Lower Palaeozoic sporomorphs: their stratigraphical distribution and possible affinities

1985 ◽  
Vol 309 (1138) ◽  
pp. 201-205 ◽  
Keyword(s):  
Lower Devonian ◽  
Land Plants ◽  
Early Devonian ◽  
Major Discrepancy ◽  
Lower Palaeozoic

Richardson & Ioannides (1973) speculated on possible bryophytic affinities of some Silurian dispersed spores. Later, at the International Palynological Congress in Cambridge (1980) I discussed the close morphological similarities of some Silurian and early Devonian spores to those from mosses and liverworts. In particular the dispersed miospore genera Streelispora and Aneurospora are similar to the spores of the extant liverwort Anthoceras and spores of some species of the extant moss genus Encalypta to fossil spores of Emphanisporites . If such similarities are indicative of affinity then many of the Silurian spores may have belonged to early bryophytic ancestors. As mosses and liverworts are not usually preserved as fossils, such an explanation would help to explain the major discrepancy between the number of dispersed Silurian and Lower Devonian miospore species and the few species of land plants known.

The location of the Iapetus Ocean suture in Newfoundland

1977 ◽  
Vol 14 (3) ◽  
pp. 488-495 ◽  
Author(s):  
W. S. McKerrow ◽  
L. R. M. Cocks
Keyword(s):  
Lower Devonian ◽  
New World ◽  
Late Ordovician ◽  
Calc Alkaline ◽  
The West ◽  
Early Devonian ◽  
Iapetus Ocean ◽  
Lower Palaeozoic ◽  
First Time ◽  
Avalon Peninsula

Brachiopod and trilobite faunal distributions indicate that the Iapetus Ocean was still wide enough to inhibit migration in the Middle and Late Ordovician. The presence of Silurian and Lower Devonian calc-alkaline rocks suggests that ocean crust was still being subducted long after the end of the Ordovician and that the Iapetus Ocean did not finally close in Newfoundland until the Acadian Orogeny. The Reach Fault divides successions containing different Lower Palaeozoic faunas; to the west, typical North American faunas occur in New World Island (Cobb's Arm Limestone), while to the east the rocks of the Gander region appear to have been attached to the Avalon Peninsula, with its European Lower Palaeozoic faunas, since the Early Ordovician. It is concluded that the Reach Fault marks the suture where the Iapetus Ocean closed at the end of the Early Devonian. This line probably extends across Newfoundland to the south of Buchans, and links up with the Cape Ray Fault in the southwest of the island. An Ordovician fauna from the Davidsville Group of the Gander area is illustrated for the first time; it is not clearly definitive of any faunal province.

The Early Devonian (Pragian) zosterophyll Bathurstia denticulata Hueber

2000 ◽  
Vol 78 (2) ◽  
pp. 193-207 ◽  
Author(s):  
Michele E Kotyk ◽  
James F Basinger
Keyword(s):  
Phylogenetic Relationships ◽  
Lower Devonian ◽  
Canadian Arctic ◽  
Land Plants ◽  
Canadian Arctic Archipelago ◽  
Large Collection ◽  
Early Devonian ◽  
Northern Canada ◽  
Early Land

Approximately 86 specimens of Bathurstia denticulata Hueber were collected from upper Bathurst Island and lower Stuart Bay beds of Bathurst Island, Canadian Arctic Archipelago. Bathurstia was a component of a zosterophyll-dominated flora of Pragian age (Lower Devonian) that existed at low paleolatitudes in northern Canada. The large collection of well-preserved materials permits reconstruction of the plant as a robust scrambler of about 30 cm in height. Stems bear short, shelf-like emergences in two rows, and branch isotomously, although sparsely. Rooting organs, representing some of the oldest known for land plants, arise from the main aerial axes, although they are also associated with small, subordinate shoots interpreted as plantlets. Numerous specimens are fertile, with sporangia borne in dense terminal spikes. Spikes include two rows of overlapping, discoid sporangia. Isospores are round and featureless, and assignable to the genus Calamospora. While Bathurstia apparently originated from among the isotomously branching bilaterally symmetrical zosterophylls, the phylogenetic relationships of Bathurstia to known taxa is unclear, although some resemblance to Serrulacaulis, Barinophytaceae, and the Gosslingiaceae can be documented. Bathurstia denticulata is now one of the best known of early land plants, and contributes significantly to our understanding of zosterophylls and their role in Early Devonian vegetation.Key words: Bathurstia, zosterophyll, Devonian, Canada, Arctic, evolution.

Interpretation of Pb isotope compositions of galenas from the Midland Valley of Scotland and adjacent regions

1984 ◽  
Vol 75 (2) ◽  
pp. 85-96 ◽  
Author(s):  
John Parnell ◽  
Ian Swainbank
Keyword(s):  
Lower Devonian ◽  
Lead Isotope ◽  
Sedimentary Rocks ◽  
Isotope Ratios ◽  
Igneous Rocks ◽  
Pb Isotope ◽  
Lower Carboniferous ◽  
Granite Magma ◽  
Lower Palaeozoic ◽  
Caledonian Granite

ABSTRACTThe lead isotope compositions of 61 galenas from central and southern Scotland vary markedly between different regions. Most galenas from the southern Grampian Highlands yield isotope ratios (206Pb/204Pb 17·77 ± 0·25, 207Pb/204Pb 15·47 ± 0·05, 208Pb/204Pb 37·63 ± 0·26) less radiogenic than those from Midland Valley galenas (18·22 ± 0·12, 15·55 ± 0·05, 38·13 ± 0·14) whilst galena lead from the Southern Uplands (18·28 ± 0·12, 15·56 ± 0·03, 38·21 ± 0·18) is more radiogenic than that from the southern Midland Valley (18·12 ± 0·06, 15·52 ± 0·02, 38·06 ±0·10). The change in isotopie composition across the Highland Boundary fault reflects the presence or absence of Dalradian rocks which included a magmatic component of lead. Galenas from the Dalradian sequence in Islay, where igneous rocks are lacking, have a composition (18·14±0·04, 15·51±0·01, 37·90±0·02) more like Midland Valley galenas. In the Southern Uplands, galenas yield lead isotope ratios similar to those of feldspars from Caledonian granite (18·30 ± 0·14, 15·57 ± 0·04, 37·96 ± 0·15) analysed by Blaxland et al. (1979). The similar ratios reflect the incorporation of Lower Palaeozoic sedimentary rocks into the granite magma, rather than a granitic source for the mineralisation. The granites were then thermal-structural foci for later mineralising fluids which leached metals from the surrounding rocks. Within the Midland Valley, galenas hosted in Lower Devonian-Lower Carboniferous lavas are notably more radiogenic (18·31 ±0·12, 15·58 ± 0·06, 38·20 ± 0·16) than sediment-hosted galenas (18·14 ± 0·07, 15·52 ± 0·02, 38·08 ± 0·10). The Devonian lavas at least may have inherited lead from subducted (? Lower Palaeozoic) rock incorporated in the primary magma.

The first zosterophyll from the Lower Devonian Rhynie Chert, Aberdeenshire

1991 ◽  
Vol 82 (4) ◽  
pp. 324-332 ◽  
Author(s):  
A. G. Lyon ◽  
Dianne Edwards
Keyword(s):  
Lower Devonian ◽  
New Genus ◽  
New Genus And Species ◽  
Early Devonian ◽  
Precise Positioning ◽  
Cortical Zone ◽  
Lack Of Information ◽  
Rhynie Chert

ABSTRACTFragmentary remains of a vascular sporophyte from the Rhynie Chert are described as a new genus and species, Trichopherophyton teuchansii. The plant, which is characterised by the possession of unicellular spinous hairs, exarch xylem and laterally attached, marginally dehiscent sporangia, is assigned to the Zosterophyllophytina, but lack of information on the arrangement of sporangia prevents its more precise positioning within the subdivision. Unusual features include the combination of circinate tips to axes with almost terete xylem strands, and the lack of a thick-walled outer cortical zone. Associated axes, lacking spinous hairs, but having papillate or rhizoid-like epidermal emergences, are interpreted as likely rhizomes of Trichopherophyton. Features, such as unicellular spinous hairs, rhizoid-like emergences, circinate tipsand parenchymatous cortex are considered in relation to the functioning and growth of aplant inhabiting an early Devonian wetland.

scholarly journals Further evidence for fungivory in the Lower Devonian (Lochkovian) of the Welsh Borderland, UK

PalZ ◽  
2020 ◽  
Vol 94 (4) ◽  
pp. 603-618
Author(s):  
Dianne Edwards ◽  
Lindsey Axe ◽  
Jennifer L. Morris ◽  
Lynne Boddy ◽  
Paul Selden
Keyword(s):  
Carbon Cycling ◽  
Lower Devonian ◽  
Terrestrial Ecosystems ◽  
Lower Surface ◽  
Early Devonian ◽  
Faecal Pellets ◽  
Terrestrial Invertebrates ◽  
Terrestrial Animal ◽  
Complete Digestion ◽  
Terrestrial Fungi

Abstract The recent demonstrations that widespread mid-Palaeozoic Prototaxites and other nematophytes had fungal affinities indicate that terrestrial fungi were important elements in carbon cycling in the Early Devonian. Here, we provide evidence for their participation in the recycling of nutrients by early terrestrial invertebrates. Evidence is in the form of coprolites, both those associated with nematophytes or containing their fragmentary remains. Cylindrical coprolites consistently associated with fungal mats are placed in a new ichnospecies, Bacillafaex myceliorum. Their contents are granular to amorphous, suggestive of complete digestion of the ingested hyphae, with the inference of possession of chitinases in the digestive tracts of the consumers. A further single example comprises a cluster of cylindrical bodies attached to the lower surface of a Nematothallus fragment. Here, homogenisation was less complete, with traces of hyphae remaining. Terrestrial animal fossils have not been found at the locality, but scorpions, pseudoscorpions, Opiliones, mites, centipedes (carnivores) and millipedes, and Collembola (detritivores) have been recorded from the slightly younger Rhynie cherts. Studies of fungivory in extant arthropods have concentrated on Collembola and, to a lesser extent, mites, but their faecal pellets are much smaller than the fossil examples. Millipedes, based on body size and faeces of extant forms, are considered more realistic producers, but little is known about fungal feeding in these animals. Regardless of the affinities of the producers, the diversity in morphology, sizes, aggregations, and composition of nematophyte-containing examples suggests that fungivory was an important component of carbon cycling in early terrestrial ecosystems.

Kobayashiceras gifuense, a new actinocerid cephalopod from the Lower Devonian of Japan

1998 ◽  
Vol 72 (1) ◽  
pp. 36-38 ◽  
Author(s):  
Shuji Niko
Keyword(s):  
New Species ◽  
Lower Devonian ◽  
Shell Morphology ◽  
Central Japan ◽  
Early Devonian

A new actinocerid genus, Kobayashiceras, is defined on the basis of Kobayashiceras gifuense new species from the Lochkovian (Early Devonian) of the Fukuji Formation, central Japan. This genus shares with known actinocerids in the apical shell morphology, but is diagnosed by its orthocerid like stenosiphonate form in the adoral shell. Its taxonomic and paleobiogeographic implications are discussed.

scholarly journals The dawn of symbiosis between plants and fungi

2011 ◽  
Vol 7 (4) ◽  
pp. 574-577 ◽  
Author(s):  
Martin I. Bidartondo ◽  
David J. Read ◽  
James M. Trappe ◽  
Vincent Merckx ◽  
Roberto Ligrone ◽  
...  
Keyword(s):  
Vascular Plant ◽  
Land Plants ◽  
Evolutionary Trees ◽  
Early Devonian ◽  
Present Evidence ◽  
Plant Fossils ◽  
Biological Innovations ◽  
New Hypothesis ◽  
Colonization Of Land ◽  
Early Land

The colonization of land by plants relied on fundamental biological innovations, among which was symbiosis with fungi to enhance nutrient uptake. Here we present evidence that several species representing the earliest groups of land plants are symbiotic with fungi of the Mucoromycotina. This finding brings up the possibility that terrestrialization was facilitated by these fungi rather than, as conventionally proposed, by members of the Glomeromycota. Since the 1970s it has been assumed, largely from the observation that vascular plant fossils of the early Devonian (400 Ma) show arbuscule-like structures, that fungi of the Glomeromycota were the earliest to form mycorrhizas, and evolutionary trees have, until now, placed Glomeromycota as the oldest known lineage of endomycorrhizal fungi. Our observation that Endogone -like fungi are widely associated with the earliest branching land plants, and give way to glomeromycotan fungi in later lineages, raises the new hypothesis that members of the Mucoromycotina rather than the Glomeromycota enabled the establishment and growth of early land colonists.

The Gametophyte Generation of Some Early Devonian Land Plants

1993 ◽  
Vol 154 (1) ◽  
pp. 35-58 ◽  
Author(s):  
Winfried Remy ◽  
Patricia G. Gensel ◽  
Hagen Hass
Keyword(s):  
Land Plants ◽  
Early Devonian
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