植物研究雑誌 1. 1. Jpn. Bot. 71: 71: 168-177 (1 996) A Revisioo 00 the Chioese Megafossils of F agus (Fagaceae) Yu-Sheng Lm a， Arata MOMOHARA b and Sheng-Wu MEI a aDepartment aDepartment of Palaeobotany ，Nanjing Institute of Geology and Palaeontology ， Academia Academia Sinica ，Nanjing ，210008 CHINA; bDepartment bDepartment ofEnvironmental Studies ，Chiba University ， 648 Matsudo ，Chiba ， 271 JAPAN (Received (Received on June 29 ， 1995) revision A revision on the Chinese Cenozoic megafossils of Fagus is undertaken. Seven species are recognized ， among among which one is represented by cupule fossils ，while all the others are leaves. The oldest species ，F agus sp.1 with with similarities to two Chinese living endemic beeches ， F. engleriana Seem. and F. longipetiolata Seem. ，is documented documented from the Late Eocene to Early Oligocene of Guizhou Province ，S. W. China. This species also seems to to represent the earliest megafossil record of Fagus in the world. In the meantime ， two species previously documented documented as Fagus (e.g. ， F. chinensis Li and F.? feroniae Unger) are now excluded from the genus. The present present study shows that “ F. englerian α"-like leaves were common during the Cenozoic era in China. Furthermore ，the Chinese fossil records appear to display a low diversity of beeches in the geological past as compared compared with the recent Chinese beeches. F agus is a quite small genus within the family evolutionary trend of F agus around the Pacific Ocean Fagaceae ， but it is frequently encountered in fossil during the Cenozoic. In the present paper ， an attempt floras floras of the N orthern Hemisphere. Modern beeches ， is made to revise the beech megafossils reported from however ， are now disjunctly restricted to temperate China and then discuss their geological history. zones zones and mountainous regions of the subtropics in the the Northern Hemisphere (Chang and Huang 1988). Materials and Methods China with more than half of the species in the genus Fossil specimens checked by the present authors F agus ranks as one of the main centers of distribution. 訂 e mainly housed at the N anjing Institute of Geology These Chinese species are now distributed in the and Palaeontology ，Academia Sinica. Those which mountains mountains of southern China (Cao 1995). are not available to us were examined on the basis of More and more paleobotanical works have pro- published accounts. As most of the Chinese materials vided vided details on the fossil Fagus ，particularly from are leaves ， which all are only preserved as impres- Japan ， North America and Europe (e.g. ， Tanai 1974 ， sions ， a foliar architectural analysis on most of extant Zetter Zetter 1984 ， Minaki 1985 ，Kvacekand Walther 1991). Fagus was undertaken for comparisons with fossils. Unfortunately ，no review ofthe Chinese fossil records Cleared leaves were prepared by using a routine has has been carried ou t. Tanai (1974) excluded the Chi- method (Hickey 1973 ， Li 1987). Hickey's terminol- nese nese beech fossils in his comprehensive paper on the ogy on foliar morphology (Hickey 1979) is followed -168 ー June June 1996 Joumal of Japanese Botany Vo l. 71 No. 3 169 through through the present paper. species of Fagus in China (see Table 1， Figure 1). For Hill Hill and Read (1991) noted that leaf architecture of easier recognition ，a simple key to the species is given modem Nothofagus (Fagaceae) alone has limited first. value value for infrageneric taxonomy. Liu (in pr~ss a) mentioned a similar case for betulaceous leaves. Our Key to the fossils of the Chinese F agus recent recent study on leaf architecture of F agus shows that 1. Material preserved as leaves it it is also true for F agus although the foliar architec- 2. Laminas big ，and number of secondary veins tural tural characters between the only two J beeches apanese high (ca. 16) …...・ H ・..…..，・ H ・.....・ H ・.....・ H ・..F. sp. 1 (Fagus crenata B l. and F. japonica Maxim.) are quite 2. Laminas small ，and numbe .r of secondary veins useful useful for classification. Without strong evidence ，it about 10... ・H ・......・ H ・....・ H ・....・ H ・-…...・ H ・-… .F. sp. 2 might be a safe way for current revision that uncertain 2. Laminas in middle size ，number of secondary specific specific names are applied for most cases. veins around 8-13 3. 3. Margin entire to undulate …・ Fossil Fossil Records of F agus in China …...・ H ・...F. engleriana Seem. About 779 megafossil species belonging to 281 3. Margin se 打 ate genera genera and 99 families ofhigherplants and bryophytes 4. Leaf index low (ca. 187) ，and leaf base cor- reported reported from the Chinese Cenozoic up to and includ- date ...・ H ・..…...・ H ・.....・ H ・..…… F. praelucida Li ing ing 1993 have been found throughout the country 4. Leaf index high (more than 200) (Li u，Guo and Ferguson ， in press) ， but there are only 5. Margin between adjacent teeth more or less a few fossils of F αgus documented in the Chinese straight ...・ H ・.F. stuxbergi (Nathorst) Tanai literature. literature. Meanwhile ， these fossils ， mainly leaves ， 5. Margin between adjacent teeth convex .…・ 訂 e mostly poorly preserved. Although features of …F. galbanifolia Guo vegetative vegetative and reproductive organs in F agus are rela- 1. Material preserved as cup 'u les ....・ H ・....・ H ・.F. sp. 3 tively tively stable (Jones 1986) ，misidentifications are still being being made in the Chinese paleobotanicalliterature. 1) Fagus sp. 1，Zhang ， Papers Stra t. Paleon t. 138 ， pl. The following is a brief revision of the seven fossil 1 ，fig. 15 (1 983) [Fig. lA] Table Table 1. Comparison of megafossil species of F agus in China a Taxa Taxa Size Number of Living Geological secondary secondary veins equivalent(s) age F. F. sp. 1 10 cm x 5 cm 16 F. engleri α na/ Late Eocene to F. F. long 伊etiolata Early Oligocene F. F. galh αnifolia 4-6 cm x 1.8-2.2 cm 8-10 F.lucida Oligocene F. F. sp. 2 3 cm X 1. 2 cm 10 F. multinervis/ Oligocene F. F. engleriana F. F. stuxbergi 4-10 cm X 2-5.6 cm 1cト 13 F. engleri αna Early 恥1iocene F. F. engleriana b ヲ 8-10 F. engleriana Miocene F. F. praelucida 5.6 X 3 cm 8-9 F.lucida Pliocene F. F. sp. 3 0.9 cm (l ength) F. engleriana/ Early Pleistocene F.lucid ，α aAll aAll the taxa are fossilleaves except that F. sp. 3 represents cupules. bThe bThe size of the species is unknown. 170 170 植物研究雑誌第71 巻第3 号 平成 8 年 6 月 Fig. Fig. 1. Selected fossilleaves of F agus from China. A: F agus sp. 1. B: F. sp. 2. C， D: F. galbanifolia Guo. Bar = 1 cm. Discussion: Discussion: One fossil leaf reported by Zhang is extremely difficult to elucidate which one is cor- (1 983) is actually two broken of portions beechlike rec t. laminas laminas which are overlapped each othe r. Consider- Zhang (1 983) assigned the fossils to the Eocene in ing ing features of margin and secondary veins of the age on basis the ofleaf assemblages and stratigraphical lower lower lamina ， the pronounced zigzag midrib and correlation. Recently ， she thought it might be as late relatively relatively straight secondary veins of the upper leaf ， as the Late Eocene to Early Oligocene (Zhang per- the the two broken leaves should be attributed to the sonal communication). genus genus F agus even though no strong evidence presents. Material: Deposited at the Guizhou Regional Geo- A concept of Tanai' s leaf index (l ength/width x logical Survey. 100) 100) (see Tanai 1974) is employed for identifying Locality and age: Panxian County ，Guizhou Prov- different different species within the genus of F αgus. The index ince ， southwestern China; Late Eocene-Early is is quite simple and convenient to group fossil beech Oligocene. leaves. leaves. For the cu 打 ent fossils ，their estimated leaf 2) Fagus galbanifolia Guo ，Paleon t. Atlas Jilin 571 ， indexes indexes are probably around 200 ， which show the pl. 262 ，figs. 4，8 ，9 (1 992). [Fig. C1 ，D] fossiIs fossiIs might be close to F. engleriana Seem. in the Discussion: The fossilleaves with their relatively “Fagus grand ゆlia group" (see Tanai 1974). How- well preserved venation pattern and distinct tooth ever ，Zhang (1 983) suggested that the fossil leaves morphology indicate that even in the absence of a resembled resembled that of F. longipetiolata Seem. Anyhow ，it cuticle they should be attributed to the genus Fagus. June June 1996 Joumal of Japanese Botany Vo l. 71 No. 3 171 The most evident character is the comparatively big ， it is also possible that both of the fossil species in this asymmetrical asymmetrical teeth with convex/acuminate basal side locality could belong to one and the same species. and straight/concave apical side. This distinct feature However ， in order to substantiate this idea ，more has has not been documented in any fossils from China. material is needed. The present treatment can only be Therefore ， the specific status of the cu 汀 ent fossil considered as provisiona l. should should be reasonable. It appears that the fossil has entire or undulate Judging Judging from the tooth morphology ， the following margin although Guo (1 992) reported as being ser- extant extant species are probably closed to the present rate. The gross mo 叩hology of the fossil is rather fossils ， those are F. crenat αB， l. (in Japan; only se 町 ate similar to those of young leaves of F. multinervis type) ， F. hayatae Palib. ex Hayata var. zhejiangensis N akai. Furthermore ， the present fossil is also closed to Liu Liu & Wu (in Zhejiang Province ， eastem China) ， F.