摘要:

Two disturbing trends are seen in current thinking behind the establishment of new genera of fossil brachiopods; the emphasis on their applications stratigraphi‐cally, and the use of progressively finer distinctions in diagnoses. The genus is a biologically based concept and thus fossil genera are only justifiable if the basis of their establishment is also biological; any stratigraphical applications are merely a by‐product. The use of finer morphological distinctions in the establishment of fossil brachiopod genera in recent years runs contrary to the findings of field zoologists working on modern marine shells. Examples of the wide morphological variation in modern shells, apparently phenotypically induced, are given, the importance of this work in keeping the genus concept of the palaeontologist in perspective is stressed, and a revision of the established taxonomy of the triple‐siaceanOnychotretaundertaken as an illustr

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1972.tb00836.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SEM studies ofNannoceratopsis gracilisAlberti reveal details of ridge and groove arrangement in the subapical region. Transversal and longitudinal furrows can be compared with the furrow system inDinophysisand other Dinophysiales. A median sagittal ‘groove’ observed in corroded specimens is possibly derived from a sagittal suture as found in the thecae of these groups. It is, however, still impossible to assignNannoceratopsisto any living genus. Although preformed archaeopyles have not been observed, surface and ridge structures leave little doubt that we are dealing with cysts, similar in this respect to the proximate cysts of the Peridiniales.Neue Untersuchungen anNannoceratopsis gracilisAlberti im Elektronen‐Raster‐Mikroskop gaben Aufschluβüber die Anordnung von Leisten und Rinnen im subapikalen Bereich und erlauben die Rekonstruktion des Quer‐ und Längsfur‐chensystems. Dadurch werden genauere Vergleiche mit den Furchenverhältnissen beiDinophysisund anderen Dinophysiales möglich. Zusätzliche Indizien geben mediane sagittale ‘Rinnen’, die durch Verwitterung dort entstehen, wo sich bei Theken von Dinophysiales die Sagittalnaht befinden würde. Eine Zuordnung zu bekannten rezenten Gattungen ist jedoch nicht möglich. Präformierte Archaeopyle konnten nicht gefunden werden. Doch ähneln die Strukturen von Wandoberfläche und Leisten denen von proximaten Peridiniales‐Zysten, so daβ wir beiNannoceratopsisebenfalls auf Zy

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1972.tb00837.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Absolute age and season of death data, obtained by observation of daily growth increments in shell cross‐sections, are compiled for RecentGemma gemma(Eulamellibranchia: Veneridae) collected from four different assemblages. When absolute age and size‐frequency data are compared for the same assemblage, the resulting histograms are quite different. Part of this difference is attributed to the fact that there is no definitive, linear correlation between shell length and absolute age.The value of absolute age determinations made by counting and observing external growth increments is questioned. It is found that by observing the shell's exterior it is easy to confuse sickness or spawning patterns with winter growth patterns. Such confusion results in assigning anomalously high absolute ages for individual shells. Also, the amount of time represented by external individual riblets varies geographically.CollectedGemmaare found to have died at various times of the year, but primarily in autumn. This variability in season of death indicates that the assemblages are the result of natural rather than catastrophic mortal

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1972.tb00838.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Two species of the foraminiferal genusTurrilinaAndreae, 1844, occurring in the Tertiary beds of Denmark and Holland, can be distinguished by their wall structure only. In consequence it is recommended that the wall structure as a systematic character may in this and similar cases be of specific value only.

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1972.tb00839.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Arillate seeds ofSpirematospermum wetzleri(Heer) Chandler (Zingiberaceae) are described from the Fasterholt Miocene locality in Denmark, and five other European Tertiary localities. Investigations made involving the use of a scanning electron microscope showed a good correspondence between the aril ofSpirematospermum wetzleri(fossil), and the aril ofCenolophon oxymitrum(Schumann) Holttum (recent, Thailand). TheSpirematospermumaril is well developed at the base of the seed and in some specimens covers the seed entirely. The tissue of the aril is found carbonized or pyritized or as an impression on the palisade sclerenchyma of the testa.The discovery of an aril proves thatSpirematospermum wetzleribelongs to the Zingiberaceae and shows its close relationship toCenolophon oxymitrum.The finding of theSpirematospermumaril on a number of examples reaching into the Paleogene demonstrates the antiquity of this character. Hence, the reduction of the aril in some members of the livingZingiberalescan be interpreted as a progression.Arillate Samen vonSpirematospermum wetzleri(Heer) Chandler werden aus der miozänen Fundstelle Fasterholt in Dänemark und fünf anderen Tertiär‐Fundstel‐len beschrieben. Untersuchungen mit dem Raster‐Elektronen‐Mikroskop zeigen eine gute Übereinstimmung zwischen dem Samenmantel vonSpirematospermum(fossil) undCenolophon oxymitrum(Schumann) Holttum (rezent aus Thailand). Der Arillus ist am Hilum besonders stark entwickelt und hüllt bei einigen Ex‐emplaren den gesamten Samen ein. Arillusgewebe wird in inkohltem Zustand, in pyritisierter Form und als Eindruck in der Testa nachgewiesen.Der Nachweis eines Arillus bekräftigt erneut die Zugehörigheit vonSpirematospermumzu den Zingiberaceae und die nahe Verwandtschaft zuCenolophon oxymitrum.Die Entdeckung des Arillus beiSpirematospermum‐Samen,bereits aus Ablager‐ungen aus dem Paläogen, zeigt das hohe Alter dieses Merkmals an. Die Reduk‐tion des Arillus bei einigen Gruppen der rezentenZingiberalesist daher a

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1972.tb00840.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Tank experiments with the terebratuloidMegerlina pisumindicate that food is obtained by filtration of sea‐water drawn into the shell at the sides and exhaled anteriorly. Under laboratory conditions feeding periods of up to 12 hours were interspersed with resting periods of about equal duration. During the feeding periods the valves were maintained at full gape except for brief interruptions by complete or partial closures. Complete closures lasted several minutes whereas partial closures occurred about half as frequently and lasted only 1 or 2 seconds. Most of these closures did not involve the expulsion of faecal pellets. During the resting periods the valves remained closed for several hours at a time and this condition occasionally continued for 10 hours or more. Apparently a very low respiratory rate operates during these resting period

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1972.tb00841.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

The Early Ordovician bathyurid faunal province includes North America, Greenland, Spitsbergen, Scotland, and western Ireland and Norway. Dominant provincial lithofacies and biofacies include a Dolomite Suite with molluscan‐stromatolite fossil content rimmed by Limestone Belts with dominantly trilobite‐brachiopod faunas on a platform. Shale Belt rocks bearing graptolites, deposited on the platform slopes, rim the Limestone Belts. Volcanic rock‐rich terrain partly borders the Shale Belts. Correlation between the lithofacies indicates that change from an expansion to contraction phase of a proto‐Atlantic coincided with uplift of the carbonate platform and with tectonic activity in the Atlantic volcanic rock rich terrain. Brachiopods replaced trilobites as dominant faunal elements in more shallow platform waters at the same time. High trilobite diversity remained in deeper waters near platform margins. The changes took place in Earliest Mohawk‐ian (Latest Arenig‐Earlies

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1972.tb00842.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

The appendages of the Ordovician trilobiteCryptolithus tesselatusare restudied, and particular reference is made to the exite branch. Details formerly borrowed fromTriarthrusto complete the reconstruction of the appendages ofCryptolithusare now found in part to be significantly different in the two trilobites. The exite ‘filaments’ ofCryptolithusevidently are strong spines that pointed ventrally and may have been used to stir up deposited mud. The broadened view of trilobite appendages indicates that some trace fossils(Cruziana semi‐plicatatype) may be interpreted as being partly made by the exites, while others (C.rugosatype) are perhaps made exclusively by the e

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1972.tb00843.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

In Silurian loboliths(Camarocrinus, bladder‐like root ofScyphocrinites)two morphogenetic types are recognized: an older and previously almost unknown ‘cirrus lobolith’, and the familiar cosmopolitan ‘plate lobolith’. Their functional interpretation as buoys, for the latter type so far mainly based on its unusual form and mode of occurrence, is supported by (1) approximation to the paradigm, (2) buoyancy calculations of the gas contents, and (3) physical‐technical considerations based on the optimation involved in the phylogenetic transition from cirrus to plate loboliths.Die lange Zeit umstrittene Funktion der Lobolithen (hohle, kugelförmige Wurzelregion vonScyphocrinites)wird an zwei verschiedenen, aber phylogenetisch nahe verwandten Bautypen, dem bisher praktisch unbekannten, stratigraphisch älteren ‘Cirren‐Lobolithen’ und dem schon mehrfach bearbeiteten ‘Platten‐Lobolithen’, untersucht. Beide hatten mit Sicherheit Ballon‐Funktion; denn(l) entspricht ihr Bau dem Paradigma dieser Funktion, (2) besaßen beide Lobolithen auf Grund ihrer Gasfüllung eine mehr als ausreichende Tragkraft, (3) entspricht der Übergang von Cirren‐ zu Platten‐Lobolithen einer weiter

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1972.tb00844.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

In articles provided with an abstract (‘extended title with connected sentences’), there is no reason to overcrowd the title with information of key‐word character. The title should be formulated to assist the selective reader. Additional information for the needs of secondary publications should be supplemented in the abstract and in a special line of key‐words for indexing. We should aim at clean titles, using bibliographic and documentalishc fo

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1972.tb00845.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY