ANNULAR PANCREAS—Peptic Ulcer as Late Postoperative Sequela

Two cases of annular pancrease with late postoperative sequelae of duodenal and gastric ulcer are presented. In each case operation was limited to the annulus. Because symptoms are not permanently relieved by this procedure and subsequent peptic ulceration is not prevented, it is suggested that partial gastric resection be performed and decompression of the duodenal stump be effected by resection of the pancreatic ring.     

PALM THORN INJURIES—Difficulty in Diagnosis of Late Sequelae

Injuries in which palm thorns become embedded in soft tissues or cartilage, leaving no external evidence of their presence, sometimes present a baffling diagnostic problem. A high index of suspicion is the most important aid in diagnosis. Laboratory findings are not helpful and rarely can conclusive diagnosis be made from clinical examination. Surgical excision of the buried thorn is the only satisfactory treatment.     

Late sodium current in failing heart: Friend or foe?

Most cardiac Na⁺ channels open transiently upon membrane depolarization and then are quickly inactivated. However, some channels remain active, carrying the so-called persistent or late Na⁺ current (I_NaL) throughout the action potential (AP) plateau. Experimental data and the results of numerical modeling accumulated over the past decade show the emerging importance of this late current component for the function of both normal and failing myocardium. I_NaL is produced by special gating modes of the cardiac-specific Na⁺ channel isoform. Heart failure (HF) slows channel gating and increases I_NaL, but HF-specific Na⁺ channel isoform underlying these changes has not been found. Na⁺ channels represent a multi-protein complex and its activity is determined not only by the pore-forming subunit but also by its auxiliary β subunits, cytoskeleton, calmodulin, regulatory kinases and phosphatases, and trafficking proteins. Disruption of the integrity of this protein complex may lead to alterations of I_NaL in pathological conditions. Increased I_NaL and the corresponding Na⁺ flux in failing myocardium contribute to abnormal repolarization and an increased cell Ca²⁺ load. Interventions designed to correct I_NaL rescue normal repolarization and improve Ca²⁺ handling and contractility of the failing cardiomyocytes. This review considers (1) quantitative integration of I_NaL into the established electrophysiological and Ca²⁺ regulatory mechanisms in normal and failing cardiomyocytes and (2) a new therapeutic strategy utilizing a selective inhibition of I_NaL to target both arrhythmias and impaired contractility in HF.     

云南施甸志留纪霍梅晚期(Late Homerian)笔石

首次记述了云南西部施甸地区志留纪文洛克世Ｈｏｍｅｒｉａｎ晚期笔石２属５种。其中Ｃｏｌｏｎｏｇｒａｐｔｕｓｐｒａｅｄｅｕｂｅｌｉ,Ｃｏｌｏｎｏｇｒａｐｔｕｓｄｅｕｂｅｌｉ和Ｃｏｌｏｎｏｇｒａｐｔｕｓｌｕｄｅｎｓｉｓ是这个时期全球分布的标准种,但在中国却鲜为人知。它们也是Ｈｏｍｅｒｉａｎ早期ｌｕｎｄｇｒｅｎｉ事件后辐射演化的产物,又是志留纪晚期一些单笔石类的先躯。     

Late Jurassic ichthyosaurs from the Neuquén Basin,Argentina

Late Jurassic ichthyosaurs are well represented in the Tithonian of the Neuquén Basin, in northwestern Patagonia, Argentina. Most of the ichthyosaur material from the Neuquén Basin was originally identified as Ophthalmosaurus. Recently, the new ichthyosaur genus Caypullisaurus was described, based on an almost complete mature specimen from Cerro Lotena. Some material previously referred to Ophlhalmosaurus has been referred to the new genus. However, both genera are present in the Tithonian of the Neuquén Basin. The discovery of an articulated forefin in Cajón de Almanza (near Loncopue, Neuquén) confirms the presence of Ophthalmosaurus in the uppermost Tithonian of the Neuquén Basin.     

Shark faunas from the Late Jurassic—Early Cretaceous of northeastern Thailand

A revision of the freshwater shark fauna from the Phu Kradung Formation in NE Thailand allows the recognition of a new species of Acrodus, which represents the youngest occurrence of the genus and confirms its displacement in freshwater environments after the Toarcian. The rest of the shark fauna includes teeth of Hybodus sp., aff. Hybodus sp., hybodontid dermal denticles, Jiaodontus sp., Lonchidion sp. A, Lonchidion sp. B, Heteroptychodus cf. H. kokutensis and dorsal fin spines. The presence of Jaiodontus and of unusual hybodontid dermal denticles suggests a Jurassic age for most of the Phu Kradung Formation, whereas the presence of Heteroptychodus suggests an Early Cretaceous age for the top of the Formation. However, the age of the Phu Kradung Formation is still uncertain, with contradictory signals coming from palynology, detrital zircon thermochronology and vertebrate palaeontology. In any case, it appears that this is the oldest occurrence of the genus Heteroptychodus, and suggests a Thai origin for this genus, which may have replaced Acrodus in the Thai freshwater palaeoecosystems. Together with Acrodus, the presence of Lonchidion sp. A suggests some European affinities for the shark fauna from the Phu Kradung Formation.     

Late Miocene—Early Pliocene paleotemperatures for California from marine diatom evidence

Paleotemperatures have been interpreted from the evidence of the diatom flora for an Upper Miocene section of marine diatomaceous sediment near Lompoc, California. The diatom flora has been compared with the distribution of modern diatoms in surface sediments of the North Pacific Ocean to propose a Miocene sea paleotemperature curve for this area of California. Temperatures declined sharply in the Late-Mohnian (Upper Miocene) to a winter minimum of about 10°C. Thereafter, a gradual and fluctuating rise in temperature characterized the latest Miocene (Delmontian); minimum seasonal temperatures approached 17°C by the Early Pliocene.This diatom assemblage paleotemperature curve is supported by other evidence. Independent studies of particular diatom temperature indicator species show the same trends, as do the paleotemperature indications of a fossil fish fauna and the foraminiferal fauna in the section. Furthermore, the curve shows a marked correspondence to paleotemperature curves based on planktonic foraminifers and on radiolarians for the Upper Miocene of southern California, providing an additional tool for paleotemperature reconstruction.     

Is Torosaurus Triceratops? Geometric Morphometric Evidence of Late Maastrichtian Ceratopsid Dinosaurs

Background

Recent assessments of morphological changes in the frill during ontogeny hypothesized that the late Maastrichtian horned dinosaur Torosaurus represents the “old adult” of Triceratops, although acceptance of this finding has been disputed on several lines of evidence.

Methodology/Principal Findings

Examining the cranial morphology of 28 skulls in lateral view and 36 squamosals of Nedoceratops hatcheri, Triceratops spp. and Torosaurus spp. by means of landmark-based geometric morphometrics, we compared ontogenetic trajectories among these taxa. Principal Component Analysis and cluster analysis confirmed different cranial morphologies. Torosaurus shape space is well separated from Triceratops, whereas Triceratops horridus and Triceratops prorsus partially overlap within Triceratops shape space. Linear regressions between shape and size suggest different ontogenetic trajectories among these taxa. Results support the “traditional” taxonomic status of Torosaurus. We hypothesize that ontogeny drives cranial morphology with different patterns between Torosaurus and Triceratops.

Conclusions/Significance

Torosaurus is a distinct and valid taxon. Whether looking at entire skulls, skulls without the frill, frills alone, or squamosals, Torosaurus has different morphologies and distinct allometric trajectories compared to Triceratops. This new approach confirms the taxonomic status of Torosaurus as well as the comparatively low diversity of ceratopsids at the end of the Maastrichtian in North America.     

The Late Palaeozoic phytoplankton blackout — Artefact or evidence of global change?

The fossil record of the Palaeozoic documents one of the most dramatic changes in Phanerozoic marine primary production, although causes and effects of these changes have been the subject of rather controversial discussions. During the early Palaeozoic the marine phytoplankton experienced an enormous radiation and diversification of taxa especially among acritarchs, which was punctuated by a few extinction events possibly associated with climate changes. Phytoplankton diversity was drastically reduced at the Devonian/Carboniferous boundary, a phenomenon here designated as the “Phytoplankton Blackout”.After a lapse of about 130 million years phytoplankton diversity was gradually restored during the Late Triassic with the appearance of dinoflagellates and somewhat later of coccolithophorids and diatoms. Evidence from recent phytoplankton suggests that the dominant groups of phytoplankton differ from those of the Palaeozoic in their nutritional requirements and that fundamental changes in ocean chemistry have played an important role.The remarkable temporal coincidence of the Phytoplankton Blackout with plate tectonic processes during the assembly and breakup of Pangaea and the concomitant rise of land plants towards the end of the Devonian provide arguments that nutrient depletion in the ocean may have played a decisive role in controlling the phytoplankton blackout. Contrary arguments in favour of oceanic eutrophication, changes in life cycles of dominant phytoplankton groups or selective preservation are discussed and weighed against the scenario presented here. Metazoan evolution seems only loosely linked with the phytoplankton blackout. However, there is good agreement between phytoplankton and reef evolution throughout the Phanerozoic.     

Late Holocene mangrove dynamics of Marajó Island in Amazonia,northern Brazil

Two sediment cores from the eastern coastal region of Marajó Island, Pará State, northern Brazil have been studied by pollen analysis to reconstruct late Holocene mangrove dynamics and environmental changes. Seven AMS radiocarbon dates provide time control. Mangrove vegetation became established at the Barra Velha site at about 2750 B.P. (2880 cal B.P.) and at the Praia do Pesqueiro site at about 650 B.P. (670 cal B.P.). Rhizophora was the dominant mangrove tree throughout the recorded period, while Avicennia and Laguncularia were rare. Existing remnants of the former coastal Amazon rain forest were replaced by mangrove in the Barra Velha area between about 2750 and 740 B.P. (2880–760 cal B.P.) and at Praia do Pesqueiro area between about 650 and 530 B.P. (670–540 cal B.P.), suggesting a rise in relative sea level or, alternatively, an increase in discharge from the river Amazon. Areas of coastal shrub and herb vegetation, the so-called restinga vegetation, also became slightly reduced during the late Holocene. The largest area of mangrove at the two sites suggests that the highest sea level was probably reached during the last 200–250 years. The only evidence of human activity at the two sites is an indication of cattle pastureland at the Barra Velha area during the last decades.     

How many species of Hipposideros have occurred on Madagascar since the Late Pleistocene?

Populations of the Malagasy Hipposideros commersoni (family Hipposideridae) are threatened by deforestation and hunting. Maximum likelihood and Bayesian analysis of 148 cytochrome b sequences found this species to be paraphyletic and composed of three well‐supported monophyletic clades. Clades B and C form a monophyletic lineage that can be referred to H. commersoni; these two clades are separated by 6% sequence variation. Clade A represents a distinct evolutionary lineage separate (9–11% average sequence divergence) from H. commersoni (clades B and C) and is named herein as a new species, H ipposideros cryptovalorona sp. nov. In the phylogeny presented herein, this species is strongly associated with the outgroup taxa Hipposideros gigas and Hipposideros vittatus, both restricted to Africa. External, cranial and dental measurements taken from the same individuals used in the molecular study indicate no clear distinction in morphology amongst these three clades; this includes noseleaf structure and craniodental characteristics. Principal component analyses showed limited separation of the three clades. Comparison to a Quaternary fossil species from north‐west Madagascar, Hipposideros besaoka, found little morphological overlap between any of the three clades and this extinct species. Hence, at least three species of Hipposideros have occurred on Madagascar since the Late Pleistocene, two extant (H. commersoni s.s. and H. cryptovalorona sp. nov.) and one extinct (H. besaoka). © 2015 The Linnean Society of London     

Did incumbency play a role in maintaining boundaries between Late Ordovician brachiopod realms?

Studies of ecosystem level changes in the geological record have found that the major extinction events eliminated many incumbent clades that had been ecologically dominant for long intervals. Surviving clades that had not been able to compete with the extinct incumbents were then able to evolve adaptations that allowed them to move into the niches vacated by the incumbents. Underlying this pattern is the inability of clades that do not occupy a particular niche to evolve adaptations that would permit them to compete with incumbent clades that are already successfully occupying that niche. The zoogeographic distributions of brachiopods in the Late Ordovician of Laurentia may also have been maintained by incumbency, which was disrupted by the end-Ordovician extinction event. Following the extinction event, an Early Silurian zoogeographic reorganization occurred, during which surviving clades evolved into the vacated epeiric sea niches in the Early Silurian. Just as incumbency plays a role in long-term evolutionary patterns, zoogeographic realms and provinces are also partially maintained by incumbency.     

Two new theropod egg sites from the Late Jurassic Lourinhã Formation,Portugal

Two new Late Jurassic (uppermost Late Kimmeridgian) dinosaur eggshell sites are described, Casal da Rola and Porto das Barcas, both near Lourinhã, central-west Portugal. Casal da Rola yields eggshells with an obliquiprismatic morphotype comparable to those from a nest with the associated fossil embryos from Paimogo, tentatively assigned to the theropod Lourinhanosaurus antunesi. The Porto das Barcas eggshells have a dendrospherulitic morphotype with a prolatocanaliculate pore system. This morphotype was also recognised in eggshells from a clutch with associated Torvosaurus embryos at the Porto das Barcas locality. A preliminary cladistic analysis of eggshell morphology suggests theropod affinities for the Casal da Rola eggs, but is unable to resolve the phylogenetic position of the Porto das Barcas eggs. The eggshells at both sites are preserved in distal flood plain mudstones and siltstones. Carbonate concretions within the deposits indicate paleosol development.     

Late Devonian and early Carboniferous microfloras from the Hakkarı Province of southeastern Turkey

Late Devonian and early Carboniferous miospore and microphytoplankton assemblages are described for the first time from southeastern Turkey. The preliminary data show that assemblages recorded from the upper part of the Yiginli Formation are late Famennian in age and can be correlated with the VH, LL, LE Miospore biozones of western Europe, whilst assemblages from the overlying Köprülü Formation are considered to be middle to late Tournaisian in age and are tentatively assigned to the PC Miospore biozone of western Europe. Regional palynological correlations with other sections in North Africa and the Middle East are proposed. A new species, Verruciretusispora loboziakii is described.     

The Late Eocene ‘Whiskey Creek’ methane-seep deposit (western Washington State)

Summary Large limestone boulders are eroding from a landslide west of the mouth of Whiskey Creek, Clallam County, Washington State. These boulders are composed of micrite, carbonate cement, and densely-packed fossil bivalves. Siltstone in the landslide, and on the surfaces of the boulders, indicates that these limestones are derived from the lower part of the Pysht Formation. The molluscan taxa and their localised occurrence within limestone are typical features of ancient chemosymbiotic cold-seep communities. Formainiferans from both the siltstone and the limestone indicate that deposition occurred during Late Eocene time, at water depths of between 500 to 1,500 m. Lipid biomarkers, particularly isoprenoid hydrocarbons and fatty acids, with δ¹³C values as low as −101‰ PDB, reveal that the anaerobic oxidation of biogenic methane was an important component in the biogeochemical cycling of carbon in the ancient seep environment.     

The Middle–Late Ordovician brachiopod Plectorthis from North America and its paleobiogeographic significance

Plectorthis is a commonly reported Late Ordovician brachiopod genus from Laurentia and several other tectonic plates. Examination of shells from the Cincinnati Arch type area shows that species previously assigned to the genus have a considerable range of variability, such as ribbing style, shell outline, and musculature. The type species, Orthis plicatella Hall, 1847 is characterized by generally simple costae, with double-rowed aditicules on each rib, and a cordate ventral muscle field. Some species previously attributed to Plectorthis have a subtriangular ventral muscle field and hence a closer affinity to the plaesiomyid genus Austinella. Orthis fissicosta is here demoted to a subspecies of Plectorthis plicatella based on its similar ribbing style to some specimens of the type species. In Laurentia, Plectorthis first appeared in the Darriwilian–Sandbian boundary interval, achieved a relatively high species diversity and wide paleogeographic distribution in pericratonic seas during the early Katian; the subequatorial species attained a notably larger shell than those in the higher paleotropics. The genus did not invade the intracratonic basins of Laurentia and became extinct by the late Katian.     

Late Darriwilian–early Katian (Ordovician) ostracods of northeastern Yunnan,Southwest China

Ordovician silicified ostracods of the western Yangtze Platform, South China, are documented for the first time from the Huadan Formation of Qiaojia County, northeastern Yunnan Province, Southwest China. Twenty-one species of 17 genera are identified with new taxa including Vendona spinifera n. sp. and Nikitinella songliangensis n. sp. These two species, together with Medianella gigantea are the most common constituents of the fauna. Faunal comparison shows close connections between South China, Baltica, the Argentine Precordillera, Kazakhstan, Tarim, and Sibumasu during this time interval. This fauna is considered to be related to a nearshore carbonate environment, and biostratigraphical analysis of it supports a late Darriwilian to early Katian age for the Huadan Formation.