The trilobite Reedops (Phacopidae) in the Lower Devonian of Argentina (Malvinokaffric Realm)

2012 ◽  
Vol 86 (2) ◽  
pp. 253-257 ◽  
Author(s):  
David J. Holloway ◽  
Juan J. Rustán
Keyword(s):  
Type Species ◽  
Lower Devonian ◽  
Middle Part ◽  
Early Devonian ◽  
Northwestern Argentina ◽  
Old World ◽  
Devonian Age ◽  
La Rioja

The trilobite Reedops is documented from strata probably corresponding to the middle part of the Talacasto Formation in the Sierra de las Minitas, at the northernmost extent of the Precordillera in La Rioja Province, northwestern Argentina. The specimens resemble the type species of the genus, R. bronni, indicating a Pragian (Early Devonian) age for the strata, and suggesting the occurrence at this time of faunal exchange between the Old World Realm, particularly the Bohemian area, and the Malvinokaffric Realm. The taxon represents the first Early Devonian macrofaunal element in the Malvinokaffric Realm with global biostratigraphical significance.

scholarly journals A Lower Devonian age for the Corvock Granite and its significance for the structural history of South Mayo and the Laurentian margin of western Ireland

2021 ◽  
Author(s):  
John Graham ◽  
Nancy Riggs
Keyword(s):  
Lower Devonian ◽  
Early Devonian ◽  
North East ◽  
The North ◽  
Granite Emplacement ◽  
History Of ◽  
Western Ireland ◽  
Laurentian Margin ◽  
Devonian Age ◽  
Restraining Bend

The Silurian Croagh Patrick succession, which crops out just south of a fundamental Caledonian structural zone near Clew Bay, western Ireland, is a series of psammites and pelites with a strong penetrative cleavage. These rocks are intruded by the Corvock granite. A suite of minor intrusions associated with the granite contains the regional cleavage whereas the Corvock granite is undeformed. New U-Pb dates are 413 + 7 / -4 Ma for a strongly cleaved sill and 410 ± 4 Ma for the main granite and closely constrain the age of crystallization of the granite and coeval cleavage formation as Lower Devonian (Lochkovian or Pragian), implying syn- to late-kinematic granite emplacement. These data are consistent with evidence for strong sinistral shear shown by the Ox Mountains granodiorite just to the north-east dated at 412.3 ± 0.8 Ma. This Devonian cleavage is superimposed on Ordovician rocks of the South Mayo Trough. The localisation of the strong deformation is interpreted as being due to its position at a restraining bend during regional sinistral motion on a segment of the Fair Head-Clew Bay Line to the north. Contemporaneous deformation in the syn-kinematic Donegal batholith suggests a transfer of sinistral motion to this intra-Grampian structure rather than simple along-strike linkage to the Highland Boundary Fault in Scotland. Our new data indicate diachronous deformation during the late Silurian and early Devonian history of the Irish and Scottish Caledonides and also support previous interpretations of diachronous deformation between these areas and the Appalachian orogens.

Vertebrate remains from Upper Silurian – Lower Devonian beds of Hall Land, North Greenland

1999 ◽  
pp. 1-80 ◽  
Author(s):  
Henning Blom
Keyword(s):  
Lower Devonian ◽  
Age Determination ◽  
Early Devonian ◽  
Marine Strata ◽  
South Of Siberia ◽  
Minor Part ◽  
Upper Silurian ◽  
A Minor ◽  
Devonian Age ◽  
North Greenland

NOTE: This monograph was published in a former series of GEUS Bulletin. Please use the original series name when citing this monograph, for example: Blom, H. (1999). Vertebrate remains from Upper Silurian – Lower Devonian beds of Hall Land, North Greenland. Geology of Greenland Survey Bulletin, 182, 1-80. https://doi.org/10.34194/ggub.v182.5126 _______________ Vertebrate microscopic remains of twenty-six taxa of thelodonts, heterostracans, osteostracans, anaspids, acanthodians and chondrichthyans are described from limestone beds in two localities of Late Silurian - Early Devonian age of the Chester Bjerg Formation, Hall Land, North Greenland. The limestone beds form a minor part of a monotonous calcareous sandstone-siltstone-mudstone sequence at the top of the Franklinian Basin succession.Stratigraphical recognition using several thelodont and acanthodian taxa, supported by regional geological and structural trends, suggests a Silurian-Devonian boundary interval between beds of the Halls Grav and Monument localities. This possible resolution of the previous problematic correlation between the two distant sections of monotonous nature demonstrates the potential biostratigraphic utility of thelodonts in Silurian -Devonian marine successions.The Chester Bjerg Formation thelodont assemblage is unique with several new endemic taxa, but Loganellia cf. L. tuvaensis is very similar to the type material of the Tuva region south of Siberia, Russia and indicates a Late Silurian age for the beds of the Halls Grav locality. Canonia cf. C. grossi suggests an Early Devonian age for the Monument locality, since Canonia is so far only found in Lower Devonian marine strata of Arctic Canada and Russia. Fragments of cosmopolitan acanthodian genera such as Poracanthodes, Gomphonchus and Nostolepis are found together with heterostracans, osteostracans, anaspids and chondrichthyans at both localities but do not give a more exact age determination than Late Silurian - Early Devonian. New thelodont taxa are Loganellia almgreeni sp. nov., Paralogania foliala sp. nov., Praetrilogania grabion gen. et sp. nov. and Thulolepis striaspina gen. et sp. nov. Nostolepis halli sp. nov. is a new acanthodian species.

First occurrence of Orthotheca Novák, 1886 (Hyolitha, Early Devonian) in North America

2009 ◽  
Vol 83 (4) ◽  
pp. 588-596 ◽  
Author(s):  
John M. Malinky
Keyword(s):  
North America ◽  
Cross Section ◽  
Type Species ◽  
Lower Devonian ◽  
Early Cambrian ◽  
Early Devonian ◽  
Generic Concept ◽  
Ventral Furrow ◽  
First Occurrence ◽  
Shaped Cross Section

Family Orthothecidae Sysoev, 1958 is herein emended to encompass only hyoliths that possess a very shallow longitudinal ventral concavity and a tightly rounded dorsum, resulting in a near-triangular to only slightly kidney-shaped cross section. Orthotheca Novak, 1886 is restricted to orthothecids that possess longitudinal ornamentation on the dorsum, with Cryptocaris suavis Barrande, 1872 now recognized as the type species of that genus. Based on the revised generic concept, orthothecids from the Lower Devonian (Emsian) Shriver Chert of northeastern Pennsylvania are here included within the genus as Orthotheca shriveri n. sp., making this the first occurrence of the genus in North America. The Orthothecida were a group of sessile, benthic hyoliths that ranged from Early Cambrian to Early Devonian. Their life habit appeared to have included filter-feeding. Their ability to retract the operculum into the shell when closed probably aided in preventing sediment influx, and the ventral furrow may have been an adaptation to differing degrees of firmness of the underlying substrate. Despite faunal linkages between the Devonian paleocontinents, the majority of orthothecid genera seem to be largely restricted to their type areas, although Orthotheca documented herein has eroded slightly their endemic character.

scholarly journals The Cosheston Group (Lower Old Red Sandstone) in southwest Wales: age, correlation and palaeobotanical significance

1998 ◽  
Vol 135 (3) ◽  
pp. 397-412 ◽  
Author(s):  
C. H. WELLMAN ◽  
R. G. THOMAS ◽  
D. EDWARDS ◽  
P. KENRICK
Keyword(s):  
Lower Devonian ◽  
New Age ◽  
Early Devonian ◽  
Red Sandstone ◽  
South Wales ◽  
Upper Silurian ◽  
Devonian Age ◽  
Sandstone Facies

Upper Silurian–Lower Devonian ‘Lower Old Red Sandstone’ facies deposits cropping out in southwest Wales are poorly age-constrained and difficult to correlate. Spore assemblages have been recovered from sequences of these deposits belonging to the lower part of the Cosheston Group. The spore assemblages are equated with the breconensis–zavallatus and polygonalis–emsiensis Spore Assemblage Biozones and indicate an early Devonian age (late Gedinnian (late Lochkovian)–Siegenian (Pragian)). The new biostratigraphical data enable correlation of the lower part of the Cosheston Group with the Senni Beds from the main outcrop of the Lower Devonian in South Wales and the Welsh Borderland. In addition, the new age data and stratigraphical correlation place important plant megafossil assemblages from the Cosheston Group and Senni Beds in a more secure stratigraphical framework, thus facilitating comparisons with other Lower Devonian plant megafossil assemblages and enhancing palaeobotanical understanding. Evidence from palynofacies analysis supports sedimentological interpretations which suggest that the ‘Lower Old Red Sandstone’ facies deposits belonging to the Cosheston Group accumulated in a continental fluviatile environment.

Lower Devonian conodonts from Port St. Nicholas, southeastern Alaska

1977 ◽  
Vol 14 (12) ◽  
pp. 2928-2936 ◽  
Author(s):  
Norman M. Savage ◽  
Michael Churkin Jr. ◽  
G. Donald Eberlein
Keyword(s):  
Lower Devonian ◽  
Early Devonian ◽  
Devonian Age

Conodonts from a limestone interval exposed above Port St. Nicholas, Prince of Wales Island, southeastern Alaska, include Pandorinellina exigua philipi (Klapper), Eognathodus sulcatus Philip, and Pelekysgnathus serratus Jentzsch. These conodonts indicate an early to middle Pragian age (informal faunal units 5 or 6 of Klapper et al). This middle Early Devonian age is supported by the presence of the graptolites Monograptus yukonensis, M. craigensis, and M. pacificus in shales above the limestone and by some shelly fossils from within the limestone.

scholarly journals New observations on a Pridoli plant assemblage from north Xinjiang, northwest China, with comments on its evolutionary and palaeogeographical significance

1993 ◽  
Vol 130 (2) ◽  
pp. 155-170 ◽  
Author(s):  
Cai Chong-Yang ◽  
Dou Ya-Wei ◽  
D. Edwards
Keyword(s):  
North Africa ◽  
Lower Devonian ◽  
Northwest China ◽  
Early Devonian ◽  
Plant Assemblage ◽  
Plant Remains ◽  
North Xinjiang ◽  
Devonian Age ◽  
North America North ◽  
Precise Assessment

AbstractDetailed descriptions of plant remains from a late Silurian (Pridoli) locality in Xinjiang Province, northwest China are presented. They include Junggaria spinosa Dou, interpreted as identical with Cooksonella sphaerica Senkevich, Salopella xingjiangensis Dou, and a number of sterile axes, including one with a leafy appearance superficially resembling a lycophyte, and others of probable algal affinity. Lack of anatomical and reproductive characteristics precludes a more precise assessment of relationships. A justification for the Pridoli rather than Lower Devonian age of the assemblage is based on graptolites. The composition of the assemblage is compared with coeval ones from Europe, North America, north Africa and Kazakhstan and has closest similarities with the latter. Palaeogeographic proximity on the Kazakhstan palaeocontinent is postulated, but the dearth of global Silurian occurrences of land plants make it premature to evaluate the significance of Kazakhstan and Chinese assemblages in terms of global provincialism in the late Silurian. The most distinctive element in these assemblages (Junggaria/Cooksonella) has sporangia with more complex, indeed more enigmatic organization, than seen in most Silurian and early Devonian rhyniophytoids.

New porcellioidean gastropods from early Devonian of Royal Creek area, Yukon Territory, Canada, with notes on their early phylogeny

2008 ◽  
Vol 82 (3) ◽  
pp. 595-603 ◽  
Author(s):  
Jiří Frýda ◽  
Robert B. Blodgett ◽  
Alfred C. Lenz ◽  
Štěpán Manda
Keyword(s):  
Lower Devonian ◽  
Yukon Territory ◽  
Shell Morphology ◽  
Western Canada ◽  
Evolutionary Trend ◽  
Early Devonian ◽  
Old World ◽  
The Road ◽  
Classical Models

This paper presents a description of new gastropods belonging to the superfamily Porcellioidea (Vetigastropoda) from the richly diverse Lower Devonian gastropod fauna of the Road River Formation in the Royal Creek area, Yukon Territory. This fauna belongs to Western Canada Province of the Old World Realm. The Pragian speciesPorcellia(Porcellia)yukonensisn. sp. andPorcellia(Paraporcellia) sp. represent the oldest presently known members of subgeneraPorcellia(Porcellia) andPorcellia(Paraporcellia). Their simple shell ornamentation fits well with an earlier described evolutionary trend in shell morphology of the Porcellinae. Late Pragian to early EmsianPerryconcha pulchran. gen. and n. sp. is the first member of the Porcellioidea bearing a row of tremata on adult teleoconch whorls. The occurrence of this shell feature in the Porcellioidea is additional evidence that the evolution of the apertural slit was much more complicated than has been proposed in classical models of Paleozoic gastropod evolution.

scholarly journals Braquiópodos del Devónico Inferior (Lochkoviense-Praguiense) de la región Cántabro- Celtibérica (España)

2017 ◽  
Vol 35 (35) ◽  
pp. 99
Author(s):  
J. L. García-Alcalde ◽  
Z. A. Herrera
Keyword(s):  
Type Species ◽  
Lower Devonian ◽  
Anterior Commissure ◽  
Old World ◽  
Cordillera Ibérica ◽  
Iberian Chain ◽  
First Time

Resumen: Se estudian varios taxones nuevos de braquiópodos del Devónico inferior (Lochkovien-se-Praguiense) de la región cántabro-celtibérica de la cuenca Iberoarmoricana que contribuyen a apo-yar la existencia y continuidad a lo largo del tiempo de dicha cuenca. Trigonirhynchia palentina n. sp. y T. celtiberica n. sp. son formas de rinconélidos próximas a la especie armoricana T. fallaciosa, y de similar edad que ella, Praguiense inferior. El género Eucharitina, bien conocido en el Dominio paleo-geográfico del Viejo Mundo, se identifica y describe formalmente por primera vez en el área estudiada, donde está representado por tres especies: E. bultyncki n. sp., de la parte alta del Lochkoviense inferior del Guadarrama oriental y E. carlsi n. sp., de la parte baja del Praguiense inferior y E. cf. eucharis, de fines del Praguiense medio, de la Cordillera Ibérica Oriental. Se menciona y figura también material de comparación de la especie armoricana, E. oehlerti. Se propone el nuevo género del Orden Athyri-dida Chopinia, constituido solo por su especie-tipo, C. petercarlsi n. sp., del Lochkoviense superior o del Praguiense inferior de Palencia y Celtiberia. La concha muy transversa, de contorno elíptico, con buen desarrollo del área cardinal y ornamentación de lamelas concéntricas escamosas en Chopinia lo aproxima a la Subfamilia Plicathyridinae, en particular al género Anathyris. Sin embargo, la ausencia de elementos radiales (pliegues y surco ventral) en la concha y la comisura anterior no invaginada po-dría indicar que Chopinia es un tronco ancestral, primitivo, de la subfamilia, cuya ulterior evolución hasta llegar a Anathyris en el Emsiense se desconoce.Palabras clave: Región Cántabro-Celtibérica, Cuenca Iberoarmoricana, Devónico Inferior, bra-quiópodos rinconélidos y atirídidos, Trigonirhynchia, Eucharitina, Chopinia.Abstract: Several new Lower Devonian (Lochkovian-Pragian) brachiopod taxa from the Canta-bro-Celtiberian region of the Ibero-Armorican basin are described and figured. These taxa support the occurrence and continuity of the Iberoarmorican basin along time. Trigonirhynchia palentina n. sp. and T. celtiberica n. sp. are Lower Pragian rhynchonellid species close to the Armorican species T. fallaciosa. The genus Eucharitina, well-known along the paleogeographic Old World Domain, is formally identified and described for the first time in the studied region. There, it is represented by three species, E. bultyncki n. sp. from the upper part of the Lower Lochkovian in Eastern Guadarrama, and E. carlsi n. sp., lowermost Pragian and E. cf. eucharis, middle Pragian of the Eastern Iberian Chain. Comparison material of the Armorican species E. oehlerti are also mentioned and figured. A new Athyrididae genus, Chopinia, constituted only by the type-species C. petercarlsi n. sp. from the upper Lochkovian or the lower Pragian of Palencia and Celtiberia is proposed here. The very transverse elliptical outline, good development of the cardinal area and ornamentation of concentric, squamose growth lamellae, are features close to those of the Subfamily Plicathyridinae, in particular to the genus Anathyris. However, the lack of radial elements (plications and sulci) on the shell, and non-emarginate anterior commissure could indicate that Chopinia was the subfamily ancestor whose further evolution to reach Anathyris in the Emsian remains unknown.Keywords: Cantabro-Celtiberian region, Iberoarmorican basin, Lower Devonian, rhynchonellid and athyridid brachiopods, Trigonirhynchia, Eucharitina, Chopinia.

scholarly journals Early Devonian vertebrates from Hall Land, North Greenland

1974 ◽  
Vol 65 ◽  
pp. 13-16
Author(s):  
S.E Bendix-Almgreen ◽  
J.S Peel
Keyword(s):  
Acetic Acid ◽  
Lower Devonian ◽  
Acid Digestion ◽  
Early Devonian ◽  
Devonian Age ◽  
North Greenland ◽  
Age Determinations

During investigation of collections from North Greenland made by P. R. Dawes and J. H. Allaart, as part of Operation Grant Land 1965-66, one of the authors (J. S. P.) found vertebrate remains in samples which had been subjected to acetic acid digestion. The vertebrate material was subsequently examined by S.E.R.A. who found it to comprise thelodonts, heterostracans and acanthodians (illustrated in Bendix-Almgreen, in press) suggestive of an approximate late Silurian (Pridoli) - Lower Devonian age. This age is in general agreement with the late Silurian - early Devonian date suggested by Berry et al. (this report) for graptolites from stratigraphically slightly lower beds in the same sequenee of strata in western Hall Land. The two age determinations provide the first palaeontological evidence for the presenee of late Silurian (Pridoli) and early Devonian strata in the Franklinian geosynclinal sequence of North Greenland.

Reef trilobites from the Formosa Limestone (Lower Devonian) of southern Ontario

1987 ◽  
Vol 24 (4) ◽  
pp. 676-688 ◽  
Author(s):  
Rolf Ludvigsen
Keyword(s):  
North American ◽  
Type Species ◽  
Lower Devonian ◽  
Southern Ontario ◽  
Old World ◽  
Reef Fauna

A reef trilobite fauna of five species from the Formosa Limestone Member of the Amherstburg Formation (Lower Devonian, Emsian) of southern Ontario is strongly dominated by the proetids Crassiproetus and Mannopyge; it also includes the brachymetopid Mystrocephala, the lichid Acanthopyge, and the aulacopleurid Harpidella. This is the first fully documented trilobite fauna from North American Devonian reefs. The proetid-dominated Formosa reef fauna from the Appalachian Province is more similar to Carboniferous reef trilobite faunas than it is to other Devonian reef trilobite faunas from the Old World Province in Europe, Africa, and Australia that are dominated by scutelluids. Crassiproetus Stumm is assigned to the Proetinae; Mannopyge n. gen. (type species, M. halli (Stumm)), to the Warburgellinae.

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