Lower Ordovician Conodonts of Europe

Abstract

In Europe, a Lower Ordovician conodont zonation can be established for the calcareous, partially condensed succession of the Baltic Shield. Sporadic conodont occurrences in the graptolitic shale fades can be correlated with this zonation. The Tremadocian to Llanvirnian Series are dealt with, and eleven conodont zones are established in these series. From below, these are the zones of Cordylodus angulatus, Paltodus deltifer (both Tremadocian), Paroistodus proteus, Prioniodus elegans, P. evae (corresponding to the Arenigian extensus Zone), Baltoniodus triangularis, B. navis, Paroistodus originalis, Microzarkodina parva (corresponding to the main part of the Arenigian hirundo Zone), and Amorphognathus variabilis (top of hirundo Zone, Llanvirnian bifidus Zone). For handling the material, some new taxa have had to be described. The taxonomy is based on multielement species, where such can be established. The multielement species are defined on morphologic and statistical criteria, as well as on the pattern of evolution. The taxonomic approach allows a more "natural" classification on the suprageneric level than the form-taxonomy previously used for this material. An evolutionary pattern is discernible for the drepnodids (each species containing drepanodiform and oistodiform elements) and the prioniodids (species containing prioniodiform elements, branched compound elements with symmetry transition, and oistodiform elements). On a suggestion from Professor 0. H. Walliser, elements belonging to multielement species are distinguished by adding the ending "-form" to the name of the genus they would have been brought to in a purely formal taxonomy. The word formed in this 21 on July 10, 2015 memoirs.gsapubs.org Downloaded from 22 SYMPOSIUM ON CONODONT BIOSTRATIGRAPHY way is an adjective. The following new taxa are named: Drepanoistodus gen. nov., Paroistodus, gen. nov., Protopanderodus, gen. nov., Stolodus, gen. nov., Baltoniodus, gen. nov., Microzarkodina, gen. nov., Microzarkodina parva n. sp., M. ozarkodella n. sp. The following genera are redefined:

Lower–Middle Ordovician δ13C chemostratigraphy of western Baltica (Jämtland, Sweden)

“…The base of the Tøyen Shale is apparently diachronous, belonging to the Tetragraptus phyllograptoides Zone in some areas and the Phyllograptus densus Zone, equivalent to the upper Baltograptus minutus Zone of Maletz and Ahlberg (2011), in other areas. The lowermost, graptolite-bearing shales in sections recording the Tøyen Shale in the area south of Storsjön (near Brunflo) fall in the P. densus Zone, and in terms of conodont biostratigraphy roughly correlate to the basal part of the Oepikodus evae Zone (Lindström, 1971). The base of the Lanna Limestone is normally characterized by the occurrence of the Megistaspis lata (= Megistaspis polyphemus) trilobite zone in Jämtland (Karis, 1998), whose age is slightly older than the base of the Baltoniodus triangularis conodont zone (Löfgren, 1994), indicating that deposition of the Lanna Limestone may have started in the latest Floian.…”

“…The correlation chart for the Ordovician in the Brunflo area provided by Wickström (2007) is followed herein ( Fig. 3; based on Bergström, 1971;Lindström, 1971;Löfgren, 1994;Karis, 1998;Wickström, 2007;Pärnaste et al, 2013).…”

“…Chart showing the correlation of lithostratigraphy in Brunflo with the Baltoscandian graptolite, trilobite, and conodont zones. Modified fromBergström (1971),Lindström (1971),Löfgren (1994),Karis (1998),Wickström (2007),Maletz and Ahlberg (2011) andPärnaste et al (2013).…”

Ordovician vertebrate habitats: A Gondwanan perspective

“…New conodont samples collected from the middle unit during this study have yielded a few hundred specimens, including Erismodus (Bran son and Mehl 1933), Paraprioniodus? (Ethington and Clark 1982), Drepanoistodus (Lindström 1971) and Oistodus (Pander 1856) that accord with a broad Darriwilian age. Cope (2004: fig.…”

Conodont biozonation in the upper Arenig of Sweden

“…The Microzarkodina parva Zone was first defined, as an assemblage zone, by Lindström (1971) to include the interval 'where Protopanderodus cornuformis coexists with Microzarkodina and Scandodus brevibasis'. He correlated this interval with the Langevoja Substage (upper part of the Volkhov Stage; see Fig.…”