UPPER ORDOVICIAN BRACHIOPODS FROM KAZAKHSTAN 



25 



tecturmasi, Dulanaspis levis anderkensis and Styginella 

 macrophtalma, whereas Bmnteopsis extraordinaris, Pliomerina sp. 

 and Remopleurides sp. are relatively rare. Bivalved molluscs include 

 Anderkenia ledomorpha, Clionichia crispa, Edmondia obliqua and 

 Praemyopltorisl antiqua (Khalfin 1958), and gastropods are repres- 

 ented mostly by Lophospira cribrosa Vostokova. Other fossils include 

 unidentified fenestrate and ramose bryozoans of at least three differ- 

 ent species, cystoid and crinoid columnals identified by Stukalina 

 (1988) as Clivosisystis clivosus, Communicystis communis, 

 Digiticrinus levis , Ordinacrinus punctatus, Ristnacrinus bifidus and 

 Shizocrinus lentiformis, the cystoidean Polycosmitesl sp. and the 

 starfish Stenaster obtusus. 



4. Acculina-Dulankarella Association (Diversity Index 3.14; 

 observed range 1.25-5.07, N=5) is characteristic of a nodular algal 

 limestone with abundant dasyclad algae which was deposited in the 

 base and flanks of carbonate build-ups in the upper Anderken Forma- 

 tion. It is a medium to high diversity association defined by the 

 occurrence of the plectambonitoideans/\ccM//'«fl kulanketpesica and 

 Dulankarella larga. Other brachiopods include Teratelasmella 

 chugaevae, Kajnaria rugosa, Gacella institata and Austinella 

 sarybulakensis which do not exceed 5% in other associations. Other 

 components of the assemblage are taxa common in the Parastrophina- 

 Kellerella Association (Tables 4-5), whereas Christiania egregia is 

 the only abundant species characteristic also of the Mabella- 

 Sowerbyella Association. Mabella conferta and Shlyginia fragilis 

 occur sporadically and do not exceed 5% in a particular sample. There 



are abundant green algae: Apidium parvulum, Cyclocrinites nikitini, 

 Mastopora reticulata, Mastopora nana and Sinuatipora bucera and 

 the red alga Contexta binaria (Gnilovskaya in Nikitin et al. 1974). 

 Small organic build-ups up to 30cm across of the algae Girvanella and 

 Renalcis are also characteristic and encrust brachiopod shells and 

 green algae. The substrate was mainly of silt and lime mud with 

 patches of hardground and numerous bioclasts.The abundance of 

 brachiopods preserved as conjoined valves (45-64%) in combination 

 with the abundant flora of algae suggests quiet environments within 

 the euphotic zone of BA-3. Strophomenides (61-90%) constitute the 

 most diverse and abundant component of the brachiopod fauna. The 

 second most abundant group is the camarelloideans (4-14%), mostly 

 Parastwphina iliana and relatively rare Parastrophina plena, Eoana- 

 strophia unicostata, Liostrophiapravula and Schizotretina margarita, 

 which do not exceed 5% in a particular sample; and orthides, 

 rhynchonellides and spire-bearing groups form an insignificant part 

 of the association. Among other groups trilobites are the most abun- 

 dant. These were partly studied by Weber (1948) and Chugaeva 

 (1958), but details remain inadequate. The most characteristic taxa 

 are: Illaenus sp.,Acrolichas punctata, Cheirurus sp., Eokosovopeltis 

 romanovskyi, Mesotaphraspis spinosus, Pliomerina sulcifrons and 

 Sphaerexochus sp. A diverse echinoderm fauna was identified mostly 

 from cystoid and crinoid columnals (Stukalina 1988). Among mol- 

 luscs the most characteristic is the cephalopod Discoceras 

 kazakhstanensisBarskov. The rare coralsAmsassia sp. andLichenaria 

 sp., clathrodictyid stromatoporoids, gastropods and bivalved mol- 

 luscs are also reported, but remain poorly known. 



Table 5 Composition of Parastrophina- Kellerella Association from the Anderken Formation showing number of complete shells, ventral and dorsal valves 

 respectively. 



Sample number 



948 



2538 



8214 



8226 



8217 



8223 



8223a 



8223b 



8256 



Number of individuals 



200 



200 



33 



12 



13 



15 



18 



9 



31 



Diversity index 



2.64 



4.91 



2.63 



1.61 



2.34 



2.58 



3.11 



2.76 



2.33 



Nushbiella dubia 





0:1:1 











0:1:0 







Bellimurina sp. 



0:2:1 



0:1:0 



1:2:0 













0:1:0 



Limbimurina sp. 





0:0:1 













0:0:2 





Christiania aff. sulcata 





0:2:1 



1:4:1 



0:1:0 



0:1:0 



0:2:0 



0:1:1 



0:2:1 





Foliomena prisca 













0:0:1 









Craspedelia tata 



2:2:1 



8:4:3 



1:2:0 









0:1:0 



0:1:0 





Kajnaria rugosa 













1:1:0 









Sortanella aff. quinquecostata 



3:2:1 



4:0:2 

















Anoptambonites convexus 





9:6:2 









0:3:1 







1:3:4 



Sowerbyella aff. ampla 



2:2:1 



3:1:1 



2:2:2 





0:2:0 





3:1:0 



1:0:0 





Trip/esia aff. subcarinata 





2:0:0 

















Placotriplesia spissa 





3:1:7 







2:1 







1:1:0 







0:0:1 



Grammoplecia wrighti 











2:1 















Skenidioides sp. 







1 



0:0 



0:1:0 









0:1:0 





Dolerorthis pristina 



4:5:7 



0:1:1 



2 



1:3 





0:0:1 



0:0:1 





0:1:0 





Glyptorthis sp. 



0:2:1 



2:2:1 



3 



1:1 









0:1:1 





0:0:1 



Plectorthis burultasica 





3:1:1 

















Phaceloorthis sp. 





1:0:0 

















Bowanorthisl devexa 



7:0:0 



5:0:0 

















Phragmorthis conciliata 





2:0:1 











0:0:1 







Parastrophina iliana 



15:0:0 



15:0:1 















2:0:0 



Parastrophina plena 



62:0:0 



17:0:1 



3:0:0 



2:1:1 



2:0:0 





1:0:0 



1:0:0 



5:0:0 



Uistrophina tesikensis 



14:0:0 



















Liostrophia pravula 



7:0:0 



13:0:1 









3:0:0 







3:0:0 



Plectosyntrophia ? unicostata 





1:0:0 







0:0:1 











Sch izostroph ina marga rita 





16:0:0 







0:0:1 



0:0:1 







5:3:2 



Didymelasma cf. transversa 





1:0:0 

















Rhynchotrema akchokense 



2:0:0 



2:0:0 

















Pectenospira pectenata 



14:1:1 



3:0:0 



1:0:0 









3:0:0 







Kellerella misiusi 



15:0:1 



39:0:0 





2:0:0 



5:0:0 





2:0:0 





5:0:0 



Nikolaispira guttula 



13:0:0 



20:0:0 





1:0:0 







2:0:0 







Acculina sp. 





0:1:1 

















