摘要:

A distinctive rocky subtidal benthic community (theTerebratulinaCommunity) is described from the Bay of Fundy, Canada. It is shown to consist of three closely intcrspersed sub‐communities: acavitysub‐community, characterised by chitons, coelenterates, brachiopods, bryozoans, chordates and annelids; arock‐facesubcommunity, similar in composition but enriched in brachiopods and sponges; and anupper‐surfacesubcommunity, dominated by algae, chitons, bivalves and echinoids.Comparison with recently described Jurassic, Cretaceous and Recent (Mediterranean) hard‐ground communities suggests a relative constancy in composition, in terms of higher taxa, since the Mesozoic. Development of these (sub‐)communities occurs wherever crevice or cavity systems on hard substrates lead to microenvironments differentiated mainly on the basis of water energy and light.The composition and trophic structure of the community and the life habits ofTerebratulina septentrionalis(Couthouy) are related to aspects of the environment. Marked differences in composition between the living cavity sub‐community and the death assemblage in the sediments are shown to be due to differential preservation, fragmentation, population dynamics and limited local t

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1976.tb00942.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1976.tb00943.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

The northern Canadian Cordillera can be divided into three more or less parallel arrayed lithofacies, which from east to west correspond to progrcssively deepening waters. The shallow water, yellow, or orange‐weathering carbonates occupy essentially the eastern half of the region and northwestern Yukon. Shallowest water carbonates yield fairly abundant ostracodem faunas, ostracodes, and little else. Slightly deeper water carbonates contain brachiopod faunas rich in individuals but low in generic diversity. The nameHowellella‐ProtathyrisCommunity is applied to the Lower Lochkovian shallow water faunas: theSieberella‐Nymphorhynchia‐AthyrhynchusCommunity is the approximate Upper Pragian‐Zlichovian equivalent. Deep water calcareous shales and limestones occupy a narrow band and yield faunas rich both in number and diversity. These faunas are designated theSkenidioides‐Spirigerina‐VagraniaCommunity and are recognized through the entire Lower Devonian interval. An intermediate depth fauna from Upper Pragian and Zlichovian dark carbonates is probably recognizable in northwestern Yukon, and termed theStrophochonetes‐Proreticularia‐receptaculitid Community. The widespread deep water graptolitic shales and carbonates contain a rich fauna of graptolites and relatively rare trilobite, sponge, and

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1976.tb00944.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1976.tb00946.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Isopodichnus stromnessisp. nov. from the Lower Stromness Flags of Orkney is described in detail, and the range of variation in the traces ascribed to different habits of different sized individuals producing the traces. Activity diagrams illustrate scme of the burrowing habits of the organism.Isopodichnusis typical of non‐marine strata, particularly those of shallow impermanent lacustrine environments, and can be distinguished fromCruzianaon the basis of the shape of the trace ending. AsSociated burrows are briefly described and indicate the presence of a hitherto undescribed invertebrate fauna associated with the Orcadian flagstone sequence of the Middle Old Red Sandston

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1976.tb00947.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1976.tb00948.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

The Middle Precambrian problematical microorganismEosphaeraBarghoorn andEosphaera‐like structures known from Early and Middle Precambrian banded iron formations have been compared with the recently discovered Devonian volvocacean algaEovolvoxKaźmierczak and some modern colonial Volvocales. The volvocacean interpretation ofEosphaeraimplies that algal eukaryotes (green phytoflagellates) werc already prewmt in the earth biosphere before at least 1.9 b. y. ago (Gunflint Iron Formaticn), and probably before 2.7 b. y. ago (Soudan Iron Formation). The type of metabolism and thc oxygen requirements of modern colonial Volvocales indicate thatEosphaerawas most probably a photoorgano‐trophic (mixotrophic) organism able to live in the extremely oxygen‐deficicnt or anoxy‐genous Early Precambrian environment. As an oxygen‐releasing photosynthesizer,Eosphaeracould have played a considerable role in the production of free oxygen during the Precambrian. The abundance ofEospkaera‐like ferriferous structures in the iron microbands of many banded iron formations implies active participation of these organisns in the formation of Precambrian sedimentary iron ores. The exclusively fresh‐water habitat of extant volvocacean algae suggests that the Procambrian environments inhabited byEosphaeraw

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1976.tb00949.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1976.tb00950.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

The main generic feature of the hyolithid genusPterygothecaNovlk, 1891 ‐ the fringe on the lateral edges and on the dorsal side of the conch ‐ is interpreted here as a colony of a tabulate coral,Hyostragulumgen. n. This coral covered the living specimens of different hyolithid species in the Bohemian and Moravian Lower and Middle Devonian and occasionally also of nautiloids and gastropods. Because of this discovery it is necessary to withdraw the order Pterygothecida Syssoiev, 1968 and probably also the family Ptery‐gothecidae Syssoiev, 1958. The genusPterygothecais questionable, but further study may prove its validity. The character of the epifaunal coral strongly supports the interpretation of a benthic life of hyoli

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1976.tb00951.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Hyolitha constitute an extinct group of class rank assigned to Molhsca. Two orders, Ortho‐thecida and Hyolithida, are well established and most knowledge of morphologic detail is derived from the latter. Both orders had an operculum not hinged to the conch. Hyolithida also had paired, curved, whiskerlike appendages, requiring complex musculature to move them and the operculum. The Hyolithida were probably deposit feeders living in shallow water, and accordingly were tentaculate. A reconstruction of the soft parts of this sedentary organism is given — a shallow mantle cavity on the dorsal side, anterior tentacles, a long intestine, and a reduced ventral foot. Except for the more complex musculature associated with an elaborate operculum, Orthothecida are judged to have had a similar anat

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1976.tb00952.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY