Non-marine Faunas Research Articles

Understanding Triassic tetrapod community evolution across Pangaea: Contributions from the South American record

The Triassic Period witnessed major macroevolutionary patterns among non-marine faunas including the origin and diversification of many key tetrapod linages that later dominated terrestrial ecosystems during the rest of the Mesozoic and Cenozoic. In this context, detailed knowledge of individual Triassic tetrapod fossil assemblages in a precise geochronologic framework is of upmost importance for elucidating similarities and differences in communities across biogeographic boundaries. Although, there is a bias towards data from the modern Northern Hemisphere continents, the importance and relevance of the Southern Hemisphere tetrapod fossil record has been widely recognized, particularly the record of non-mammalian therapsids (cynodonts and dicynodonts), stem turtles, non-archosaurian archosauromorphs, early crocodylomorphs, and early dinosaurs and dinosaur precursors. This volume focused in the southern South American record highlights how this outstanding fossil record, together with its temporal and paleoenvironmental context, impacts on our perception of Triassic non-marine ecosystems across Gondwana and the rest of Pangea.

Filling the Bearpaw gap: Evidence for palaeoenvironment-driven taxon distribution in a diverse, non-marine ecosystem from the late Campanian of west-Central Alberta, Canada

Patterns of Late Cretaceous terrestrial vertebrate diversity across North America have been interpreted primarily in terms of biogeographic provincialism driven by latitude or coastal-inland habitat gradients. A major difficulty in determining the influence of these two gradients is the existence of some large gaps in the terrestrial fossil record, notably the ‘Bearpaw gap’ caused by a transgression of the inland Bearpaw Seaway during the latter part of the Campanian. In this context, the terrestrial fauna preserved in the Campanian deposits of the Wapiti Formation (west-central Alberta, Canada) is crucial for addressing the information deficit. Deposited at the edge of the palaeo-circumpolar region, Unit 3 of the strictly terrestrial Wapiti Formation (WU3) is coeval with the ‘Bearpaw gap’, a period when the terrestrial record from better-sampled areas elsewhere in Canada and the U.S.A. gives way to marine sediments. Here we show, based largely on evidence from the recently discovered DC (Dinosaur-Chelonian) Bonebed locality, that the diverse WU3 vertebrate fauna shares similarities with lowland to marginal marine ecosystems in the Oldman and Dinosaur Park formations which were deposited in southern Alberta prior to the Bearpaw gap. In addition, a major change in faunal composition demarcates the upper boundary of WU3, related to the disappearance of the Bearpaw Sea in Canada. Data presented here help, first and foremost, to bridge an ~1.2-million-year gap in the North American record of Campanian terrestrial vertebrates. Resemblances between the WU3 vertebrate fauna and slightly older assemblages from southern Alberta underscore the importance of determining the spatiotemporal changes in environmental factors (e.g., coastal proximity). The occurrence of one seemingly endemic lizard, together with differences in relative taxon abundance, suggest additional latitude-correlated factors, implicating both latitudinal and coastal-inland habitat gradients in driving the taxonomic composition of Late Cretaceous terrestrial faunas. • We introduce a new microvertebrate site from the late Campanian of western Canada. • A diverse non-marine fauna coeval with the Bearpaw Formation is discussed. • Vertebrate community is compared with others from the Campanian of Alberta. • Data help filling the information deficit related to the ‘Bearpaw Gap’.

Discovery of a new Lower Cretaceous Wealden-type ostracod fauna from the Bouhedma Formation, Central Tunisian Atlas, North Africa

Micropalaeontological investigations of the Bouhedma Formation in the Jebel Majoura section from the southern Central Tunisian Atlas revealed four successive ostracod associations (in total 16 species of 13 genera) of higher palaeoenvironmental, and thus far limited biostratigraphic and palaeobiogeographic utility due to poor preservation. The most notable of these is a new upper Hauterivian?–Barremian non-marine Wealden-type ostracod assemblage of high diversity from the Lower Member of the Bouhedma Formation, the first one documented from the southern Central Tunisian Atlas, which consists of 9 species: Cypridea cyrtorostralis, Cypridea aff. tenuis, Cypridea aff. insulae, Cypridea sp., Theriosynoecum cf. fittoni, Vecticypris polita, Alicenula? leguminella, as well as Klieana sp. and Fabanella sp. The subsequent two ostracod assemblages from the Lower Member are characterized by the brackish species Rehacythereis? sp., Fabanella sp., Ilyocypris sp., and Schuleridea? sp. indicating transition to lagoonal environment. The subsequent ostracod assemblage from two levels of the Middle Member of the Bouhedma Formation is exclusively composed of the euryhaline marginal marine Paracypris sp., and the marine species Antepaijenborchella praealta, Protocythere cf. bedoulensis and Metacytheropteron aff. grosdidieri, reflecting a marine incursion event.The biostratigraphic utility, particularly that based on the non-marine fauna, is limited thus far but the results are consistent with an upper Hauterivian?–Barremian age previously assigned to the Bouhedma Formation from the southern Central Tunisian Atlas, facilitating its regional stratigraphic correlation with coeval series from the northern part of this palaeogeographic domain.The discovery of Tunisian Wealden-type non-marine ostracods from the southwestern margin of the Tethys (North Africa) sheds new light on the dispersal patterns and palaeobiogeography of these ostracods, their potential utility as biostratigraphic tool, as well as on the significance of the north Gondwanan continental basins and peri-Tethyan islands of the Central Tunisian Atlas for recording Early Cretaceous non-marine microfaunas and -floras.

Origins and diversity of the Bering Sea Island fauna: shifting linkages across the northern continents

We synthesize the historical biogeography of non-marine fauna (mammals, birds, fish, non-parasitic and parasitic invertebrates) occurring across Bering Sea islands, considering endemism, species with origins in both North America and Far East Asia, and the impacts of introduced species through the Bering region. Insular communities often constitute assemblages of unique evolutionary lineages that reflect both neutral and selective processes of diversification as a consequence of isolation and through responses to in situ environmental change. However, current knowledge of the basic distribution, ecology, and evolutionary identity of the majority of terrestrial species through the Bering Sea region is still generally lacking. A preponderance of scientific effort associated with these islands has instead focused on conservation and management of marine-associated species and economically viable biological resources. Given the critical role that terrestrial environments play in maintaining evolutionary and ecological linkages between land and sea, a greater understanding of existing biodiversity, and the biological processes that influence community integrity through this remote region is warranted. Resolving responses of resident insular species to rapidly warming Arctic climate and to modern human-associated disturbances provides valuable insight for effective management of future population trajectories and for revealing the dynamics of intra- and inter-specific connectivity across the northern hemisphere and between marine and terrestrial ecosystems. The location of this region at a high-latitude cross-roads has led to a preponderance of island taxa having trans-Beringian distributions. Species associated with the Palearctic or the Nearctic occur across a strong longitudinal gradient, reflecting the role of the Bering Sea as a dispersal filter between mainland areas. Aleutian oceanic islands reflect different biogeographic histories among taxonomic groups from land-bridge islands of the Bering Sea. We discuss evidence of recent biodiversity responses to modern environmental perturbations, including continued colonisations and novel species interactions, and call for increased scientific scrutiny of terrestrial fauna across these remote outposts.

Upper Mesozoic stratigraphy of Sikhote-Alin (Russian Far East) and northeastern China: Non-marine and marine correlations. Part 2: Barremian–Albian

The present paper is the second article in a series of publications dedicated to the upper Mesozoic stratigraphy of Sikhote-Alin (Russian Far East) and northeastern China. The Barremian–Albian stratigraphy of Sikhote-Alin and northeastern China is reviewed and a correlation scheme between these regions is proposed. Barremian–Albian rocks in Sikhote-Alin are mainly represented by marine deposits. Non-marine deposits occur in the south of Sikhote-Alin in the Partizansk and Razdolny basins. In northeastern China, in contrast, the Barremian–Albian rocks are mainly non-marine often intercalated with volcanic rocks. Non-marine deposits alternating with marine ones occur in northeastern Heilongjiang near the border with Russia. They fill a system of sedimentary basins restricted to the Dunhua-Mishan Fault Zone and linked in the east with the Alchan Basin of Sikhote-Alin. The deposits of these basins, represented by the Jixi, Longzhaogou, Dajiashan and Huashan groups, and the Assikaevka and Alchan formations, are of high importance for non-marine and marine correlation because they contain non-marine fauna and flora assemblages together with marine molluscs. The range of the Jixi and Longzhaogou groups is clarified based on the correlation with the Assikaevka Formation containing marine index fossils and is considered here as Barremian (possibly extending to Hauterivian)–middle Albian. The Jixi Group yielding elements of the Jehol Biota corresponds to the Jehol Group, and, therefore, the range of the Jehol Group is also considered as Barremian–middle Albian.

Upper Mesozoic stratigraphy of Sikhote-Alin (Russian Far East) and northeastern China: Non-marine and marine correlations. Part 1: Upper Jurassic–Hauterivian

Upper Mesozoic (Upper Jurassic and Cretaceous) rocks are widely distributed in Sikhote-Alin (Russian Far East) and northeastern China. In Sikhote-Alin, the Upper Jurassic and Lower Cretaceous rocks are represented mainly by marine deposits, whereas the Upper Cretaceous rocks are mainly volcanic and non-marine sedimentary-volcanic. In northeastern China, the upper Mesozoic rocks are, on the contrary, mainly non-marine. Fully marine Upper Jurassic–Valanginian deposits are restricted to the northeastern Heilongjiang Province near the border with Russia. Barremian–Albian non-marine deposits alternating with marine ones also occur in this region. They contain marine and non-marine fauna and, therefore, represent an important object for non-marine and marine correlation. On the rest of the territory of northeastern China, upper Mesozoic rocks are represented by non-marine sedimentary and volcanogenic deposits. The complex geological structure of the region as well as different types of sedimentary basins cause difficulties in correlation between the upper Mesozoic rocks of Sikhote-Alin and northeastern China. Despite the long history of investigations, their correlation schemes are still rare. Creation of a correlation scheme between Sikhote-Alin and northeastern China should be based on revision of published stratigraphic data on both regions. This article is the first in a series of articles devoted to the upper Mesozoic stratigraphy of Sikhote-Alin and northeastern China. In the present article the Upper Jurassic–Hauterivian stratigraphy of Sikhote-Alin and northeastern China is reviewed. The Upper Jurassic–Hauterivian deposits of Sikhote-Alin and northeastern China contain abundant Buchia and rarer ammonites. Based on stratigraphic distribution of buchiid assemblages, the correlation scheme for Kimmeridgian–Valanginian (possibly lowermost Hauterivian) strata of northeastern China and Sikhote-Alin is proposed. The succession of Jurassic–Cretaceous buchiid assemblages of Sikhote-Alin and northeastern China is similar to those of the other regions, e.g., Northern Siberia (Arctic Realm) and California (North Pacific Realm).

Criteria for differentiating microbial-caddisfly bioherms from those of marine polychaetes in a lacustrine setting: Paleocene second member, Funing Formation, Subei Basin, East China

Paleogene carbonate successions from lacustrine basins across East China yield microbial bioherms containing abundant agglutinated fossil tubes. Historically, these have been interpreted as the dwellings of polychaetes introduced by marine incursions. This is problematic, because these tubes are associated with abundant non-marine fauna and algae. Diverse and exceptionally well-preserved fossil tubes from carbonate microbial bioherms were studied in outcrops and drill cores of the second member of the Paleocene Funing Formation, Subei Basin, East China. Detailed macro-, meso-, and micro-structural investigations of these tube-dominated bioherms reveal that the putative “marine polychaete tubes” better fit the morphologies and construction styles of lacustrine caddisfly (Insecta: Trichoptera) larval cases, eliminating the need for a marine influence on this lacustrine setting.Individual caddisfly cases are commonly 10–25 mm in length and 1–2.5 mm in diameter, and form slightly curved, tapered tubes or coiled spirals. Twelve tubular case construction styles were further identified, based on caddisfly-case wall structures and dominant grain types. Caddisfly cases are commonly single-walled, with rarer nested instar cases comprising double- or triple-walls of different sizes. Most cases are fully agglutinated with neatly arranged, similarly sized and closely connected particles of clastic grains, carbonate particles, plant fragments, and phosphatic fish bones. Sparsely agglutinated cases are also present but much rarer, and conform to the silk larval cases of caddisflies.The caddisfly cases appear as gregarious aggregations within carbonate microbial-bioherms. The microbial-caddisfly bioherms in this study are commonly developed on carbonate hardground or mudstone within the wave-washed, high-energy, shallow-lacustrine littoral zone and can be traced along the western paleolake margin of the Jinhu Depression of the Subei Basin for up to 60 km. The bioherms are composed of repeated microbial-caddisfly couplets, made up of randomly arranged and similarly sized caddisfly cases encrusted by domed, planar, columnar or cauliflower-like microbial layers. Cyclic microbial-caddisfly couplets fit well with caddisfly biology but are not known to occur with marine polychaetes. This is the first report of microbial-caddisfly bioherms in Cenozoic strata of China, and is the oldest Cenozoic record of caddisflies in China.

TO THE STUDY OF THE NON-MARINE FAUNA OF THE MOSPINO FORMATION (MIDDLE CARBONIFEROUS, DONETS BASIN)

The article presents the results of studies of the remains of the non-marine fauna from the site located near the village of Makedonivka (Lutuginsky district, Lugansk region). This site belongs to deposits of the Mospino Formation (Upper Bashkirian, Middle Carboniferous). From the deposits of this locality, the remains of bivalves, horseshoe crabs, Crossopterygii and Chondrichthyes were found. Animal traces belonging to ichnogenus Cochlichnus, Diplichnites, Diplopodichnus, Planolites, Selenichnites, and also, apparently, coprolites were studied. Traces of the damages of arthropods on plant organs were studied: ovipositions, galls, and eating of plants leaves. The oldest oviposition of an insect was found. Deposits were accumulated in the conditions of a lake, lagoon, swamp and delta.

The dawn of the Cretaceous Period in the English South Midlands

The Early Cretaceous (probably Berriasian – Valanginian) Whitchurch Sands Formation of Oxfordshire and Buckinghamshire, English South Midlands, was deposited as coastal-marine and alluvial sediment along the northern edge of the Wessex Basin. The type succession at Whitchurch in Buckinghamshire includes a marine horizon, probably of Berriasian age. Alluvial sediments dominate the formation elsewhere and are tentatively linked to mid-Valanginian uplift of the nearby London – Brabant Massif. The Valanginian alluvial plain is thought to have bordered a coastal lagoon and barrier complex, accounting for non-marine faunas in the Whitchurch Sands Formation, and limiting seawater influx into the Weald Basin of south-east England, from a South Midlands seaway. Detrital and palaeobiological data from the Whitchurch Sands Formation and type Wealden (Weald Basin) suggests a connection between the seaway and the East Midlands Shelf, through much or all of the Valanginian – early Aptian interval.

An Updated Checklist of Land and Freshwater Gastropod Fauna on Ulleung Island, South Korea

We investigated nonmarine gastropod fauna on Ulleung Island, an oceanic island in South Korea. Surveys were conducted in June and September 2018, which newly recorded four terrestrial gastropod species (Paludinellassiminea cf. japonica (Pilsbry, 1901), Vallonia costata (Muller, 1774), Meghimatium cf. bilineatum (Benson, 1842) and Ambigolimax sp.) and two freshwater snails (Galba truncatula (Muller, 1774) and Physella acuta (Draparnaud, 1805)). All records of nonmarine gastropods obtained from Ulleung Island so far were compiled as well.

A Tournaisian (earliest Carboniferous) conglomerate-preserved non-marine faunal assemblage and its environmental and sedimentological context.

A conglomerate bed from the Tournaisian Ballagan Formation of Scotland preserves a rich array of vertebrate and other nonmarine fossils providing an insight into the wider ecosystem and paleoenvironment that existed during this pivotal stage of Earth history. It challenges hypotheses of a long-lasting post-extinction trough following the end-Devonian extinction event. The fauna recovered includes a wide size range of tetrapods, rhizodonts, and dipnoans, from tiny juveniles or small-bodied taxa up to large adults, and more than one taxon of each group is likely. Some fauna, such as actinopterygians and chondrichthyans, are rare as macrofauna but are better represented in the microfossil assemblage. The fauna provides evidence of the largest Carboniferous lungfish ever found. The specimens are preserved in a localized, poorly-sorted conglomerate which was deposited in the deepest part of a river channel, the youngest of a group of channels. In addition to the fossils (micro- and macro-), the conglomerate includes locally-derived clasts of paleosols and other distinctive elements of the surrounding floodplains. Charcoal fragments represent small woody axes and possible larger trunk tissue from arborescent pteridosperms. Preservation of the fossils indicates some aerial exposure prior to transport, with abrasion from rolling. The findings presented here contrast with other published trends in vertebrate size that are used to interpret a reduction in maximum sizes during the Tournaisian. The richness of the fauna runs counter to the assumption of a depauperate nonmarine fauna following the end-Devonian Hangenberg event, and charcoal content highlights the occurrence of fire, with the requisite levels of atmospheric oxygen during that stage.

Some Reports of Paratethyan Ostracods from the Central Mediterranean Area

Uppermost Miocene stratigraphic sections have been sampled in Sicily and eastern Tunisia. Some of the stratigraphic levels contained in them are related to the continentalization phase (“Lago Mare”) of the Mediterranean Basin, which occurred at the end of the Messinian Salinity Crisis. Within these levels, ostracod associations reflecting fresh or brackish water environments are reported here for the first time. Species considered to be Paratethyan in affinity lived in these environments. The discovery, both in Sicily and Tunisia, of species such as C agrigentina, A propinqua, and M. punctate, suggests that the Sicilian Channel did not prevent the migration of the non-marine fauna from NW to SE in the Paleomediterranean area during the Post Evaporitic Phase

Mid-Cretaceous/Albian (Cretaceous) ostracod assemblages from NW Hungary reflecting deep marine, nearshore and non-marine environments

The Albian sediments of the Transdanubian Range in Hungary were deposited in non-marine to fully-marine environments. The studied sections revealed diverse benthic ostracod faunas with moderately-preserved specimens. Forty-six taxa are identified and Cypridea zalanyii n. sp. is newly described. The detailed palaeoecological study of these ostracod faunas provided an opportunity to distinguish eight assemblages. The assemblages include limnic, brackish lagoon, shallow marine, reef and low oxygenated semi-enclosed basin environments in the Northern Tethys region we investigated. This work contributes to the knowledge about Albian non-marine faunas from Europe and explores ecological requirements of brackish faunas.

Preliminary report on the living non-marine Ostracoda (Crustacea) from Tunisia with the description of a new Psychrodromus species.

Since 1928, Henri Gauthier has been the only zoologist to describe the extant non-marine ostracod fauna of Tunisia. In 2010, new samples of living non-marine ostracods were collected from central and southern Tunisia. A complete list of the 41 non-marine ostracods of Tunisia is presented, including the species of Gauthier's work, published Holocene records, and new results from our field study. Historical faunal variations (El Melah Lagoon, Lac de Tunis, Sebkhas El- Guettiate and Dreiaa, and Lac Ichkeul) are briefly discussed and related to recent environmental changes. In 2006, El Melah Lagoon contained a freshwater, brackish, and a marine ostracod assemblage. In the future, this lagoon will probably dry up and become a sebkha. Lac de Tunis has developed from a marine bay over a lagoon connected to the Mediterranean Sea to a brackish/freshwater environment. Sebkhas El-Guettiate and Dreîaa have developed from marine bays to dry salt flats. Lac Ichkeul is eutrophied and has become brackish since the time of Gauthier. We also describe a new species, Psychrodromus tunisicus n. sp., and present a determination key for the genus. The finding of a species of the genus Psychrodromus is the first report of this genus in North Africa.

Krömmelbein Mesozic ostracod collections

Karl Krömmelbein (1920–1979) worked on both Paleozoic and Mesozoic sequences but is best remembered for his pioneering work on late Jurassic–early Cretaceous ostracod assemblages from Brazil and West Africa, clearly demonstrating in a series of publications between 1961 and 1972 the presence of comparable marginal-marine and non-marine faunas in continental margin basins on each side of the modern South Atlantic. These ostracods and their biostratigraphical distributions have assumed great importance in recent years consequent on the discovery of hydrocarbons, especially offshore Brazil. All Krömmelbein's published and background material is housed the the Senckenberg Forschungsinstitut und Naturmuseum, Frankfurt-am-Main, Germany with the sole exception of the material figured in Krömmelbein & Weber (1971) which is housed in the Bundesanstalt für Geowissenschaften und Rohstoffe and Landesamt für Bergbau, Energie und Geologie, Hannover, Germany. Do Carmo et al. (2008) make a number of erroneous statements about the material, i.e., that material of Krömmelbein (1965) was moved from Hannover to Frankfurt, and that Do Carmo et al.'s figured specimens from the Krömmelbein Collection in Frankfurt are ‘types’ when they are exclusively topotypic and not primary types. A statement in Poropat and Colin (2012, p. 701) attempts to clarify this situation, however, Antonietto et al. (2012, p. 663) compound the confusion by stating that the holotype of Hourcqia angulata salitrensis Krömmelbein and Weber, 1971 is housed in the Senckenberg, which it is not. The confusion may have arisen as a result of a temporary loan of the Krömmelbein and Weber (1971) specimens to Senckenberg.

End-Devonian extinction and a bottleneck in the early evolution of modern jawed vertebrates

The Devonian marks a critical stage in the early evolution of vertebrates: It opens with an unprecedented diversity of fishes and closes with the earliest evidence of limbed tetrapods. However, the latter part of the Devonian has also been characterized as a period of global biotic crisis marked by two large extinction pulses: a "Big Five" mass extinction event at the Frasnian-Famennian stage boundary (374 Ma) and the less well-documented Hangenberg event some 15 million years later at the Devonian-Carboniferous boundary (359 Ma). Here, we report the results of a wide-ranging analysis of the impact of these events on early vertebrate evolution, which was obtained from a database of vertebrate occurrences sampling over 1,250 taxa from 66 localities spanning Givetian to Serpukhovian stages (391 to 318 Ma). We show that major vertebrate clades suffered acute and systematic effects centered on the Hangenberg extinction involving long-term losses of over 50% of diversity and the restructuring of vertebrate ecosystems worldwide. Marine and nonmarine faunas were equally affected, precluding the existence of environmental refugia. The subsequent recovery of previously diverse groups (including placoderms, sarcopterygian fish, and acanthodians) was minimal. Tetrapods, actinopterygians, and chondrichthyans, all scarce within the Devonian, undergo large diversification events in the aftermath of the extinction, dominating all subsequent faunas. The Hangenberg event represents a previously unrecognized bottleneck in the evolutionary history of vertebrates as a whole and a historical contingency that shaped the roots of modern biodiversity.

LATE MIDDLE PLEISTOCENE COOL NON-MARINE MOLLUSC AND SMALL MAMMAL FAUNAS FROM LIVORNO (ITALY)

New stratigraphic data (exposed sections and boreholes) allowed a detailed reconstruction of the northern sector of the Terrazzo di Livorno (Central Italy). A new unit, called Corea was discovered and correlated to marine isotope stage (MIS) 6 and to its transition to MIS 5. This formation comprises, at its base, fluvial gravels and sands followed by fine-grained alluvial plain deposits. Non-marine molluscs, small mammals and pollen allow a reconstruction of the environment present during the deposition of the alluvial plain deposits. The environment was mainly an open space, though sparse woodlands should have been present. The non-marine fauna shows features intermediate between typical interglacial and glacial assemblages described so far in Italy. Worth of note is the presence of Orcula dolium and Vallonia enniensis , which now inhabit northern Italy. These findings improve our knowledge on the biogeography of Quaternary non-marine faunas of Central Italy. Stable isotopes data on land snail shells, freshwater shells and pedogenic carbonates showed that climate conditions were cooler than today (possibly 1-2°C less) with a significant amount of C4 vegetation, in an environment with moderately dry conditions.

Hybodont sharks from the Middle Jurassic of the Inner Hebrides, Scotland

ABSTRACTNon-marine Bathonian (Middle Jurassic) strata on the Isles of Eigg and Skye in Scotland have yielded fossil remains of eight hybodont shark taxa. Faunas from several horizons within the Lealt Shale and Valtos Formation on the Isle of Eigg include six species: Hybodus grossiconus, Hybodus sp. 1, Hybodus sp. 2, Lissodus leiodus, L. leiopleurus and Parvodus pattersoni. Large collections of teeth of L. leiodus and L. leiopleurus enable a better understanding of the dentitional patterns of the two species and their differential diagnosis. Surface-collecting from exposures of the Kilmalaug Formation on the Isle of Skye yielded hybodont teeth of two taxa: Hybodus sp. 3 and Acrodus caledonicus sp. nov. The occurrence of Acrodus in the Bathonian of Scotland is one of the youngest known occurrences of this genus, and the only non-marine record in the European Jurassic. Collectively, the hybodont assemblages from the Scottish Bathonian provide evidence that non-marine faunas of the group were specifically diverse in the Middle Jurassic.

Early Cretaceous non-marine mollusc faunas of Japan and Korea

A biostratigraphic correlation of Early Cretaceous marine and non-marine mollusc faunas of south-west Japan and exclusively freshwater faunas of Korea is proposed. The material originates from the Inner Zone of central Japan (Tetori, Sanchu), the Outer Zone of south-west Japan (Kyushu, Shikoku, Kii Peninsula), and the Kyongsang Basin of south-west Korea. It includes new collections of freshwater molluscs from the Monobegawa Group (Shikoku). The alternation of well-dated marine strata with non-marine beds in Kyushu, Shikoku and central Honshu (Sanchu area) provides accurate age constraints to the well-studied non-marine faunas. In the Inner and Outer Zones of Japan, four non-marine bivalve associations alternate with marine faunas: (1) Hauterivian: brackish–freshwater Hayamina naumanni– Unio ogamigoensis Assemblage of the Tatsukawa faunal association; (2) Hauterivian: brackish Hayamina carinata– Isodomella matsumotoi Assemblage of the Shobu faunal association; (3) Barremian: marine Yabea shinanoensis, Pterotrigonia kawaguchiensis and Nanonavis yokoyamai, with the ammonite Shasticrioceras nipponicum and radiolarians ( Archaeodictyomitra pseudoscalaris assemblage); (4) Late Barremian: brackish Hayamina matsukawai, Costocyrena radiatostriata, and Pulsidis tashiroi of the non-marine Sebayashi faunal association, with Nippononaia ryosekiana in Sanchu, passing upwards to marine deposits with ammonites; (5) Early Aptian: brackish Costocyrena minor, and Pulsidis rostratus of the non-marine Hibihara faunal association, passing upwards to marine Pterotrigonia pocilliformis and Goshoraia minor, with the ammonite Cheloniceras sp.; (6) Middle Albian: marine Inoceramus anglicus, and Parvamussium tosaense, with ammonites, radiolarians and calcareous nannoplankton. Viviparus onogoensis (gastropod) in the Hauterivian Tatsukawa association enables correlation of the Ryoseki and Tatsukawa formations (Monobegawa Group) with the Izuki, Kuwajima and Okurodani formations (Tetori Group) and the Myogog Formation (Korea). Plicatounio naktongensis links the Kitadani Formation (Tetori Group) and Sengoku Formation (Kanmon Group) directly with the Hasandon Formation (Korea). The Kitadani and Sengoku faunas share components with the Sebayashi fauna (Central Honshu), define the Late Barremian Hibihara faunal association, and correlate with the Yunoki-Hiura fauna (Monobegawa Group). The faunas are controlled by salinity and temperature. Relationships between the environmental conditions indicate a geographic continuity between the Early Cretaceous deposits of Japan and Korea that accumulated on the continental side of Asia.

Evolutionary History of the Ostracoda and the Origin of Nonmarine Faunas

The Ostracoda are one of the most diverse arthropod groups alive today; they also have a tremendous fossil record. Because of their widespread environmental distributions, small size and carbonate shell, they have become extremely useful biostratigraphic and paleoenvironmental proxy indicators, particularly in nonmarine environments. Despite this utility, little is known about the phylogenetic history of this important group. We reconstructed a phylogenetic history of the major orders and suborders of Ostracoda in order to test the legitimacy of current classification schemes, determine if it is possible for ostracodes to have a Precambrian origin, and test the fidelity of some of the major morphological characters that have documented trends of either increased complexity, such as the hinge and marginal pore canals, or reduction in segments, such as the adductor muscle scar.In our phylogenetic analysis to test taxonomic fidelity, we coded seven morphological hard part characters for nine taxa from the orders Archaeocopida, Leperditicopida, Palaeocopida, Podocopida, and Myodocopida. A parsimony analysis was performed using PAUP (v. 4.0) yielding 4 trees of 17 steps with low levels of homoplasy and a strong phylogenetic signal. A majority rule consensus tree indicates there is not complete agreement between the standard classification scheme and the phylogeny produced by the characters used to establish the classification. In our complete analysis of Ostracoda, we coded 28 morphological characters that included 14 hard part and 14 soft part characters for twelve taxa that include the Archaeocopida, Leperditicopida, Podocopida, and Myodocopida. A parsimony analysis was completed using PAUP (v. 4.0) yielding 1 tree of 125 steps with low levels of homoplasy and a strong phylogenetic signal. An unrooted analysis of this character set has the Cambrian Archaeopodocopida and the Ordovician-Devonian Leperditicopida in an unresolved polytomy with much younger groups such as the Myodocopina, suggesting a much deeper split in the lineage and a possible Precambrian origin for the Ostracoda. Testing the various character state acquisitions over the tree indicates that the hinge does not show an increase in complexity within a phylogenetic context, while the adductor muscle scars do show a significant trend of decrease in complexity across the tree topology. The marginal pore canals, which are functionally tied to osmoregulation as well as carapace secretion, are extremely homoplastic, indicating that this character, which is related to nonmarine invasions and tolerances, was acquired many times throughout the evolutionary history of Ostracoda.By creating an evolutionary framework for the Ostracoda such as is presented here, we can further assess character state acquisition, and how it functionally and evolutionarily relates to ostracode paleoenvironmental tolerances. The framework will not only allow us to understand the overall evolution ofthis group but will also allow us to compare the history of the ostracode clade with other groups that also have a history ofmarine and nonmarine transitions.