scholarly journals General regularities in the development Gzhelian-Asselian conodonts

LITOSFERA ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 471-485
Author(s):  
V. V. Chernykh
Keyword(s):  
Related Species ◽  
Morphological Evolution ◽  
Lower Boundary ◽  
Wide Distribution ◽  
Evolutionary Development ◽  
Evolutionary Trends ◽  
Gradual Development ◽  
Cyclic Type ◽  
Directed Change ◽  
Rapid Appearance

Subject of study. The features of the evolutionary changing of Gzhelian-Asselian conodonts are examined. Materials. The data on Ural and North American conodonts are used. Results. The cyclic type of change of the Pa-element morphology in the process of the evolutionary development of the representatives of the genus Streptognathodus is established. Morphological evolutionary trends of gradual development alternate with the periods of the rapid appearance of a group of the forms of original constitution. The species of this group are characterized by wide distribution and short lifetime. Such species are used as the markers of the boundaries of stratigraphic subdivisions. Lower boundary of Gzhelian is determined by the appearance of species of the group simulator; the species of group isolatus mark lower boundary of Asselian. Model of the ensemble evolution of the related species is used for explaining the directed change in the morphology of conodonts. The saltational appearance of the determined indication is explained by the phenomenon of evolutionary oscillations. Conclusion. We can make conclusion about the sexual multiplication of this group of the organisms according the established alternation of the periods of the slow and rapid morphological evolution of conodonts.

scholarly journals Polymastiidae (Porifera: Demospongiae) of the Nordic and Siberian Seas

2017 ◽  
Vol 98 (6) ◽  
pp. 1273-1335 ◽  
Author(s):  
Alexander Plotkin ◽  
Elena Gerasimova ◽  
Hans Tore Rapp
Keyword(s):  
North Atlantic ◽  
Related Species ◽  
Molecular Data ◽  
Wide Distribution ◽  
Morphological Data ◽  
Nordic Seas ◽  
Norwegian Sea ◽  
The North ◽  
Western Norway ◽  
The North Atlantic

Polymastiidae (Porifera: Demospongiae) of the Nordic and Siberian Seas are revised and compared with the related species of the North Atlantic based on the morphological data from the type and comparative material and the molecular data from fresh samples. Twenty species from six polymastiid genera are recorded. Two species,Polymastia svensenifrom Western Norway andSpinularia njordifrom the Norwegian Sea, are new to science. One species,Polymastia andrica, is new to the Nordic Seas and two species,Polymastiacf.bartlettiandP. penicillus, are new to the Scandinavian Coast. Distribution of the polymastiids in the North Atlantic and Arctic is discussed and the allegedly wide distribution ofSpinularia sarsiiandS. spinulariais questioned.

scholarly journals New evidence on the origin of non-spinose pitted–cancellate species of the early Danian planktonic foraminifera

2013 ◽  
Vol 64 (3) ◽  
pp. 237-251 ◽  
Author(s):  
Ignacio Arenillas ◽  
Jose Antonio Arz
Keyword(s):  
Morphological Evolution ◽  
Planktonic Foraminifera ◽  
Middle Part ◽  
External Morphology ◽  
Evolutionary Trends ◽  
Test Size ◽  
Evolutionary Path ◽  
Origin And Evolution ◽  
Large Pore ◽  
New Evidence

Abstract Intermediate forms identified in some of the most continuous lower Danian sections allow a better understanding of the origin and evolution of pitted (Globanomalina) and cancellate (Praemurica) planktonic foraminifera. Both Globanomalina and Praemurica are part of a major Paleocene lineage, namely the “non-spinose lineage”, which started to diverge in the early Danian. Transitional specimens strongly suggest the evolution from Parvularugoglobigerina to Globanomalina, and then to Praemurica. These evolutionary turnovers were quite rapid (probably lasting less than 10 kyr), and seem to have begun in the time equivalent of the lower part of the E. simplicissima Subzone, namely the middle part of the standard Zone Pa. The initial evolutionary trends within this non-spinose lineage were the increase of test size and lip thickness, and the evolution from tiny pore-murals to large pore-pits, and from smooth to pitted and finally cancellate walls. Biostratigraphic data suggest that evolution of the wall texture preceded the morphological evolution within each genus. The oldest species of both Globanomalina and Praemurica, namely G. archeocompressa and Pr. taurica, initially retained the external morphology of the ancestral Parvularugoglobigerina eugubina. Since their divergence, Globanomalina and Praemurica followed a separate evolutionary path, evolving into morphologically different species.

New dasycladalean algal species from the Kalana Lagerstätte (Silurian, Estonia)

2015 ◽  
Vol 89 (2) ◽  
pp. 262-268 ◽  
Author(s):  
Viirika Mastik ◽  
Oive Tinn
Keyword(s):  
Calcium Carbonate ◽  
Related Species ◽  
Algal Species ◽  
Wide Distribution ◽  
The Arctic ◽  
Algal Flora ◽  
Closely Related Species ◽  
Iapetus Ocean ◽  
Extant Species ◽  
Cymopolia Barbata

AbstractA Silurian (Llandovery, Aeronian) Lagerstätte in Kalana, Estonia, has revealed exceptionally preserved noncalcified thalli of dasycladalean (divison Chlorophyta) algal fossils. The siphonous, serially segmented fossils of Palaeocymopolia silurica n. sp. are closely similar to P. nunavutensis, a Ludlovian species from the Arctic Canada. The occurrence of closely related species at Baltica and Laurentia paleocontinents indicates a wide distribution of noncalcified algal flora on both sides of the Iapetus Ocean in the Paleozoic. The exceptionally well-preserved specimens from the Kalana Lagerstätte show similarity to extant species Cymopolia barbata, with lack of a calcium carbonate skeleton being the major observable difference from the latter.

scholarly journals Deep sea without limits—four new closely related species of Emertonia Wilson, 1932 (Copepoda: Harpacticoida: Paramesochridae) show characters with a world-wide distribution

Zootaxa ◽  
2021 ◽  
Vol 5051 (1) ◽  
pp. 443-486
Author(s):  
ANNABEL MATHISKE ◽  
DAVID THISTLE ◽  
HENDRIK GHEERARDYN ◽  
GRITTA VEIT-KÖHLER
Keyword(s):  
Related Species ◽  
Deep Sea ◽  
Large Scale ◽  
Wide Distribution ◽  
Weddell Sea ◽  
Closely Related Species ◽  
The Pacific ◽  
Harpacticoid Copepods ◽  
The Family ◽  
Biogeographical Pattern

The large-scale dispersal of deep-sea harpacticoid copepods is an increasing focus for ecological studies. A fundamental prerequisite for monitoring and explaining their geographical distribution is precise descriptions of their morphology. Four new, closely related species of the family Paramesochridae (Copepoda, Harpacticoida) were found in the deep sea of the Pacific (San Diego Trough and off Chile), the Atlantic Ocean (Porcupine Abyssal Plain and Angola Basin), and the Atlantic and Indian Ocean sectors of the Southern Ocean (Weddell Sea and off Crozet Island). The discovery of Emertonia berndi sp. nov., E. hessleri sp. nov., E. ilse sp. nov., and E. serrata sp. nov. increases the number of known deep-sea species in this genus to ten. The new species are placed in Emertonia Wilson, 1932 because of their one-segmented endopods on the second and third swimming legs. The presence of a two-segmented endopod on the fourth swimming leg allocates them to the “andeep-group” within this genus. The four species can be distinguished from their congeners by the strongly serrated spines on the exopods of their swimming legs and an outwardly directed flexible seta on the exopod of the fifth leg. It is conveivable that these two specific characters evolved only once in the genus Emertonia. Their apparently cosmopolitan distribution covers thousands of kilometres and spans all major oceans. This biogeographical pattern may be explained by resuspension events followed by passive transport by benthic currents. Discrepancies in their dispersal ranges may be a result of changing geological and oceanographic boundaries.  

The Cambrian Lower Boundary Problem

1967 ◽  
Vol 104 (5) ◽  
pp. 415-434 ◽  
Author(s):  
A. Yu. Rozanov
Keyword(s):  
Boundary Problem ◽  
Boundary Layers ◽  
Lower Boundary ◽  
Wide Distribution ◽  
Regular Distribution ◽  
Leading Role ◽  
The World ◽  
Carbonate Composition ◽  
Organic Remains

ABSTRACTBased on the study of distribution of assemblages of skeletal organic remains we have established the synchronous appearance of a skeleton in certain fossil groups; this enables us to draw the lower boundary of Cambrian according to the first zone with a certain assemblage of skeletal fossils.Wide distribution, in sections of various parts of the world, of deposits having no trilobites but containing similar assemblages of other skeletal fossils, has made it possible to distinguish them as an independent Tommotian stage. In Siberian sections this can be subdivided into three zones based on archaeocyathans.The deposits of the Tommotian stage are underlain by deposits containing no skeletal fossils; in their carbonate composition they are, as a rule, rich in oncolites and catagraphs (algae of uncertain affinities or products of algal activity), and stromatolites of a socalled “Vendian” or “Yudomian” assemblage.A regular distribution of assemblages of organic remains in the Cambrian-Pre-Cambrian boundary layers point to a leading role for a biostratigraphical method in the solution of the problem of the Cambrian lower boundary.

Revision of the Loboptera species of Morocco (Blattaria: Blattellidae: Blattellinae)

1991 ◽  
Vol 22 (3) ◽  
pp. 251-295 ◽  
Author(s):  
Horst Bohn
Keyword(s):  
New Species ◽  
Endemic Species ◽  
Related Species ◽  
Wide Distribution ◽  
The Other ◽  
Closely Related Species ◽  
New Subspecies ◽  
Western Algeria

AbstractIn this second part of a revision of the genus Loboptera Brunner v. W., the Moroccan species are treated. In addition to the 6 species already known (L. alluaudi Chopard, L. decipiens (Germar), L. irregularis Chopard, L. maroccana Bolívar, L. minor Bolivar, L. truncata Chopard), 5 new species and 1 new subspecies are described (L. cuneilobata, L. cryptofoveata, L. foveolata, L. glandulifera, L. ovolobata, L. minor semicirculolobata). Only one of the species (L. decipiens) has a wide distribution; the other species appear to be endemic to Morocco except for L. ovolobata which also reaches into western Algeria. The endemic species (incl. L. ovolobata) form a well defined group of closely related species (the maroccana group). The characteristics of the maroccana group are described. A key for the identification of the Moroccan species is also given.

Biosystematic studies in the North American species of Linum, section Adenolinum (Linaceae)

1971 ◽  
Vol 49 (8) ◽  
pp. 1379-1388 ◽  
Author(s):  
Theodore Mosquin
Keyword(s):  
North American ◽  
Morphological Evolution ◽  
North American Species ◽  
Evolutionary Trends ◽  
Isolated Populations ◽  
Life Habit ◽  
Good Pollen ◽  
The North ◽  
Native North American ◽  
Variation Patterns

Variation patterns and interpopulational relationships were examined in Linum lewisii Pursh and L. pratense (Norton) Small, the two native North American blue-flowered flax species. The two principal evolutionary trends in the North American populations have been toward self-pollination and an annual life habit. A third trend, toward greater outcrossing, is considered probable. Hybridizations between and within species indicate that evolution has occurred mainly by the accumulation of small genic changes in geographically isolated populations. The buildup of sterility barriers between populations regardless of species has not been extensive and in no case do hybrids have less than 30% good pollen. In general, morphological evolution has occurred independently of the buildup of sterility barriers. A new taxonomic combination, L. lewisii ssp. lepagei (Boivin) Mosquin, is adopted.

scholarly journals To the Issue About the Dating of the Bolshemysskaya Culture

2020 ◽  
Vol 32 (4) ◽  
pp. 147-156
Author(s):  
Stepanova N. ◽  
◽  
Keyword(s):  
Lower Boundary ◽  
Wide Distribution ◽  
Reliable Data ◽  
Distribution Area ◽  
Burial Ground ◽  
Altai Mountains ◽  
Radiocarbon Dates ◽  
Population Groups ◽  
Ceramic Assemblages

The article deals with the problems of the chronology of the Bolshemysskaya culture, which is usually attributed to the Eneolithic era. The sites of this culture have a wide distribution area: the Barnaul-Biysk the Ob region, the Altai Mountains (Middle Katun), the upper reaches of the Alei and Northern Kulunda rivers. However, its chronological boundaries are not clearly defined, which is due to the small number of radiocarbon dates and the lack of reliable data for dating based on relative analogies. Calibration of dates from the burials of the Bolshoi Mys burial ground and Nizhnetytkesken cave-1 showed a significant range between them. An analysis of the ceramic assemblages of the Novoilinka-III settlement from Northern Kulunda revealed signs of interaction between the Cyprinsko-Penkovsky and Bolshemyssky population groups. Contacts can be traced in the ornamentation of ceramics with an object that leaves imprints similar to the ones of bird feathers, and in the addition of bird fluff to the pottery paste. Calibration of radiocarbon dates from Novoilinka-III showed that they all include 34–29 centuries BC. Based on the data obtained, the lower boundary of the Bolshemyskaya culture can be tentatively dated to the second half of the 4th millennium BC.

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