Ordovician-Silurian boundary graptolites of the Southern Alps, Austria

Abstract

Seven species of graptoloid graptolites are described from Hirnantian and lower Rhuddanian formations of the Austrian part of the Carnic and western Karavanke Alps. The Plöcken Formation, of latest Ordovician (Hirnantian) age, yields the biozonal index graptolite <i>Metabolograptus persculptus </i>in the Cellon Reference Section and, tentatively, the Feistritzgraben Section. A distinctive graptolite assemblage indicating an earliest Silurian (early Rhuddanian) age comes from the Waterfall Section near Zollnersee Hütte. Along with the presence of the biozonal index <i>Parakidograptus acuminatus </i>and accompanying taxa, common <i>Rickardsograptus</i>? <i>bifurcus </i>(Ye) has been recorded - for the first time outside China. The absence of <i>Neodiplograptus lanceolatus </i>Štorch & Serpagli, <i>Normalograptus trifilis </i>(Manck) and other easily recognizable lowermost Rhuddanian species which are dominant in this level throughout peri-Gondwanan Europe indicates the peculiar character of the <i>acuminatus </i>Biozone assemblage encountered in the Carnic Alps

Earliest Silurian graptolites from Kalpin, western Tarim, Xinjiang, China

“…He suggested that many narrower forms should be reassigned to N. ajjeri, a similar species with narrower width. This idea obtained some support from Štorch & Schönlaub (2012). One of the Chinese N. normalis specimens from the Yangtze region has a relatively wide and blunt proximal end and a small rhabdosome width, which may suggest a close relationship to N. ajjeri (Chen et al 2005, text- fig.…”

The Bohemo‐Iberian regional chronostratigraphical scale for the Ordovician System and palaeontological correlations within South Gondwana

“…This is the third or fourth Gondwanan record of this uppermost Ordovician assemblage (Underwood et al . ; Loydell ; Štorch & Schönlaub ). Probably the same ‘interregnum’ at high palaeolatitudes may be an equivalent to the uppermost Ordovician Spinachitina oulebsiri–Euconochitina moussegoudaensis chitinozoan assemblage, recorded from northern Chad and SE Libya (Thusu et al .…”

Revised conodont stratigraphy of the Cellon section (Silurian, Carnic Alps)

“…The overall thickness of Silurian strata does not exceed 60 m. The Silurian transgression in the region started at the beginning of the Llandovery. The duration of the gap separating the Ordovician and Silurian successions is highly variable and a rock succession corresponding to several conodont zones of Llandovery or Llandovery to Early Wenlock age is locally missing (Schönlaub & Histon ; Štorch & Schönlaub ).…”

“…(), graptolites by Jaeger (), Jaeger et al . (), Štorch & Schönlaub (), foraminifers by Langer (), Kristan‐Tollmann (), ostracods by Schallreuter (), acritarchs by Martin () and subsequently by Priewalder (), chitinozoans by Priewalder (, , ), trilobites by Haas () and Santel () and corals by Pickett (). In addition, after Walliser (), Ferretti & Schönlaub () studied the distribution of conodonts in the Hirnantian in the Cellon section.…”