The characterization of the Permian Cathaysia Flora based on fossil cuticles
Final Report Abstract
During the Permian four distinct floral provinces can be distinguished, two of them in palaeoequatorial latitudes, i.e. Euramerica and Cathaysia. The latter includes most of China and adjacent parts of South-East Asia. Cathaysian floras are based on compression fossils and little was known on the natural relationships, growth habits and reproduction strategies of the characteristic taxa. The aim of this project was to characterize typical Cathaysian compression taxa based on their cuticle, in order to reach a better delimitation of individual taxa, clarify their natural relationships and, if possible, to reconstruct whole-plant taxa that can be used in phylogenetic analyses. Cuticles should also provide information on the ecology and climate. During two field campaigns in the Palougou section near Baode, Shanxi, North China, c. 600 kg of material was collected from eleven newly discovered horizons with cuticle-bearing plant fossils. Altogether, over 56 taxa could be identified from lower and upper Permian strata, about half of them with cuticles. As a result of this project three genera of Callistophytales, a small group of seed ferns so far only known from Euramerica, could be described. Two of these genera are new. Macrofossils show the gross morphology and cuticles the epidermal anatomy. All three genera could be reconstructed as whole-plant taxa and all show adaptations to a climbing growth habit, such as hydathodes, adventitious roots or climbing hooks. Of all three genera reproductive organs are known; ovules and pollen organs were found in organic connection with the foliage. For one genus reproductive organs in different developmental stages were found, enabling a detailed reconstruction of the reproductive cycle. The Callistophytales, a very sophisticated group of pteridosperms, were apparently much more diverse and wider distributed than previously thought. Compsopteris wongii (Halle) Zalessky is an enigmatic foliage type of unknown systematic affinities, endemic to the Permian Cathaysia flora. The material from the Lower Shihhotse formation at Palougou yielded exquisitely preserved cuticles indicating that C. wongii had a high photosynthetic capacity and high assimilation rates; the species was adapted to an ever-wet environment. It is well comparable to peltaspermalean seed ferns from Euramerica and Angara, such as Glenopteris and Protoblechnum. Cordaitales are typical plant fossils of Cathaysian floras and several species were found. One of them has very small leaves, superficially similar to conifer leaves, but the fertile organs are typical cordaitalean. A new genus and species, Wangjunia microphylla, was established for this particular cordaite that could be described as a whole-plant species. In addition, a number of other typical Cathaysian taxa from Palougou could be characterized on the basis of their cuticles for the first time, such as some species of the Noeggerathiales, a group of progymnosperms and a gigantopterid. Most exciting is the discovery of the oldest representative of the Bennettitales, a group of gymnosperms with cycad-like leaves that is traditionally regarded to be typical for the Mesozoic. In Late Triassic to the Early Cretaceous floras this group is often dominant. The first occurrence of this group can now be traced back from the Middle Triassic to the late Cisuralian (early Permian). Bulk macerations of a cuticle-bearing bed in the Sunjiagou Formation in the upper part of the section revealed a mesoflora that is very similar to those known from the European Zechstein, showing that the clear differentiation into different floral provinces at lower latitudes no longer existed in the late Permian.
Publications
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A diverse Flora from the Upper Permian of Shanxi, China. – 19th International Congress on the Carboniferous and Permian, Köln
Bäumer, R., Backer, M. & Kerp, H.
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The epidermal anatomy of typical Cathaysian plant fossils from the Lower Permian of Shanxi, China. – 2nd Joint Conference of the Palaeontological Society of China and the Paläontologische Gesellschaft, Yichang, China
Backer, M.
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2016. Die Charakterisierung permischer Gymnospermen aus Shanxi (China) mit Hilfe fossiler Kutikulen. – 87th Annual Conference of the Paläontologische Gesellschaft, Dresden
Backer, M., Kerp, H.
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2017. Morphology and epidermal anatomy of Taeniopteris leaves from the Lower Permian of Shanxi, China. – 88th Annual Conference of the Paläontologische Gesellschaft, Münster
Backer, M., Kerp, H.
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2018. Reconstructing Cathaysian Cordaitales from the Permian of Shanxi (China) by the means of cuticular analysis. – 10th European Palaeobotany and Palynology Conference, Dublin, Ireland
Backer, M., Kerp, H.
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2019. Frond morphology and epidermal anatomy of Compsopteris wongii (T. Halle) Zalessky from the Permian of Shanxi, China. PalZ 93, 453–464
Backer, M., Wan, M., Wang, J.
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2019. Proposal to conserve the name Callistophytaceae against Emplectopteridaceae (Pteridospermopsida). Taxon 68, 872–873
Backer, M., Kerp, H., Bomfleur, B.
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2019. Reconstruction of a small-leaved Cordaitalean plant from the Permian of North China by means of cuticular analysis. Int. J. Plant Sci. 180, 709–723
Backer, M., Bomfleur, B., Kerp, H.
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2019. Reinvestigation of conchostracans (Crustacea: Branchiopoda) from the Permian–Triassic transition in Southwest China. Palaeoworld, 29, 368–390
Scholze, F., Shen, S.-Z., Backer, M., Wei, H.-B., Hübner, M., Cui, Y.-Y., Feng, Z., Schneider, J.W.
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2019. Reproductive biology of Cathaysian Callistophytales. – 19th International Congress on the Carboniferous and Permian, Köln
Backer, M., Bomfleur, B., Kerp, H.
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2021. Bennettitalean leaves from the Permian of equatorial Pangea—the late Paleozoic radiation of an iconic Mesozoic gymnosperm group. Frontiers Earth Sci. 9, Article 652699, 14 pp.
Blomenkemper, P., Bäumer, R., Backer, M., Abu Hamad, A., Wang, J., Kerp, H., Bomfleur, B.
