ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1967.tb01389.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Errol White was the first to elaborate an extensive scheme of vertical distribution of vertebrate remains in the Anglo‐Welsh Lower Devonian (1950). This was shown later to be valid also in Western Europe (White, 1956; Schmidt, 1959) and comparable with Lower Devonian successions throughout the world (e.g. Denison, 1956; Obruchev, 1958; Friend, 1961). To White's papers we still turn when we wish to correlate any sections of that age with the English type one. Thus it seems appropriate to dedicate a paper in this volume to showing how on the foundation laid down by White a further construction can be built up in the vast area of eastern Europ

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1967.tb01390.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

The presence ofTraquairaspis symondsiandPtertispis (Simopteraspis) whiteiin the Knoydart Formation of Arisaig and Pictou Counties, Nova Scotia, has been taken as good evidence of the upper part of the Downtonian and the lower part of the Dittonian stages, respectively. Further discoveries ofP. (S.) whiteiandCephalaspis novaescotiaeallow some estimate of the thickness of the lower part of the Dittonian stage (more than 60 ft). Near Ardness a fauna occurring near the top of the Knoydart Formation includesPteraspis (Belgicaspis) crouchiwhich confirms a lower Dittonian age for the greater part of the formation.

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1967.tb01391.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Recent classifications of Pteraspididae are considered, and it is concluded that because of rapid and sometimes parallel evolution, the vent ral face of the rostrum cannot be relied upon as the sole or most important diagnostic feature of a genus. A revised classification, based on several characters, is proposed, as follows:genusPteraspis, including subgeneraProtopteraspis, Althaspis, andPteraspis;genusRhinopteraspis;genusProtaspis, including subgeneraProlaspisandCyrtaspidichthys;genusDoryaspis(name preoccupied).A new species from the Early Devonian Water Canyon formation of northeastern Utah is described asProtaspis (Protaspis) erroli.

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1967.tb01392.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

This paper confirms that inDrepanaspis gemuendenensisthe principal plates of the head‐shield are rather variable, as Gross showed in his description. Clear homologies are shown to exist between drepanaspid plates and those of pteraspids. The prerostral plates ofDrepanaspisseem to correspond to the hypothetical superior labial dental platesdrawnby Stensiö in his reconstruction ofPoraspis pompeckji; the prerostral plates ofDrepanaspiswere probably fixed on a palatosubnasal lamina. The growth of some plates ofDrepanaspisis considered and seems to have occurred at different speeds in various specime

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1967.tb01393.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

The earliest and most primitive heterostraeans possessed a tessellated carapace. Isolated dentine tubercles scattered in the skin formed primordia around which concentric rings of further tubercles were laid down. This pattern of growth produced a characteristic terrazzo. From this stage the gradual elimination of tesserae can be traced in several groups. Beginning with areally growing or cyclomorial tesserae, the individual units appear simultaneously or synchronomorially, thereafter they become fused into a system of large discrete plates. Finally these synehroriomorial units appear earlier and earlier in ontogeny with progressively wider zones of cyclomorial growth being added on to them. Thus a pattern of cyclomorial plates is eventually produced.In the psammosteids there was a redevelopment of tesserae so that the latest stages were comparable to the very early stages, although the tesserae were developed on an already existing pattern of large plates.The possible origin of the tessellated pat tern of dermal armour is discussed. The apparent macular nature of dermal structures is not considered to be an inherent property of skin but instead due to simple physico‐chemical factor

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1967.tb01394.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

A new tremataspidid genusTyriaspis(type speciesT. whiteigen. et sp. nov.) is described from a new Upper Ludlovian locality at Ringerike, southern Norway. The genus is assigned to the subfamily Dartmuthiinae Robertson. Six specimens are known, thus allowing a fairly complete diagnosis and reconstruction of the species which has a flat head‐shield with wing‐like cornua and dorsal and caudal fins. The scale arrangement of the body differs from that found in typical cephalasp

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1967.tb01395.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Ateleaspis tessellataTraquair, a non‐cornuate cephalaspid from the U. Silurian of Scotland, is re‐examined on the evidence of new material from the original localities. The species is found to be less ‘primitive’ than was previously thought in that the pectoral fins are separated from the trunk posteriorly by a distinct sinus and the two dorsal fins are developed essentially as inAceraspis robustusKiaer. The ventral visceral exoskeleton is described for the first time.AteleaspisandAceraspisare so close in so many respects that retention of separate genera is unnecessary;Aceraspismust be suppressed sinceAteleaspishas priority. Revised diagnoses of the genusAteleaspisand its two species,A. tessellataTraquair andA. robustus(Kiaer), are given and their relationships with other non‐cornuate cephalaspids

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1967.tb01396.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

It is shown that the stratigraphical assignment ofRadotinaneeds considerable revision.Radotina tuberculataGross is conspecific withCoccosteus primusBarrande and should be known asR. prima(Barrande); this species differs from its contemporaryR. tesselatain the same way as extreme forms ofR. kosorensisbut the question of further synonymy is unsettled. The dermal bones ofRadotinaare considered to represent a, modified pattern closely related to that of Macropetaliehthyida; to this general grouping may be added the Rhenanida and Stensioellida. It is highly probable that the Radotinida and Acanthothoraci are synonymous.Consideration of the tesserate condition in arthrodires suggests that this is a secondary condition in the known members. The Psammosteida also show the development of secondary tesseration among the Heterostraci. An hypothesis based on Holmgren's principle of delamination is apparently illustrated by these forms. In certain Rhenanida this delamination goes so far as to produce cartilage bones in the same position, but at a deeper level, as compared with dermal bones in earlier forms.

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1967.tb01397.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

A brief account and new restorations of the Scottish Middle Old Red Sandstone fishRham phodopsisare given, based largely on new material from Edderton, Ross‐shire. The Edderton material is of the speciesRliamphodopsis threiplandiWatson, previously known only from A chanarras, Caithness. The known material ofRhamphodopsis trispinatusWatson, from Moray Firth and Cromarty nodule beds, has been restudied for comparative purposes, and notes are also given on some ptyctodonts from the Upper Devonian of Wildungen, Germany. New points in the structure ofRhamphodopsisconcern mainly the sensory line system, jaws, cervical joint, and pelvic fins and associated structures. The occurrence of strong sexual dimorphism in the pelvic region is confirmed, and descriptions are given of the ‘claspers' in males, and of the large scale‐bearing pelvic fins and their endoskeleton in females. Some consideration is given to the biology of ptycto

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1967.tb01398.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY