摘要:

Among the abundant plant microfossils obtained from the late Silurian Burgsvik Sandstone are spores and filaments whose morphology suggests a fungal origin. These include large multiseptate spores resembling conidia of present‐day Fungi Imperfecti; ovate, reniform, rugulately ornamented unicellular spores; branched filaments with perforate septa; and filaments with flask‐shaped appendages resembling phialides. We suggest that these microfossils represent the remains of the imperfect stages of terrestrial Ascomycetes, and provide evidence for an origin of this group at least contemporaneous with the earliest land plants. Larger, ovoid and cylindrical heterogeneous bodies composed of hyphal fragments resemble the fecal pellets of mycophagous microarthropods. The implications of these in terms of early terrestrial ecosystems are discus

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1985.tb00680.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Burrowing and plowing gastropods may have existed prior to the Mesozoic, contrary to the conservative tendency of categorizing Paleozoic archaeogastropods as herbivorous hardground dwellers. We propose thatEuphemitesand other bellerophontiform molluscs such asPraematuratrophandBeyrichidiscusmake functional and paleoecological sense only if reconstructed with an internal shell adapted to an infaunal mode of life. Attributes diagnostic of a probable infaunal mode of life in fossil bellerophontiform molluscs include: (1) lack of apertural flare; (2) restricted aperture; (3) low rate of whorl expansion; (4) semi‐radial aperture; (5) extensive secondary shell deposits; (6) absence of extensive collabral ornament; (7) dorsolateral or umbilical furrows; (8) color patterns indicative of mantle extension and retraction capabilities; (9) absence of shell breakage and repair; and (10) associated lithologies indicative of penetrable substrates such as mudstones. Niche diversity in the bellerophontacean molluscs was probably much greater than previously suspected. This is entirely consistent with their long geologic range. Most bellerophontaceans, particularly the Late Paleozoic forms, were probably either ‘nestling’ or semi‐infaunal with the apertural margins enwrapped by mantle or mantle and foot. As such they may have been particularly susceptible to predation during the postulated Mesozoic increase in number of infaunal predators‐ a factor which may have been contributory to the bellerophontace

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1985.tb00681.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1985.tb00682.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The adductor muscle scars of cavellinids from the Visean (in one case from the Upper Devonian) of the European part of the RSFSR have revealed a significant diversity in their morphology. Aggregate, multiserial with up to five series, bi‐ to triserial and nearly biserial muscle scars existed simultaneously. The verticaliserial muscle scars were initiated by a biserial larval group which in the course of evolution may have passed, due to neoteny, into the adult stage. Together withCytherellasp. from Syria, the new data show that the genusCytherellaappeared not in Triassic nor Jurassic time, hut originated among cavellinids possibly in the Early Carboniferous. A new genus isBorovitchella, with the type speciesB. egorovin. s

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1985.tb00683.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The silicified Wenlockian (Silurian) bivalve fauna from MÖllbos, Gotland, is part of a life assemblage. The vast number of shells show unusual phenomena, e.g. shell repair, pearl and tumour formation, etc. A number of shells contain epibionts and bored, round holes. Presumptive predators of the bivalve community are discussed. Size‐frequency distribution of the two most abundant species possibly reflects age classes. The fauna, comprising eleven species, is dominated by deposit‐feeders (90 %). They exhibit niche diversification, including at least three different feeding levels within the sedi

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1985.tb00684.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Later Mississippian (upper Chesterian) to Early Pennsylvanian (lower Morrowan) conodont faunas were recovered from limestones and calcareous mudstones of the Alaska Bench Formation in central Montana. These faunas define four biofacies, each recognized by the dominance of a particular single element genus for which the biofacies is named. TheAdetognathusbiofacies represents lagoonal, tidal flat, and barrier sediments. TheDeclinognathodus/Idiognathoidesbiofacies represents a deposition in shallow, open marine, offshore conditions. TheRhachistognathusbiofacies represents a transitional environment between restricted, intertidal environments and normal marine, offshore environments. TheNeognathodusbiofacies represents shallow‐water bay or lagoonal deposition, where environmental controls have effectively excluded other conodont faunas. The investigation of conodont biofacies provides improved biostratigraphic and paleoenvironmental uses of conodont

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1985.tb00685.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1985.tb00686.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Shell morphology in relation to soft parts is described in the modem speciesCytherella abyssorumG. O. Sars, based on microtome sections, serial peels and thin sections. Functionally important features of the cytherellids include the extensive development of the intervalvar cuticle (‘ligament’) along a strongly curved Line, the consequently very narrow ventral slit between valves in opened carapaces, and a special mode of egg care which is associated with a distinctive (domatial) type of sexual shell dimorphism. Platycope ostracodes represent a pronouncedly conservative evolutionary lineage; their essential characters are fully developed already in the earliest known true platycopes from the Silurian Period. The cause of the slow evolutionary change is suggested to have been the virtual impossibility to change their specific morphological organisation to fit some other mode of life or to diversify widely within the given morphological framework. The same obviously applies to the lingulaccan brachiopods and probably also other bradytelic gro

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1985.tb00687.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY