摘要:

The following basic growth parameters of the ammonoid shell are analysed: radius of the coiling spiral; whorl width; plane of cross‐section; umbilical spiral. The absolute growth of these parameters follows a general growth formula which is based on the probability theory (time‐dependent stochastic processes). The in crease of all basic parameters is ruled by analogous formulas which are derived from the general growth formula; the increase of the coiling spiral results in the geometrical figure of a logarithmic spiral, because this is the only one that meets the conditions of the general growth formula. The relative growth can be described as a morphogenetic program that is subdivided in presumably three formally connected subprograms. Each subprogram is defined by specific allometry and integration constants.Folgende Grundparameter des Wachstums von Ammonoideen‐Gehäusen werden analysiert: Radius der äuβeren Spirale, Windungsbreite, Querschnittsfläche, Nabelspirale. Das absolute Wachstum dieser Parameter folgt einer allgemeinen Wachstumsformel, die sich aus der Wahrscheinlichkeitstheorie (zeitabhängige stochastische Prozesse) ergibt. Die Zunahme aller Grundparameter folgt analogen Formeln, die sich aus der allgemeinen Wachstumsformel ableiten lassen; das Anwachsen des äuβeren RadiS führt zur geometrischen Figur einer logarith‐mischen Spirale, da nur diese der allgemeinen Wachstumsformel genügt. Das relative Wachstum läβt sich als ein morphogenetisches Wachstumsprogramm beschreiben, das sich in vermutlich drei formal miteinander verknüpfte Unter‐programme aufteilt. Jedes Unterprogramm ist durch spezifische Allometrie‐ und Integratio

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1972.tb00847.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

True colonies are more than aggregated individuals, they are integrated operational units which can be explained in functional terms. At the same time each constituent individual is fully functional. Paleobiological hypotheses about colonies must withstand testing on both individual and colonial levels. We illustrate our argument by analysis of fenestellid bryozoans. We propose that ciliary feeding currents swept through the fenestrules from frontal side to reverse, with the fenestrules as operational filtering units manned by co‐operating zooids. We reconstruct viable current systems applicable to most fenestellids. For the amazing spiral structure ofArchimedeswe suggest a downward current spiralling about the central axis, since at each ‘deck’ the fenestrules filtered water down

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1972.tb00848.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Reexamination of the specimen ofHystoceroceras varicosum(Sow.) ‘var. angolana’ Haas with allegedly inverted last septal sutures (Haas, 1941) has proved Schindewolf's (1968) assumption to be correct, i.e., the relevant whorl fragment had been inserted inversely during reassembly. The specimen is a nonpathologic adultH. varicosum angola

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1972.tb00849.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

The Phyllopod Bed of the Burgess Shale, in which Walcott found the famous soft bodied fossils, consists of thin graded beds of calcareous siltstone and mud‐stone, which are probably turbidites. The Burgess Shale was deposited on a reef front submarine fan, and the preservation of the fossils is probably due to rapid buria

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1972.tb00850.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

The carapace ultrastructure of three Recent[Heterocypris incongruens(Ramdohr),Cypridopsis uidua(Müller), andConchoecia belgicaMüller] and one Cretaceous ostracode species[Cypridea propunctataSylvester‐Bradley] has been studied by means of standard electron microscope techniques. The carapace is shown to be an organic structure divisible into an outer epicuticle, a median exocuticle and an inner endocuticle in the three cypridacean ostracodes examined. InConchoecia belgicaonly an outer epicuticle and an inner endocuticle were observed, but this may be due to preservation. The chitin structure of the carapace of calcareous ostracodes is shown to be essentially an interlocking lattice, more coarsely developed in the exocuticle; layered (lamellar) chitin is only present in the selvage and in the connective tissue joining the valves at the hinge. The non‐calcareousConchoecia belgicapossesses the layered chitin structure common to other crustaceans and to insects. The relationship of the carapace structure to that present in the decapod and insect exoskeleton is discussed. The technical problems met with during this study are considered in order to outline the difficulties associated with the study of organisms of this

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1972.tb00851.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Recent data generally substantiate the most recent incarnation of the Cenozoic time‐scale (Berggren, 1969c). Newly obtained dates in the type section of the Chattian (Upper Oligocene) support a previous suggestion that a hiatus may separate the top of the stratotype Chattian from the base of the stratotype Aquitanian. TheOrbulinaDatum is placed at 16 my and theGlobigerina nepenthesat 13.5 my. The junction of Eurasia and Africa in the early Miocene (ca. 18 my ago) and of Europe and Africa in the middle Miocene (ca. 15 my ago) markedly affected the Tethyan paleogeography and, concomitantly, the biogeographic dis tribution of larger and smaller Foraminifera, as well as various land mammal groups, including hominoid

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1972.tb00852.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Quantitative data on the carbonate constituents of the early Viruan (‘Middle Ordovician’) Segerstad Limestone of Sweden are given, based on modal ana lyses of thin sections. The grain size of the sediment transgressed the boundary between carbonate mud mixed with skeletal sand (micritic calcarenite), and skeletal sand mixed with carbonate mud (calcarenitic calcilutite). Increase in grain size is largely due to the increase in the abundance of echinoderm particles.The termostraconzassis introduced for the total mass of the skeletal material produced by the organisms in a given area at a given time. The composition of the skeletal sand is completely different from that of the macrofossils in the same beds. The originally aragonitic grains constitute only one to ten per cent of the skeletal sand. This supports suggestions that during the early Palaeozoic the aragonite‐calcite ratio of the ostracomass was low. Attention is drawn to some observations which indicate that the aragonite‐calcite ratio of skeletal sand in the modern temperate marine shallow‐water environment may be considerably lower than in tropical and subtrop

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1972.tb00853.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

The hypostoma, which is a ventral sclerite that covers the oral region, has recently been discovered in four species of agnostid trilobites. The discovery is significant because the suborder Agnostina is the only major trilobite taxon for which the hypostoma has not been described. The agnostid hypostoma is distinctly different in shape from that of non‐agnostid trilobites. Minus its wings, it is widest posteriorly, lacks border furrows, has unusually long wings, and in some species is fenestrate. It is unattached to other sclerites, and presumably was held in place beneath the anterior part of the glabella by muscle tissue. Hypostomal differences probably indicate basic differences in food or feeding habits of agnostid and non‐agnostid trilobites. This, along with other evidence, suggests a major divergence in mode of life of these two trilobite groups, and should be given strong consideration in future attempts at trilobite classificat

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1972.tb00854.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

There is a great need in palaeontology for description of fossil floras and faunas and for a revision of major systematic groups of fossils. The publication of the regional routine descriptions should not be financed by subscribers to jouinals or by members of professional societies with publishing activities. It is largely a national responsibility, and the proper media are rather ‘memoir’ or ‘monograph’ series of Geological Surv

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1972.tb00855.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1972.tb00846.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY