The genus Discoceras (Tarphyceratida, Cephalopoda; Ordovician) from Estonia and glacial erratics in north-central Europe Author Aubrechtová, Martina Institute of Geology, Czech Academy of Sciences, Rozvojová 269, Prague, 16500, Czech Republic. & University of Tartu, Faculty of Science and Technology, Institute of Ecology and Earth Sciences, Department of Geology, Ravila 14 a, 50411 Tartu, Estonia. aubrechm@gmail.com Author Korn, Dieter Museum für Naturkunde, Leibniz-Institut für Evolutions-und Biodiversitätsforschung, Invalidenstrasse 43, 10115 Berlin, Germany. dieter.korn@mfn.berlin Author Kröger, Björn Finnish Museum of Natural History, University of Helsinki, P. O. Box 44, Fi- 00014, Finland. bjorn.kroger@helsinki.fi text European Journal of Taxonomy 2026 2026-01-29 1036 1 54 https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3173/14109 journal article 314311 10.5852/ejt.2026.1036.3173 58eef89e-653a-483e-8d9e-1ac617c7d923 2118-9773 18479586 0784B061-33CD-498B-B6D6-5CA4CF5BC2E4
Table 2. Parameters and ratios used for the description of the specimens of the genus Discoceras Barrande, 1867 studied herein.
Parameter [unit]Abbrev.Calculation
conch diameter [mm]dm–
whorl height [mm]wh–
whorl width [mm]ww–
umbilical width [mm]uwdm1-wh1-wh2
apertural height [mm]ahdm1-dm2
imprint zone [mm]izwh1-ah
whorl expansion rate (outline)WERdm(dm /dm)2 1 2
whorl expansion rate (apertural height)WERah[dm /(dm -ah)]2 1 1
imprint zone rateIZRiz/wh
umbilical width indexUWIuw/dm
conch width indexCWIww/dm
whorl width indexWWIww/wh