Barry A. Thomas

A review of fossil cycad megasporophylls, with new evidence of Crossozamia pomel and its associated leaves from the lower permian of Taiyuan, China

Four species of cycad megasporophyll from the Lower Permian of Taiyuan, China, are described as Crossozamia chinensis (Zhu and Du) comb. nov., C. minor sp. nov., C. spadicia sp. nov. and C. cucullata comb. nov. together with the associated leaves Tianbaolinia circinalis gen. et sp. nov., Yuania chinensis Zhu and Du and Taeniopteris taiyuanensis Halle. An axis bearing megasporophylls in organic connection is described for the first time. Two possible evolutionary pathways from this structure to those of the female reproductive organs of extant cycads are proposed, involving either the reduction of the megasporophylls and their compaction on the axis, or the reduction of the “strobilus” axis. It is suggested that migration of cycads from North China to Europe might have occurred through transportation of their buoyant seeds by the palaeoceanic currents of the Tethys sea.

Plant fossils from the Writhlington Geological Nature Reserve

This is currently the best locality for upper Westphalian D plant fossils in the Radstock Basin, one of the classic areas for studying the palaeobotany of this age. The assemblage includes a diverse range of gymnosperms, ferns, ‘horsetails; and ‘club-mosses’, and reflects the vegetation of the levee-banks within the Late Carboniferous coal-forming swamps. The assemblage belongs to the Dicksonites plueckenetii Subzone (upper Lobatopteris vestita Zone) and can be compared with coeval assemblages from South Wales, the Forest of Dean and the Maritime Provinces of Canada.

Ambient Temperature Hydrolysis of Carbonyl Sulfide Using γ-Alumina Catalysts: Effect of Calcination Temperature and Alkali Doping

The hydrolysis of COS using γ-alumina as catalyst at 20 °C is described and discussed. In particular, the effect of calcination on the catalyst activity is investigated. Catalysts calcined at 100 and 500 °C are found to give the highest catalyst activities, in terms of both specific (mol COS converted/g catalyst/h) and intrinsic (mol COS converted/m2 catalyst/h) activity. Calcination at other temperatures leads to diminished catalyst activity. The effects are discussed in terms of the known surface chemistry of γ-alumina involving physisorbed water, surface dehydroxylation and defect formation. The addition of alkali additives (Li+, Na+, K+, Cs+, Mg2+, Ca2+, Ba2+, Si2+) is also reported. Only K+ and Cs+ give a sustained enhancement in catalyst activity, whereas all the other additives act as catalyst poisons for the steady-state performance measured following 5 h time-on-stream. Interestingly, addition of Na+ and Mg2+ leads to a very high initial activity (>95% COS conversion) but the effect is very short-lived and, after 5 h time-on-stream, a much lower steady-state activity (∼15-30% COS conversion) is observed.

The use of in-situ spores for defining species of dispersed spores

Abstract The ranges of character variations found in spores recovered from fructifications can only very rarely be equated with those of individual species of dispersed spores. It is proposed that comparisons of in-situ spore populations from parent fructifications should be used to assess biological variation, which can then be taken as representing the range of variation that should be recognised for deliminating species of dispersed spores. Type speciments of dispersed spore species that can be included within such in-situ spore populations may then be used as the taxonomic bases for naming for the species. Emended diagnoses are proposed in this way for Lycospora noctuina Butterworth et Williams 1958 and L. granulata osanke 1950.

The Westphalian fossil floras from the Cattybrook Claypit, avon (Great Britain)

Abstract Cattybrook Claypit, on the northwest margin ofthe Bristol-Somerset Coalfield, yields an upper Westphalian A (Middle Carboniferous) fossil flora. Most of the fossils are of small plant fragments, transported mainly by winds into floodbasin muds. They represent a variety of plant-types, including pteridosperms, ferns, cordaites, sphenophytes and lycophytes. Of particular interest are finely preserved examples of Lonchopteris , and Corynepteris , which are generally scarce in British floras of this age. Also found at Cattybrook are plant fragments in a crevasse-channel sandstone. These are preserved nearer their original position of growth, and are thus more complete than those found in the floodbasin deposits. They include almost complete fronds of Karinopteris attached to a thick lianatype stem, and large pieces of a Sphenophyllum plant. This is now the best documented late Westphalian A flora in Britain.

A new species of Discinites from the Lower Permain of China

Abstract A new species of Discinites, D. dentilongus , is described from the Lower Shihhotse Formation, Lower Permian, of Taiyuan, Shanxi Province, China. It has circular, bowl-shaped sporophylls with long teeth and decurrent bases. The genus is redefined and a new family, Discinitaceae, proposed.

A probable botryopterid fructification with Verrucosisporites miospores from Mar-Schacht, Poland

Abstract A large pear-shaped fructification, from the Westphalian C of Poland, is the first compression fossil probably assignable to the Botryopteridaceae. Its spores are referable to Verrucosisporites verrucosus; their sporoderm consists of a single, homogeneous layer (sexine).

Lower Westphalian D fossil plants from the Nolton-Newgale Coalfield, Dyfed (Great Britain)

Abstract The beach cliff between Nolton and Newgale, on the northern edge of the Pembrokeshire Coalfield, yields a Westphalian D (Upper Carboniferous) Fossil Flora. This can be correlated with the Rhondda Beds in the eastern part of the South Wales Coalfield and has similarities with assemblages reported from northern France (Faisceau de Du Souche) and Piesberg, Germany.

An enigmatic cone from the Lower Permian of Taiyuan, China

Abstract A slender cone from the Lower Shihhotse Formation, Lower Permian, of East Hill, Taiyuan, North China is given the name Shuangnangostachya gracilis . It has spirally arranged sporophylls, each one with a pair of adjacent sporangia on its adaxial surface. The margins of the proximal part of the sporophyll project upwards and forwards.