摘要:

An assemblage of microfossils from the mid‐Proterozoic Mara Dolomite Member of the Emmerugga Dolomite, McArthur Group, Northern Territory, Australia, has been studied. The assemblage contains 10 species, of which one is new. The classification of Proterozoic microfossils is reviewed and a morphographic scheme adopted. The new assemblage is compared with other McArthur Group assemblages, and the differences between the assemblages are explained in terms of environmental differences. Comparison with other microfossil assemblages world‐wide, suggests that these assemblages have stratigraphic potent

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1983.tb00714.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

An assemblage of macroplants preserved as highly coalified compressions which lack anatomy is described from a Wenlock locality in County Tipperary, Ireland. Most of the fertile specimens are assigned toCooksoniaLang. The taxonomic status of this genus is discussed. Some poorly preserved palynomorphs, including miospores, acritarchs, chitinozoans and a variety of tubes, have been isolated from associated sediments, but the age of the flora is based on graptolites. Sedimentological and palaeontological studies of the region are summarized. They provide little direct evidence for the habitats of the plants which are considered to have been terrestrial. The relevance of this flora to the current debate on the colonization of the land is evaluated and it is concluded that these plants provide the earliest record of erect fertile land plants of possible pteridophyte affinity.

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1983.tb00715.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

New material collected from the Rhynie Chert Bed (Siegenian age) has revealednewfilamentous and unicellular algae. Two of the filamentous forms and one palmelloid form are described. Filamentous and unicellular algae are particularly common in a white kind of chert not previously reported and which is interpreted as having been formed by thein situsilicification of a silicate‐rich pond.Some rhizoid‐nodes ofPalaeonitella cranii(Kidston&Lang) Pia and a possible rhizoid‐borne pro‐embryo are also described and compared with similar structures in living Cha

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1983.tb00716.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Baragwanathia abitibiensisis described from the Sextant Formation of northern Ontario, Canada (middle to upper Kmsian age). The plant remains are primarily compressions in which flattened xylem strands, epidermis with stomata, and cuticle are well preserved. Pyrite permineralization of the leaves was Ibiuid in one specimen. Comparison withB. longijoliaLang&Cookson indicates remarkable morphological similarities and probable anatomical similarities although details of the structure of the epidermis and cuticle are lacking inB. longijolia.No information is available on the outline of the cauline xylem strand inB. abitibiensisnor on the form and position of the sporangia it bore. Comparisons are also made to species ofDrepanophycus.The age of/?,longijoliaand theBaragwanathiaFlora, is discussed with particular reference to the putative dating of some specimens as Silurian. The morphological and anatomical complexity ofBaragwanathiais at a level of advancement typical of Early to Middle Devonian lycopods. There is no evidence of precursors to the genus associated with the fragments of land vascular plants in the well‐dated Silurian sediments of Wales, Czechoslovakia, New York State, or Podoli

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1983.tb00717.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Drepanophycus colophyllusGrierson&Banks is transferred tollaskinsiaGrierson&Banks on the basis of the morphology of its leaves and its anatomical structure. Slender, dichotomizing axes bear helically arranged leaves that are falcate, petiolate, simple, lanceolate and entire. A solid cylinder of metaxylem is surrounded by ridges of protoxylem. Pitting on tracheid walls is annular, helical, reticulate, scalariform to circular‐bordered. This lycopod extends from early Givetian into early Frasnian time in the Catskill strata of eastern New York State. The effect of cleavage of fossiliferous rock on patterns observed on the exposed fossils and the bearing of recent research on the fossil history of lycopods are discusse

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1983.tb00718.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

A new genus of pleridosperms is described from the uppermost Devonian beds from Ballyheigue, Ireland.I.aceya hibernicaMay&Mat ten is represented by stems bearing spirally arranged fronds. The base of the frond is swollen and is about the same size as the stem. Pinnae are borne alternately and apparently in one plane on the rachis. The anatomy of the stem reveals a three‐fluted protostele. Secondary xylem consists of rays and trachcids and secondary phloem is present. The inner cortex contains probable secretory and/or sclerotic cells. The outer cortex is of the spargaimm‐type. Rachial trace formation is described. The U‐shaped xylem strand of the rachis lacks secondary tissue. Pinnae traces are V‐ to C‐shaped. A presumed adventitious root has a triarch protostele, a parenchymatous cortex and lacks a ‘sparganum’ outer zone.I.aceyais believed to be a member of the Lyginopleridaceae. The divisions of the sympodial protoxylem strand forming the rachial trace is compared among the Aneurophytales, Buteoxylonaceae, Calamopityaceae and Lyginopteridaceae and is shown

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1983.tb00719.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Lepidostrobusis a genus that was established by Brongniart for Palaeozoic lycopod cones. Since then the genus has been used for a variety of cones that have similar characters. There is now compelling evidence that the genus represents a heterogeneous group of monosporangiate and bisporangiate cone species and that it should be divided.Lepidostrobusis rediagnosed as a genus of microsporangiate cones.FtemingitesCarruthers is rediagnosed as a genus of those bisporangiate cones formerly included inLepidostrobus.

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1983.tb00720.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Measurement of leaf length and stem diameter in three Upper Carboniferousl.epidodendronspecies shows an exponential relationship between these parameters. Larger axes bear longer leaves even in material which had apparently completed its primary' growth. It is suggested that this is a direct product of the determinate growth pattern of the ontogeny of arborescent lycopods. Measurements ofCyclostigmafrom the Irish Devonian are not explicable in these terms, and it is suggested that some specimens were immature at fossilization. It is recommended that the term leaf cushion be applied to the expanded leaf base in the Lepidodendrales at all growth stages, and not only after leaf abscission. Problems in the terminology of ‘young’ and ‘old’ growth stages in these determinate plants are di

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1983.tb00721.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Pachypteris papulosa(Thomas&Bose) Harris, leaves of a pteridosperm, are locally abundant in the Middle Jurassic of Yorkshire. Microsporophylls too are known but the stem has been represented only by a few puzzling fragments. Better‐preserved stem material is now described. When young the stems were thick (up to 15 mm) and largely composed of soft parenchyma and thus succulent. The leaves are borne sparsely, each at the end of a prominent mamilla. The stem surface is covered by hemispherical emergences with a thickly cutinized epidermis which, when isolated, are beret‐shaped. This cuticle is the only robust part of the young stem.Later the stem formed a thick cylinder of wood and the surface was stretched. A new surface i presumed to be cork), was formed and the ‘berets’ and mamillac were lost. Branching occurs at distant intervals, when the stem divides nearly equally into widely diverging parts.Pachypteris papillosais pictured as a large shrub forming a mangrove‐like thicket along tid

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1983.tb00722.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Conifer fragments from the Lower Cretaceous of Sudan are preserved as internal and external silica moulds. Low viscosity silicone rubber has been used to prepare casts showing fine epidermal details which enable identification of the plants. One isI'seudofrenelopsis parceramosa(Fontaine) Watson, the other is described as a new species ofFrenelopsisSchenk.

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1983.tb00723.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY