Sedimentary facies, depositional evolution of the Upper Cambrian–Lower Ordovician Santa Rosita formation in northwest Argentina

2003 ◽  
Vol 16 (5) ◽  
pp. 343-363 ◽  
Author(s):  
Luis A Buatois ◽  
M Gabriela Mángano
Keyword(s):  
Sedimentary Facies ◽  
Upper Cambrian ◽  
Northwest Argentina ◽  
Lower Ordovician ◽  
Depositional Evolution

A new Late Cambrian pentastomid and a review of the relationships of this parasitic group

2005 ◽  
Vol 96 (2) ◽  
pp. 163-176 ◽  
Author(s):  
Dieter Waloszek ◽  
John E. Repetski ◽  
Andreas Maas
Keyword(s):  
Systematic Position ◽  
Host Group ◽  
Upper Cambrian ◽  
Late Cambrian ◽  
Lower Ordovician ◽  
Stem Lineage ◽  
New Form ◽  
Available Information ◽  
High Degree ◽  
Derivatives Of

ABSTRACTPentastomida, tongue worms, are a taxon of about 130 species of parasites, living exclusively in the respiratory tracts of vertebrates. Three-dimensionally preserved Upper Cambrian larvae already demonstrate a high degree of adaptation to parasitism, striking morphological conservatism, and a high diversification by the Late Cambrian, thereby suggesting a likewise diversified host group. Not least due to their highly modified morphology, the systematic affinities of pentastomids remain controversial. The two major alternatives place the group as either close to branchiuran crustaceans or as stem-lineage derivatives of the Euarthropoda. To this set of Cambrian fossil representatives of the pentastomids we can add a new form from Lower Ordovician boundary beds from Sweden, most likely reworked from Upper Cambrian horizons. Based on this new species, named Aengapentastomum andresi gen. et sp. nov., and the available information about fossil and Recent pentastomids, we review the diverging ideas on the systematic position of this fully parasitic taxon.

New Monoplacophora (Mollusca) from Late Cambrian and Early Ordovician of Missouri

1986 ◽  
Vol 60 (3) ◽  
pp. 606-626 ◽  
Author(s):  
Bruce L. Stinchcomb
Keyword(s):  
New Species ◽  
New Genus ◽  
New Genera ◽  
New Genus And Species ◽  
Upper Cambrian ◽  
Early Ordovician ◽  
New Family ◽  
Late Cambrian ◽  
Lower Ordovician ◽  
A New Species

Fourteen new species and six new genera of the molluscan class Monoplacophora are described from the Upper Cambrian Potosi and Eminence formations and the Lower Ordovician Gasconade Formation of the Ozark Uplift of Missouri and some new biostratigraphic horizons are introduced. A new superfamily, the Hypseloconellacea nom. trans. Knight, 1956, and a new family, the Shelbyoceridae, are named. The genus Proplina is represented by five new species: P. inflatus, P. suttoni from the Cambrian Potosi Formation, P. arcua from the Cambrian Eminence Formation and P. meramecensis and P. sibeliusi from the Lower Ordovician Gasconade Formation. A new genus and species in the subfamily Proplininae, Ozarkplina meramecensis, is described from the Upper Cambrian Eminence Formation. Four new monoplacophoran genera in the superfamily Hypseloconellacea and their species are described, including: Cambrioconus expansus, Orthoconus striatus, Cornuella parva from the Eminence Formation, and Gasconadeoconus ponderosa, G. waynesvillensis, G. expansus from the Gasconade Formation. A new genus in the new family Shelbyoceridae, Archeoconus missourensis, is described from the Eminence Formation and a new species of Shelbyoceras, S. bigpineyensis, is described from the Gasconade Formation.

scholarly journals Echinochiton dufoei: A New Spiny Ordovician chiton

2003 ◽  
Vol 77 (4) ◽  
pp. 646-654 ◽  
Author(s):  
John Pojeta ◽  
D. J. Eernisse ◽  
R. D. Hoare ◽  
M. D. Henderson
Keyword(s):  
New Genus ◽  
New Genus And Species ◽  
Upper Cambrian ◽  
Lower Ordovician ◽  
Plate Shape ◽  
Tail Plate

Echinochiton dufoei new genus and species is described from the Ordovician age Forreston Member, Grand Detour Formation (Blackriveran) near Beloit, Wisconsin. For a variety of reasons, we regard E. dufoei as a chiton; the species is known from four articulated or partially articulated specimens, one of which has eight plates and two of which have a mucro on the tail plate. Echinochiton dufoei differs from other chitons in having large hollow spines that project from each of the known plates. In plate shape and position, E. dufoei is much like the Upper Cambrian species Matthevia variabilis Walcott, 1885, and the Lower Ordovician species Chelodes whitehousei Runnegar, Pojeta, Taylor, and Collins (1979).

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.

Non-trilobite arthropods from the Silver Peak Range, Nevada

2003 ◽  
Vol 77 (4) ◽  
pp. 706-720 ◽  
Author(s):  
Ben Waggoner
Keyword(s):  
Great Basin ◽  
Lower Cambrian ◽  
Upper Cambrian ◽  
Extant Taxon ◽  
Lower Ordovician

Two non-trilobite arthropods are described from the Emigrant Formation (Lower Cambrian-Lower Ordovician) in the Silver Peak Range, Esmeralda County, Nevada. A Middle or Upper Cambrian “arachnomorph” arthropod with a phosphatic exoskeleton has been noted in previous faunal lists, but has not been previously described. This fossil is here named Quasimodaspis brentsae gen. et sp. nov. Q. brentsae belongs in the Aglaspidida, a close outgroup to the true chelicerates; this is the second report of an aglaspidid from the Great Basin. Esmeraldacaris richardsonae gen. et sp. nov. is a newly discovered arthropod from the lower Ordovician, from beds transitional between the Emigrant Formation and the overlying Palmetto Formation. It is a survivor of an early arthropod lineage that does not belong in any extant taxon, but which may also include the Ordovician Corcorania and the Cambrian Mollisonia.

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