The sequence of Silurian graptolite zones in the British Isles

Abstract

Much modern work on graptolite sequences in the British Isles has provided considerably greater detail regarding species occurrence and range than was available to Ella and Wood (1901-18) and fequires that the more refined zonal schemes of, for example, Rickards (1967example, Rickards ( , 1969example, Rickards ( , 1970 and ToghiM (1968a) should be more fully discussed than was possible in Strachan (1971). Cocks er al., (1971), or Ziegler et ul. (1974). The zonal scheme favoured by the writer is discussed zone by zdne, and reference is made to the various difficulties which may obtain, to other zonal schemes in use, and to the questions of local, national and international usage. A summary range chart of British Silurian graptoloids is included as Table 1.

Graptolite faunas of the Llandovery “phtanites” at Les Fresnaies (Chalonnes-sur-Loire, southeastern Armorican Massif): Palaeontology and biostratigraphy

“…4J) Rhaphidograptus extenuatus (Elles & Wood) and "Monograptus" a. austerus. Atavograptus atavus occurs in the lower part of the Cystograptus vesiculosus Biozone, as is the case in Bohemia (Štorch 1994), which correlates with the Atavograptus atavus Biozone of Great Britain (Rickards 1976) and Arctic Canada (Melchin 1989). In the middle part of the biozone, we have identified a distal fragment questionably attributed to Huttagraptus acinaces (Törnquist).…”

Graptolites from the Rhuddanian-Aeronian boundary interval (Silurian), Prague Synform, Czech Republic

“…Whilst Nd. magnus gives its name to a biozone above the triangulatus Biozone in the British scheme (Rickards 1976b, Zalasiewicz et al 2009, Nd. fezzanensis is a prominent constituent of the cyphus Biozone assemblages at all relevant sections of the Prague Synform.…”

Llandovery sporomorphs and graptolites from the Manbo Formation, the Mojiang County, Yunnan, China

“…(Regional Geological Survey of Yunnan 1973;Zhang & Lenz 1999). Among the reported species, M. f. primus occurs commonly in the early Wenlock strata in the British Isles (Rickards 1976), and therefore the Manbo Formation was partly regarded as of early Wenlock age. Based on the regional geological map, the rocks of our locality were always considered as Triassic (without any fossil evidence).…”