47. on the Oriental Province of the Tethyan Realm in the Triassic Period

No. 7] Proc. Japan Acad., 59, Ser. B (1983) 203

47. On the Oriental Province of the Tethyan Realm in the Triassic Period

By Teiichi KOBAYASHI,M. J. A., and Minoru TAMURA (CommunicatedSept. 12, 1983)

Palaeontological studies on the Triassic Bivalvia well advanced in Japan in last three decades, in The Thai-Malay Peninsula and Singapore in last two decades and in China in last decade. These new results are schematized with those of Himalaya, Indochina, Indonesia and Primoria of the USSR in order to sketch the faunal aspect, because the Bivalvia bears greater importance for provinciality than the ammonoids and conodonts which are, on the contrary, two keen indices for age-determination. Recently Nakazawa (1975) and Yin (1981) have discussed the early Triassic provinciality with reference to Claraia and Eumor- photis. On the basis of Claraia griesbachi concentrica Yabe and C. multistriata intermedia Ichikawa and Yin from the Gua Musang formation on the Kelantan-P'ahang border, however, it is acceptable that Malay was located in the eastern Tethyan province in the Skytian age. Li and Ding (1981) instituted two new Olenekian genera, Peri- claraia and Guichiellca respectively in the Pectinidae and Pterinidae, both indicating endemism in the lower Yangtze region. Our knowledge is better advanced on the Middle and Upper Triassic bivalves, particularly Carnian and Norian ones. Their com- parison is made with the European ones in the level of genera. As a result many European members are known now to be Eurasiatic ones as follows. Hof eria Bittner, 1894. Middle and Upper Triassic ( Ladinian-Carnian), Alps; Upper Trias. (Norian), Yunnan Protopia Kittl, 1904. Lower-Upper Trias. (Carnian), Alps-Balkan,Qing- hai, Timor Pleuronectites Schlotheim, 1820. Mid.and Up. Trias., Europe (Germany, France, S. Alps) ; Anisian, Qinghai; Ladinian, Guizhou; Anisian and Carnian, Japan AmonotisKittl, 1904. Up. Trias. ( Carnian), Yugoslavia,Guizhou, Qing- hai Enteropleura Kittl, 1912. Anisian-Norian, Alps, Hungary; Anisian, Qinghai Pergamidia Bittner,1891. Up. Trias. ( Norian), Anatolia, Tibet, Qinghai, Yunnan, Timor Arcavicula Cox, 1964. Mid. and Up. Trias., Europe; Norian, Hubei, Up. Trias., Qinghai 204 T. KOBAYASx1and M. TAMURA [Vol. 59(B),

Mysidiella Cox, 1964. Ladinian-Rhaetian, Alps, Hungary, Anatolia, Greece; Norian, Sichuan Protopis Kittl, 1904. Lower-Upper Trias., South Alps, Balkan, Timor; Norian, Sichuan Chlamys (Antijanira) Bittner, 1901. Up. Trias., Hungary; Carnian, Guizhou Plicatula (Pseudoplacunopsis) Bittner, 1895. Up. Trias., Europe-Jordan- Indonesia, Mid. Trias. Malay (Pahang), Japan Badiotella Bittner, 1890. Mid. Trias. (Ladinian), S. Tirol; Up. Trias, Guizhou Heminajas Neumayr, 1891. Low.-Up. Trias., Austria, Hungary; Up. Trias., Guizhou Myophoricardium von Wohlmann, 1889. Up. Trias. (Carnian), Alps, Sicily, Hungary, Jordan; Norian, S. Tibet, Yunnan Palaeocardita Conrad, 1867. Up. Trias. (Rhaetian), Tirol; Norian, S. Tibet, Yunnan; Up. Trias., Sichuan Leptoch,ondria Bittner, 1891. Low.-Up. Trias., S. Tirol; Low. Trias., Qinghai; Anisian, Qinghai, Sichuan, Yunnan Rhaetidia Bittner, 1895. Trias, Europe; Norian, Yunnan.

Recently the junior author described Grunewaldia decussata and Elegantinia sp. from Kumamoto Pref., Kyushu and some bivalves of St. Cassian affinity from the Buko limestone near Tokyo (1972, 1981) and discovered Dicerocardium cf, himalayensis and other megalodontids in the Yaritaoshi limestone along the Kuma river, south Kyushu, Japan (Tamura, 1981). Isozaki and Matsuda (1982) found Rhaetian conodonts including Epigondorella posthernsteini in the limestone. In China megalodontids are reported to occur in the Middle Triassic of Guizhou and the Anisian Gulandgi group and the Carnian-Norian Jieza group, both in Qinghai. A few species of megalodontids are also reported from Upper Triassic of Yunnan and Guizhou. Five species of Neomegalodon from the Carnian of Primoria (Kiparisova,1972) indicate the eastern terminus in Eurasia. Putting aside cosmopolitans, many Eurasiatic genera are thus distributed from the Alps to China, Indochina, and USSR. They as a whole show that the faunal relationship between the oriental and occidental sides of the Tethyan realm is closer than thought before. At the same time, however, it can hardly be overlooked that there are many genera indigenous to Eastern and Southeastern Asia. They have been instituted for Indonesian, Burmese and Himalayan bivalves. More than ten genera were added to them in China as follows :

Parahalobia Yin and Hsu, 1938. Mid.-Up. Trias. Yunnan (Ladinian- Anisian), Sichuan, Qinghai Ynnnanophorus Chen, 1962. Norian, Yunnan, Qinghai, Sichuan, Jiangxi, V1~t-Nam Quadrata Yin, 1974. Mid. and Up. Trias., Guizhou No. 7] Oriental Province of Tethyan Realm 205

Veteranella (Ledoites) Chen, Wen et Lan,1974. Carnian-Norian, S. Tibet Cardium (Tulongocardium) Chen, J. Chen et Zhang, 1976. Up. Trias., Himalaya, S. Tibet, Qinghai, Viet-Nam, Eur.-Asia Jiangxiella Liu, 1976. Up. Trias. (Carnian), Jiang-xi Prostrea Chen, 1976. Mid. Trias. (Anisian), Guizhou Radiastarte Chen et Liu, 1976. Up. Trias. (Carnian) , Hunan Sichuania Chen et Liu, 1976. Up. Trias., Sichuan, Yunnan, Qinghai, S. Tibet Tulongella Chen et J. Chen, 1976. Up. Trias. (Norian), Tibet, Burma Jianchuania Chen et J. Chen, 1980. Up. Trias., Yunnan. Most of these genera are indigenus to China, but Cuspidaria sp. inlet. by Healey is a Napeng member referred to Tulongella. Cardium (Tulongocardium), is an exception of a large Eurasiatic genus comprising more than 13 species, all Upper Triassic and mostly Norian of Yunnan, Laos, Viet-Nam, Indonesia and Singapore where in the last it is represented by Cardium (s.l.) scrivenori Kobayashi and Tamura. Cardium cloacinum Quenstedt, 1858 referred to this genus is a Rhaeto-Norian species most extensively distributed as far as Yunnan and Viet-Nam from Germany and the Alps in the west. Beside these genera there are some Himalayan, Burmese and Indonesian genera whose occurrences were found later in the Triassic of China, for example

Datta Healey, 1908. Upper Trias., Burma (Napeng) , Kashimir, Yunnan Krumbeckia Diener, 1908. Upper Trias., Sumatra, Yunnan Lilangina Diener, 1908. Upper Trias., Kashimir; Carnian Guizhou Pomarangina Diener, 1908. Upper Trias., Himalaya, Sichuan Prolaria Healey, 1908. Upper Trias., Burma (Napeng), Yunnan and Guizhou ( Norian) , Armenia, Indonesia. Burmesia Healey, 1908 was originally a Napeng genus, but now its distribution is expanded from Norian to Liassic and from Jordan to Japan through Burma and Indonesia. Likewise, Indopecten Douglas, 1929 is distributed in the Upper Triassic rocks in Himalaya, Qinghai and easterly in Primoria, USSR, although it is unknown from Japan. Prosogyrotrigonia Krumbeck, 1924 is known from Timor and South Tibet in Upper Triassic and P'rorotrigonia Cox from Ceram and South Tibet also in Upper Triassic rocks. Krum- beckiella Ichikawa, 1958 is reported from Upper Triassic of Timor and Norian of Yunnan and Tibet. Except for Burmesia, Indopecten and Prolaria these genera are endemic to Himalaya, China and Indonesia. Catella primarily described by Healey from the Napeng series, Burma is distributed widely in the Upper Triassic-Jurassic period. The boundary between the oriental and occidental provinces 206 T. KoBAYASHIand M. TAMURA [Vol. 59(B), appears not very sharp. It was probably shifted from time to time to east or west to some extent, but it was presumed that the oriental province was generally extended as far as Pamir-Kashmir. Myophoria s. str. and Costatoria are two important genera most flourished in the Triassic period, but the center of distribution was the occidental province for the former and the oriental province for the latter. The Middle Triassic transgression took place in the occidental province through which the Muschelkalk sea flooded northerly into the German basin and westerly into the western Mediterranean basin and further the Parana basin, Brasil. Giebel's two small genera, Leproconcha and St orthodon are indigenous to the Muschelkalk sea. Isocyprina (Eotrapezium) Douville, 1912 occurs in the Upper Tri- assic (and Lower Jurassic) rocks of Europe and South America, but it is as yet uncovered in Asia. Coelopis (Cyrtocoelopis) Bittner, 1895 is a Middle Triassic genus endemic to Austria. At the transition from the Triassic to the Jurassic period the Rhaetian sea again ingressed through the Viderian mountains. There the Avicula contorta beds were deposited. Rhaetavicula founded on this species had the trans-Pacific distribution as far as Nevada, but the Rhaetian sea was quite limited in the oriental province.

References

Committee of Chinese Lamellibranch Fossils, Nanjing Inst. Geol. Palaeont., Acad. Sinica (1976) : Fossil Lamellibranchiata of China. 522 pp., 150 pls. Hayami, I. (1975) : A systematic survey of the Mesozoic Bivalvia from Japan. Univ. Mus. Univ. Tokyo, Bull. no. 10, 249 pp., 10 pls. Kobayashi, T., and Tamura, M.: The Triassic bivalvia of Malaysia, Thailand and adjacent areas. Geol. Pal. SE Asia, 25 (in press). Tamura, M. (1981) : Preliminary report on the Upper Triassic megalodonts discovered in South Kyushu, Japan. Proc. Japan Acad., 57B, 290-295. Tamura, M. et al. (1975) : The Triassic system of Malaysia, Thailand and some adjacent areas. Geology and Palaeontology of Southeast Asia (GPSEA), 15, 103-149. Vu Khuc et al. (1965) : Les f ossiles caracteristiques du Trias au Nord Viet-Nam. 118 pp.