UPPER ORDOVICIAN BRACHIOPODS FROM KAZAKHSTAN 



27 



Table 7 Additional list of brachiopod taxa from localities in the Anderken Formation not referred to a particular association 



Sample number 

 Number of specimens 



42 

 3 



1628 

 4 



8215 

 10 



620 

 13 



8251a 



8135 



Glyptomena onerosa 

 Christiania aff. sulcata 

 Craspedelia tata 

 Dulankarella larga 

 Mabella conferta 

 Sh lyg in ia frag His 

 Anaptambonites orientalis 

 Sowerbyella! aff. ampla 

 Sowerbyella rukavishnikovae 

 Triplesia aff. subcarinata 

 Placolriplesia spissa 

 Grammoplecia wrighti 

 Plectorthis burultasica 

 Eodalmanella extera 

 Dolerorthis pristina 

 Pionodema opima 



0:1:0 



1:0:0 

 0:0:1 



2:0:0 



2:0:0 



1:3:0 



1:4:1 

 0:1:0 



2:1:0 

 1:0:0 



0:1:0 

 5:7:2 



2:1:8 

 1:0:1 

 2:0:1 



0: 1 :0 



0:1:0 



2:0:0 



relative abundance and taxonomic composition from one sample to 

 another, which may reflect its opportunistic character and higher 

 environmental stress, whereas the Mabella-Sowerbyella Associa- 

 tion, in spite of its low diversity (4 to 8 genera per sample), shows a 

 relatively constant taxonomic composition in most samples (Table 

 3), and this association forms a compact cluster in the Principal 

 Components Analysis (Fig. 9). Comparison with somewhat younger 

 Ctenodonta-Sowerbyella,Altaethyrella-Nalivkinia (Pronalivkinia) 

 and Dinorthis Associations of the lower Dulankara Formation which 

 inhabited similar environments on the shallow clastic shelf on the 

 Chu-Ili Plate in the late Caradoc-early Ashgill (Popov et al. 2000), 

 suggest a rapid faunal turnover. In these younger faunas Sowerbyella 

 and Shlyginia retained their dominant position and Anoptambonites 

 also remained a characteristic minor component, but most of the 

 Anderken genera disappeared (e.g. Tesikella, Eodalmanella and 

 Pionodema) or moved into the middle shelf {Mabella and 

 Glyptomena) and were replaced by rhynchonellides such as 

 Altaethyrella and atrypides such as Nalivkinia (Pronalivkinia). In 

 contrast, the orthides (e.g. Plaesiomys, Bokotorthis and Dinorthis) 

 became increasingly abundant. 



The diverse Acculina-Dulankarella and Parastrophina-Kellerella 

 Associations, which were closely linked with carbonate build-ups, 

 have little in common with the faunas which inhabited shallow 

 clastic shelves nearby. In the Acculina-Dulankarella Association 

 strophomenides remain the most abundant brachiopods but they are 

 mostly different genera, such as Bellimurina, Teretelasmella, 

 Craspedelia, Acculina, Dulankarella. Kajnaria and Sortanella. 

 Anoptambonites occurs in both associations, but as different species. 

 Mabella and Shlyginia are mostly confined to the Mabella- 

 Sowerbyella Association, as well as occurring in a few samples of the 

 Acculina-Dulankarella Association, but as less than 5% of the 

 sample (Table 4). They disappear in the Parastrophina-Kellerella 

 Association (Table 5), which is possibly the earliest known 

 brachiopod assemblage in which pentamerides together with spire- 

 bearing taxa come to a dominant position. In contrast to the 

 brachiopod fauna of the shallow clastic shelf, assemblages associ- 

 ated with carbonate build-ups did not undergo any significant 

 taxonomic change during the Caradoc. The late Caradoc to early 

 Ashgill brachiopod fauna of the Dulankara carbonate mud-mound in 

 the north Betpak-Dala Desert (Nikitin et al. 1 996), which was also on 

 the same Chu-Ili Plate, retained a close similarity to the Anderken 

 fauna and contained 14 genera in common including Parastrophina 

 and the early athyridides Kellerella and Nikolaispira. The 



strophomenide component was largely unchanged and such genera 

 as Bellimurina, Limbimurina, Christiania, Craspedelia, Sortanella 

 and Anoptambonites are common to both faunas. 



The significance of the Foliomena fauna was discussed by Cocks 

 & Rong (1988) and Rong et al. (1994, 1 999). In the Lower to Middle 

 Caradoc it was confined mostly to South China and only in the 

 Ashgill did it become cosmopolitan. In Kazakhstan there are no 

 previous reports of the occurrence of Foliomena, but the associated 

 Ovalocephalus trilobite fauna occurs in many outer shelf environ- 

 ments from the Middle Caradoc (Apollonov 1975; Nikitin et al. 

 1974). In the Anderken Formation Foliomena itself is not restricted 

 to BA 4—5, but occurs occasionally in the Parastrophina-Kellerella 

 (Sample 8223) and Mabella-Sowerbyella (Sample 8228) Associa- 

 tions. However, the other taxa, which include the two new genera and 

 species Olgambonites insolita and Zhilgyzambonites extenuata 

 together with rare Anisopleurella, Chonetoidea and Kassinella, are 

 not present in shallow shelf associations. In addition, there are seven 

 localities (Table 7) whose brachiopods cannot be referred with 

 confidence to any of the six named associations. 



Although comprehensive comparisons of the Anderken faunas 

 with other contemporary brachiopods from elsewhere are beyond 

 the scope of this paper, it is worth noting here that the total Anderken 

 assemblage has much in common with that described from north- 

 west China (Fu 1982). 



SYSTEMATIC PALAEONTOLOGY 



Figured and cited specimens are housed in the Natural History 

 Museum. London (BB and BC collection numbers). Institute of 

 Geological Sciences, Almaty, Kazakhstan (IGNA collection num- 

 bers), and in the CNIGR Museum, St. Petersburg, Russia (CNIGR 

 collection numbers). All the quoted sample numbers are from the 

 Anderken Formation except where stated. Bibliographical refer- 

 ences to families and above are omitted if they are in the Treatise on 

 Invertebrate Paleontology (Kaesler 2000). 



Abbreviations given in tables of measurements and in the text are: 

 Lv, Ld - sagittal ventral and dorsal valve length; W - maximum 

 width; T - maximum thickness; Ml, Mw - length and width of the 

 muscle field; Sw, St - width and height of tongue in the ventral valve; 

 BB1, BBw length and distance between outer margins of 

 brachiophores or socket ridges; SI - length of median ridge; LP1, 



