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M. MOHANTI AND C.H.C. BRUNTON 



Fig. 22 World palaeogeographical map of the Middle Devonian (from Scotese & McKerrow. 1 990) showing the distribution of Isopoma species. A - 

 Lower Devonian. Pragian; ▲ - Lower Devonian, Emsian; ♦ - Middle Devonian. Eifelian to Givetian; - Upper Devonian. Frasnian. 1 - north Spain (/. 

 hertae); 2 - Devon, England (/. lummatoniensis); 3 - Eifel, Germany (/. brachyptyctum, gryps, orthoglossa. ren. xestum); 4 - Czech Republic (/. 

 brachyptyctum, hertae, and in Pragian, /. alecto); 5 - Poland (/. brachyptyctum); 6 - west Urals (/. brachyptyctum and in Emsian. /. nekhoroshevi); 7 - 

 east Urals (/. brachyptyctum); 8 - Guizhou, China (/. brachyptyctum, ovale); 9 - Burma (/. maymyoensis); 10 -Yukon (?/. alecto); 1 1 - Ardennes (/. 

 aptyctum); 12 - Kuznetsk, Russia (/. isiliensis, ?/. lummatoniensis). 



which are on the eastward extension of the Ural-Tien Shan marine 

 belt, and brachiopods here are similar to those in Europe, including the 

 Urals. During the early part of the Middle Devonian, three facies- 

 related assemblages of brachiopods existed, reflecting different 

 palaeoecological conditions. Isopoma is associated with the Zdimir 

 community (Hou Hong-Fei, 1981) and restricted to limestone facies 

 bordering platform areas. The facies is characterized by reefal 

 limestones and biostromes composed of corals and stromatoporoids, 

 together with abundant accumulations of Zdimir shells and occa- 

 sional occurrences of other brachiopod genera. Farther to the north, in 

 western Nei Monggol (Inner Mongolia), Eifelian brachiopods of the 

 Rhenish-Bohemian Region, as well as taxa with Uralian affinites, 

 have been described by Zhang Yan (1985; 1986). This indicates a 

 biogeographic boundary transition comparable to that observed by 

 Nalivikin (in Boucot et al., 1988: 365) from the western Tien Shan. 

 Camaroforia lummatoniensis, as recorded by Anderson et al. ( 1969: 

 118) from the Eifelian of western Yunnan, may belong to Isopoma. 

 Adjacent to western Yunnan, Eifelian brachiopods with Rhenish 

 affinites have also been described from the northern Shan State of 

 Burma (Anderson et al., 1969). These Middle Devonian (Eifelian to 

 Lower Givetian) shelly faunas of Padaukpin are strikingly similar to 

 those of the Eifel region of Germany and were first described from 

 Burma by Reed (1908). The brachiopod fauna from the Padaukpin 

 beds can be compared to the Middle Devonian Rhenish brachiopod 

 faunas of the European Eifel region, Germany, the southern Cantabrian 



Mountains, Spain, and the Holy Cross Mountains, Poland. The 

 presence of Beckmannia and Isopoma in the Padaukpin brachiopod 

 assemblage adds further evidence for the European Rhenish affinities 

 of this brachiopod fauna as an eastern extension of the Rhenish- 

 Bohemian Region of the OldWorld Realm. In view of the global high 

 level of provincialism during the Eifelian, the similarity of the Middle 

 Devonian shelly faunas of Padaukpin, Burma, to those of the distant 

 Eifel region in Germany seems to be a biogeographic anomaly 

 (Boucot etal., 1988), as was also emphasized by Struve (1982b). 



Acknowledgements. We thank Prof Dr Willi Ziegler and the late DrW. 

 Struve for providing specimens from the Senckenberg Museum (Frankfurt, 

 Germany) and also for hospitality to one of us (M.M.) during a short stay at 

 the Senckenberg Museum for the research. One of us (M.M. ) is grateful to Dr 

 C.F. Winkler-Prins for providing facilities for studying Spanish collections at 

 the National Museum of Natural History, Leiden, Netherlands, and Dr and 

 Mrs C. Lalau for their kind hospitality. Mohanti is thankful to Prof Dr Hou 

 Hong-fei and Dr Chen Xiu-qin for useful discussions during a visit to China 

 and also for providing relevant literature. We thank Dr R.T. Gratsianova for 

 brachiopod information from Russia and Dr. B.I. Chuvashov for supplying 

 valuable Russian literature. We also thank Dr V.P. Kovach and Zara Frenkiel 

 for helping with Russian translation. We are grateful to Prof A.J. Boucot, Dr 

 Norman Savage and Mr Rex Doescher for their kind help in various ways. 

 Mohanti thanks Mr. Prafulla Mohanti and Mr Derek Moore for their kind 

 hospitality during visits to London. 



