摘要:

Mülkr. Klaus 1. 1979 01 IS: Phosphatocopine ostracodes with preserved appendages from the Upper Cambrian of Sweden.Lethaia. Vol. 12. pp. 1–27. Oslo. ISSN 0024–1164.More than 400 specimens of phosphatocopine ostracodes. representing different moult stages ofVestrogothia. FalitesandHesslandonahave been recovered, with body and appendage structures preserved in minute detail. from anthraconites in the Upper Cambrian of Sweden and drift boulders deriving from that area. The secondary phosphatization of these structures, leading to preservation. is extensively discussed. It comprises even the inner lamella, but the abdomen is not preserved. Hypostome and lower lip are well developed. The large antennula is composed of a basipodite with probably two podomeres and a long exopodite with up to 18 podomeres bearing long spines, forming a natatory organ, and a broad endopodite of two to three podomeres. The biramous organization of the antennula is a unique, most primitive feature of phylogenetic significance. The antennae and up lo four additional pairs of appendages are also biramous and similar to the antennulae, not yet differentiated for specialized functions. Only the last pair is uniramous, but a second branch may have developed in subsequent moult stages not represented in the material. The movement of food into the mouth was achieved by the endites of antennulae and antennae, a function transferred backwards to other appendages during the course of ostracode phylogeny and reflected in ontogenetic trends among Recent ostracodes. The phosphatocopines were nectobenthic, filtering plankton fee

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1979.tb01234.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1979.tb01235.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1979.tb01236.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Wright, Anthony D. 197901 15: The origin of the spiriferidine brachiopods.Lethaia. Vol. 12. pp. 29–33. Oslo. ISSN 0024–1164.In recent years doubts have been expressed as to whether the strophic spiriferidines should continue to be grouped with the non‐strophic spiriferids in the order Spiriferida or not. The solution to this problem will only be found by establishing the origin of the spiriferidines. A characteristic feature of the spiriferidines is their well developed micro‐ornament; this is shared also by the orthid Platystrophiinae, and together with the striking similarity in overall morphology (well recognized in the early nineteenth century) it suggests that here, in thePlatystrophiaplexus, is the ancestral stock of the strophic spirebearers.The Platystrophünae share with the non‐strophic Rhynchonellida the potential to develop a spire. It is here considered that the former gave rise to the spiriferidines and the latter to the non‐strophic spire‐bearers. These quite separate developments justify the separation of the spire‐bearers into the two orders Spirifer

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1979.tb01237.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1979.tb01238.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1979.tb01239.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Cherns. Lesley 1979 01 15: The environmental significance ofLingulain the Ludlow Series of the Welsh Borderland and Wales.Lethaia. Vol. 12. pp. 35–46, Oslo. ISSN 0024–1164.The inarticulate brachiopodLingulais commonly regarded as an indicator of very nearshore environments, particularly when found in monospecific assemblages. However, neither of the two common species in the Lower Leintwardine Beds,L. lewisiiandL. lata. which occur commonly in such associations, have distributions indicative of such an environment. Their Occurrence correlates closely with the Leintwardinian palaeogeography. The former species is concentrated in shelf areas, the latter is confined to the basin; the two distributions overlap little. Individuals of both species are found articulated and perpendicular to the bedding, apparentlyin situ. Hence, the species may be inferred to have equivalent, infaunal modes of life comparable to living representatives of the family. The basinal distribution ofL. larais an original feature. The depth of the actively subsiding basin was relatively great, judging from sedimentological and palaeogeographical evidence. Therefore,L. latawas a species adapted to ‘deep‐water’ environments. The lingulid distributions, reviewed against the concept of brachiopod depth‐related communities previously defined for the Ludlow show the latter to be inapplicable in the Leintwardinian. The depth significance postulated for the recurrent species associations typical of the shelf sequences cannot

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1979.tb01240.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Taylor, Paul D. 1979 01 15: The inference of extrazooidal feeding currents in fossil bryozoan colonies.Lethaia, Vol. 12, pp. 47–56. Oslo. ISSN 0024–1164.Previous studies on live bryozoan colonies have shown that the feeding autozooids in a colony may cooperate in differing ways to produce an extrazooidal watercurrent system organised on a colony‐wide or subcolony‐wide basis. The presence of an extrazooidal current system may be inferred in fossil stenolaemate bryozoans which exhibit either a differential spacing of open autozooecial apertures or a systematic variation across the marial surface in the orientation of automoecial distal portions. By inference, aggregations of autozooecial apertures represented loci of inhalant extrazooidal flow whereas zoarial protuberances (e.g. monticules) with outwardly leaning autozooecia acted as loci of exhalant extrazooidal flow. Bryozoans having automoecia opening obliquely into gaps or fenestrules in their zoaria probably drew a unidirectional extrazooidal current of water through the fenestrules. Extrazooidal water currents may function to accelerate colony clearance rate, decrease the chances of recycling filtered water, aid spermatoman and larval dispersal, and clear sediment from the colony

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1979.tb01241.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1979.tb01242.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Gray, Jane&Boucot, ArthurJ. 197901 15: The Devonian land plantProtosalvinia. Lethaia. Vol. 12, pp. 57–63. Oslo. ISSN 0024–1164.Protosalvinia (=Foerstia) shows a number of morphological features which suggest that it was a land plant, possibly an emergent aquatic. Certain kinds of biochemical data, as presently interpreted, also support the morphological evidence. The weight of evidence supports neither a fucoid nor even an algal attribution for this enigmatic plant.Protosalviniashould be treated as the representative of a separate group of land plants, as previously advocated. Tracheid‐like tubes with internal spiral thickenings appear on the basis of direct comparison to be morphologically identical to those of nematophytalean origin. They may have functioned in a capacity similar to the tracheids of vascular plants. The Nematophytales are non‐marine plants of uncertain taxonomic p

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1979.tb01243.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY