The class Somasteroidea (Echinodermata, Asterozoa): morphology and occurrence

2015 ◽  
Vol 89 (3) ◽  
pp. 465-486 ◽  
Author(s):  
Daniel B. Blake ◽  
Thomas E. Guensburg
Keyword(s):  
Czech Republic ◽  
The Czech Republic ◽  
Middle Ordovician ◽  
Early Ordovician ◽  
Lower Ordovician ◽  
Stratigraphic Interval

AbstractThe class Somasteroidea Spencer, 1951, is basal within the subphylum Asterozoa. Members are most readily recognized by presence of series of rod-like so-called virgal ossicles extending laterally from each ambulacral ossicle. Five somasteroid genera are recognized and assigned to two families. Four genera are Gondwanan, three of these (Chinianaster, Thoralaster, Villebrunaster) from the Lower Ordovician Tremadocian of France and one (Archegonaster) from the Middle Ordovician upper Darriwilian of the Czech Republic. The fifth genus, Ophioxenikos, is Laurentian from the Floian of Nevada. Catervaparmaster, previously assigned to the Somasteroidea, is left in open nomenclature; absence of virgal-series ossicles favors a lineage apart from the principal asterozoan clades. Asterozoan fossils are readily separated from fossils of other echinoderm groups. The subphylum therefore is thought to be monophyletic, its ancestry unknown. Skeletonized representatives of the four major asterozoan clades first occur through a relatively narrow Early Ordovician stratigraphic interval. Robust skeletons therefore are thought to have evolved after a time of unknown duration including only lineages that were no more than weakly calcified. The French occurrences are from a relatively deep distal shelf setting on soft substrates whereas the Nevada occurrence was in a shallower, active setting. Differences document early ecologic diversification.

New echinoderms from the Early Ordovician of west Texas

1994 ◽  
Vol 68 (2) ◽  
pp. 324-338 ◽  
Author(s):  
James Sprinkle ◽  
Gregory P. Wahlman
Keyword(s):  
North America ◽  
El Paso ◽  
Middle Ordovician ◽  
Early Ordovician ◽  
West Texas ◽  
Lower Ordovician ◽  
Single Well ◽  
Thecal Plate ◽  
Stem Segments

Four specimens of blastozoan and crinozoan echinoderms are described from the Lower Ordovician El Paso Group in the southern Franklin Mountains just north of El Paso, west Texas.Cuniculocystis flowerin. gen. and sp., based on two partial specimens, appears to be a typical rhombiferan in most of its morphologic features except that it lacks pectinirhombs and instead has covered epispires (otherwise known only from Middle Ordovician eocrinoids) opening on most of the thecal plate sutures. The covered epispires inCuniculocystisindicate that some early rhombiferans had alternate respiratory structures and had not yet standardized on pectinirhombs, a feature previously used as diagnostic for the class Rhombifera.Bockia?elpasoensisn. sp. is a new eocrinoid based on one poorly preserved specimen that has a small ellipsoidal theca and unbranched brachioles attached to a flat-topped spoutlike summit. It is the earliest known questionable representative of this genus and the only one that has been described from North America.Elpasocrinus radiatusn. gen. and sp. is an early cladid inadunate crinoid based on a single well-preserved calyx. It fits into a lineage of early cladids leading to the dendrocrinids and toCarabocrinus.Several additional separate plates, stem segments, and a holdfast of these and other echinoderms are also described.

An aglaspidid arthropod from the Upper Ordovician of Morocco with remarks on the affinities and limitations of Aglaspidida

2005 ◽  
Vol 96 (4) ◽  
pp. 327-350 ◽  
Author(s):  
Peter Van Roy
Keyword(s):  
Czech Republic ◽  
Lower Cambrian ◽  
New Combination ◽  
Upper Ordovician ◽  
Filter Feeding ◽  
Feeding Mode ◽  
The Czech Republic ◽  
Lower Ordovician ◽  
Mode Of Life

ABSTRACTA new aglaspidid arthropod, Chlupacaris dubia gen. et sp. nov., is described from the Pusgillian (lower Ashgill, Upper Ordovician) Upper Tiouririne Formation near Erfoud, southeastern Morocco. Although disarticulated, careful documenting of the tergites allows a reconstruction of the exoskeleton to be made. Although somewhat trilobite-like in appearance, the lack of facial sutures, a well-defined axis with articulating half-rings and a pygidium clearly prove Chlupacaris gen. nov. is not a trilobite. An interesting feature is the presence of a hypostome in this non-trilobite arthropod. In contrast to other aglaspidids usually considered to be carnivorous, a filter-feeding mode of life is proposed for Chlupacaris gen. nov., based on the strongly vaulted cephalon, subvertical orientation of the hypostome and less strongly vaulted trunk. Chlupacaris gen. nov. is probably most closely related to the atypical aglaspidid Tremaglaspis unite from the Tremadoc (Lower Ordovician) of the U.K., but it can also be tentatively linked to the problematic Lower Cambrian arthropods Kodymirus vagans and Kockurus grandis from the Czech Republic. The relevance and validity of previous definitions and of possibly significant characters used for identifying aglaspidids are evaluated, and as a result, a new combination of characters diagnosing Aglaspidida is proposed. Contrary to previous reports, it is suggested that aglaspidids are probably more closely related to trilobites than they are to chelicerates. This notion may be supported by the shared possession of a mineralised cuticle, a possibly similar number of cephalic appendages, and the presence of a hypostome in some forms, although this last character may alternatively be homoplastic.

A revision of the stratigraphic nomenclature of the Cambrian–Ordovician strata of the Philipsburg tectonic slice, southern Quebec

2007 ◽  
Vol 44 (12) ◽  
pp. 1775-1790 ◽  
Author(s):  
O Salad Hersi ◽  
G S Nowlan ◽  
D Lavoie
Keyword(s):  
Middle Ordovician ◽  
Upper Cambrian ◽  
Early Ordovician ◽  
Late Cambrian ◽  
Lower Ordovician ◽  
Stratigraphic Position ◽  
Stratigraphic Nomenclature ◽  
Unconformable Contact ◽  
Tectonic Slice ◽  
Upper Boundary

The Philipsburg tectonic slice is bounded to the west by a northeast–southwest-trending thrust fault (Logan’s Line) and preserves 10 formations of Middle (?) to Late Cambrian (Milton, Rock River, and Strites Pond formations), Early Ordovician (Wallace Creek, Morgan Corner, Hastings Creek, and Naylor Ledge formations), and early Middle Ordovician (Luke Hill, Solomons Corner, and Corey formations) age. The strata were previously assigned to the Philipsburg Group. Early correlations between the Philipsburg succession and coeval strata of the St. Lawrence Platform were mainly based on sparse macrofauna and inferred stratigraphic position. Unconformities at the Cambrian–Ordovician and Early Ordovician – Middle Ordovician boundaries occurring in autochthonous St. Lawrence Platform and the allochthonous Philipsburg succession (Philipsburg tectonic slice) highlight new stratigraphic interpretations between the inner-shelf (St. Lawrence Platform) and the outer-shelf (Philipsburg) successions. The succession in the Philipsburg tectonic slice is divided into three new groups. The Middle (?) to Upper Cambrian Missisquoi Group (new) includes the Milton, Rock River, and Strites Pond formations. The upper boundary of the Missisquoi Group is defined by the upper unconformable contact between the Upper Cambrian Strites Pond Formation and overlying Lower Ordovician Wallace Creek Formation. The Missisquoi Group correlates with the Potsdam Group of the St. Lawrence Platform. The Lower Ordovician School House Hill Group (new) includes the Wallace Creek, Morgan Corner, Hastings Creek, and Naylor Ledge formations. The upper boundary of this group is marked by a regionally extensive unconformity at the top of the Naylor Ledge Formation and correlates with the younger Beekmantown-topping unconformity. The School House Hill Group is correlative with the lower to upper part of the Beekmantown Group (Theresa Formation and the Ogdensburg Member of the Beauharnois Formation) of the St. Lawrence Platform. The Middle Ordovician Fox Hill Group (new) consists of the Luke Hill, Solomons Corner, and Corey formations. This group correlates with the uppermost part of the Beekmantown Group (Huntingdon Member of the Beauharnois Formation and the Carillon Formation).

Evidence for a Caledonian orogeny in Poland

1994 ◽  
Vol 85 (2) ◽  
pp. 131-142 ◽  
Author(s):  
J. D. Johnston ◽  
J. A. Tait ◽  
G. J. H. Oliver ◽  
F. C. Murphy
Keyword(s):  
Central And Eastern Europe ◽  
The Czech Republic ◽  
Middle Ordovician ◽  
Continental Scale ◽  
Holy Cross Mountains ◽  
Tectonic History ◽  
Iapetus Ocean ◽  
Lower Ordovician ◽  
History Of ◽  
Lower Palaeozoic

AbstractThe Lower Palaeozoic tectonic history of central and eastern Europe is poorly understood because of extensive Variscan and/or Alpine reworking. The trace of the Tornquist Sea, the SE arm of the Lower Palaeozoic Iapetus Ocean, extended from NE Britain to Asia Minor. The site of this ocean is constrained by the tectonostratigraphy and faunal provinciality of Lower Palaeozoic inliers in northern Czechoslovakia, and southern Poland. In this paper, the collage of contrasting tectonostratigraphic histories of terranes in the Lower Palaeozoic of Poland is reviewed. Fossil evidence demonstrates that the Holy Cross Mountains and the Krakovian Belt display Lower Ordovician and Lower Devonian angular unconformities. Faunal data suggest that the Tornquist Suture Zone must lie south of the Holy Cross and between Upper Silesia and the Barrandian of the Czech Republic. Between these areas, in the Sudeten Mountains, a continental scale sinistral mylonite zone (along the line of the Intra-Sudetic Fault) was periodically active between the Middle Ordovician and the Upper Triassic. Various dismembered ophiolite, island arc and batholith terranes from alongside the Intra-Sudetic Fault have Ordocivian and Silurian magmatic and metamorphic zircon isotopic and fossil ages. Thus the often stated view that deformation in the Sudetes is Variscan (i.e. post-Middle Devonian) must be called into question. It is proposed instead that the Tornquist Suture is located within the Sudeten mountains, and as in the Holy Cross Mountains, much of the observed deformation is post-Cambrian and pre-Gedinnian in age, i.e. Caledonian.

Early Ordovician Dounans Limestone fauna, Highland Border Complex, Scotland

1985 ◽  
Vol 76 (4) ◽  
pp. 481-513 ◽  
Author(s):  
J. Keith Ingham ◽  
Gordon B. Curry ◽  
Alwyn Williams
Keyword(s):  
North American ◽  
Red Sandstone ◽  
Middle Ordovician ◽  
Early Ordovician ◽  
Incertae Sedis ◽  
Lower Ordovician ◽  
Carbonate Sequence

ABSTRACTA diverse, but sparsely distributed silicified fauna of over 30 taxa has been recovered from 7·5 tonnes of acid-etched Lower Ordovician Dounans Limestone from the Highland Border Complex, near Aberfoyle. The 13 trilobite taxa obtained include 3 new formally named species: Distazeris adoceta, Punka aetholiciocorus and Ischyrotoma stubblefieldi. Other elements, representing Carolinites, Illaenus, Goniotelina, Sycophantia, Kawina, Heliomeroides, Strotactinus, Ectenonotus, Ceratocephala and an indeterminate bathyurelline are described under open nomenclature although at least 4 are also probably new and 2 more may be conspecific with previously described species. The brachiopods include representatives of Archaeorthis, Nothorthis, Orthidium, ?Camerella, Idiostrophia, Orthambonites and 4 other indeterminate stocks. Gastropods tentatively assigned to Murchisonia, Subulites, Straparollina, Maclurites and Cyrtodiscus are described, as are bryozoans, an orthocone, crinoids, and Incertae sedis.This profoundly North American fauna is Late Canadian ( = mid Arenig) in age and equates with the Cassinian Stage: it is key evidence in showing that the Highland Border rocks are not part of the Dalradian Supergroup whose earliest deformations and metamorphism predate the Ordovician. The field relationships of the limestone, together with evidence from derived clasts in Middle Ordovician and Devonian sequences near Girvan in SW Scotland and at Stonehaven in eastern Scotland suggest that it forms part of a widespread sub-Old Red Sandstone carbonate sequence of Early Ordovician age beneath the northern Midland Valley.

Social variation in size at birth and preterm delivery in the Czech Republic and Sweden, 1989-91

1998 ◽  
Vol 12 (1) ◽  
pp. 7-24 ◽  
Author(s):  
Koupilova ◽  
Vagero ◽  
Leon ◽  
Pikhart ◽  
Prikazsky ◽  
...  
Keyword(s):  
Czech Republic ◽  
Preterm Delivery ◽  
The Czech Republic ◽  
Social Variation ◽  
Size At Birth

On Geropsychology in the Czech Republic

GeroPsych ◽  
2012 ◽  
Vol 25 (3) ◽  
pp. 161-166
Author(s):  
Hana Stepankova ◽  
Eva Jarolimova ◽  
Eva Dragomirecka ◽  
Irena Sobotkova ◽  
Lenka Sulova ◽  
...  
Keyword(s):  
Czech Republic ◽  
Clinical Practice ◽  
Old Age ◽  
Cognitive Rehabilitation ◽  
The Czech Republic ◽  
Rehabilitation Research

This work provides an overview of psychology of aging and old age in the Czech Republic. Historical roots as well as recent activities are listed including clinical practice, cognitive rehabilitation, research, and the teaching of geropsychology.

Contemporary Psychology in the Czech Republic

2000 ◽  
Vol 5 (1) ◽  
pp. 62-65 ◽  
Author(s):  
Jiří Hoskovec ◽  
Josef M. Brožek
Keyword(s):  
Czech Republic ◽  
The Czech Republic
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