The rate of origination of chitinozoan
species increases considerably within this biozone (Nestor 2009b): 9-10 species appear in the Kolka, Ohesaare, Ruhnu and Kaugatuma cores, fewer in the others.
The data from the Ikla core have been used for elaboration of the regional chitinozoan
Only a few very poorly preserved (unidentifiable) chitinozoan
and scolecodont remains were found.
The succession begins with the upper-most part of the lower Wenlock chitinozoan
Interzone IV, established between the Margachitina margaritana and Conochitina manilla biozones (V.
The stratigraphical position of the ash beds was established using chitinozoan
and graptolite biozonation (Gailite et al.
Their opinion was based on lithological correlation with sections on the Estonian mainland and the stratigraphical distribution of the chitinozoan
Cyathochitina regnelli sensu Nolvak & Grahn (1993).
For example, those of the ostracodes Plicibeyrichia numerosa-Undulirete baltica (Sarv 1982; Gailite 1986); the thelodont Thelodus sculptilis (Marss 1997); the conodont Ozarkodina crispa (Brazauskas 1993; Viira 1999); and the chitinozoan
Eisenackitina barrandei (Nestor 2009).
Morphs A and B occur (in the Stirnas-18 core) with the Hindella-Cliftonia brachiopod Association in the lower part of the Conochitina scabra chitinozoan
The first attempt to divide the upper Silurian of the Ohesaare core section on the basis of chitinozoan
assemblages was made by Nestor (1976).
Those of seven chitinozoan
biozones are presented according to Nestor (2009, 2011, 2012), seven conodont ones from Viira & Aldridge (1998) and Viira (1999, 2000) and seven vertebrate indices according to Marss (1986, 1997) and Marss & Mannik (2013).
Precise time-correlation in the Ordovician can be achieved by biostratigraphical methods, particularly using graptolite, conodont and chitinozoan
In the chitinozoan
biozonation, the Eisenackitina rhenana Subzone of the Laufeldochitina stentor Zone corresponds to the lower part of the Kukruse Stage (Nolvak & Grahn 1993; Nolvak 1997).