Brachiopod Synecology in a Time of Crisis (Late Ordovician-Early Silurian)

Paleobiology ◽  
1975 ◽  
Vol 1 (2) ◽  
pp. 205-212 ◽  
Author(s):  
Peter M. Sheehan
Keyword(s):  
North America ◽  
Sea Level ◽  
North American ◽  
Late Ordovician ◽  
North American Species ◽  
European Species ◽  
Geologic Time ◽  
Stable Conditions ◽  
Low Diversity ◽  
Shallow Seas

The extinction of endemic brachiopods in North America at the end of the Ordovician and recolonization by European species has been related to glacio-eustatic lowering of sea level which disrupted conditions in epicontinental seas. North American species may have been narrowly adapted to relatively stable conditions of broad, tropical shallow seas. European invaders may have been less specialized because they were adapted to conditions in both the open ocean and in narrow European epicontinental seas. Being less narrowly adapted, European species probably were better able to cope with changing environmental conditions than were North American species.During the Lower and Middle Llandovery, shallow water, low diversity communities of Pentamerus Community depth were unstable and characterized by repeated extinctions and invasions. Following the crisis at the Ordovician-Silurian boundary 3 to 5 million years were needed to reestablish communities that were persistent in geologic time.

scholarly journals Origin of the Late Ordovician Lepidocyclus brachiopod fauna in North America and its biogeographic significance

1992 ◽  
Vol 6 ◽  
pp. 149-149
Author(s):  
Jisuo Jin
Keyword(s):  
North America ◽  
Sea Level ◽  
North American ◽  
Plate Tectonics ◽  
Late Ordovician ◽  
Sea Level Changes ◽  
Stepping Stones ◽  
Shell Size ◽  
Larval Stages ◽  
The North

Three rhynchonellid brachiopod genera, Hiscobeccus, Lepidocyclus, and Hypsiptycha, are the most diagnostic elements of the Lepidocyclus fauna of North America in Late Ordovician time. These are characterized by relatively large, strongly biconvex to globular shells with coarse imbricating growth lamellae and, internally, with septiform cardinal processes in brachial valves. Among the three genera, Hiscobeccus appears the earliest, now known from rocks of late Trentonian-Edenian age in the Canadian Rocky Mountains and Mackenzie Mountains. Morphologically, Hiscobeccus is distinguished from the other two genera by its open delthyrium in the pedicle valve. Early forms of Hiscobeccus show close morphological similarity to Rhynchotrema in their non-globular biconvex shells covered by strong growth lamellae only in the anterior portions. It has been suggested that Hiscobeccus evolved from the Rhynchotrema wisconsinense stock through increase in shell size, globosity, and strength of growth lamellae. Earliest species of Rhynchotrema has been documented convincingly from rocks of early Trentonian age, and the derivation of Hiscobeccus most likely took place during the mid-Trentonian. Lepidocyclus and Hypsiptycha evolved from either Rhynchotrema or Hiscobeccus by developing a pair of deltidial plates covering the delthyrium.Rhynchotrema and other rhynchonellids that evolved before mid-Trentonian time are common to the North American (Laurentian) and the Siberia-Kazakhstan paleocontinents. In contrast, Hiscobeccus, Lepidocyclus, and Hypsiptycha that evolved after the mid-Trentonian are virtually restricted to Laurentia. Therefore, Rhynchotrema marked the last successful intercontinental migration of rhynchonellids during their Llandeilian-Caradocian cosmopolitanism. The pronounced provincialism of the North American Lepidocyclus fauna may have been caused by a number of factors. Facies control is not likely the explanation because these rhynchonellids occur in nearly all the inland and marginal platform seas of Laurentia and commonly are found together in the same types of rocks. Plate tectonics and sea-level changes are considered major causes. The Ordovician rhynchonellids lived in shallow marine (intertidal-subtidal) environments and were incapable of crossing vast, deep oceanic barriers because of their sedentary mode of life and short-lived motile larval stages. The widening of the ocean between North America and Siberia, coupled with high sea-level stand, may have created a sufficiently wide oceanic barrier to interrupt faunal mixing between the two paleocontinents by late Trentonian time. Moreover, the rise in sea level would have resulted in the disappearance of island faunas, which could have served as stepping stones for intercontinental migration of shallow-water benthic faunas during low sea-level stand.

A New Species of Myzocallis Passerini, With a Key to the North American Species (Homoptera: Aphididae)

1966 ◽  
Vol 98 (8) ◽  
pp. 876-880 ◽  
Author(s):  
W. R. Richards
Keyword(s):  
New Species ◽  
North America ◽  
North American ◽  
North American Species ◽  
Quercus Agrifolia ◽  
European Species ◽  
The North ◽  
A New Species

AbstractMyzocallis (Agrioaphis) agrifolicola new species is described from specimens collected on Quercus agrifolia Nee in California. To aid in its recognition a key to the known North American species is given. The key includes Myzocallis (Myzocallis) carpini (Koch), which is a European species previously unknown in North America.

scholarly journals Cortinarius subgenus Leprocybe, unexpected diversity and significant differences in species compositions between western and eastern North America

2021 ◽  
Author(s):  
J. Ammirati ◽  
K. Liimatainen ◽  
D. Bojantchev ◽  
U. Peintner ◽  
R. Kuhnert-Finkernagel ◽  
...  
Keyword(s):  
North America ◽  
North American ◽  
Molecular Data ◽  
North American Species ◽  
Eastern North America ◽  
Type Specimens ◽  
European Species ◽  
The North ◽  
Morphological And Molecular Data

The focus of this paper is the North American species of Cortinarius in subg. Leprocybe. Eighteen species, including twelve new ones, and two tentative (aff.) species, are delimited based on morphological and molecular data (DNA ITS-LSU sequences). Existing type specimens of species in subg. Leprocybe were also studied, and neo- or epitypes designated for C. cotoneus, C. melanotus, C. phrygianus and C. venetus to stabilize the nomenclature. In addition, to improve the infrasubgeneric classification of Leprocybe three new sections are proposed: sect. Fuscotomentosi, sect. Melanoti and sect. Squamiveneti. This study adds substantial information to the knowledge of subg. Leprocybe in North America against a background of European species. To date only two species, C. phrygianus and C. squamivenetus have been reported from both continents.

A nomen novum to replace the junior homonym, Diaptomus (Leptodiaptomus) intermedius, Anderson and Fabris 1970

1971 ◽  
Vol 49 (1) ◽  
pp. 133-133 ◽  
Author(s):  
R. Stewart Anderson
Keyword(s):  
North America ◽  
North American ◽  
North American Species ◽  
European Species ◽  
The North ◽  
Nomen Novum

The name Diaptomus intermedius has been applied to two species, one in North America and one in Europe. Because the European species name takes precedence, a nomen novum is proposed for the North American species.

Hirnantia Fauna from the Condroz Inlier, Belgium: another case of a relict Ordovician shelly fauna in the Silurian?

2021 ◽  
pp. 1-27
Author(s):  
Sofia Pereira ◽  
Jorge Colmenar ◽  
Jan Mortier ◽  
Jan Vanmeirhaeghe ◽  
Jacques Verniers ◽  
...  
Keyword(s):  
Sea Level ◽  
Mass Extinction ◽  
Late Ordovician ◽  
Lake District ◽  
Low Diversity ◽  
Hirnantia Fauna ◽  
And Sea Level

Abstract The end-Ordovician mass extinction, linked to a major glaciation, led to deep changes in Hirnantian–Rhuddanian biotas. The Hirnantia Fauna, the first of two Hirnantian survival brachiopod-dominated communities, characterizes the lower–mid Hirnantian deposits globally, and its distribution is essential to understand how the extinction took place. In this paper, we describe, illustrate, and discuss the first macrofossiliferous Hirnantia Fauna assemblage from Belgium, occurring in the Tihange Member of the Fosses Formation at Tihange (Huy), within the Central Condroz Inlier. Six fossiliferous beds have yielded a low-diversity, brachiopod-dominated association. In addition to the brachiopods (Eostropheodonta hirnantensis, Plectothyrella crassicosta, Hirnantia sp., and Trucizetina? sp.), one trilobite (Mucronaspis sp.), four pelmatozoans (Xenocrinus sp., Cyclocharax [col.] paucicrenulatus, Conspectocrinus [col.] celticus, and Pentagonocyclicus [col.] sp.), three graptolites (Cystograptus ancestralis, Normalograptus normalis, and ?Metabolograptus sp.), together with indeterminate machaeridians and bryozoans were identified. The graptolite assemblage, from the Akidograptus ascensus-Parakidograptus acuminatus Biozone, indicates an early Rhuddanian (Silurian) age, and thus, an unexpectedly late occurrence of a typical Hirnantia Fauna. This Belgian association may represent an additional example of relict Hirnantia Fauna in the Silurian, sharing characteristics with the only other known from Rhuddanian rocks at Yewdale Beck (Lake District, England), although reworking has not been completely ruled out. The survival of these Hirnantian taxa into the Silurian might be linked to delayed post-glacial effects of rising temperature and sea-level, which may have favored the establishment of refugia in these two particular regions that were paleogeographically close during the Late Ordovician–early Silurian.

The North American Species in Group X of Ips De Geer (Coleoptera: Scolytidae)

1965 ◽  
Vol 97 (8) ◽  
pp. 803-809 ◽  
Author(s):  
G. R. Hopping
Keyword(s):  
North America ◽  
North American ◽  
North American Species ◽  
The North ◽  
Variable Species ◽  
Ips Calligraphus

AbstractIps calligraphus (Germar), I. ponderosae Swaine and I. interstitialis (Eichhoff) represent one variable species with the oldest name, Ips calligraphus (Germar) taking precedence. Ips calligraphus can always be recognized by the six spines on each side of the declivity. All other species in North America have less than six spines on each side.

The Natural Groups of Species in the Genus Ips De Geer (Coleoptera: Scolytidae) in North America

1963 ◽  
Vol 95 (5) ◽  
pp. 508-516 ◽  
Author(s):  
G. R. Hopping
Keyword(s):  
North America ◽  
North American ◽  
Related Species ◽  
North American Species ◽  
Closely Related Species ◽  
The North ◽  
The World ◽  
Group Relationships ◽  
Natural Groups

AbstractThe genus Ips is one of four closely related genera in the tribe Ipini, sub-tribe Ipina (De Geer 1775, Balachowsky 1949, Nunberg 1954, Hopping 1963). There are now 32 species of Ips recognized in North America, with a few more as yet undescribed. This paper defines the groups of closely related species with observations on the group relationships of species from other parts of the world. Work is in progress to define the North American species in each group.

A New Gunnel, Pholis clemensi, from the Coast of Western North America

1964 ◽  
Vol 21 (5) ◽  
pp. 933-939 ◽  
Author(s):  
Richard H. Rosenblatt
Keyword(s):  
British Columbia ◽  
New Species ◽  
North America ◽  
North American ◽  
North American Species ◽  
Western North America ◽  
The North ◽  
The Family ◽  
Juan De Fuca ◽  
A New Species

A new species, Pholis clemensi, referred to the family Pholidae, is named and described from 12 specimens taken in southern British Columbia waters and the Strait of Juan de Fuca. Pholis clemensi is compared with other members of the genus, and a key is given to the North American species.

scholarly journals Notes on the biology and distribution of the tribe Agallissini in North America (Coleoptera: Cerambycidae: Cerambycinae)

Zootaxa ◽  
2018 ◽  
Vol 4457 (3) ◽  
pp. 444
Author(s):  
THOMAS AUSTIN ◽  
DANIEL HEFFERN ◽  
ROBERT GEMMILL ◽  
BRIAN RABER ◽  
MIKE QUINN
Keyword(s):  
North America ◽  
North American ◽  
North American Species ◽  
Distribution Maps ◽  
The North ◽  
Larval Host

New distributional records, new larval host records, various collecting notes, and observations are reported for the North American species of the tribe Agallissini LeConte, 1873 (Coleoptera: Cerambycidae: Cerambycinae): Agallissus lepturoides (Duponchel & Chevrolat, 1841), Osmopleura chamaeropis (Horn, 1893), and Zagymnus clerinus (LeConte, 1873). The species are illustrated and distribution maps are provided.

Revision of Tenticospirifer Tien, 1938, and similar spiriferid brachiopod genera from the Late Devonian (Frasnian) of Eurasia, North America, and Australia

2000 ◽  
Vol 74 (3) ◽  
pp. 444-463 ◽  
Author(s):  
Xueping Ma ◽  
Jed Day
Keyword(s):  
North America ◽  
Sea Level ◽  
South China ◽  
North American ◽  
Type Species ◽  
Western Europe ◽  
Late Devonian ◽  
Carbonate Platforms ◽  
The North ◽  
New Family

The cyrtospiriferid brachiopod genus Tenticospirifer Tien, 1938, is revised based on restudy of the type species from the Frasnian (Late Devonian) of the Russian Platform. As revised the genus includes cyrtospiriferid species with pyramidal ventral valves, catacline ventral interareas, a narrow delthyrium, few sinal plications, and lack a median dorsal septum and pseudodeltidium. All species retained in the genus are of Givetian and Frasnian age. All Famennian age species described from South China and North America are rejected from the genus. It appears that Tenticospirifer evolved during the early Givetian in western Europe and remained endemic to that region during the remainder of the Givetian. Successive migrations of Tenticospirifer from eastern Laurussia to North America, then to South China and possibly Australia, coincided with middle and late Frasnian eustatic sea level rises, respectively. The North American species Spirifera cyrtinaformis Hall and Whitfield, 1872, and related species identified as Tenticospirifer by North American workers, are reassigned to Conispirifer Lyashenko, 1985. Its immigration to and widespread dispersal in carbonate platforms of western Laurussia, northern Gondwana and tropical island arcs (?) coincided with a major late Frasnian eustatic sea level rise. The new family Conispiriferidae is proposed with Conispirifer Lyashenko, 1985, selected as the type genus. The new family also includes the new genus Pyramidaspirifer with Platyrachella alta Fenton and Fenton, 1924, proposed as the type species. The affinity of the new family remains uncertain pending restudy of key genera currently included in the Superfamily Cyrtospiriferoidea. Available data from the Devonian brachiopod literature indicate that species of Pyramidaspirifer are restricted to late Frasnian deposits of central and western North America.

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