The late Oligocene molluscan fauna from Otranto (Apulia, Southern Italy): an example of alternating freshwater, lagoonal and emerged environments

Abstract:  Eighteen gastropod and five bivalve species are taxonomically described from an Upper Oligocene succession cropping out near Otranto (southern Salento, Apulia, Italy). Among these, Tectarius ( Echininus ) japigiae , Hydrobia dubuissoni hydruntina , Pseudamnicola messapica , Pseudamnicola palmariggii and Stenothyrella salentina are new taxa. Nonmarine and lagoonal environments characterize almost the whole succession, as testified by species-poor assemblages rich in specimens of freshwater and oligo- to mesohaline prosobranchs, such as Neritinidae, Hydrobiidae, Stenothyridae, Thiaridae, Potamididae, Batillariidae, pulmonates, including Planorbidae and bivalves comprising Dreissenidae and Cyrenidae. The genera Theodoxus , Hydrobia , Melanoides , Potamides , Terebralia , Batillaria , Granulolabium , Mytilopsis and Polymesoda alternately dominate. Littoral marine elements, such as Tectarius , Turritella , Barbatia , Anadara and Chama , are scattered present in the succession, but some prevail towards the top. The fauna is palaeobiogeographically significant having strong affinities with those of the Oligo–Miocene basins of Aquitaine, Mainz, Bavaria, North Alpine Foreland, Vienna, Greece and Turkey. The analysed Otranto succession is assigned to the Chattian Galatone Formation of southernmost Apulia (Salento) based on lithological evidence and supported by the palaeontological data.     

The composition and relationships of the marine molluscan fauna of the Pitcairn Islands

The recent expedition has doubled the number of marine molluscs known from the Pitcairn Islands. Over 80 taxa are recorded from Ducie and Pitcairn (both still poorly known), 240 from Oeno and 320 from Henderson. A total exceeding 400 taxa is now known from the group as a whole. Most of this increase results from a vastly improved knowledge of the small taxa that had been neglected in earlier surveys. Important faunal differences exist between the four islands in the group which are related to the different character of each island. These totals still underestimate the true diversities, but they provide data that are comparable in quality to those from adjacent regions. In this context the molluscan fauna from the Pitcairn Islands is seen to be impoverished when compared to those from islands further west. Most of the fauna is composed of widespread Indo-West Pacific species, but there are several taxa that have more restricted ranges centred on S.E. Polynesia. A few, including some undescribed taxa discovered on the expedition, appear to be endemic. Significantly, many of these are characterized by non-planktotrophic larval development. Comparison of the modern fauna from Henderson with the fossil fauna from the Pleistocene reef on its plateau reveals important differences. About 25% of the fossil molluscs are currently unknown from the group and about 5% appear to be undescribed. These high rates of turnover demonstrate that the faunas are temporally unstable.     

The molluscan fauna of Chagos (Indian Ocean) and an analysis of its broad distribution patterns

A detailed survey of molluscs in the Chagos Archipelago was made (1) to determine whether this isolated atoll group has a diverse fauna, and (2) to identify broad-scale distribution patterns of molluscs in relation to depth, exposure and substrate type: 384 confirmed species (including 282 gastropods and 99 bivalves) compares with reported diversities from other island and continental reef areas, suggesting that Chagos is not depauperate. Molluscs were sampled from 18 zones, which encompassed all habitats to 40 m deep. Cluster analysis based on species similarity revealed 4 main groups from hard substrate and 1 from soft substrate. On hard substrate, depth or depth-related parameters were a stronger determinant of molluscan distribution than seaward or lagoonal position, and greatest diversity occurred between 10–20 m deep on reefs of all exposures.     

辽宁獐子岛马牙滩潮间带及近岸海区大型底栖动物群落特征

为摸清辽宁獐子岛潮间带及近岸海区的大型底栖动物的分布现状和群落受扰动情况,作者于2011年11月中旬在马牙滩潮间带和近岸海区采集大型底栖动物,采用优势度指数、Shannon-Wiener多样性指数、Margalef丰富度指数、Pielou均匀度指数,Bray-Curtis相似性聚类分析、MDS标序和ABC曲线等方法,分析该区域内大型底栖动物群落的生态学特点.结果表明,在潮间带共鉴定大型底栖动物39种,优势类群为多毛类、甲壳类和软体类;优势种均为多毛类,即小头虫(Capitella capitata)、多美沙蚕(Lycastopsis augenari)、仙居虫(Naineris laevigata)和短叶索沙蚕(Lumbrineris latreilli);平均生物量为25.76±41.08 g/m2,以软体动物占优势;平均栖息密度为315.11±160.73个/m2,以多毛类占优势;丰富度指数、均匀度指数与Shannon-Wiener多样性指数的平均值分别为1.17±0.89,0.74±0.17和1.80±1.09.近岸海区共鉴定大型底栖动物40种,优势类群为多毛类、甲壳动物、软体动物和棘皮动物.优势种包括4种棘皮动物和1种多毛类,即紫蛇尾(Ophiopholis mirabilis)、日本倍棘蛇尾(Amphioplus japonicus)、短叶索沙蚕、心形海胆(Echinocardium cordatum)和浅水萨氏真蛇尾(Ophiura sarsiivadicola).近岸海区的平均生物量和平均栖息密度分别为218.86±152.24g/m2和700.00±471.51个/m2,均以棘皮动物占优势.丰富度指数、均匀度指数与Shannon-Wiener多样性指数的平均值分别为1.40±0.60,0.64±0.19和2.04±0.78.聚类分析结果表明,潮间带不同潮区间和近岸海区不同断面间群落差异显著.ABC曲线分析显示,獐子岛潮间带底质环境受到中度扰动,大型底栖动物群落结构处于不稳定状态;近岸海区受到轻度干扰,群落结构未发生明显变化.     

A new look at evolution in the Galápagos: evidence from the late Cenozoic marine molluscan fauna

Endemism is not as common in the marine invertebrate fauna of the Galápagos Islands region as in the adjacent terrestrial biota. Marine invertebrates in the Galápagos are largely cosmopolitan species from the Panamic, Indo-Pacific, Californian, or Peruvian faunal provinces. However, an endemic component is also present in the fauna. The observed pattern among marine invertebrate organisms can be accounted for by at least two processes: (1) genetic continuity between mainland and island populations mediated through planktonic larvae; and (2) lower rates of intrinsic evolutionary change. The evolutionary scenario standardly applied to terrestrial organisms in the Galápagos, namely, adaptive radiation and speciation in reproductive isolation from mainland source populations, does not apply to all marine invertebrates. Evidence in support of the alternative scenario for marine invertebrates comes from both published records of species occurring in the islands and recent studies of fossil-bearing deposits on several islands in the archipelago. Two misconceptions–considering the islands and sedimentary deposits to be older than now thought, and equating the rate of evolution of the terrestrial biota with the marine biota–can lead to an incorrect interpretation of evolution in the Galápagos Contrasts between marine invertebrate and terrestrial organisms serve to illustrate some fundamental differences which have important evolutionary implications. Some of these are: endemism; dispersal; taxonomic relationships; island definitions; rates of evolutionary change; and age of fossils. In terms of Darwin's evolutionary scenario, terrestrial organisms represent the paradigm and marine organisms represent the paradox.     

Late Ordovician brachiopods from eastern North Greenland: equatorial offshore migration of the Red River fauna

Abstract: Late Ordovician rhynchonelliformean brachiopods, typical of the North American Red River fauna, are found sporadically in the Børglum River Formation of the Centrum Sø area, Kronprins Christian Land, eastern North Greenland. The geographical distribution of this characteristic brachiopod fauna is thus extended to the easternmost extremity of the Laurentian craton. The assemblage compares specifically with the Hiscobeccus brachiopod fauna, based on key taxa such as notably Hiscobeccus gigas (Wang, 1949), and indicates a late Katian age for this part of the succession. For the first time, this typically inland, shallow‐water fauna is found associated with genera like Bimuria, suggesting a transitional marginal facies with outer shelf benthos. The current study describes a Hiscobeccus fauna that lived at the seaward edge of its preferred habitat. Furthermore, an unpublished Hiscobeccus fauna, from the Børglum River Formation of Peary Land, central North Greenland, as well as several occurrences from the Kap Jackson and Cape Calhoun formations in various parts of Washington Land, western North Greenland, are described here. These show a distinct shift from older strata containing H. capax (Conrad, 1842) to younger strata exclusively yielding specimens of H. gigas. As H. gigas occurs in the upper part of the Cape Calhoun Formation in Washington Land, it indicates that the upper boundary of the Cape Calhoun Formation is considerably younger than previous estimates, reaching into the uppermost Katian (middle Cautleyan–Rawtheyan). The Cape Calhoun Formation correlates with the upper member of the Børglum River Formation and further demonstrates that the Hiscobeccus fauna was widespread in Laurentian marginal settings of North Greenland. Even though the Hiscobeccus fauna was pan‐continental during the late Katian (Richmondian), it possesses a strong provincial signal during the later Ordovician. The new occurrences indicate that this fauna extended to the north‐eastern margin of the Laurentian Craton. It lived in close association with cosmopolitan faunal elements that may have been the earliest sign of the succeeding invasion of migrants from Baltica that arrived later during the Hirnantian. The offshore migration of this atypical Hiscobeccus fauna likely demonstrates the path of warm‐water currents as the Centrum Sø locality was located at the equator during the Late Ordovician.     

Diversity and distribution of molluscan fauna of Asthamudi estuary,Kerala, India

The survey of molluscan fauna of Ashtamudi estuary of the southwest coast of India recorded the presence of 119 species classified under 3 classes (Polyplacophora, Gastropoda and Bivalvia), 57 families and 96 genera. The species diversity was dominated by the Gastropoda (69 species), followed by the Bivalvia (49 species) and the Polyplacophora (1 species). The report includes four species recorded for the first time from India: Desmaulus edgarianus (Melvill, 1898), Pilosabia trigona (Gmelin, 1791), Nassarius javanus (Schepman, 1891) and Jorunna labialis (Eliot, 1908). The true diversity of the mangrove region was as good as that of a community with 31.380 (=?31) equally common species; the respective values for the bar mouth and lake regions were 15.516 and 8.997, respectively, indicating that the molluscan species assemblage of the mangrove was the most diverse and of the lake, the least. True β-diversity across this gradient registered 1.792, which means that though there were three communities, they were equivalent to only 1.792 (=?2) effective communities, i.e., the three actual communities were as different from each other as 2 with equal weights and no species in common.

     

Permian Toxeumorphorida from Greenland: an appraisal of the molluscan class Xenoconchia

Macrotheca Waagen 1880, previously known only from the Salt Range of Pakistan and from Timor, and Toxeumorphora Shimanskiy, previously known only from the Ural Mountains, have been identified in the Permian of northern East Greenland. The new specimens are assigned to the order Toxeumorphorida which is transferred to the class Hyolitha. The class Xenoconchia tentatively proposed by Shimanskiy two decades ago to include the toxeumorphorids is abandoned. Macrotheca almgreeni n. sp. is described. Mollusca, Hyolitha, Toxeumorphorida, Xenoconchia, Permian, Greenland.     

Echinoid fauna from a Late Oligocene (Chattian) reef at Damon Mound,Brazoria County,Texas

The echinoid fauna collected from the Late Oligocene (Chattian) reef at Damon Mound, Brazoria County, Texas, includes at least seven species. The reef can be divided into four zones, in ascending order: reef drape, Porites thicket, reef core, and back-reef. The reef drape represents the deepest water and includes the echinoid species Clypeaster marinanus, Agassizia mossomi, and Lovenia alabamensis. The overlying zone consists of interbedded calcilutites and Porites coral thickets, and includes the species Echinometra prisca, C. marinanus, Clypeaster cf. oxybaphon, and Brissus exiguus. The reef core includes Prionocidaris cojimarensis and E. prisca. The shallow back-reef deposits include only C. marinanus. The Damon Mound fauna is more closely related to tropical Oligocene faunas of Mexico and the Antilles than to Gulf and Atlantic Coast faunas of the United States of the same latitude. During the Oligo-Miocene, Damon Mound and similar salt dome reef buildups in the northwestern Gulf of Mexico may have been havens for tropical species that could not have otherwise survived at that latitude.     

Predatory gastropod boreholes in an Eocene molluscan assemblage from Nigeria

Arua, Ingela & Hoque, Mominul. 1989 01 15: Predatory gastropod boreholes in an Eocene molluscan assemblage from Nigeria. Lethaia . Vol. 22, pp. 49–59. Oslo. ISSN 0021–1164.
Morphometric data of 1, 346 boreholes belonging to eleven gastropod species and nine bivalve species have been studied. On the basis of hole-wall geometry and concentricity of the inner and outer holes, six different borehole types are identified: (1) concave with concentric openings (A-type); (2) concave with aconcentric openings (B-type); (3) planar tapering with concentric openings (C-type); (4) planar tapering with aconcentric openings (D-typc); (5) vertical with concentric openings (E-typc); and (6) concave-planar with aconcentric openings (F-type). The preferred gastropod and bivalve prey species for each bole type are named. In identifying the borers of a particular hole type, the mode of life of the most preferred prey species is used as a diagnostic parameter. Preferred infaunal prey species are dominantly bored by naticids, preferred epifaunal prey is mainly bored by muricids. The presence of a boss at the base of an inoomplete hole and the presence of countersunk holes are the additional criteria for identifying naticid borings. The hole type analysis suggests that hde types A, B and D belong to muricids and C, E and F to naticids. All the naticid and muricid hole types studied have a preferred site for boring. They are located purposefully where they would intercept internal organs of the prey. It appears that in ornamented bivalve shells these predators would rather drill between ribs than on top of the ribs. □ Gastropoda, predation, boreholes, molluscan assemblage, Eocene. Ameki Formation, Nigeria. Ingela Arua, Department of Geology, University of Nigeria, Nsukka. Nigeria; Mominul Hoque, Geo-Mechanis Inc., Elizabeth, PA 15037, U. S. A.; 14th October, 1987 .     

Palaeobiology of Triassic procolophonids,inferred from bone microstructure

Procolophonoidea represent the most successful radiation of Parareptilia that lived during the Permo-Triassic. They are one of the few vertebrate groups that survived the end-Permian extinction and are thus important for studying the recovery of the post-extinction terrestrial ecosystem. Here, we investigate the palaeobiology of three Triassic procolophonid parareptiles, namely Sauropareion anoplus, Procolophon trigoniceps and Teratophon spinigenis, from the Karoo Basin of South Africa, inferred from histological analyses of their limb bones. Results reveal that all three taxa exhibit parallel-fibered bone tissue. Growth rings are absent in the Early Triassic Sauropareion and Procolophon whereas annuli are present in the Middle Triassic Teratophon, even during early ontogeny, suggesting a difference in life histories. Morphology and bone histology imply fossorial lifestyles for all three taxa, suggesting that burrowing may have played an important role in their survival during the harsh post-extinction Triassic environment.     

A comparison of the parasite fauna of young whiting, Odontogadus merlangus (L.) (Gadidae) from an inshore and an offshore location off the Isle of Man

The occurrence of 12 helminth and 4 crustacean parasites on young whiting 0–2 years old from an inshore (Port Erin Bay) and an offshore (off Bradda Head) area of the Isle of Man were compared. No parasites were found on whiting 4.5–15 mm long and the intestinal digenean Lecithaster gibbosus Rudolphi together with the larvae of the copepod Caligus rapax M. Edwards were the first parasites to appear in whiting 15–42 mm long. This appears to be the only time during the life history of the whiting that C. rapax is of importance as a parasite. In whiting 6 months-2 years old from off Bradda Head such helminths as the acanthocephalan Echinorhynchus gadi Muller and the digeneans Podocotyle atomon Muller and Cryptocotyle lingua Creplin (metacercariae) were found in significantly fewer fish than in an equivalent group from Port Erin Bay. The differences are correlated with the availability of intermediate hosts and the different food spectra of the two groups of fish and are used to support the theory that inshore and offshore whiting of these age groups form separate populations and that the offshore fish may be more important than the inshore fish in replenishing stocks of older whiting.     

Metagenomic analysis of microbial consortium from natural crude oil that seeps into the marine ecosystem offshore Southern California

Crude oils can be major contaminants of the marine ecosystem and microorganisms play a significant role in the degradation of its main constituents. To increase our understanding of the microbial hydrocarbon degradation process in the marine ecosystem, we collected crude oil from an active seep area located in the Santa Barbara Channel (SBC) and generated a total of about 52 Gb of raw metagenomic sequence data. The assembled data comprised ~500 Mb, representing ~1.1 million genes derived primarily from chemolithoautotrophic bacteria. Members of Oceanospirillales, a bacterial order belonging to the Deltaproteobacteria, recruited less than 2% of the assembled genes within the SBC metagenome. In contrast, the microbial community associated with the oil plume that developed in the aftermath of the Deepwater Horizon (DWH) blowout in 2010, was dominated by Oceanospirillales, which comprised more than 60% of the metagenomic data generated from the DWH oil plume. This suggests that Oceanospirillales might play a less significant role in the microbially mediated hydrocarbon conversion within the SBC seep oil compared to the DWH plume oil. We hypothesize that this difference results from the SBC oil seep being mostly anaerobic, while the DWH oil plume is aerobic. Within the Archaea, the phylum Euryarchaeota, recruited more than 95% of the assembled archaeal sequences from the SBC oil seep metagenome, with more than 50% of the sequences assigned to members of the orders Methanomicrobiales and Methanosarcinales. These orders contain organisms capable of anaerobic methanogenesis and methane oxidation (AOM) and we hypothesize that these orders – and their metabolic capabilities – may be fundamental to the ecology of the SBC oil seep.     

New faces of Aegyptopithecus from the Oligocene of Egypt

Three recently discovered faces of Aegyptopithecus zeuxis from the Oligocene Jebel Qatrani Formation of Egypt provide new information about the shape and variation of the facial cranium, the earliest preserved for a presumed forerunner of apes and humans. Although varying considerably in details of shape and proportion, the new finds and a skull found in 1966 all appear to be of males, a conclusion based in part on the development of temporal and sagittal crests and on the large size of upper canines or their sockets (female canines are much smaller). The snouts of the three new faces all are shorter and broader than that of the earlier found skull as reconstructed. As in most later species of Anthropoidea, variation between these specimens is high.Aegyptopithecus helps define the nature of the oldest Anthropoidea and generally most resembles later-occurring apes. Many features, both derived and shared primitive, link Aegyptopithecus, the large Miocene great apes of the Proconsul group, and modern great apes. That these shared features and proportions are not direct allometric consequences of body size is indicated by Aegyptopithecus' resemblance to the large apes and its many distinctions from similar-sized Hylobates.In Aegyptopithecus brain volume scales smaller than in later catarrhines relative to facial size, the ectotympanic tube is less developed and the premaxilla is more primitive than in later higher primates. In closure of orbits and conformation of forehead, face and dentition, Aegyptopithecus closely resembles higher primates and not prosimians. Taken together, its overall cranial and dental anatomy constitutes one of the most important connecting links in primate evolutionary history.     

Crossing the boundary: an elasmobranch fauna from Stevns Klint,Denmark

The chondrichthyan faunas from the Danish Maastrichtian chalk and the K/T boundary clay, the Fiskeler, are described for the first time. The rich and diverse fauna discovered in the late Maastrichtian chalk experienced a massive drop in diversity prior to the boundary. However, the fauna started to recover immediately after the deposition of the impact layer during earliest Danian times and had regained much of its diversity during the first few millennia after the bolide impact. Precision sampling has made it possible to document the recovery of the fauna, which did not suffer an extinction event of the same magnitude, as apparently observed in Morocco. At Stevns Klint, only 33 per cent of the chondrichthyan fauna became extinct compared with the 96 per cent in Morocco. The drop in diversity before the boundary is attributed to a sudden change in sea level. Among the sharks found in the chalk and Fiskeler are rare species such as Parasquatina and Echinorhinus and the first representative of Nebrius in Europe.     

The fossil fauna from an Upper Pleistocene site in Jordan

The fossil fauna from an Upper Pleistocene habitation site in Jordan is described. Seven species of mammal are represented, three of these being recorded for the fist time from Jordan. The faunal remains are compared with those from Mount Cannel and other Pleistocene sites in the Near East. It is suggested that the site was occupied during an early inter- stadial of the last glaciation when savannah conditions prevailed.     

Palaeobiology and taxonomy ofPachyperna laverdana Oppenheim,an Eocene bivalve of Mesozoic heritage

Pachyperna laverdana is a large Eocene bivalve characterized by an extremely thick shell wall. Rediscovery of the type locality(Pernabank Auctt.) after more than a century has made it possible to collect abundant material which is used here to provide a better morphological definition of the taxon. In particular, indication is given of its broad intraspecific variability mostly due to the gregareous habit (ecomorphism) and by change of mode of life through ontogenesis. As regards the latter factor, functional analysis of the shell suggests that in its early juvenile stages the bivalve was an epibyssate, pleurothetic form, attached to hard substrata. Then, it moved to soft-bottom substrates, where a “heavy-weight” strategy was developed to compensate for a weak byssal attachment. In the adult stage, it may be considered a reclining, orthothetic form. The shell is made up of a thin outer layer formed by simple prismatic calcite and by thick, aragonitic, irregular fibrous-prismatic inner layers, both with a well marked periodicity of growth. Mechanical, functional and systematic significance of shell microstructures are discussed. The diagnosis of the genusPachyperna is herewith emended.     

Survey of the terrestrial and freshwater molluscan fauna of the Pilliga forest area in northern inland New South Wales,Australia

The Pilliga forest in northern inland New South Wales, Australia, is one of the largest surviving remnants of native forest on the western slopes of the Great Dividing Range. The Pilliga landscape is a challenging environment for molluscs, dominated by dry sclerophyll forest and with limited and largely ephemeral aquatic habitats. A field survey of the area in 2006–2012 identified a surprisingly rich and relatively intact aquatic native molluscan fauna with five species of bivalves in three families and nine species of freshwater gastropods (four families), including some rare species and range extensions. The native land snail fauna comprised 18 species (six families), including an unusually rich pupillid fauna with nine species. Some range extensions are recorded and some species are narrow-range endemics. The distributions of many aquatic and terrestrial species were correlated with geology or soil type. Introduced molluscs were predominantly found in anthropogenic habitats and include two freshwater gastropods (two families) and nine terrestrial snails and slugs (eight families). This study provides insight into the original molluscan fauna of the western slopes prior to landscape-scale agricultural development and provides a benchmark for future reference.