Middle Ordovician Drepanoistodus (Vertebrata, Conodonta) from Baltica, with description of three new species
Open Access
- 8 October 2021
- journal article
- research article
- Published by Museum National D'Histoire Naturelle in European Journal of Taxonomy
- Vol. 774, 106–134
- https://doi.org/10.5852/ejt.2021.774.1533
Abstract
Drepanoistodus basiovalis (Sergeeva, 1963) is a common conodont species in Middle Ordovician strata of Baltica. For many years it has been widely accepted that the species encompasses a wide range of morphological plasticity. Hence, several different morphotypes that significantly deviate from the holotype have nonetheless been included in the broad species concept. In this study, we performed a detailed taxonomical study on 112 predominantly well-preserved specimens (geniculate elements) from the St. Petersburg region of Russia; 37 of these were selected for morphometric analyses together with 21 well-illustrated specimens from the published literature. The results demonstrate that, among the morphotypes that share some characteristics with D. basiovalis sensu lato, at least five species can be readily distinguished. Hence, three new species – Drepanoistodus iommii sp. nov., D. svendi sp. nov. and D. viirae sp. nov. – are here added to the previously known D. basiovalis and D. contractus (Lindström, 1955). In addition, some specimens were left under open nomenclature and assigned to Drepanoistodus aff. basiovalis and D. cf. suberectus (Branson & Mehl, 1933). In order to objectively compare the Drepanoistodus taxa and test the validity of the new species, we performed a Principal Component Analysis combined with non-parametric (PERMANOVA) tests based on 21 morphological characters.Keywords
This publication has 50 references indexed in Scilit:
- The origin of conodonts and of vertebrate mineralized skeletonsNature, 2013
- High resolution trilobite stratigraphy of the Lower–Middle Ordovician Öland Series of BaltoscandiaGeological Magazine, 2012
- Conodont dating of the Middle Ordovician breccia cap-rock limestone on Osmussaar Island, northwestern EstoniaEstonian Journal of Earth Sciences, 2012
- Darriwilian (Middle Ordovician) conodont biostratigraphy in NW EstoniaEstonian Journal of Earth Sciences, 2012
- False teeth: conodont-vertebrate phylogenetic relationships revisitedGeodiversitas, 2010
- The new chronostratigraphic classification of the Ordovician System and its relations to major regional series and stages and to δ 13 C chemostratigraphyLethaia, 2009
- Untangling a Darriwilian (Middle Ordovician) palaeoecological event in Baltoscandia: conodont faunal changes across the ‘Täljsten’ intervalEarth and Environmental Science Transactions of the Royal Society of Edinburgh, 2009
- Resolving early Mid-Ordovician (Kundan) bioevents in the East Baltic based on brachiopodsGeobios, 2008
- First Middle Ordovician biota from southern New Brunswick: stratigraphic and tectonic implications for the evolution of the Avalon continentCanadian Journal of Earth Sciences, 2003
- Faunal composition and dynamics in unconsolidated sediments: a case study from the Middle Ordovician of the East BalticGeological Magazine, 2003