The Middle–Upper Cambrian Transition in Southeastern Newfoundland, Canada

1975 ◽  
Vol 12 (12) ◽  
pp. 2065-2079 ◽  
Author(s):  
Valdemar Poulsen ◽  
Michael M. Anderson
Keyword(s):  
Basal Part ◽  
Eastern Canada ◽  
Middle Cambrian ◽  
Upper Cambrian ◽  
First Time

The Middle-Upper Cambrian transition in southeastern Newfoundland is shown to be very similar to the transition in Scandinavia and in the English Midlands. The late Middle Cambrian Lejopyge laevigata Zone, which is recorded for the first time from eastern Canada, is contained in the basal part of the Elliott Cove Formation and is conformably overlain by the Upper Cambrian Agnostus pisiformis Zone. The following trilobite species from the Lejopyge laevigata Zone at Manuels River and on Random Island are described: Andrarina costata (Angelin), Paradoxides sp., Lejopyge laevigata (Dalman), and Peronopsis insignis (Wallerius).

scholarly journals Small shelly fossils in the cambrian basement of the West Siberian geosyneclise

2019 ◽  
Vol 27 (1) ◽  
pp. 3-11
Author(s):  
N. V. Novozhilova ◽  
I. V. Korovnikov
Keyword(s):  
Lower Cambrian ◽  
Skeletal Remains ◽  
The West ◽  
Middle Cambrian ◽  
Upper Cambrian ◽  
Small Shelly Fossils ◽  
Tomsk Region ◽  
First Time

This paper describes for the first time the entire Cambrian skeletal problematics from the parametric well Vostok-1 (Tomsk region, eastern part of the West Siberian Plate) found in the Lower Cambrian Churbiga Formation, Middle Cambrian Pudzhelga Formation, and Upper Cambrian Kondes and Shedelga formations. The investigation has made it possible to detail the biostratigraphic division of the Lower Cambrian in the studied well using the small shelly fossils and to reveal confinement of the main findings of problematic skeletal remains to the shallow carbonate shelf settings.

Early Paleozoic Hyolitha from North America: reexamination of Walcott's and Resser's type specimens

1988 ◽  
Vol 62 (2) ◽  
pp. 218-233 ◽  
Author(s):  
John Mark Malinky
Keyword(s):  
North America ◽  
Lower Cambrian ◽  
Type Species ◽  
New Genus ◽  
Early Paleozoic ◽  
Type Specimens ◽  
Middle Cambrian ◽  
Upper Cambrian ◽  
New Family ◽  
The Family

Concepts of the family Hyolithidae Nicholson fide Fisher and the genera Hyolithes Eichwald and Orthotheca Novak have been expanded through time to encompass a variety of morphologically dissimilar shells. The Hyolithidae is here considered to include only those hyolithid species which have a rounded (convex) dorsum; slopes on the dorsum are inflated, and the venter may be flat or slightly inflated. Hyolithes encompasses species which possess a low dorsum and a prominent longitudinal sulcus along each edge of the dorsum; the ligula is short and the apertural rim is flared. The emended concept of Orthotheca includes only those species of orthothecid hyoliths which have a subtriangular transverse outline and longitudinal lirae covering the shell on both dorsum and venter.Eighteen species of Hyolithes and one species of Orthotheca from the Appalachian region and Western Interior were reexamined in light of more modern taxonomic concepts and standards of quality for type material. Reexamination of type specimens of H. similis Walcott from the Lower Cambrian of Newfoundland, H. whitei Resser from the Lower Cambrian of Nevada, H. billingsi Walcott from the Lower Cambrian of Nevada, H. gallatinensis Resser from the Upper Cambrian of Wyoming, and H. partitus Resser from the Middle Cambrian of Alabama indicates that none of these species represents Hyolithes. Hyolithes similis is here included under the new genus Similotheca, in the new family Similothecidae. Hyolithes whitei is designated as the type species of the new genus Nevadotheca, to which H. billingsi may also belong. Hyolithes gallatinensis is referred to Burithes Missarzhevsky with question, and H. partitus may represent Joachimilites Marek. The type or types of H. attenuatus Walcott, H. cecrops Walcott, H. comptus Howell, H. cowanensis Resser, H. curticei Resser, H. idahoensis Resser, H. prolixus Resser, H. resseri Howell, H. shaleri Walcott, H. terranovicus Walcott, and H. wanneri Resser and Howell lack shells and/or other taxonomically important features such as a complete aperture, rendering the diagnoses of these species incomplete. Their names should only be used for the type specimens until better preserved topotypes become available for study. Morphology of the types of H.? corrugatus Walcott and “Orthotheca” sola Resser does not support placement in the Hyolitha; the affinities of these species are uncertain.

scholarly journals Lithostratigraphic and allostratigraphic framework of the Cambrian–Ordovician Potsdam Group and correlations across Early Paleozoic southern Laurentia

2017 ◽  
Vol 54 (5) ◽  
pp. 550-585 ◽  
Author(s):  
David G. Lowe ◽  
R.W.C. Arnott ◽  
Godfrey S. Nowlan ◽  
A.D. McCracken
Keyword(s):  
Climate Change ◽  
Early Paleozoic ◽  
Middle Cambrian ◽  
Shallow Marine ◽  
Upper Cambrian ◽  
Subaerial Exposure ◽  
Marine Sedimentation ◽  
Lower Ordovician ◽  
Fluvial Sedimentation ◽  
Mixed Carbonate

The Potsdam Group is a Cambrian to Lower Ordovician siliciclastic unit that crops out along the southeastern margins of the Ottawa graben. From its base upward, the Potsdam consists of the Ausable, Hannawa Falls, and Keeseville formations. In addition, the Potsdam is subdivided into three allounits: allounit 1 comprises the Ausable and Hannawa Falls, and allounits 2 and 3, respectively, the lower and upper parts of the Keeseville. Allounit 1 records Early to Middle Cambrian syn-rift arkosic fluvial sedimentation (Ausable Formation) with interfingering mudstone, arkose, and dolostone of the marine Altona Member recording transgression of the easternmost part of the Ottawa graben. Rift sedimentation was followed by a Middle Cambrian climate change resulting in local quartzose aeolian sedimentation (Hannawa Falls Formation). Allounit 1 sedimentation termination coincided with latest(?) Middle Cambrian tectonic reactivation of parts of the Ottawa graben. Allounit 2 (lower Keeseville) records mainly Upper Cambrian quartzose fluvial sedimentation, with transgression of the northern Ottawa graben resulting in deposition of mixed carbonate–siliciclastic strata of the marine Rivière Aux Outardes Member. Sedimentation was then terminated by an earliest Ordovician regression and unconformity development. Allounit 3 (upper Keeseville) records diachronous transgression across the Ottawa graben that by the Arenigian culminated in mixed carbonate–siliciclastic, shallow marine sedimentation (Theresa Formation). The contact separating the Potsdam Group and Theresa Formation is conformable, except locally in parts of the northern Ottawa graben where the presence of localized islands and (or) coastal salients resulted in subaerial exposure and erosion of the uppermost Potsdam strata, and accordingly unconformity development.

Archaeocyathids: Morphology and Affinity

1983 ◽  
Vol 7 ◽  
pp. 178-190
Author(s):  
Francoise Debrenne
Keyword(s):  
Calcium Carbonate ◽  
Marine Organisms ◽  
Early Cambrian ◽  
Middle Cambrian ◽  
Upper Cambrian ◽  
The Family ◽  
Reef Environments

The Archaeocyatha were marine organisms developing mineral skeletons and using calcium carbonate for this purpose. Remains of their cups are found in carbonate shelfs and reef environments of the Early Cambrian seas. Few representatives of the family Archaeocyathidae are found through the Middle Cambrian to the Upper Cambrian (Debrenne, Rozanov and Webers, in press).

Cambrian and Ordovician linguliform brachiopods from the Shallow Bay Formation (Cow Head Group), western Newfoundland

2001 ◽  
Vol 75 (2) ◽  
pp. 241-260 ◽  
Author(s):  
Sean P. Robson ◽  
Brian R. Pratt
Keyword(s):  
New Species ◽  
Continental Slope ◽  
Head Group ◽  
Lower Paleozoic ◽  
Middle Cambrian ◽  
Middle Ordovician ◽  
Upper Cambrian ◽  
Three New Species ◽  
Brachiopod Fauna ◽  
Shallow Bay

Linguliform brachiopods were recovered from the Upper Cambrian Downes Point Member (lower Sunwaptan) and from the Middle Ordovician Factory Cove Member (Arenig) of the Shallow Bay Formation, Cow Head Group, of western Newfoundland. These rocks are a series of Middle Cambrian to Middle Ordovician conglomerates, lime mudstones, and shales that formed a sediment apron at the base of the lower Paleozoic continental slope of Laurentia. The linguliform brachiopod fauna consists of sixteen species assigned to twelve genera. Three new species are described: Picnotreta lophocracenta, Neotreta humberensis, and Siphonotretella parvaducta.

Asynchronous trilobite extinctions at the early to middle Cambrian transition

Geology ◽  
2020 ◽  
Vol 48 (5) ◽  
pp. 441-445 ◽  
Author(s):  
F.A. Sundberg ◽  
K.E. Karlstrom ◽  
G. Geyer ◽  
J.R. Foster ◽  
J.W. Hagadorn ◽  
...  
Keyword(s):  
Critical Time ◽  
Data Sets ◽  
Early Cambrian ◽  
Earth System ◽  
Middle Cambrian ◽  
West Gondwana ◽  
Paleoclimatic Data ◽  
First Time ◽  
Age Constraints ◽  
Prior Models

Abstract Trilobites appeared and diversified rapidly in the Cambrian, but it is debated as to whether their radiations and extinctions were globally synchronous or geographically restricted and diachronous. The end of the early Cambrian is a classic example—it has traditionally been defined by the extinction of olenellid and redlichiid trilobites and the appearance of paradoxidid trilobites. Here we integrate the global biostratigraphy of these three trilobite groups with high-precision tuff and tandem detrital zircon U-Pb age constraints to falsify prior models for global synchronicity of these events. For the first time, we demonstrate that olenellid trilobites in Laurentia went extinct at least 3 Ma after the first appearance of paradoxidids in Avalonia and West Gondwana (ca. 509 Ma). They also disappeared before the extinction of redlichiids and prior to the base of the Miaolingian at ca. 506 Ma in South China. This indicates that these three trilobite groups (paradoxidids, olenellids, and redlichiids) and their associated biotas overlapped in time for nearly 40% of Cambrian Epoch 2, Age 4. Implications of this chronological overlap are: (1) trilobite transitions were progressive and geographically mediated rather than globally synchronous; and (2) paleontological databases underestimate the diversity of the early Cambrian. This ∼3 Ma diachroneity, at a critical time in the early evolution of animals, also impacts chemostratigraphic and paleoclimatic data sets that are tied to trilobite biostratigraphy and that collectively underpin our understanding of the Cambrian Earth system.

Cambrian agnostoid trilobites from Mendoza, Argentina: A systematic revision and biostratigraphic implications

1997 ◽  
Vol 71 (1) ◽  
pp. 74-86 ◽  
Author(s):  
M. Franco Tortello ◽  
Osvaldo L. Bordonaro
Keyword(s):  
South America ◽  
Natural Sciences ◽  
Systematic Revision ◽  
Middle Cambrian ◽  
Late Cambrian ◽  
Global Correlation ◽  
First Time

Agnostoid trilobites from the Carlos Rusconi collections in the Museum of Natural Sciences of Mendoza, Argentina, are revised. The agnostoids were collected in the southern Precordillera of Mendoza Province, western Argentina. Revised taxa include Agnostus microcephalus (Rusconi), Lotagnostus (Lotagnostus) peladensis? (Rusconi), Lotagnostus (Lotagnostus) lasherensis (Rusconi), Homagnostus pehuenchensis Rusconi, Kormagnostus seclusus (Walcott), Kormagnostus? beltensis (Lochman in Lochman and Duncan), Hypagnostus parvifrons (Linnarsson), Ptychagnostus cuyanus (Rusconi), Ptychagnostus aculeatus (Angelin), Lejopyge laevigata (Dalman), Tomagnostella exsculpta (Angelin), Diplagnostus planicauda (Angelin), Oedorhachis typicalis Resser, Clavagnostus calensis Rusconi and Clavagnostus repandus (Westergård in Holm and Westergård). Some taxa of uncertain affinities are recognized and new specimens assignated to Lotagnostus and Pseudagnostinae are illustrated. Hypagnostus parvifrons, L. laevigata and C. repandus are reported for the first time in South America. Global correlation with previously described agnostoid faunas indicates that the outcrops range from middle Middle Cambrian to latest Late Cambrian in age.

A NEW SPECIES AND TWO NEW RECORDS OF POLYCHAETA FROM EASTERN CANADA

1956 ◽  
Vol 34 (4) ◽  
pp. 267-271 ◽  
Author(s):  
E. Berkeley ◽  
C. Berkeley
Keyword(s):  
New Species ◽  
New Records ◽  
Eastern Canada ◽  
Nereis Diversicolor ◽  
The Third ◽  
First Time ◽  
A New Species

Two of the three species recorded in this paper (Ceratonereis scotiae sp. n. and Nereis diversicolor O. F. Müller) were collected some years ago, but hitherto their occurrence has not been noted. The third (Tharyx marioni (Saint-Joseph)) was collected recently for the first time in Canadian waters.

Taxonomy, distribution, and ecology of the freshwater bryozoans (Ectoprocta) of eastern Canada

1994 ◽  
Vol 72 (2) ◽  
pp. 339-359 ◽  
Author(s):  
Anthony Ricciardi ◽  
Henry M. Reiswig
Keyword(s):  
Lake Erie ◽  
Eastern Canada ◽  
Freshwater Habitats ◽  
Freshwater Bryozoa ◽  
Distribution And Ecology ◽  
Cristatella Mucedo ◽  
Lophopodella Carteri ◽  
First Time ◽  
Hard Substrates ◽  
Alkaline Waters

The freshwater Bryozoa (Ectoprocta) are one of the most poorly known faunal groups in Canada. A recent survey of 80 freshwater habitats in eastern Canada (from Ontario to Newfoundland) revealed 14 species of bryozoans, representing 56% of described species in North America. The greatest numbers of species and specimens were found in alkaline waters (pH 7.0–9.8) near lake outflows, wherever hard substrates were present. Paludicella articulata, Cristatella mucedo, Fredericella indica, and Plumatella fungosa are among the most frequently encountered, widely distributed, and eurytopic species. Pottsiella erecta and Plumatella fruticosa are rare, and new to eastern Canada. Lophopodella carteri, an exotic Asian species discovered in Lake Erie in the early 1930s, has become firmly established in the lower Ottawa and upper St. Lawrence rivers. Detailed notes on taxonomy, morphology, distribution, and ecology are given for each bryozoan. New limits of tolerance to water temperature, pH, and calcium and magnesium hardness are established for several species. A taxonomic key to the freshwater bryozoans of eastern Canada, including a key to statoblast types, is presented for the first time.

Protorthacean brachiopods from the Middle Cambrian of Morocco

1997 ◽  
Vol 71 (5) ◽  
pp. 791-812 ◽  
Author(s):  
Gerd Geyer ◽  
Michal Mergl
Keyword(s):  
Middle Cambrian ◽  
Morphologic Characteristics ◽  
First Time

Protorthacean brachiopods from the Middle Cambrian of the Moroccan Atlas regions are described in terms of morphology and systematic affinities. The superfamily Protorthacea is revised to include both Protorthidae and Bohemiellidae. Newly introduced is the protorthid genus Saesorthis, the morphologic characteristics as well as the significance of which are discussed in detail together with their bearing on early phylogeny of the Orthacea. A reinvestigation of Brahimorthis antiqua led to the recognition of additional morphologic peculiarities and enhances understanding of its stratigraphic occurrence. Additional descriptions and discussions deal with informally described protorthid and bohemiellid species. Bohemiella and Jamesella are reported from Africa for the first time.

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