that the chert breccia is of sedimentary origin. The radiolarian assemblages reported here, together with previously known lithological and paleontological evidence, further indicate that the chert breccia was deposited in the Paleotethys with chert clasts derived from fine grained siliceous rocks in the continental margin to deep ocean basin of the Sibumasu Terrane.     

Middle Permian ostracod fauna from the Khao Khad Formation (Indochina Terrane), Central Thailand

Permian ostracods are reported for the first time from the Wordian (Middle Permian) Khao Khad Formation of Saraburi Group (Lopburi Province, Central Thailand). The ostracod fauna consists of 18 species belonging to 11 genera including Bairdia, Bohlenatia, Liuzhinia, Silenites, Acratia, Bairdiacypris, Basslerella, Aurigerites, Microcheilinella, Paraparchites and Shemonaella. The studied Khao Khad Limestone, which are rich in fusulinids, gastropods, ostracods, bivalves and brachiopods, was deposited in a shallow carbonate platform on the western margin of the Indochina Terrane. The ostracod assemblage is typically Palaeo-Tethyan and similar to faunas from the other Lower to Middle Permian limestones in central Thailand.     

New fish assemblages from the Middle Permian from the Guadalupe Mountains,West Texas,USA

Late Wordian/Capitanian (Guadalupian, Middle Permian) fish assemblages are described from the “McKittrick Canyon Limestone”, Lamar Limestone and Reef Trail Members of the Bell Canyon Formation in the Patterson Hills and the PI section (Hegler/Pinery Members) along Highway 62/180 in the Guadalupe Mountains, West Texas. The assemblages contain chondrichthyan teeth of Stethacanthulus meccaensis, Texasodus varidentatus, Cooleyella cf. amazonensis, C. cf. peculiaris, and the new genus and species Lamarodus triangulus; and buccopharyngeal denticles of undetermined symmoriiform; chondrichthyan scales of eight morphotypes; fragment of an actinopterygian jaw, isolated teeth; the scales of Alilepis sp., Varialepis sp. and undetermined elonichthyid and haplolepid fishes. Using microtomography, the vascularization system has been observed for the first time for the teeth of Texasodus varidentatus and a new taxon Lamarodus triangulus. The distribution of chondrichthyan taxa was analyzed for the known fish assemblages of the Early, Middle, and Late Permian of the world. The end-Guadalupian crisis in the evolution of chondrichthyan fishes involved substantially more taxonomic change than the Permian–Triassic mass extinction.     

Plio-Pleistocene giant tortoises from Tha Chang sandpits,Nakhon Ratchasima Province,Thailand

Giant tortoises have been found from the Plio-Pleistocene sediments of Tha Chang sandpits, Nakhon Ratchasima Province, Thailand. These tortoises are represented by several individuals and are described based on carapace, plastron, limb bones, and isolated plates. Three different morphotypes of epiplastral projection are recognized, pertaining to different sexes or different ontogenetic stages. Based on their large size, thick shell, single supracaudal, well-developed epiplastral projection, gulars covering anterior part of the entoplastron or in contact with the latter, and humeropectoral sulcus posterior to entoplastron, these Thai giant tortoises are assigned to the genus Megalochelys. Thai specimens show strong similarities with large tortoises from India as well as those from Flores and Timor, and are therefore very close morphologically to Melgalochelys atlas. Our study provides new evidence about polymorphism and additional information about distribution of Plio-Pleistocene fossil giant tortoises in South and Southeast Asia.     

A biogeographically mixed, Middle Permian brachiopod fauna from the Baoshan Block, western Yunnan, China

A small brachiopod fauna is described from the carbonate rocks of the basal Shazipo Formation of the Baoshan Block, western Yunnan, south-west China, including significant new ventral and dorsal internal morphological features of Cryptospirifer omeishanensis Huang. This fauna is regarded as Wordian (Middle Guadalupian, Middle Permian) because of the presence of Cryptospirifer omeishanensis Huang and associated fusulinids ( Neoschwagerina craticulifera Zone). Palaeobiogeographically, the brachiopod fauna is of considerable interest because of its admixed nature characterized by typical warm-water Cathaysian elements intermingled with temperate Peri-Gondwanan taxa. This in turn is interpreted to indicate that the Baoshan Block may have been situated in an intermediate palaeogeographical position between Gondwanaland to the south and Cathaysia to the north during the Mid Permian and, as such, it probably furnished an important 'stepping stone' for the dispersal of Mid Permian eastern Tethyan marine invertebrate taxa (e.g. Cryptospirifer ) to the western Tethys.     

New insects (Insecta: Mecoptera,Grylloblattida) from the Middle Permian Chepanikha locality,Udmurtia

New scorpionflies, Asiachorista europaea sp. nov. and Petromantis udmurtica sp. nov. (Mecoptera: Permochoristidae), and new grylloblattids, Tshepanichoptera lacera gen. et sp. nov. (Grylloblattida: Aliculidae) and Miralioma urzhumica sp. nov. (Liomopteridae), are described from the Urzhumian of Udmurtia (Chepanikha locality). Liomopterites novissimus Aristov, 2004 (Liomopteridae) is redescribed.     

Quantative analysis and paleoecology of Middle to Upper Eocene Ostracods from Jebel Jebil,central Tunisia

One hundred and seventy collected samples from Jebil section have been carefully studied for their ostracod content and referred to 41 species belonging to 20 genera. Their vertical distribution allowed to distinguish five successive associations of ostracod assemblages; two of which are correlated with the Early Lutetian, one with the Late Lutetian, another association with the Bartonian and the last one with the Priabonian. Community structure of the collected ostracod fauna has been studied; three indices have been calculated for each sample: Shannon (diversity), Margalef (richness) and Equitability indexes. In the lower and the middle part of the Formation, they indicate a stable environment supporting high diversity ostracod communities; whereas in the upper portion the environmental conditions were unstable characterized by low diversity. The results of a multivariate statistical method, using the cluster analysis and the Detrended Correspondence Analysis of the 41 ostracod species and the 170 samples, have led to conclude that the most effective environmental factor in the study area is the paleodepth and of less importance oxygenation and salinity. Thus, it allowed to distinguish four palaeoenvironmental intervals within the Cherahil Formation: the first one represented by taxa that are known from the shallower parts of the shelf; the second interval includes the majority of the encountered species of inner neritic shelf with normal salinity; the third one, corresponding to an outer neritic domain; and the last interval refers to a circalittoral environment, is comprised mainly of Cytherella angulata and of Soudanella laciniosa triangulata.     

Sequence boundary and related sedimentary and diagenetic facies formed on Middle Permian mid-oceanic carbonate platform: Core observation of Akiyoshi Limestone,Southwest Japan

Detailed core observation of the Akiyoshi Limestone, Southwest Japan, reveals a sequence boundary and related sedimentary and diagenetic facies formed on a late Murgabian (Middle Permian) mid-oceanic carbonate platform. The sequence boundary lies upon karstified bioclastic grainstone and is overlain by peritidal lime- and dolo-mudstone. The karstified bioclastic grainstone, which had been affected by subaerial exposure and early diagenetic processes, is characterized by crystal silts, prismatic, bladed and dogtooth cements, blackened limestone features, and alveolar textures. The overlying peritidal lime- and dolo-mudstone is 8 m thick and exhibits fenestrae, fissures, laminations, black pebbles, and low-diversity biota composed exclusively of ostracodes and calcispherids. The sequence boundary almost coincides with a major fusulinoidean biostratigraphic boundary. A sea-level fall in the late Murgabian resulted in a biotic turnover and formed the sequence boundary and the karst textures. The following relatively slow transgression resulted in the deposition of the thick transgressive peritidal unit.     

A new family of the order Grylloblattida (Insecta) from the Middle Permian of Russia

A new family, Ivapteridae fam. nov. (Insecta; Grylloblattida), is described from the Middle Permian locality of Soyana (Arkhangelsk Region; Kazanian Stage). It is most similar to Sojanoraphidiidae O. Martynova, 1952, differing from it in the subcostal field being traversed in the basal half of the wing by long, curved, and strongly oblique crossveins that form a double row of cells, the base of CuA being free, and CuA₁ thin compared to CuA₂. The new family is represented by a single species, Ivaptera sharovi, gen. et sp. nov. An overview of the modern system of the order Grylloblattida is included.     

A new large chonetid (Brachiopoda) from the Middle Permian of the southern Kitakami Mountains, northeast Japan

A new chonetid genus and species, Kitakamichonetes multicapillatus gen. et sp. nov. (subfamily Chalimochonetinae, family Rugosochonetidae), from the Middle Permian (Wordian-Capitanian, Kanokura Formation) of the southern Kitakami Mountains (northeast Japan) is described.     

The Shanita fauna (Permian foraminifera) from Baoshan area, western Yunnan Province, China

Studies in the past decade have proven the Shanita fauna to be an excellent marker of the northern peri-Gondwana tectonic blocks.Thus,a study of the Shanita fauna from the Baoshan area in western Yunnan Province,China,could provide pivotal paleontological evidence for the paleogeographic reconstruction of the Baoshan block.We systematically analyzed the composition and the age of the Shanita fauna from the Permian Da'aozi Formation in Woniusi Section of the Baoshan area.Results suggested that the characteristic genera Shanita and Hemigordiopsis in this fauna comprised eight species (including two new species),and ten genera of other nonfusulinid foraminifera were also recognized from this fauna.Further comparative study showed that the Shanita fauna from the Baoshan area were probably late Maokouan (Lengwuan)to Wuchiapingian in age.In general composition,this fauna is comparable to those Shanita faunas from Shan State of Burma,Peninsular Thailand,and Nagri of Tibet,China.However,the relatively low generic diversity and occurrence of some endemic species,as well as the absence of fusulinids,indicate certain regional features of the Shanita fauna from the Baoshan area.     

Biologic response to environmental stress in tropical reefs: Lessons from modern Polynesian coralgal atolls and Middle Permian sponge and Shamovella-microbe reefs (Capitan Limestone USA)

Despite prejudices that comparisons of paleoecological patterns in modern and fossil reef communities are of doubtful validity, we compare the biologic response of living coralgal reefs in French Polynesia to environmental stress with an exceptionally well exposed Middle Permian sponge reef and Shamovella-microbial reef of the Capitan Limestone in New Mexico. In the western Tuamotu Archipelago, reef margins are characterized by depth-related changes of biodiversity. The subtidal basic reefbuilding community contains the highest diversity (23 coral and 6 calcareous algal species). With decreasing water depth and increasing environmental stress, diversity reaches a minimum of five taxa on the reef flat. The Capitan consists of two reef stages. Reefbuilders of the lowermost exposed part of Stage 1 formed a cement-rich sponge reef with 42 taxa (28 sponge species). Decreasing water depth along the reef face is accompanied by loss of five taxa, variations in the gross morphology of sponges and changes in framework architecture. Stage 2, dominated by Shamovella obscura, one bryozoan species and microbes, is sandwiched between two unconformities suggesting much shallower water and higher environmental stress. Despite differences in shelf profile and taxonomy, both the modern and Permian reefbuilders respond to increasing environmental stress with diversity impoverishment and dominance of binders.     

Guadalupian and Lopingian (Middle and Late Permian) deposits from Mexico and Guatemala, a review with new data

This work describes stage by stage the biostratigraphy of the Middle to Late Permian in Mexico and Guatemala. Roadian deposits are very poorly represented, as a consequence of tectonic movements at the end of the Kungurian/Leonardian stage. In fact Middle and Late Permian deposits are almost completely lacking in South Mexico and the whole Latin America, due to a probable climatic barrier. The main data concern the Las Delicias sequences from Coahuila, North Mexico, and the Mixteca Terrane, South central Mexico, with some precisions on the Wordian-Capitanian from Los Hornos (Puebla) and from Olinalá, Guerrero, respectively with the discoveries of Parafusulina sellardsi and Polydiexodina capitanensis. New data are provided on Capitanian mudmounds from Olinalá. A hypothetical reconstruction of the different terranes of Mexico at the Pangea stage, is finally presented.     

Extinction process and patterns of Middle Permian Fusulinaceans in southwest China

Study of the extinction process of 179 fusulinacean species belonging to 34 genera in southwest China demonstrates that diversity changes in the small (shell length ≤6  mm) and large (shell length >6  mm) species groups were very similar throughout the 'Maokouan' (∼Guadalupian). However, significant differences in the timing of extinction pulses occur between different fusulinacean clades with different wall structures, i.e. the nankinellids, schwagerinids, verbeekinids and neoschwagerinds, and between the large and small species groups within the schwagerinids and verbeekinids. Fusulinacean diversity reveals that the Guadalupian mass extinction began in the Middle 'Maokouan' and greatly intensified in the late 'Maokouan'. With only seven species of five genera surviving into the Late Permian, the extinction of fusulinaceans in the Guadalupian mass extinction is 96% at species level and 85% at generic level in southwest China. The preferential extinction of large, morphologically complicated species and the survival of simpler, ecologically more tolerant species of the nankinellids suggest that the extinction of Guadalupian fusulinaceans was caused by falling sea level and the consequent effects related to salinity, temperature and substrate changes. It is also demonstrated that biological characters of fusulinaceans such as shell size and test structures could have certain effects on survivorship of species in the early stages of mass extinction when extinction pressure was less intensive but were ineffectual during the extinction climax.