The biofacies of the Lower Palmatolepis rhenana Biozone to Palmatolepis triangularis Biozone in the Mae Sariang section, northwestern Thailand, are marked by alternations of Palmatolepis-dominated biofacies and Polygnathus-dominated biofacies related to fluctuations in seawater depth. Fine-grained limestone accumulated through the Lower Palmatolepis rhenana Biozone, Upper Palmatolepis rhenana Biozone, Palmatolepis linguiformis Biozone, Palmatolepis subperlobata Biozone, and Palmatolepis triangularis Biozone. A regression in the Upper rhenana Zone was followed by a recovery transgression that extended up through the linguiformis Zone. Conodont faunas increased until near the end of the linguiformis Zone, but in the overlying subperlobata Zone and triangularis Zone, conodont numbers dropped and most conodont species disappeared. It is possible the event coincides with a glacially forced regression, but there is no evidence of this in the section apart from a positive spike in delta 13C. Another possible cause of the global marine extinction event is toxic levels of metals resulting from widespread volcanism. New taxa in this paper are Palmatolepis chaemensis new species, Palmatolepis thamensis new species, and Polygnathus tenellus surinensis new subspecies. UUID: http://zoobank.org/f2b55ba8-fe49-46f6-a2d5-bfd0208f1460

Conodonts collected from sections near the small towns of Thong Pha Phum and Mae Sariang in the westernmost part of Thailand are used to reconstruct the neodymium (Nd) isotopic composition of seawater during the Late Devonian. The study provides the first Devonian seawater signatures recognized within the Australian shelf of northeastern Gondwana and the adjacent Paleotethys Ocean. At Thong Pha Phum site, the seawater was characterized by very low εNd values (from −13.1 to −18.2) and very high Sm/Nd ratios (between 0.36 and 0.66). In contrast, the seawater at the Mae Sariang site was characterized by much more radiogenic signatures (εNd values from −8.7 to −11.1) and uniform, low Sm/Nd ratios (between 0.20 and 0.23). Extremely low εNd values recognized at Thong Pha Phum attest to a passive margin continental setting and a paleogeographic position very close to a continental area where Paleoproterozoic and Neoarchean rocks were eroded. Thus, the isotopic data provide strong evidence that during Late Devonian time the Sibumasu terrane was situated in the proximity to the Archean cratons of Western Australia, presumably adjacent to the Carnarvon intracratonic basin. Moreover, Sibumasu may not have been situated in an outboard position on the shelf, as previously suggested, but could have been directly attached to the Australian continental crust. By contrast, low and uniform Sm/Nd ratios of seawater at Mae Sariang resemble those of the Variscan and the present-day oceanic seawaters. Therefore, a pelagic setting within the Paleotethys Ocean is postulated for the Mae Sariang succession. This conclusion is also constrained by minor temporal changes in εNd values and suggests that the Paleozoic of Mae Sariang is not part of the Sibumasu terrane but belongs to the Inthanon Zone.

An 11 m thick condensed sequence of Late Devonian limestones in northwestern Thailand exhibits faunal associations and sedimentological-/microfacies data which are indicative of a pelagic facies setting. The entire long-ranging section is completely free from clastic input. Similar successions are known worldwide in a few sections only. The Mae Sariang section is characterised by low sedimentation rates as recognised by a number of hardgrounds, neptunian dikes and Fe/Mn crusts. The succession comprises a number of pelagic faunal elements e.g. conodonts, cephalopods and pelagic ostracodes. The fauna records rare macrofossils and the faunal diversity is low. The very condensed section ranges from the Late rhenana to praesulcata conodont biozones, but contains some global events as undoubtedly shown by biostratigraphical and carbon-isotope results (including major Kellwasser and Hangenberg biotic crises). In terms of plate tectonics this important succession most probably belongs to the Inthanon Zone comprising remnants of the Paleotethys Ocean. (C) 2012 Elsevier Ltd. All rights reserved.

Conodonts from the eastern end of Heceta Island and from a small island of the Ham Island group in the Karheen Passage, southeastern Alaska, include Ozarkodina eberleini n. sp., Eognathodus sulcatus Philip, Pandorinellina exigua philipi (Klapper), Icriodus angustoides castilianus Carls, and Pelekysgnathus klamathensis Savage. Both localities are in the Karheen Formation. The age of the faunas is considered to be early Pragian (Faunal units 5 and 6 of Klapper et al.). The early form of Eognathodus sulcatus predominates in the Heceta Island collection from Locality 1, suggesting Fauna 5, and the late form predominates in the Ham Island collection from Locality 2, suggesting Fauna 6. A middle Early Devonian age for the faunas is significant in that Locality 1 is also USGS locality 2689 which previously has yielded brachiopod and coral faunas considered to be of Late Silurian age.

Savage (1995, p. 550, figure 8.8, 8.9) named a conodont Polygnathus praetrigonicus from the Middle Devonian Wadleigh Limestone, southeastern Alaska. This name is now known to be a junior homonym of Polygnathus praetrigonicus Bardashev (1992, p. 56, 57, pl. 2, figs. 32–34), a taxon from the Middle Devonian of the Zeravshan Range, southern Tien-Shan. The southeastern Alaskan fossil is clearly a different species and I here rename it as Polygnathus bagialensis after Port Bagial, near Alberto Island from where the holotype of the species was collected.

Throughout their history, species had to face environmental variations spatially and temporally. How both levels of variation interact will be of key importance in conditioning their response to major perturbations. We addressed this question by focusing on a period in Earth's history marked by dramatic environmental and faunal changes, the Late Devonian Frasnian/Famennian boundary. From a paleogeographic point of view, this period is characterized by a cosmopolitanism of the faunas across a large ocean, the Prototethys. We considered the biotic reaction at a seldom considered scale, namely within a single subgenus of conodont, Palmatolepis (Manticolepis). Patterns of spatial and temporal differentiation were quantified using morphometrics of its platform element. The recognized cosmopolitanism of the faunas was confirmed at this scale of variation since temporal records gathered in distant areas around the Prototethys, including the seldom documented regions located nowadays in South-East Asia, displayed similar morphological trends in response to the major F/F crisis. Beyond this overall cosmopolitanism, subtle geographic structure was evidenced but was not stable through time. Geographic differentiation was maximal shortly before the F/F crisis, suggesting that despite high sea-level, tectonics leaded to complex submarine landscapes promoting differentiation. In contrast any geographic structure was swamped out after the crisis, possibly due to a global recolonization from few favorable patches.

The study of Late Devonian Frasnian and Famennian conodonts in western Thailand confirms these species are mostly cosmopolitan. The Thailand section includes the Upper Kellwasser Event recorded in Europe, North America, China, and elsewhere, and probably also includes the upper part of the Lower Kellwasser Event. Stable isotope geochemistry for this interval shows a positive d13C excursion in the Late rhenana conodont Zone followed by a gradual return to normal, followed by a sudden positive excursion near the conodont extinction event. The latter has been chosen elsewhere as the Frasnian-Famennian boundary. The extinction event seems a consequence of unsteady conditions that could include eutrophic, oxygen, carbon dioxide, eustatic, and temperature fluctuations. There was a regional disappearance or extinction of several conodont species at the Frasnian-Famennian boundary followed by recovery and the spread of new species during the early Famennian.

The Frasnian–Famennian (F–F) boundary is well biostratigraphically documented in the Palmatolepis−rich deposits ex− posed along the Syv’yu River in the lower slopes of the Subpolar Urals. The thin−bedded calcareous−clayey−siliceous deep−slope succession of the Vorota Formation appears to represent continuous Domanic−type deposition throughout the world−wide carbonate crisis time, without evidence for the basal Famennian hiatus or a large−scale sedimentary perturba− tion within a regressive setting. The northernmost Laurussian sequence exhibits many well known signatures throughout the broad F–F timespan: the appearance of organic− and clay−rich deposits, icriodontid and radiolarian blooms, and a cor− relative shift of several geochemical proxies towards hypoxic and high−productivity regimes, perfectly recorded by posi− tive Ccarb excursions of +3.5‰. Integrative biotic, microfacies and geochemical data substantiate a longer−term ocean− ographic destabilization, attributable to multiple Earth−bound triggering factors in (episodically enhanced?) greenhouse climate and punctuated eustatic sea−level highstands, superimposed on the elevated deposition of organic carbon−rich sediments during the Upper Kellwasser Event. Unsteady eutrophicated, and oxygen−depleted ecosystems during the F–F biotic crisis interval could be assumed, especially when intensified by various spasmodic tectono−volcanic phenomena in the incipiently closing Ural Ocean.

ALWYN WILLIAMS, C. H. C. BRUNTON, and S. J. CARLSON with FERNANDO ALVAREZ, A. D. ANSELL, P. G. BAKER, M. G. BASSETT, R. B. BLODGETT, A. J. BOUCOT, J. L. CARTER, L. R. M. COCKS, B. L. COHEN, PAUL COPPER, G. B. CURRY, MAGGIE CUSACK, A. S. DAGYS, C. C. EMIG, A. B. GAWTHROP, REMY GOURVENNEC, R. E. GRANT, D. A. T. HARPER, L. E. HOLMER, H O U HONG-FEI, M. A. JAMES, JIN YU-GAN, J. G. JOHNSON, J. R. LAURIE, STANISLAV LAZAREV, D. E. LEE, SARAH MACKAY, D. I. MACKINNON, M. O. MANCENIDO, MICHAL MERGL, E. F. OWEN, L. S. PECK, L. E. POPOV, P. R. RACHEBOEUF, M. C. RHODES, J. R. RICHARDSON, RONG JIA-YU, MADIS RUBEL, N. M. SAVAGE, T. N . SMIRNOVA, SUN DONG-LI , DEREK WALTON, BRUCE WARDLAW, and A. D. WRIGHT

The generaLissopleura, Sphaerirhynchia, Pectorhyncha, Yanishewskiella, andTerebratuloideahave been investigated to elucidate their internal features and taxonomic relationships. Specimens of the type species of these genera were sectioned.Lissopleuraremains slightly enigmatic in that the holotype ofLissopleura aequivalvisis thinner and has a less pronounced fold than most specimens in the collection, including the one sectioned by us. The holotype is probably immature and is within the range of variation of specimens from the type area. The internal features lead us to assignLissopleurato the Trigonirhynchiidae.Sphaerirhynchia wilsonihas a short septalium without a cover plate and other features that place it in the Hebetoechiidae.Pectorhyncha obtusiplicatahas a very thick shell and a septalium filled by a large, bilobed cardinal process. The genus has several features similar toObturamentella, and is assigned to the Obturamentellidae.Yanishewskiella angulata, which is retained within the Tetracameridae, has a spondylium with lateral buttresses, and a septalium into which the medium septum projects.Terebratuloidea davidsonihas small dental plates, and is assigned to the Allorhynchidae.

As part of the preparation for reviewing the Paleozoic rhynchonellids for the revised brachiopod treatise, one of us (NMS) requested help from Dr. Howard Brunton, of the Natural History Museum (British Museum, London) in obtaining type material of Propriopugnus pugnus (Martin) to further investigate the internal features. Dr. Brunton kindly sent a Natural History Museum specimen that he considers to be close to the lectotype. This specimen has been photographed and sectioned, and it is described below.

Alaska Statute 41, "to determine the potential of Alaskan land for produc tion of metals, minerals, fuels, and geothermal resources; the location and supplies of groundwater and construction materials; the potential geologic hazards to buildings, roads, bridges, and other installations and structures; and shall conduct such other surveys and investigations as will advance knowledge of the geology of Alaska." BetaSite-Analytic Age Calibrated age sample number Description ( 14 C yr B.P.) range (yr B.P.) A-1 45204 Wood from a stump rooted 16 cm 3,470 ± 70 3,560-3,890 above tephra T1 (minimum age) a A-2 50332 3-cm-thick bulk peat in contact 3,510 ± 60 3,630-3,920 with overlying tephra T1 (maximum age) A-3 50333 3-cm-thick bulk peat in contact with 4,550 ± 70 4,980-5,450 underlying tephra T2 (minimum age) A-4 50334 3-cm-thick bulk peat in contact with 4,970 ± 100 5,480-5,920 overlying tephra T2 (maximum age) B-1 45210 4-cm-diameter branch of stump rooted 3,590 ± 70 3,690-4,090 10 cm above tephra T1 (minimum age) B-2 50336 3-cm-thick bulk peat in contact with 3,540 ± 70 3,630-3,990 overlying tephra T1 (maximum age) T1 average -Weighted average of A-1, A-2, B-1, B-2 b 3,530 ± 70 3,690-3,880 Hayes set -Average of numerous published samples 3,650 ± 150 3,730-4,150 (Riehle, 1985)a In view of a slight age reversal, we chose to use the age of this wood sample in preference to that of a bulk peat sample superjacent to tephra T1 at site A (see fig. 2).The rooted wood probably gives a more reliable age.If the peat age (3,310 ± 70 yr B.P.) is used, the weighted average age is 3,490 ± 70 radiocarbon yr B.P. (3,640-3,840 cal yr B.P.).b Averaging all four samples above and below tephra T1 assumes contemporaneous deposition at sites A and B and that tephra accumulation was sufficiently brief that plant remains immediately above and below it are essentially identical in age. Location-CPX/ AMP: sample CPX OPX AMP Other Total OPX/AMP

A brachiopod fauna from the upper part of the Wadleigh Limestone, Alexander terrane, southeastern Alaska, is of late Frasnian age and includes the new taxa Gypidula cornuta alaskensis n. subsp., Gypidula upatensis n. sp., Gypidula perryi n. sp., Gypiduloides craigensis n. gen. and sp., Parapugnax: schmidti n. sp., Westbroekina chaconenesis n: gen. and sp., Emanuella altus n. sp., Emanuella neumani n. sp., Adolfispirifer sanjuanensis n. sp., Theodossia albertoensis n. sp., Cyrtospirifer paridaensis n. sp., and Tenticospirifer wadleighensis n. sp. A few other taxa are cosmopolitan or conspecific with species known from elsewhere in western North America. The fauna overall may have North American affinities but includes an unusual number of previously undescribed forms. This lends support to the view, based on the affinities of Frasnian conodonts from this same locality (Savage, 1992) and Famennian brachiopods described from nearby (Savage et al., 1978), that these Alexander terrane faunas were not in general communication with Late Devonian North American cratonic faunas to the east.

Conodont faunas from the upper part of the Wadleigh Limestone, Alexander terrane, southeastern Alaska, are of Frasnian to early Famennian age and include the new taxa Polygnathus aspelundi nanus n. subsp., Polygnathus decorosus dutroi n. subsp., Polygnathus elegantulus sparus n. subsp., Polygnathus gracilis n. subsp. A, Polygnathus n. sp. A, Palmatolepis subrecta youngquisti n. subsp., and Icriodus subterminus uyenoi n. subsp. Four distinct age-determined faunal assemblages are recognized. The lowest is assigned to the Lower Palmatolepis rhenana Zone (the chronozones of Ziegler and Sandberg, 1990, are treated herein as time-rock equivalent assemblage zones). The next is exposed on three small islands just south of Wadleigh Island and is correlated with part of the Lower to Upper Palmatolepis rhenana Zones. The third assemblage, on the eastern side of Wadleigh Island from close to the top of the section, is correlated with part of the Palmatolepis linguiformis Zone. Nearby and overlying this is the fourth assemblage, which is correlated with part of the Lower Palmatolepis triangularis Zone and thus appears to be within the lower Famennian. These Wadleigh Limestone conodont faunas have affinities with faunas from equivalent horizons of the cratonic regions of the Northwest Territories and Alberta in Western Canada and to other faunas globally. The more provincial conodont taxa lend weak but positive support to brachiopod faunal evidence that places the Alexander terrane close to the North American craton during the Late Devonian.