摘要:

A specimen ofBuchiceras bilobatumis shown to have been able to maintain neutral buoyancy in water despite the ever increasing weight of epifaunal oysters which it carried on its shell. It is deduced that before settlement of the oyster spat, the camerae of the ammonite contained several grammes of water and that this was slowly pumped out as the oysters grew. Revised calculations on the densities of other ammonoids suggest that the presence of large quantities of liquid in cephalopod camerae was a common occurrence. The significance of this liquid in the growth, mode of life, and evolution of ammonoids is discussed.

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1970.tb00826.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

The calcareous shell ofBillingsellais composed of a primary layer of crystallites commonly disposed vertically or at high angles to the shell surface, and a laminar secondary layer of flat‐lying blades which usually amalgamate laterally to form a succession of plates. The succession is unlike that of other billingsellaceans such asNisusiaor contemporaneous orthaceans likeOligomysandOrusiawhich have a secondary layer composed of fibres. It is, however, closely comparable with the impunctate, laminar secondary layer of the Triplesiacea and early Davidson‐iacea. The other pene‐contemporaneous laminar‐shelled articulates, the Stropho‐menacea and Plectambonitacea, differ in being pseudopunctate. These differences in shell structure suggest that the Strophomenida were polyphyletically derived, mainly from the Nisusiidae but also from the Billingsellidae which gave rise to the Davidsoniacea (and Trip

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1970.tb00827.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

The vertebral column and caudal fin are described from species ofAcanthodes.Less‐specialized acanthodians are briefly noted and shown to resembleAcanthodesspp. closely in these structures. The anterior extent of the notochord and the nature of acanthodian fin‐rays are also considered. The phylogenetic significance of all these structures is discussed, and acanthodians are found to resemble the early members of other groups of gnathostome fishes mainly in primitive charact

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1970.tb00828.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

The generaTommotiaMissarẑevskij 1970 (1966) andCamenellaMissarẑevskij 1966 from the Lower Cambrian Tommotian Stage of the Siberian Platform represent different skeletal parts of the same organism and are consequently synonymous.Tommotiais selected as the valid name.Tommotia baltican.sp. is described from the Lower Cambrian zone ofMobergella holstiof the Kalmarsund area in the southern part of the Baltic Sea. The Lower Cambrian families Tommotiidae Missarzevskij 1970 (1969) and Tannuolinidae Fonin&Smirnova 1967 show important similarities in their basic structure and are brought together in the new order Mitrosagophora, characterized by a composite outer skeleton with two types of skeletal elements, termed ‘mitral’ and ‘sellate’, each occurring in symmetrical pairs. The group is of uncertain systematic position but may have affinities with the Machaeridia.The Scandinavian zone ofMobergella holstiis correlated with the Siberian zone ofDokidocyathus lenaicusandMajatheca tumefacta, the uppermost zone of the Tommot

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1970.tb00829.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Skeletal morphology seems to be controlled not only by evolutionary heritage and necessities of adaptation to specific environments, but also by morphogenetic programs which often appear as non‐adaptational elements of low taxonomic significance. Constructional morphology tries to find out how the three groups of factors are correlated in a given form. This article is the first of a series of papers in which these principles will be applied to different groups of organisms.Einleitende Bemerkungen zu einer Artikelserie, in der neben der historisch‐phylogenetischen und ökologisch‐adaptiven Bedingtheit fossiler und fossilisierbarer Formen auch allgemeinere morphologische «Lizenzen» beleuchtet werde

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1970.tb00830.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Ontogenetic allometries(heterauxesisaccording to Huxley) of about 50 Carboniferous goniatite species from Germany, Spain and USA have been studied by means of geometrical measurements of shell cross sections. They indicate changes of proportions during ontogeny between coiling spiral, umbilical spiral, and whorl width. The allometry constants change suddenly at defined stages. Thus the ontogenetic growth pattern is polyphase, each phase being determined by a different allometric formula.Ontogenetische Allometrien wurden bei etwa 50 karbonischen Goniatiten‐Arten aus Deutschland, Spanien und USA an Hand von Gehäuse‐Querschnitten untersucht. Während der Ontogenese erfolgen mehrfach Proportionsverschie‐bungen der äußeren Spirale, der Nabelspirale und der Windungsbreite, die sich durch scharfen Wechsel von Allometrie‐Konstanten an definierten Stellen aus‐drücken. Das Gehäusewachstum erfolgt somit in mehreren Phasen, die von unterschiedlichen Allometrieformel

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1970.tb00831.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

As a result of attachment over its entire surface, the ventral valve of the brachiopodCrania anomala(Müiller) differs from the dorsal valve not only in growth form, time sequence of calcification, and distribution of endopuncta, but also (withoutap‐parent functional reason) in ultrastructure. The secondary layer of the dorsal valve grows together from flat crystals (up to 5μ. diameter) showing screw‐like dislocations. The same layer of the ventral valve is formed later and has an irregular structure. Spiral crystals are not secreted in the ventral valve until the adult growth‐stage is attained. The periostracum and primary layer are developed in both valves in a normal fashion. Fossil representatives, in which the ventral valve is partly or completely free, show the same ultrastructure in both valves.Infolge ganzflächiger Anheftung weicht die Ventralklappe vonCrania anomala(Müller) nicht nur in Wuchsform, zeitlichem Ablauf der Kalzifikation und Verteilung der Endopuncta von der Dorsalklappe ab, sondern ohne erkennbare funktionelle Gründe auch in der Ultrastruktur. Während die Sekundärschicht in der Dorsalklappe aus spezifischen, bis 5μ. Großen Kristallen mit Schrauben‐versetzungen zusammenwächst, wird sie in der Ventralklappe verzögert und mit regelloser Struktur angelegt. Erst in adulten Wachstumsstadien können auch in der Ventralklappe spiralige Kristalle abgeschieden werden. Periostrakum und Primärschicht sind beiC. anomalanormal entwickelt. Fossile Anpassungstypen der Craniacea, deren Ventralklappen nur punktförmig oder überhaupt nicht zementiert sind, zeigen in beiden Klappen

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1970.tb00832.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

The triplesiacean shell has long been accepted as being impunctate, and has recently (Williams 1968) been shown to be of the laminar type which characterises the non‐plectambonitacean strophomenids. Examination of a specimen of the triplesiidOxoplecia, however, shows a clear development of pseudopuncta; and what appears to be a differentiated primary layer external to the laminar shell in this specimen is confirmed from the shell of anotherOxopleciaspecies.The presence of rarely developed pseudopuncta within the superfamily supports the association of the Triplesiacea with the Davidsoniacea by Williams (1970), while the establishment of a primary layer in the Triplesiacea confirms his expectation based on its presence in the presumed billingsellacean ancestor

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1970.tb00833.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

The conodonts are divided into the Westergaardodinida and Conodontophorida orders. The latter (conodonts proper) are divided into 8 superfamilies. The Distacodontacea (Proconodontidae, Clavohamulidae, and Distacodontidae families) are on the whole a simple, ‘primitive’ group. The Chirognathacea includeOistodus(s.str.),Chirognathus,andRhipidognathus.The Panderodontacea are mainly simple cones. The Prioniodinacea have compound, non‐blade elements. The Prioniodontacea include the Periodontidae, Prioniodontidae, Balognathidae, and Icriodontidae families. Bryantodontace, Gondolellacea, and Polygnathacea are based on platform‐stock genera. The Polygnathacea (spathognathodon‐tids, polygnathids, and indiognathodontids) may comprise two major stocks independent since the O

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1970.tb00834.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Vernacular names form an important element in palaeontological style. There are clear rules in English and other languages for the vernacularization of systematic names. Usage is losing stringency, however, particularly with regard to the vernacular suffix ‐id. It is recommended that this suffix should be retained only to correspond with the family suffix‐i

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1970.tb00835.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY