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Late palaeozoic plants from Yüerhung, Kansu, China
BOOK REVIEWS
317
Late Palaeozoic Plants from Yf4erhung, Kansu, China. B. Bohlin. Reports from the Scientific Expedition to the Northwestern Provinces of China under the Leadership of Dr. Sven Hedin (the Sino-Swedish Expedition); IV. Palaeobotany 1. Part 1 (text), Part 2 (Plates). Sven Hedin Foundation, Stockholm, 1971, 122 pp. text, 25 collotype plates of photographs and 28 plates of drawings. The province of Nanshan in northwest China lies on the northern edge of the mountain system associated with the impact of the Indian segment of Gondwanaland against that of Eurasia. Here four great Palaeozoic floral provinces have been brought into relative proximity - the Angara flora of Russia, the Glossopteris flora of India, the Cathaysian flora to the East, and the Euramerian flora on the West. Bohlin's latest addition to our knowledge of the palaeobotany of this critical region comes from a small depositional basin at Yiierhung, in Kansu, in the northernmost part of the Nanshan mountain range. His work is a continuation of a tradition of European palaeobotanists' interest in the Palaeozoic flora of China, represented by the researches of Schenk, Halle, Bexell and the Stockmanns, which have been built upon by Sze, Lee and Kon'no. Bohlin describes selected items from a considerable flora, collected forty years ago by the Sino-Swedish expedition. The author, although primarily a palaeontologist, describes himself as having a "weakness for botany". This has encouraged him to describe and illustrate this important but difficult collection of plant fossils. If it were not for his tireless enthusiasm, this flora would, in his own words "probably never have been described". For this, palaeobotanists owe him a debt of gratitude. The Yiierhung flora comprises over 1,000 specimens from 100 localities. Although the plant-bearing limnic deposits are many metres thick, the flora here described comes from a relatively restricted part of the sequence. The several constituent assemblages have enough in common that the author treats them as representatives from a single flora of limited duration. The nature of the fossils might have deterred many less dedicated workers. The plants are preserved as black coaly compressions on very dark matrix, giving considerable difficulty in illustration. Cuticle preparations do not seem to have been attempted, but the author has used high magnification with top illumination to reveal details of the original epidermal surface of the plants. He also offers stereo-pairs of the fossils on many of his plates, intended for observation with a stereo-viewer. This is a courageous innovation for fossil plant compressions and one only regrets that the material was not more responsive to Bohlin's ingenuity, for disappointingly little helpful topography is revealed in the third dimension. The photographs are augmented by a profusion of careful line drawings, clarifying features of outline and venation. Through the early part of the Carboniferous period, the flora of northern China has much in common with that of Europe; but by the beginning of the Permian, the Chinese flora is already showing a regional differentiation which culminates in the distinctive Cathaysian flora of that period which characterises the whole far eastern area. As would be expected then, the Ytierhung flora combines elements of the Euramerian province
318
BOOK REVIEWS
(Lepidodendron, Stigrnaria,Neuropteris, Linopteris, Cordaitanthus) with genera characteristic of the Angara province to the north (Angaridium, Yavorskya) together with early representatives of the Cathaysian flora (Tingia, Conchophyllum). In addition it has the rather surprising feature of a considerable proportion of conifers, and in this it differs from the more or less contemporaneous flora at Shansi further to the east. Bohlin invokes sorting, occurring during water transport prior to fossilisation, to explain this difference between the Yiierhung and Shansi floras. There are of course other possibilities, which are suggested by the comparable differentiation between Late Pennsylvanian floras in the western U.S.A. There, in the so-called CordiUeran province the premature appearance of a supposedly xerophytic "Permian" element in the Carboniferous floras has been attributed to the proximity of the depositional basins to a relatively arid hinterland. A similar situation might be invoked to account for the peculiarity of the Yfierhung flora. Such differences raise problems in trying to correlate fossil floras of this type; Bohlin compares his assemblage with those of Shihhotze and Kaiping, which would give an age equivalence of approximately Stephanian or Early Permian. W. G. CHALONER(London)
A tlas ofPalaeobiogeography. A. Hallam (Editor). Elsevier Scientific Publishing Company, Amsterdam, 1973,470 pp., Dfl. 120,00. There is no great virtue in studying fossils for their own sakes; the palaeontologist becomes interesting to other scientists when he can tell them something about the evolution, habits, stratigraphical or geographical distributions of his fossils. The last study had lagged behind the others and is especially difficult. The burial, destruction or metamorphism of sedimentary rocks, not to mention subsequent plate movements, make it very difficult to recover the original distributions of organisms, especially in the older rocks. This book is probably the first attempt to provide fairly consistent coverage of the major fossil groups throughout Phanerozoic time, and one is grateful to the 48 specialists who have, under Dr. Hallam's editorship, compiled the 47 chapters which comprise the volume. One expects from an atlas, first and foremost, an objective presentation of the facts, and this purpose is largely fulfilled. The reputations of the authors guarantee the reliability of the information provided. Almost all have plotted the actual occurrences of individual taxa, in most cases genera or families, and in very few cases are generalisations made without the supporting evidence. Distributions are presented on a standard outline world map, the only acceptable course since, for many cases, there is not an agreed pataeogeography which could be used. Nevertheless, many geologists will be keen to examine the relationship of faunal distributions to past configurations of the continents, and it is perhaps a disappointment that only about one-quarter of the articles dealing with pre-Cenozoic fossil groups attempt to do this. For example, C. B. Cox dealing with
317
Late Palaeozoic Plants from Yf4erhung, Kansu, China. B. Bohlin. Reports from the Scientific Expedition to the Northwestern Provinces of China under the Leadership of Dr. Sven Hedin (the Sino-Swedish Expedition); IV. Palaeobotany 1. Part 1 (text), Part 2 (Plates). Sven Hedin Foundation, Stockholm, 1971, 122 pp. text, 25 collotype plates of photographs and 28 plates of drawings. The province of Nanshan in northwest China lies on the northern edge of the mountain system associated with the impact of the Indian segment of Gondwanaland against that of Eurasia. Here four great Palaeozoic floral provinces have been brought into relative proximity - the Angara flora of Russia, the Glossopteris flora of India, the Cathaysian flora to the East, and the Euramerian flora on the West. Bohlin's latest addition to our knowledge of the palaeobotany of this critical region comes from a small depositional basin at Yiierhung, in Kansu, in the northernmost part of the Nanshan mountain range. His work is a continuation of a tradition of European palaeobotanists' interest in the Palaeozoic flora of China, represented by the researches of Schenk, Halle, Bexell and the Stockmanns, which have been built upon by Sze, Lee and Kon'no. Bohlin describes selected items from a considerable flora, collected forty years ago by the Sino-Swedish expedition. The author, although primarily a palaeontologist, describes himself as having a "weakness for botany". This has encouraged him to describe and illustrate this important but difficult collection of plant fossils. If it were not for his tireless enthusiasm, this flora would, in his own words "probably never have been described". For this, palaeobotanists owe him a debt of gratitude. The Yiierhung flora comprises over 1,000 specimens from 100 localities. Although the plant-bearing limnic deposits are many metres thick, the flora here described comes from a relatively restricted part of the sequence. The several constituent assemblages have enough in common that the author treats them as representatives from a single flora of limited duration. The nature of the fossils might have deterred many less dedicated workers. The plants are preserved as black coaly compressions on very dark matrix, giving considerable difficulty in illustration. Cuticle preparations do not seem to have been attempted, but the author has used high magnification with top illumination to reveal details of the original epidermal surface of the plants. He also offers stereo-pairs of the fossils on many of his plates, intended for observation with a stereo-viewer. This is a courageous innovation for fossil plant compressions and one only regrets that the material was not more responsive to Bohlin's ingenuity, for disappointingly little helpful topography is revealed in the third dimension. The photographs are augmented by a profusion of careful line drawings, clarifying features of outline and venation. Through the early part of the Carboniferous period, the flora of northern China has much in common with that of Europe; but by the beginning of the Permian, the Chinese flora is already showing a regional differentiation which culminates in the distinctive Cathaysian flora of that period which characterises the whole far eastern area. As would be expected then, the Ytierhung flora combines elements of the Euramerian province
318
BOOK REVIEWS
(Lepidodendron, Stigrnaria,Neuropteris, Linopteris, Cordaitanthus) with genera characteristic of the Angara province to the north (Angaridium, Yavorskya) together with early representatives of the Cathaysian flora (Tingia, Conchophyllum). In addition it has the rather surprising feature of a considerable proportion of conifers, and in this it differs from the more or less contemporaneous flora at Shansi further to the east. Bohlin invokes sorting, occurring during water transport prior to fossilisation, to explain this difference between the Yiierhung and Shansi floras. There are of course other possibilities, which are suggested by the comparable differentiation between Late Pennsylvanian floras in the western U.S.A. There, in the so-called CordiUeran province the premature appearance of a supposedly xerophytic "Permian" element in the Carboniferous floras has been attributed to the proximity of the depositional basins to a relatively arid hinterland. A similar situation might be invoked to account for the peculiarity of the Yfierhung flora. Such differences raise problems in trying to correlate fossil floras of this type; Bohlin compares his assemblage with those of Shihhotze and Kaiping, which would give an age equivalence of approximately Stephanian or Early Permian. W. G. CHALONER(London)
A tlas ofPalaeobiogeography. A. Hallam (Editor). Elsevier Scientific Publishing Company, Amsterdam, 1973,470 pp., Dfl. 120,00. There is no great virtue in studying fossils for their own sakes; the palaeontologist becomes interesting to other scientists when he can tell them something about the evolution, habits, stratigraphical or geographical distributions of his fossils. The last study had lagged behind the others and is especially difficult. The burial, destruction or metamorphism of sedimentary rocks, not to mention subsequent plate movements, make it very difficult to recover the original distributions of organisms, especially in the older rocks. This book is probably the first attempt to provide fairly consistent coverage of the major fossil groups throughout Phanerozoic time, and one is grateful to the 48 specialists who have, under Dr. Hallam's editorship, compiled the 47 chapters which comprise the volume. One expects from an atlas, first and foremost, an objective presentation of the facts, and this purpose is largely fulfilled. The reputations of the authors guarantee the reliability of the information provided. Almost all have plotted the actual occurrences of individual taxa, in most cases genera or families, and in very few cases are generalisations made without the supporting evidence. Distributions are presented on a standard outline world map, the only acceptable course since, for many cases, there is not an agreed pataeogeography which could be used. Nevertheless, many geologists will be keen to examine the relationship of faunal distributions to past configurations of the continents, and it is perhaps a disappointment that only about one-quarter of the articles dealing with pre-Cenozoic fossil groups attempt to do this. For example, C. B. Cox dealing with