Eocene Spiders from the Isle of Wight With Preserved Respiratory Structures

A new fossil spider, Vectaraneus yulei gen. et sp. nov., from the Eocene Bembridge Marls Insect Bed of the Isle of Wight, shows internal anatomy, including book lungs and tracheae, preserved by calcium carbonate replacement. The wide, medially positioned, tracheal spiracle and large tracheae which enter the prosoma are adaptations for an amphibious mode of life. The spider is placed in Cybaeidae Simon, 1898, Argyronetinae Menge, 1869, a subfamily which includes the Recent European Water Spider, Argyroneta aquatica (Clerck, 1757). The only previously described Bembridge Marls spider, Eoatypus woodwardii McCook, 1888, is redescribed; it is unrelated to Vectaraneus . The holotype of Argyroneta antiqua Von Heyden (1859) is redescribed; it is not an Argyroneta . Specimens referred to A. antiqua by Bertkau (1878) probably belong in Argyronetinae Menge, 1869, and this subfamily is emended herein.     

The palaeoecology of the dinosaurs of the Wessex Formation (Wealden Group, Early Cretaceous), Isle of Wight, Southern England

The Wessex Formation on the Isle of Wight yields an Early Cretaceous dinosaur fauna. Sedimentological evidence shows that this represents a mosaic of fluvial, floodplain and lacustrine environments within a relatively narrow east-west oriented valley. The vegetational cover on the alluvial plain had a savannah-or chaparral-like aspect, probably of low productivity. The relative scarcity of small aquatic vertebrates, absence of coals, abundance of oxidixed sediments and the presence of immature calcretes indicate seasonal water supply. The dinosaur taxa compising the Wessex Formation faunal assemblage represent a single palaeocommunity which inhabited the local alluvial plain, although some species may have been transient. The fauna had a relatively low diversity and this is attributed to the low productivity of the local vegetation. Iguanodontids and Hypsilophodon were the dominant elements in the fauna. In contrast to Late Jurassic dinosaur faunas, sauropods are less abundant in the Wessex Formation, although they remain taxonomically diverse. It is concluded that climatic changes which took place in the Late Jurassic or Early Cretaceous resulted in the appearance of low productivity vegetation and that this was incapable of supporting large sauropod populations.     

Palaeofloristic assemblages and palaeoecology of the Lower Oligocene Bembridge Marls, Hamstead Ledge, Isle of Wight

A sequence of nine, plant-macrofossil-bearing horizons has been recognized in the Lower Oligocene from the Isle of Wight, England. The plant fossils are contained in finely laminated, olive-brown to black silty-clays and clays. Some horizons exhibit rhythmic alternation of sediment couplets; others show evidence of bioturbation and rootlet penetration. These horizons are included within a sequence of finely laminated greenish grey silty-clays and clays, largely devoid of plant macrofossil material. The plant-bearing horizons contain abundant fruits, seeds, fern sporangia, Azolla megaspores, and rare leaves. The nearest living relatives of the fossils all inhabit an aquatic or marginal aquatic environment. The associated fossil fauna includes lake bottom and lake margin species. The palynoflora of the plant-bearing and immediately underlying horizons includes large numbers of planktonic algae and limited representatives of a forest vegetation. It shows a strong relationship between the occurrences of Sparganiaceaepollenites pollen and of Typha macrofossils. Palaeoecological interpretations of this plant-fossil-bearing sequence are discussed with particular reference to modern environments.
One new genus and three new species are described. Emendations are presented for four other species. Stratiotes leaf margin teeth are described.     

On a new specimen of Pseudoaraucaria major Fliche (Pinaceae) from the Cretaceous of the Isle of Wight

The well-preserved permineralized cone is identified chiefly on the basis of its large size and large seeds with a relatively thin sclerotesta. The detailed anatomy conforms to that characteristic of this highly distinctive and probably natural genus of early Pinaceae. The structure of the scale lends support to the theory that the partially embedded seeds escaped from the ripe cone by the bending back of the upper part of the scale. The specimen confirms that the seed testa typically possessed resin cavities as it does in certain living genera. The relationship of Pseudoaraucaria with other Pinaceae is discussed in the light of the results of a numerical analysis of 22 cone characters, lending support to the recent suggestion that Pseudoaraucaria may have occupied a central position in the early evolution of the family.     

The effect of environmental change on early Aptian ostracods faunas in the Wessex Basin,southern England

A major phase of transgression in the Wessex Basin (southern England) during the earliest Aptian resulted in the collapse of the generally fresh water Barremian environment and the initiation of the marine milieu.Cypridea-rich faunas in the Shepherd's Chine Member (Vectis Formation), were gradually replaced by faunas dominated by Sternbergella cornigera, Mantelliana mantelli and Theriosynoecum fittoni. This change is interpreted as indicating that salinities had passed from fresh-oligohaline to meso- and pliohaline and that ephemeral water bodies were replaced by more widespread, permanent, lagoonal waters. The ostracods from the highest part of the Vectis Formation appear to be heralding the major transgression that was about to engulf the Wessex Basin.The marine incursion during the obsoletus Ammonite Subzone brought with it newly formed environmental niches that were rapidly occupied by microfaunas. Several ostracod species are interpreted as euryhaline, but others appear to have been restricted to marine or near marine salinities. The earliest marine ostracod faunas were recorded from the Perna Bed Member, Isle of Wight, and include abundant Asciocythere albae and frequent to common Schuleridea derooi, Neocythere gottisi, N. bordeti and Cytherelloidea sp. Other species include rare Cythereis geometrica, C. semiaperta, Eocytheropteron stchepinskyi and Protocythere croutesensis. In addition, elsewhere in southern England, Protocythere mertensi langi, Dolocytheridea intermedia, Paranotacythere (P.) oertlii and P. (P.) atypica occur. The relationship of this earliest Aptian population with that of the Paris Basin cannot be mistaken.     

Habitat requirements for the conservation of wood cricket (Nemobius sylvestris) (Orthoptera: Gryllidae) on the Isle of Wight, UK

In the UK, wood cricket (Nemobius sylvestris) is a ‘Species of Conservation Concern’, being restricted to only three areas in southern England. Little information is available on the specific habitat requirements of this species. In 2006, a field investigation within three woodlands on the Isle of Wight was undertaken to identify its habitat preferences. Factors positively influencing wood cricket presence within woodlands included the presence of a well-developed leaf litter layer, relatively low ground vegetation cover and height, low canopy cover and relatively short distances between individual populations. Regression models identified the degree of isolation and variables describing vegetation structure as the main predictors for wood cricket presence within woodland fragments. The results of this study indicate the preference of wood cricket for open wooded edges. Conservation efforts for this species should focus on continuation of regular management activities aimed at providing permanent open edge habitat within woodlands, to maintain viable populations.     

Marine Ostracoda from Pitcairn, Oeno and Henderson Islands

All of the samples yielded podocopid ostracods. Most of the faunas from Pitcairn and Oeno were poorly preserved and sparse; those from Henderson were much more abundant, more diverse and better preserved. Only 33 species are recorded from the joint fauna and this may reflect the limited number of environments sampled or the remote geographical situation of the islands. At least 20 species (and a new genus) are restricted to the islands. Other species are known from the Solomon Islands, Australia and Indonesia. Of a considerable number of Indo-Pacific pandemic species, only three Kotoracythere inconspicua (Brady), Tenedocythere transoceanica (Teeter) and Triebelina sertata (Triebel) have been identified to date. The fauna is not, however, nearly so endemic as that of Easter Island on which the two authors are currently working.     

Variation in radular teeth and acuspid side of the radula in Lacuna pallidula, L. parva and L. vincta (Gastropoda: Littorinidae) from the Isle of Wight, United Kingdom

The variation in the radula of three species of Lacuna has been investigated and the back of the rachidian tooth is proposed as providing a new character set of potentially high taxonomic value. The term basal plate is introduced for the back of the rachidian tooth. Cusp and tooth morphology are closely related to diet and wear, and are subject to considerable homoplasy, whereas the structure of the basal plate of the rachidian tooth provides a more neutral character set. The difference in this character set between the lacunids has been quantified using seven measurements and the exploratory multivariate statistical procedure principal component analysis. The basal plate of the rachidian tooth showed interspecific differences. The taxonomic value of this new character set should be evaluated in further studies of other prosobranchs. Received in revised form: 25 October 2000 Electronic Publication     

A New Species of Ilyodromus Sars (Crustacea, Ostracoda) from the Philippines

The genus Ilyodromus Sars, 1895 is recorded for the first time in the Oriental Region. Ilyodromus lanaoensis sp. n. is described from Mindanao, the Philippines and compared with the other species of the genus for differential diagnosis.     

The First Iguanodontid Dinosaur Tracks from the Swiss Alps (Schrattenkalk Formation,Aptian)

Until now dinosaur tracks from Switzerland were only known from Triassic and Late Jurassic strata. We report here for the first time the occurrence of ornithopod tracks from the Schrattenkalk Formation (Late Aptian) from the Swiss Central Alps. The locality is situated in an abandoned quarry on the shore of Lake Lucerne close to the village of Beckenried. The steeply inclined surface has more than 50 tracks (in three trackways) of ornithopod dinosaurs that are attributed to iguanodontids. Three trackways can be followed for distances of 25 to 35 m. The lengths the footprints (mean: 30 cm) point to animals ranging in size of from 4 to 6 m, with estimated hip heights between 1.8 and 2 m (hip height 6 FL) and 1.4 to 1.7 m (hip height 5 FL). One of the trackways shows two succesive manus impressions, indicating facultative quadrupedal gait. The track bearing layer consists of shallow water micrites with traces of emersion, and it is overlain by bioclastic grainstones. Previously the Upper Schrattenkalk Member in the Helvetic realm was thought to have formed on a large shelf far away from any continents. The present discovery will shed new light on the paleogeographic position of the Helvetic nappes.