Leaf-like Rhodophycean Fossils in the Early Cambrian from Haikou, Kunming, Yunnan of China

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1 Acta Botanica Sinica 2004, 46 (11): Leaf-like Rhodophycean Fossils in the Early Cambrian from Haikou, Kunming, Yunnan of China XU Zhao-Liang (Laboratory of Systematic and Evolutionary Botany, Institute of Botany, The Chinese Academy of Sciences, Beijing , China) Abstract: This paper deals with the new leaf-like rhodophycean fossils in the Early Cambrian from Chengjiang Biota at Mafang Village of Haikou, Kunming, Yunnan, Southeast China. The new taxa Paradelesseria sanguinea gen. et sp. nov. is found to have a close relationship with the living Delesseria according to detailed morphological study between the fossil and modern Delesseria. These new findings show that the Chengjiang Biota is high in species diversity of fossil algae and might offer new evidence for a better understanding of the Cambrian explosive biological evolution and its paleoenvironment. The Biota in Haikou district of Kunming was living in subtidal and lower intertidal marine environment, up to 30 m below surface of the water based on the comparative study of extant red algae. Key word: Haikou, Yunnan; Early Cambrian; Chengjiang Biota; leaf-like rhodophycean fossils Macroscopic carbonaceous film fossils emerged in the geological history and they are generally preserved in the shales (Hofman, 1992). The morphology of all fossils changes from ellipsoids, rod-shaped, ached filamentous, ribbon-like, tubular to forked and other states. Almost no one likes leaf-like identifying megascopic algae. However, in the Proterozoic, these have been distinguished as bladelike fossils, such as Longfengshania from the Qingbaikou Group, North China and the Little Dal Group, Northwest Canada (Du and Tian, 1985; Hofman, 1985). About a decade later, the morphological similar fossils, Palmalga glumacea and Paraporphyra prota have been described from Doushantuo Formation (Late Sinian), Miaohe, Zigui, Hubei of China (Ding et al., 1996). Additionally, two years ago, the blade-like Plantulaformis sinensis and Longfengshania cordata were also described from the Early Cambrian in the Chengjiang Biota at Ercai Village, Haikou, Kunming, Yunnan, Southwest China (Xu, 2002). These findings are very important for understanding the origin and evolution of metaphytes and studying their paleoecology. This paper reports a kind of leaf-like rhodophycean fossil, Paradelesseria sanguinea in the Yuanshan Member, Qiongzhusi Formation, Early Cambrian at Mafang Village, Haikou, Kunming, Yunnan, China. 1 General Geology The early Cambrian fossil samples studied here were found in the gray muddy shale in the middle of Yuanshan Member of Qiongzhusi Formation, Anshan, behind of the Fengyu Temple, Mafang Village, about 3.5 km southeast of Haikou Railway Station, Kunming, Yunnan of China (Fig. 1). The general geology has been briefly described by Xu(2001a; 2001b). 2 Systematic Paleontology Rhodophyta Florideae Ceramiales Delesseriaceae Paradelesseria Xu, gen. nov. Type species Paradelesseria sanguinea Xu, gen. et sp. nov. Diagnosis Thallus brown, composed of stem and leaf ; stem subcylindrical, nodose, the length of internode greater than the diameter of stem ; leaf single, inserted in the stem, consisting of petiole and blade; petiole subcylindrical, blade lanceolate or oblanceolate, no veins, margins smooth. Discussion There have been no previous reports of algal fossil morphologically similar to Paradelesseria which possesses stem and leaf, but fossils with the same structure have been reported, such as: Punctariopsis from Qiongzhusi Formation, Ercai Village, Haikou, Kunming of Yunnan, China (Xu, 2001) and Miaohenella from Miaohecum, Zigui, Hubei in the Sinian (Late Precambrian) (Ding et al., 1992). The main features of these fossils are as follow: single or clumped, consisting of unbranched leaflike blade, stipe and holdfast. Paradelesseria differs from Received 10 May 2004 Accepted 29 Sept Supported by the National Natural Science Foundation of China ( ).

2 XU Zhao-Liang: Leaf-like Rhodophycean Fossils in the Early Cambrian from Haikou, Kunming, Yunnan of China Fig.1. Geographic map of fossil sites. a, village; b, railway station; c, city; d, mountains; e, temple; f, fossiliferous site; g, highway; h, river; i, railway. them in that mentioned above. Its leaf is larger in size and very thin in thickness, similar to those of some angiosperm in structure, and is inserted directly onto the stem. Those of Punctariopsis assigned to brown algae are very long, belt-like, inserted on the holdfast, and those of Miaohenella are hollow, flatted and also inserted on the holdfast. Obviously, there are many analogs of Paradelesseria among the living higher algae, especially in huge brown algae and red algae which are complex in structure and morphology and possess structural differentiation of root, stem and leaf superficially like those in vascular plants. For example, phaeophycean Sargassum, Laminaria, rhodophycean Delesseria and Phycodrys are very similar to the new genus described here in structure, morphology and size, but the leaves of Delesseria and Phycodrys clearly possess a mid-vein and that of Paradelesseria does not. Although Paradelesseria might have close relationships with Delesseria or Phycodrys, there exist some differences between them in morphology and structure, so it seems appropriate to establish the fossil as a new genus. Paradelesseria sanguinea Xu, gen. et sp. nov. Figs. 2 5 Diagnosis Stem subcylindrical, mm in length, mm in diameter, nodose; node 8.0 mm in length, mm in diameter; internode 3.0 mm in diameter, 3.5 mm in length; leaf lanceolate with petiole, tampering to acute or obtuse shape, mm in length, mm broad; blade thin, mm in length; petiole subcylindrical, mm in length, 3.0 mm in diameter. Reproductive structure unknown. Discussion Samples of P. sanguinea are rarely found in Chengjiang Biota, only three pieces samples and some fragments are well preserved. Until now, the structure and morphology of P. sanguinea were not reported in the geological history, but its characteristics are very similar to those of extant rhodophycean Delesseria sanguinea and Phycodrys radicusa. 3 Results and Discussion The rhodophycean is a large and complex organism in structure other than some single-celled ones in Bangiales. Its morphological features can be described as follow: single and forked filaments, flattened and thallus with blades, pinnate or branched, wide or narrow belt forms, hollow cylindroids and thallus with differentiation of roots, stems

3 Fig.2. Reconstruction sketch of the Paradelesseria sanguinea and leaves which look like those of extant vascular plants. If the concept of the root, stem and leaf in vascular plants is extended, the structure, which is flattened and enlarged in surface area for photosynthesis, could be called leaves. Thus, all of the higher algae, including chlorophycean, phaeophycean and rhodophycean have developed to the level of possessing stems and leaves, unlike the lower algae. Examples of this form are very abundant in the Phaeophyta, such as Sargassum, Macrocystis and Postelsia. The typical example in the Rhodophyta is Delesseria (Smith, 1955; Zhang and Liang, 1965; Fott, 1971). The tissue of giant rhodophyceans is relatively differentiated. Its chromoplast is mainly mosaiced in the surface layer of photosynthetic tissue, but no chromatoplasts occur in storage and conducting tissues. The huge red algae possess sieve plate-like structures in the conducting tissue which could be compared with the phloem of vascular plants in general. However, the xylemlike structure is not present in the red algae as they permanently live in water. So it is unnecessary to have the transfusion vessels to transfer water for a long distance and the mechanical tissue to support the erect thallus (Zhang and Liang, 1965; Fott, 1971). Different growth methods exist in red algae. Terminal growth occurs in the most of rhodophyceans. Intercalary growth occurs only in Delesseriaceae and Corallinaceae, and the diffuse growth takes place in a few red algae such as Porphyra. Concerning their reproduction, several unicellular species assigned to Bangiophycidae have vegetative propagation. Asexual reproduction mainly produces haploid tetraspores which sometimes change into abnormal polyspores and monospores. All of these spores are aflagellar aplanospores. Generally, asexual reproduction happens relatively rare in the red algae by fragmentation of thallus and also by attachment of fragments that float away and develop into new plants. Sexual reproduction is oogamous, but the process is very complex, having a special phenotype in the phytological biology. It is evident that the red algae have reached a higher plateau in evolution (Smith, 1955; Zheng and Wang, 1961). Red algae are a relatively large group, with more than 550 genera and species in the Rhodophyta. They are mostly marine, though some genera and species live in the fresh water (Smith, 1955; Fott, 1971). They are widely spreaded in the world, and mainly distributed in the ocean in the tropics and subtropics. All of them are red in color, as the benthos emerge near the seashore. The depth of the water they live in is based on the transparency of the marine water. In the relatively turbid water, such as the Atlantic, the rhodophyceans always live up to 30 m below the surface of water. In contrast, in relatively limpid waters, such as those of the Mediterranean Sea and the Floridian seashore, red algae can live down to m, and sometimes have been found growing as deep as 200 m below the water surface. There is an obvious distinct vertical zonation where all of the red algae grow only near the seashore. In general, the members of Delesseria and others grow between subtidal and lower intertidal zones (Zheng and Wang, 1961; Fott, 1971). Doubtless water temperature is an important ecological factor for the geographical distribution of red algae. Most of the species are sensitive to different water temperatures, and they can not tolerate temperature changes of more than 5 range each year. Some others, in contrast, grow well over a 10 range of marine water temperature, but only a few species can live in places where the temperature rang is greater (Zheng and Wang, 1961). In conclusion, the new discovery of rhodophycean fossils from the Yuanshan Member of Qiongzhusi Formation in the Early Cambrian, Anshan of Mafang Village, Haikou of Kunming, China, shows the high diversity of Chengjiang Biota, and might offer new evidence for a

4 XU Zhao-Liang: Leaf-like Rhodophycean Fossils in the Early Cambrian from Haikou, Kunming, Yunnan of China Figs.3-5. Paradelesseria sanguinea gen. et sp. nov. 3. Holotype, No. 0150, Paratype, No. 0149, Counterpart of Fig. 4, No. 0148, 2.5.

5 better understanding of the Cambrian explotion of biological evolution. Comparative studies of the fossils and extant algae, especially the similarity in their structure and morphology, suggest that there might be a close relationship between fossil genus Paradelesseria and living Delesseria. Based on the comparative study of extant red algae, the present results provide further evidence that the Chengjiang Biota in Haikou district of Kunming was living in a subtidal and lower intertidal marine environment within 30 m of the surface of the water. References: Ding L-F, Li Y, Hu X-S, Xiao Y-P, Su C-Q, Huang J-C Sinian Miaohe Biota. Beijing: Geological Publishing House. (in Chinese with English abstract) Ding L-F, Zhang L-Y, Li Y, Dong J-S The Study of the Late Sinian-Cambrian Biota from the Northern Margin of Yangtz Platform. Beijing: Scientific and Technical Documents Pusblishing House. (in Chinese with English abstract) Du R-L, Tian L-F Discovery and preliminary study of megaalgal Longfengshania from the Qingbaikou system in the Yanshan Mountain area. Acta Geol Sin 59: in Chinese with English abstract Fott B Algenkunde. VEB Gustav Fischer Verlag. Hofmann H J The Mid-Proterozoic Little Dal Macrobiota, Mackenzie Mountains, Northwest Canada. Palaeontol, 28: Hofmann H J Proterozoic Carbonaceous Films. Schopf J W, Klein C. The Proterozoic Biosphere: A Multidisciplinary Study. Cambridge: Cambridge Unversity Press Smith G S Cryptogemic Botany. Vol 1. Algae and Fungi. 2nd ed. New York McGraw-Hill Publish Company Ltd. Xu Z-L Discovery of Enteromophites in the Chengjiang Biota and its ecological significance. Acta Bot Sin, 43: Xu Z-L New discoveries of phaeophycean fossils in the Early Cambrian, Haikou, Kunming, Yunnan, Southwest China. Acta Bot Sin, 43: Xu Z-L The occurrence of Longfengshania in the Early Cambrian from Haikou Yunnan, China. Acta Bot Sin, 44: Zheng B-L,Wang X-Q Sea-water Algae. Beijing Agriculture Publishing House. (in Chinese) Zhang J-Y, Liang J-J Systematic Botany. Beijing: People s Education Publishing House. (in Chinese) (Managing editor: HAN Ya-Qin)