Devonian floral assemblages and plant megafossils from the Iberian Peninsula: A review

This paper presents a review and critical analysis of the literature on Devonian floras of the Iberian Peninsula. Although the known outcrops of Devonian strata in the Iberian Peninsula are marine, in some cases, a few fragmentary remains of vascular plants are associated with faunal remains. Records include largely specimens from the Lower Devonian of Barrancos (Alentejo, Portugal) and the Upper Devonian of Sierra de Hornachos in Badajoz province, southwest Spain; the remainder consists of drifted plant fragments from scattered sites in the Iberian Peninsula ranging in age from Lochkovian to Upper Devonian-Earliest Carboniferous. The vegetation inferred for the Lower Devonian of the Iberian Peninsula is mainly based on palynological data and corresponds to herbaceous types characterised by bryophytes, rhyniophytes (Horneophyton, Cooksonia, Rhynia), trimerophytes (Psilophyton, Pertica and Hostinella), primitive lycophytes (Drepanophycus) and incertae sedis such as Nothia and Chaleuria, all flora that developed near the coast in low-lying and, at least periodically, wet areas. In the Middle Devonian, two vegetation strata can be recognised: herbaceous (Psilophyton) and semi-arboreal (Cladoxylales). Although three levels of vegetation in the Upper Devonian, have been described from outcrops worldwide, the scarce available data from the Iberian Peninsula only indicate an arborescent lycopsid vegetation and species with uncertain botanical affinity such as Sphenopteridium keilhauii Nathorst.     

Fluctuations in a late devonian-early Mississippian phytoplankton flora of Ohio,U.S.A

Fossil diversity and abundance fluctuations of Late Devonian (Famennian)—Early Mississippian (Tournaisian) phytoplankton assemblages were determined in a stratigraphic sequence of samples in Barberton test core 3, from northeast Ohio. Both diversity and abundance were relatively high during deposition of the lower Chagrin Shale (Upper Devonian) and both decreased during deposition of the upper Chagrin Shale. The overlying Cleveland Shale (Upper Devonian) is characterized by sharply increased abundance with a corresponding (although less marked) increase in diversity; in contrast, both abundance and diversity were at relatively low levels during deposition of the Lower Mississippian Bedford Shale, the uppermost unit of the sequence. These trends agree with the phytoplankton periodicity model presented by Tappan, which indicates large-scale extinction at the end of the Devonian.Many of the acritarch and prasinophycean algal taxa have restricted stratigraphic occurrences within the section studied, making them useful for local and perhaps worldwide correlation. The stratigraphically restricted taxa provide a basis for the proposal of five biostratigraphic zones within the Upper Famennian (Upper Devonian) and a portion of the Lower Mississippian. In ascending order occur: the Gorgonisphaeridium ohioense Assemblage Zone, the Acriora petala Assemblage Zone, the Muraticavea enteichia Range Zone, the Cymatiosphaera labyrinthica Range Zone, and the Navifusa drosera Assemblage Zone.     

Taxonomical and biostratigraphical remarks on the rhynchonellide “Paurorhyncha” (Brachiopoda) in the Yidade Formation of eastern Yunnan,China

Additional specimens of rhynchonellide brachiopods from the marly limestones in the Yidade Formation at the Panxi section in eastern Yunnan have been ascribed to the species “Paurorhyncha” squamosa Wang, 1956 and “P.” depressa Wang, 1956. The two species have been used frequently as index fossils for the Frasnian (Upper Devonian), but their taxonomic assignments are problematic because their internal structures remain unknown. In this study, detailed systematical examinations on both external characters and internal structures revealed by serial sections suggest that the two species are more appropriately assigned to the genus Hadrotatorhynchus Sartenaer, 1986. Based on the stratigraphical distributions of Hadrotatorhynchus and the conodonts in the upper unit of the Yidade Formation, the Hadrotatorhynchus-bearing horizons are re-considered as the uppermost Givetian (Middle Devonian) rather than Frasnian stage, although the precise position of the Middle/Upper Devonian boundary still depends on further investigations of high-resolution biostratigraphy.     

New Devonian punctate rhynchonellids (Brachiopoda) from Transcaucasia

New genus and species of punctate rhynchonellids Sharovaella mirabilis are described from the Famennian (Upper Devonian) of Transcaucasia.     

New Devonian Palliocerida (Cephalopoda, Astrovioidea)

Eight new species of Ostreioceratidae are described from the Lower and Upper Devonian of Novaya Zemlya, Lower Devonian of the Pechora River basin, North Ural Mountains, and the Zeravshan Range: Ostreioceras admotum, O. simile, O. abruptum, O. sobolevi, Plagiostomoceras kuzmini, P. adumbratum, P.? acerbum, and P. vinogradovi. A new family Bogoslovskyidae is established in the order Palliocerida.     

Deux Lycophytesavec structures conservées du dÉvonien supérieur D'Ukraine (U.R.S.S.)

A revision of fossil plants, with preserved structures, collected in the Upper Devonian of the Donetz Basin (Ukrainia) allows us to describe 2 Lycophyta. One of them is a new species: Colpodexylon (?) schopfii nov. sp.     

The placoderm <Emphasis Type="Italic">Plourdosteus livonicus</Emphasis> (Eastman) in the early Frasnian of the Central Devonian Field and the trophic structure of the Mikhailovskii Fish Assemblage

The placoderm Plourdosteus livonicus (Eastman) (Euarthrodira, Coccosteina) from the Upper Timanian Mikhailovskii Fish Assemblage of the Central Devonian Field is described. The composition and structure of the assemblage are discussed and compared with later Frasnian fish assemblages of the Central Devonian Field.     

New bryozoans (Bryozoa) from the Upper Devonian (Lower Famennian) of the Kuznetsk Basin

New bryozoans from the Upper Devonian (Famennian) of the borderlands of the Kuznetsk Coal Basin are described: Orthopora tomensis sp. nov. and Minussina incrustata sp. nov.     

Psammosteiforms (Agnatha,Heterostraci) from the Lower Frasnian of the Mikhailovskii Mine,Kursk Region,Russia

Psammosteiforms, including Tartuosteus (?) zheleznogorskensis, sp. nov. and Psammosteus cf. P. praecursor Obruchev, from the Lower Frasnian (Upper Devonian) of the Mikhailovskii Mine (Kursk Region) are described. Agnathans, placoderms, crossopterygians, and acanthodians from this locality are determined. The similarity of the Mikhailovskii Fish Assemblage to the assemblage of southern Timan suggests it be assigned to the Upper Timan Regional Stage.     

Sphenophyllum Brongniart (Sphenopsida) from the Upper Devonian of South China

Sphenophyllum Brongniart constitutes a common and important element in the Carboniferous and Permian floras around the world, but its records in the Devonian Period are limited and remain to be investigated with respect to their morphology, anatomy, and distribution. Diversity of Sphenophyllum during Late Devonian in South China was significant with the presence of the well-known species including S. lungtanense Gothan and Sze, S. pseudotenerrimum Sze, and S. changxingense Huang et al. In this article, we describe a new species of the genus, S. fanwanense n. sp., from the Fanwan section of Changxing County, Zhejiang Province, characterized by having at least two orders of axes, with six spoon-shaped leaves attached at the node. A comprehensive review of previous records of Sphenophyllum from the Upper Devonian of South China shows that at least four species (S. fanwanense, S. lungtanense, S. pseudotenerrimum and S. changxingense), each with distinct leaf morphology, occur in South China in the Late Devonian, mostly from the Wutong Formation (Famennian). Given the lack of concrete evidence for anisophylly or heterophylly among the Devonian Sphenophyllum species (and more broadly, the Devonian sphenopsids), we suggest that the development of these features later in the Carboniferous and Permian periods was likely related to an increase in complexity of forest communities through time.     

A new coral genus (Tabulata) from the Upper Devonian of the Subpolar Urals

A new tabulate genus, Sokolovia gen. nov., with the type species B. pershinae sp. nov., from the Upper Devonian (Lower Famennian Substage) of the western slope of the Subpolar Urals is described.     

Substructure in exines of Artemisia vulgaris (Asteraceae)

Of the Silurian and Devonian macroplant genera described in the literature, about half have been recorded with spores. These in situ spores can be compared at generic level with only about a quarter of the dispersed spore genera described for the same period. Emphasis is here placed on the structure and sculpture of in situ and dispersed Silurian, Gedinnian and Siegenian spores, where records of macroplants with in situ spores are high compared with the Middle and Upper Devonian.A comparative study of the structure and sculpture of the in situ and dispersed spores, together with information from the macroplants recorded, suggests a fairly simple Silurian and Gedinnian flora, with the evolution of a more advanced upland flora during Siegenian times.     

Stenolaemate bryozoans from the Geirud Formation (Upper Devonian/Lower Carboniferous) of Central Alborz (Iran)

Two bryozoan species are described from the Geirud Formation (Upper Devonian/Lower Carboniferous) of Central Alborz (Iran). Trepostome Schulgina mutabilis Troizkaya, 1975 is known from the Upper Devonian (Famennian) of Central Kazakhstan. The new species Ascopora geirudensis n. sp. is the earliest known representative of the rhabdomesine genus Ascopora Trautschold, 1876.     

A Lower Devonian hexacrinitid crinoid (Camerata,Monobathrida) from south-west England

The most species-rich and widespread crinoid clade in the type area of the Devonian of south-west England is the monobathrid camerate family Hexacrinitidae Wachsmuth and Springer. These crinoids occur either as thecae (Middle Devonian) or pluricolumnals and columnals (Lower to Upper Devonian). The first new, nominal species of hexacrinitid, probably Oehlerticrinus Le Menn, to be described from this region since the nineteenth century is Oehlerticrinus peachi sp. nov. from the Lower Devonian Looe Basin of southern Cornwall. This specimen is mouldic and somewhat flattened, retaining the proxistele and arms. Diagnostic features include the heteromorphic proxistele with circlets of long, unbranched radices directed towards the crown; the high, box-like (=skyphosiform) theca with a flattened base; a thecal plate sculpture of tubercles and ridges arranged in triangles; and the pinnulate arms. Any uncertainty in identifying this species at the generic level rests with the arms being pinnulate, not ramulose as is common in Hexacrinites Austin and Austin, indicating that O. peachi is closer to Oehlerticrinus Le Menn.     

New Upper Devonian species of the suborder Athyrididina Boucot, Johnson et Staton from Belarus

Five new Upper Devonian species of the suborder Athyrididina are described from the Pripyat?? Depression (Belarus): Athyris? parvulus Modzalevskaya et Pushkin, sp. nov., Crinisarina neutra Modzalevskaya et Pushkin, sp. nov., C. ligularis Modzalevskaya et Pushkin, sp. nov., C. reticulatiformis Modzalevskaya et Pushkin, sp. nov., and Pachyplax rudis Modzalevskaya et Pushkin, sp. nov.     

Bryozoans from the Mitikha Formation (Lower Famennian, Upper Devonian) of the Kuznetsk Basin, Russia

Bryozoans from the Mitikha Formation (Lower Famennian, Upper Devonian) in the Kuznetsk depression are described for the first time. This bryozoan assemblage comprises both the well-known species Leioclema numerosum Moroz., L. ramosum Nekh., and Nicklesopora graciosa Troiz. and new taxa: L. kusmense sp. nov. and Megacanthopora glubokaensis sp. nov. The bryozoan assemblage contains some species common with the Famennian bryozoan assemblage of Kazakhstan.     

Hildenaspis digitalis nov. gen., nov. sp.(Agnatha,Cephalaspidomorphi), Cephalaspide nouveau du Devonien inferieur d'Allemagne

The present cephalic shield of Hildenaspis digitalis n. gen., n. sp. has a continuous exoskeleton and shows an ornamentation which stands alone among the osteostracans. It has been discovered in the Upper Siegenian or Lower Emsian of Rhineland and represents the second find of cephalaspid in the Devonian of Germany.     

New bryozoans from the Devonian of Gorny Altai (Russia)

New bryozoans Saffordotaxis altaicus sp. nov. from the Givetian Stage (Middle Devonian) and Cyphotrypa olgae sp. nov. and Crustopora aliena sp. nov. from the Famennian Stage (Upper Devonian) are described from the Devonian of Gorny Altai.     

Revision of Famennian-Tournaisian (Late Devonian – Early Carboniferous) conodont biostratigraphy of Sardinia,Italy

Conodont biostratigraphy of the Famennian and Tournaisian of Sardinia is provided on the basis of all data available in the literature. More than 130 conodont taxa documented from this time-interval allow recognition of nineteen conodont biozones. The zonation scheme adopted here is broadly similar to the standard zonation schemes used in the Upper Devonian and Lower Carboniferous, though a few variations are needed to better accommodate the species occurrences in Sardinia: the velifer Zone and the styriacus Zone have been reintroduced, even though with slightly different meanings than previously used; the Lower praesulcata Zone is expanded to include the Middle praesulcata interval. The Upper praesulcata Zone and the sulcata Zone are missing. All zones are described and discussed and a complete list of bioevents is provided.