48. the Arcto-Pacific Realm and the Trigoniidae in the Triassic Period

No. 7] Proc. Japan Acad., 59, Ser. B (1983) 207

48. The Arcto-Pacific Realm and the Trigoniidae in the Triassic Period

By Teiichi KOBAYASHI, M. J. A., and Minoru TAMURA

(Communicated Sept. 12, 1983)

The great development of the Trigoniidae is one of prime sig- nificances in the Arcto-Pacific realm in the Triassic period, because only three Triassic species of T'rigonia have been described from Europe, namely, Trigonia geytani Klipstein, 1848 from the St. Cas- sian, Trigonia (?) azzarolae Stoppani, 1861 from the Rhaetic of the Alps and T. zlambachiensis Haas, 1909 from the Ladino-Carnian of east Alps. As shown below, the family is now represented by 11 genera and a subgenus in four subfamilies besides Caledogonia Freneix and Avias, 1977 from the Carno-Norian, New Caledonia whose suprageneric reference is undetermined.

a. Trigoniinae Lamarck, 1819 1. Trigonia Lamarck, 1819 1-1. Kumatrigonia Tamura, 1959 2. Guineana Skwarko, 1967 b. Minetrigoniinae Kobayashi, 1954 3. Minetrigonia Kobayashi and Katayama, 1938 4. Myophorigonia Cox, 1952 5. Maoritrigonia Fleming, 1962 6. Perugonia Kobayashi and Tamura, 1968 c. Prosogyrotrigoniinae Kobayashi, 1954 7. Prosogyrotrigonia Krumbeck, 1924 8. Prorotrigonia Cox, 1952 d. Praegoniinae Fleming, 1962 9. Praegonia Fleming, 1962 10. Agonisca Fleming, 1963.

The Trigoniidae suddenly appeared with Trigonia tabacoensis Barthel, 1958 from the Anisian of Chile. Morphologically it is pre- sumable that the Trigoniinae were derived from the common ancestor with Gruenewaldia of the Myophoriidae. Next oldest is the Prae- goniinae which consists of two Ladinian genera in New Zealand, resembling Neoschizodus or N. (Laeviconcha) closely. The Upper Triassic Prosogyrotrigoniinae branched off in Southeast Asia proba- bly from the Praegoniinae. It is highly probable that the Minetrigoniinae were derived from Costatoria (Kobayashi and Tamura, 1967). This is the largest subfamily of the Triassic Trigoniidae and Minetrigonia the largest 208 T. KOBAYASHI and M. TAMURA [Vol. 59(B),

genus of the subfamily. It is represented by 2 species and 1 sub- species in Japan and 3 or more species in eastern Siberia in addition to some 15 species allied to Minetrigonia in China (Yunnan), New Zealand, Peru, Ellesmereland and Bear Island, as listed below. The authors have already commented on these minetrigonioids and in- stituted Perugonia on Myophoria jaworskii Steinmann, 1929 from the Carnian or Norian of Peru. Nine species and a subspecies of minetrigonioids in British Columbia suggest that western Canada will be proved to be a center of distribution for Minetrigonia by studies on their hinges. It is certain that the family Trigoniidae was evolved from the Myophoriidae polyphyletically and its wide divergence has taken place already in the middle and late Triassic age (Kobayashi and Tamura, 1968).

Myophoria szechenyii Loezy, 1898, Middle Triassic or Carnian (Diener, 1923), Yunnan, South China Trigonia margarita f era Boehm, 1903, Carnian, Bear Island Cardita (?) ursina Kittl, 1907, Carnian, Ellesmereland Myophoria suttonensis Clapp and Shimer,1911, Carnian, British Columbia Myophoria heslingtonensis Trechmann, 1928, Carnian, New Zealand Myophoria pascoensis Steinmann, 1929, Carno-Norian, Peru Myophoria (Elegantinia) grahami McLearn, 1941, Upper Carnian, British Columbia, Canada Myophoria adornata McLearn, 1943, Upper Triassic, B.C. Myophoria carnesi McLearn, 1943, Norian, B.C. Myophoria zaballos McLearn, 1943, Norian, B.C. Myophoria laeta McLearn, 1946, Norian, B.C. Myophoria laeta eminens McLearn, 1946, Norian, B.C. Myophoria heslingtonensis regalis McLearn, 1946, Carnian, B.C. Myophoria urbana McLearn, 1947, Carnian, British Columbia. In Japan about 175 species in some 50 genera are known of the Triassic Bivalvia, the major part of which is Upper Triassic. Palaeo- cucullaea, Trigonucula*, Asoella, Tosapecten, Cardinioides, Mine- phorus*, Minetrigonia, Kumatrigonia and Sakawanella* are nine Triassic genera founded on Japanese species three of which marked with asterisks are indigenous to Japan. Recently Kumatrigonia was found in the Carnian of Qinghai and the Tibetan side of Himalaya. Waagenoperna Tokuyama, 1959, i.e. Edentula Waagen, 1907, non Nittzsch, 1820 is distributed in Japan and central Europe in the range from Middle Permian to Upper Triassic. Its 2 species are known from the Ladino-Carnian in Japan and another 2 from the Carnian in Hunan, China. Asoella occurs in Japan in the Carnian-Norian rocks. In China it appeared already in the Middle Triassic age. Cardinioides in the range from Carnian to Liassic in Japan on the other hand survived probably until later Jurassic in Thailand. Minetrigonia (?) sp. from Pahang No. 7] Arcto-Pacific Realm and Triassic Trigoniidae 209 combined with Asoella listed from the Upper Triassic of Sarawak, West Borneo suggest any relationship of the Triassic fauna of West and East Malaysia with the Japanese fauna. Megalodontids occur in the Carnian of Primoria and the Rhaetian of Japan showing the terminus of the Tethyan fauna in Eurasia. Curionia, Pseudo- myoconcha and Myophoriopsis are other Eurasiatic genera reaching southern Primoria, USSR. The Upper Triassic bivalves of Japan are so closely related to those of eastern Siberia, particularly Primoria that some species of Oxytoma, Otapiria, Tosapecten and Mytilus (Falcimytilus) occur in both areas. Oxytoma Meek (Upper Trias.-Upper Cretaceous) and Cardinia Agassiz (Up. Trias.-Liassic) are 2 genera flourished in Japan and eastern Siberia in the upper Triassic age. Palaeophorus Kittl is an Upper Triassic genus extensively distributed in Bear Island, Ellesmere Island, eastern Siberia and Japan. These Japanese bivalves are related to the east Siberian ones no less than the Tethyan ones. Bureiomya Boronetz, 1937 and Ocho- tom ya Polutko, 1966 were proposed as 2 new genera in Northeastern Siberia, USSR in the Pholadomyidae and Ceromyidae respectively, but the former was synonymized with Pholadomya Rollier in Coss- mann, 1912. Hokonuia Trechmann, 1918, Carnian N.Z. Maoritrigonia Fleming, 1952, Carno-Norian, N.Z., New Caledonia Manticula Waterhouse, 1960, Carnian, N.Z., N. Caledonia Praegonia Fleming, 1962, Ladinian, N.Z. Agonisca Fleming, 1962, Ladinian, N.Z. Guineana Skwarko, 1967, Carno-Norian, N. Guinea Caledogonia Freneix and Avias, 1977, Ladinian or Carnian, N. Caled. Monotis (Inflatomonotis) Grant-Mackie, 1978, Norian, N.Z. Monotis (Maorimonotis) Grant-Mackie, 1978, Norian, N. Caled., N.Z. Bakevellia (Spia) Skwarko, 1981, Carno-Norian, N. Guinea. The Triassic bivalves of New Zealand, New Caledonia and New Guinea constitute a distinct fauna by the above genera. The faunal connection between the north and south sides of the Western Pacific can, however, be recognized with some genera. Marwick instituted Otapiria primarily on Pseudomonotis marshalli Trechmann from the Lias of New Zealand, but it is known now to be wide spread in the western Pacific areas, namely in Primoria or further in eastern Siberia and Japan, as P'leuromysidia Ichikawa, 1954 is synonymized with Otapiria (Hayami, 1975). Triaphorus Marwick, 1913 founded on Pleurophorus zealandicus Trechmann from the Upper Triassic of New Zealand is another genus occurring in Primoria. Palaeo- cucullaea Tokuyama, 1960 which is acceptable as a subgenus of Parallelodon in a range from Carnian possibly to Liassic, is dis- 210 T. KoBAYASHIand M. TAMURA [Vol. 59 (B), tributed from Japan to eastern Siberia in the north and probably to New Zealand in the south. Incidentally, Maoritrigonia( ?) bittneri (Newton) in the Carnian Mount Faber fauna and the lower Norian Jurong fauna both in Singapore suggests the Maorian affinity. Schizocardita Korner, 1937 and Pascoella Cox, 1949 together with Perugonia reveal endemism of the Andine fauna. Burckhardtia Frech, 1907 from the Upper Tri- assic of Mexico is an eastern Pacific genus. Rhynchopterus Gabb, 1964 and Myophorigonia Cox, 1952 are two Arcto-eastern Pacific genera. Finally, Monotis Bronn, 1830 is an Upper Triassic cosmopolitan genus. It has long been divided into Monotis s. str. and M. (Ento- monotis) Marwick, 1935. Lately Grant-Mackie (1978) added three more subgenera, i.e.. Eomonotis, Maorimonotis and Inflatomonotis, the last two being endemic to New Zealand and New Caledonia and represented by 2 and 1 species respectively. Prior to this Wester- mann (1973) classified Monotis species into five groups, namely the salinaria, typica, ochotica, subcircularis and zabaikalica groups and figured out their distribution explicitly. Recently Monotis subcircu- laris Gabb was found at Kuap, Sarawak, East Malaysia (Tamura and Hon, 1977). In adding this discovery to Westermann's distri- bution map, Borneo is the junction of the three Monotis seas, pre- cisely the salinaria group is distributed from Europe-Himalaya to Borneo, the ochotica group from Siberia to Borneo through Japan and the subcircularis group from Canada to New Zealand and Borneo through the east Pacific coast. Alaska may be another junction of the three groups in the Arcto-boreal areas. The zabaikalaca group is a western Pacific one; the typica group an Arcto-Pacific one, but unknown from the Andes.

References Fleming, C. A. (1964) : Austral. J. Sci., 26(7), 196-204. Freneix, S., and Avias, J. (1978) : Alcheringa, 1, 279-291. Grant-Mackie, J. A. (1978) : N. Z. Jour. Geol. Geophys., 21(1) , 97-111. Kobayashi, T., and Tamura, M. (1967) : Fossils, no. 14, pp. 40-47. (1968) : GPSEA, 5, 88-137, pls. 12-14. Tamura, M. (1972) : Mem. Fac. Educ. Kumamoto Univ., Nat. Sci., no. 21, pp. 66- 72, p1.1. (1981): ibid., no. 30, pp. 5-18, pls. l-3. Tamura, M., and Hon, V. (1975) : GPSEA, 18, 29-31, pl. 4. Westermann, G. E. G. (1973) : The Late Triassic Bivalve Monotis. Atlas of Palaeobiogeography (ed. Hallam, A.). pp. 251-258.