Thirty two seafloor samples were taken over an area of 3600 km2 off south-east Trinidad (water depths 38–102 m), north-east of the Orinoco Delta. A total of 7097 ostracod carapaces and valves from 37 species were picked from them. Total recovery was co-dominated byBairdoppilata dorsoangulata andBradleya ex gr.dictyon, with lesserRadimella ovata, Loxoconcha sp. 2sensuBreman, 1982 andCosta variabilicostata recticostata. Cluster analysis revealed four biofacies approximately perpendicular to the bathymetric contours. This arrangement is contrary to the usual pattern, in which biofacies parallel contours, and is suggested to reflect the occurrence of a shelfal, river-induced front entrained within the hypopycnal Orinoco Plume. The front marks where outflow from the Essequibo and Orinoco rivers abuts against surface water rich in outflow from the Amazon. The biofacies immediately under the front yielded particularly high proportions ofB. ex. gr.dictyon andB. dorsoangulata, but relatively fewLoxoconcha sp. 2. Application of SHE Analysis for Biozone Identification (SHEBI) indicated that within the biofacies there occur abundance biozone boundaries at ∼55m, 75 m and 100 m that separate areas with differing population structures. SHE Analysis for Community Structure Investigation (SHESCI) indicated that, although the species proportions within most abundance biozones have a logarithmic series distribution, the rate of increase in species richness as specimens were accumulated was lowest in an abundance biozone below the front.

Analysis of Early Devonian dipnoan tooth-plates has been discussed extensively over the last twenty years. A recent discussion byAhlberg et al. (2006) used cladistic methods with a range of characters, and reached the conclusion that the dentitions underwent extensive and non-parsimonious evolution in their early history.Campbell & Barwick (2000) had proposed that such morphological designs of dentition formed the basis for phylogenetic development, but the cladistic analysis indicated that this was not so. On the other hand we consider that the basic dentition types developed independently by genomic changes (gene regulation) in the Early Devonian. Further development of these designs took place in the later Devonian and subsequently, by Neo-Darwinian micro-evolutionary processes. As well as the distinguishing development of palatal biting, new evidence indicates that the Dipnoi were separated from other sarcopterygians by modification of the gill system and the long transverse anocleithrum that lay across the roof of the gill chamber. Further evolution took place within this framework of the Dipnoi so defined. New discoveries within the Early Devonian group are described. It is possible that some genera that have been difficult to place taxonomically (e.g.Diabolepis), were examples of new designs developed by genetic regulation, and they were short lived in competition from the few successful groups. The new lineages based on dental types continued into the later Devonian carrying a large number of older genetic units. These would have evolved in parallel by Neo-Darwinian principles, producing similarities that would have been recognised by cladists as synapomorphies.

The Eocene birdElaphrocnemus phasianus is a stem lineage representative of the Cariamidae (seriemas) and among the most abundant medium-sized avian species in the Quercy fissure fillings in France. We describe the previously unknown scapula of this species, which exhibits a highly unusual morphology. Most notably, the acromion is greatly elongated and there is a concave facies articularis coracoidei rather than a tuberculum coracoideum as in most other birds. These features also distinguishElaphrocnemus from other representatives of the Cariamae. The long acromion probably serves to strengthen the canalis triosseus, which in other Cariamae is achieved by a bony bridge connecting the processus procoracoideus and acrocoracoideus of the coracoid. The peculiarities of the pectoral girdle and wing ofElaphrocnemus may indicate that this taxon had better flight capabilities than other Cariamae.

This review examines the nature and chronology of the transition of ostracods from marine to non-marine aquatic environments in the Devonian and Carboniferous. There is putative evidence of ostracods in brackish waters from the middle Silurian, but more robust evidence from the Devonian. The first putative freshwater ostracods are species of the generaCarbonita andGeisina which are found in the early to middle Carboniferous Coal Measures. Freshwater ostracods are common in the middle Pennsylvanian Coal Measures of late Carboniferous age, with species of genera such asDarwinula, Carbonita, Candona andCypridopsis. The Lower Carboniferous Visean succession from the Midland Valley of Scotland provides a unique range of sedimentary environments from marine to non-marine, and a diverse range of ostracods and macrofauna. It is an ideal sequence to study the radiation of the Ostracoda from marine to non-marine realms. Non-marine species ofCarbonita are found in the lower Visean, associated with spirorbids,Naiadites, Estheria, plant and fish fragments. Marginal marine species include the generaGeisina, Parapar-chites, Sbemonaella andCapellina, all of which are eurytopic. The first non-marine environments occupied by ostracods were near the shoreline, and influenced by marine transgressions. The adaptations needed to survive in freshwater or low salinities would have included changes in osmoregulation, feeding, and reproductive strategies such as parthenogenesis, to enable opportunistic colonisation of temporary freshwater habitats such as seasonal pools.

The genusHungarocyprisVavra, 1906 is known in Europe by a unique species,Hungarocypris madaraszi (Orley, 1886). Its morphological characteristics are briefly reviewed and compared with those ofHerpetocyprella mongolicaDaday, 1909 from Lake Issyk-Kul, Kyrgyzstan. Two cypridoidean species,Hungarocypris auriculata (Reuss, 1850) andHungarocypris hieroglyphica (Mehes, 1907) from Upper Miocene deposits of Lake Pannon (Central and South-Eastern Europe), are compared toH. Madaraszi. Morphological traits of the fossil species point to close phylogenetical affinities withH. mongolica, and therefore transferred toHerpetocyprella Daday, 1909.H. auriculata is described, based on material from the Vienna Basin, the Eisenstadt-Sopron Basin and from the Styria Basin (Austria). Further, this species is compared toH. hieroglyphica from Banat (Romania). The morphological variability of the former species is presented. Palaeobiogeographical and palaeoecological implications are briefly emphasized.

The ostracode fauna across the Paleocene/Eocene boundary has been studied at 5 m intervals between 690–810 m in the Ghotaru Fort Well (GTF Well-A), Jaisalmer Basin, Rajasthan. Ostracodes and foraminifera have been utilized to provide the biostratigraphic framework. Four ostracode zones designated as POS-I to POS-IV in the Late Paleocene and one zone EOS-I in the earliest Early Eocene age sediments have been recognized. Quantitative ostracode and qualitative foraminiferal data were used to interpret the paleoenvironment across the Paleocene/Eocene boundary. Occurrence of the benthic foraminiferaDiscocyclina seunesi andMiscellanea miscella at 735–740 m depth in this well suggests a latest Late Paleocene age. The frequency and diversity of ostracodes at this depth is low. The ostracodes recorded near the top of the Paleocene are:Anommatocytkere indica, Echinocythereis contexta, Phyrocythere alfuraihi andSchizocythere prolata. This ostracode assemblage along with benthic foraminifera suggests that sediments were deposited in an inner neritic environment. This is followed by an earliest Early Eocene age transgression marked by the extinction of preceding Late Paleocene ostracodes and advent of a new ostracode suite represented byAlocopocythere abstracta in the 725–730 m interval. In the 720–725 m interval, however, there is a turnover to an entirely new suite of ostracodes represented byParagrenocythere reticulospinosa, Phalcocythere sentosa, Hornibrookella avadheshi, H. jaisalmerensis, Alocopocythere abstracta, Gyrocytbere parvicarinata, Schizocythere appendiculata, Bairdoppilata kalakotensis, Uroleberis khoslai, Loxoconchella ? guhai, Cytherella jaisalmerensis andC. tawaica. This ostracode assemblage is indicative of Early Eocene age and deposition in an inner neritic environment. The Paleocene/Eocene boundary in well GTF-A is recognised on the basis of ostracodes and foraminifera at 735–740 m, which in turn coincides with an overall sea level fall attributed to global warming, and this is further corroborated by a negative carbon excursion (δ13C=−13.63) across the Paleocene/Eocene boundary.

The extinction of the Suborder Metacopina in the early Toarcian (Early Jurassic) was a major event in the macro-evolutionary history of the Ostracoda. The disappearance of this long-ranging, essentially Palaeozoic, group coincides with a change in the composition of marine ostracod faunas from ones with residual Palaeozoic aspect in the pre-Toarcian (due to the presence of the Metacopina) to those dominated by the Cytheroidea, Cypridoidea and Platycopina, a pattern that continues to the present. The Metacopina had been present in many Palaeozoic assemblages although usually at low diversity and abundance but they were particularly successful in Triassic and Early Jurassic times, being diverse, abundant and with an apparently cosmopolitan distribution. Why did such a successful group that had survived four of the ’Big Five’ Phanerozoic extinction events (end Ordovician, Late Devonian, end-Permian, end-Triassic), succumb at this second order and apparently less significant early Toarcian event? The rapid decline and extinction of the Metacopina followed a major regressive phase in the Pliensbachian and broadly coincided with the onset of the early Toarcian Oceanic Anoxic Event (TOAE), which has been linked to global eustatic sea-level rise and is marked by a major, negative carbon isotope (δ13C ) excursion in the global carbon cycle. The nature and likely causes of the Metacopina extinction event (MEE) are reviewed in the context of new environmental data for the Toarcian, with particular reference to evidence from the Mochras Borehole (West Wales) ; the group’s survival of earlier biotic events is also discussed. The one distinct feature that sets the Toarcian extinction event apart from previous evolutionary crises is that the Metacopina never had to compete against relatively advanced ostracod, largely cytheroidean, taxa that were present during the Early Jurassic. We propose that this may have been a key factor in the demise of the Metacopina at this particular time.

The attribute traditionally used to recognise the occurrence of ostracods in the Palaeozoic stratigraphic record has in essence been the presence of a bivalved arthropod carapace of small size. Discoveries offering unparalleled insight into the soft part palaeobiology of tiny bivalved Palaeozoic arthropods, when taken together with the notion that a bivalved carapace is a convergent phenomenon within the Arthropoda, have in the last decade revolutionised our understanding of the nature and stratigraphic record of the major groups of ostracod present in the Palaeozoic. Evidence from appendages and other soft parts is crucial in determining systematic affinity. Evidence from the soft part anatomy of bradoriids and phos-phatocopids has undermined the record of ostracods in the Cambrian, but molecular and fossil evidence implies that they may be present at that time. In the absence of soft parts the case that lepetditicopids (Ordovician-Devonian) are ostracods remains uncertain. Myodocopes certainly occur in the Palaeozoic, as determined on a wealth of new palaeobiological evidence. As yet, supposed Palaeozoic podocopes are represented in practical terms only by fossil shells. The systematic affinity of palaeocopes — a major group in the Palaeozoic and hitherto recognised as a coherent taxon — remains enigmatic, and they may turn out to represent an artificial grouping.