摘要:

Two new specimens ofRangea schneiderhoehniGürich 1930 and a new fossil are here described from the Nama Group of South West Africa. A careful study of the twoRangeaspecimens and a reexamination of the holotype shows thatR. schneiderhoehniforma plana andR. schneiderhoehniforma turgida are the same species as already suggested by Gürich, Richter, and Pflug, that the puzzling outer flange of forma plana is part of an underlying second leaf‐like body, and that the Ediacara‘Rangea’does not belong to the genusRangea. Here, therefore, it is introduced as the genusGlaessnerina. The new fossil,Nasepia altae, is related toPteridinium simplexGürich 1930 andRangea schneiderhoehniGürich 1930, and also to the problematic fossilNamalia villiersiensisG

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1973.tb00870.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

In the Baltoscandian epicontinental sea the normal type of Ordovician carbonate sediments was a mixture, in various proportions, of skeletal sand and carbonate mud. In some marginal areas sediments of Bahaman type were deposited during the latest part of the Viruan Epoch, and such sediments were widely distributed from the very latest Ordovician onwards. It is suggested that deposition mostly took place in a temperate climatic zone and that the bahamitic deposits indicate an increase of temperature to subtropical or tropical level.The succession of the Ordovician lithofacies belts in Baltoscandia is mostly roughly symmetrical with regard to grain size, but asymmetrical as to the distribution of terrigenous mud. The position of the boundary between the terrigenous and carbonate mud belts may have been a result of competition in the material transport from the west and from the east. The direction of the lithofacies belts is not parallel to the axis of the Caledonian geosynclinal zone. The predominance of carbonate sediments in the Baltoscandian Ordovician epicontinental sea probably does not reflect particularly good conditions for production of carbonate material, but rather, a very low supply of terrigenous matter.In the Central Baltic area changes of sea level were probably largely opposite to those in Västergötland. This indicates differential isostatic movements in the Baltoscandian cratonic shield during parts of the Ordovician Perio

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1973.tb00871.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Well preserved receptaculitids from the Middle Ordovician in the Grapevine Mountains of Eastern California have been collected and studied. These highly variable specimens are regarded as intrapopulational variants of one species. This variation is due to differences in the microenvironment and to the occurrence of individuals at various stages of growth. These specimens are assigned toIschadites mammillaris(Walcott 1884).This species differs from the similar species ofIschaditesandReceptaculitesin the following features: (1) small, numerous outer plates; (2) interlocking rays between the elements; and (3) curved and bifurcated inner shafts.Ischadites mammillarisis described and its morphology is compared to that of sponges and dasycladacean algae. Recent algal interpretations that regard the closed extremity of the receptaculitid as the growing end are believed to be incorrect. It is concluded thatIschadites mammillarisas well as other similar receptaculitids should retain their tentative alignment with the Porifera.

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1973.tb00872.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Except in a couple of very primitive genera the cheek teeth of ornithischians are inset with a lateral space that was roofed by the overhanging maxilla and floored by the massive dentary. This lateral space was delimited by cheeks and the mouth was small. The cheek muscles were not homologous to the Musculus buccinatoris of mammals, but the function was the same, to prevent the loss of food from the sides of the jaws during chewing. The evolution of self‐sharpening cheek teeth and of cheeks enabled ornithischians to eat much more resistant plant material and resulted in ornithischians replacing prosauropods as the ‘small to medium sized’ terrestrial herbivores (up to

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1973.tb00873.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

At the General Assembly of the International Paleontological Union (I.P.U.), 20th August, 1968 a Policy Committee was formed and charged to formulate an entirely new Constitution; this was adopted 25th August, 1972 by the General Assembly. To conform with regulations of the International Union of Geological Sciences (I.U.G.S.), the new name is International Palaeontological Association (I.P.A.).

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1973.tb00874.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

The recent designation of a stratotype for the Silurian‐Devonian boundary (= the base of the Devonian) marks the end of an enterprise which has been widely referred to as a standard for the elaboration of major stratotypes. Although the philosophy of stratotypes is well developed, practical life is less ready for them. The procedure for authorization of stratotypes as well as their protection and integration with the planned urban and rural landscape call for authoritative deliberations and initiativ

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1973.tb00875.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1973.tb00876.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1973.tb00877.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY