Rare Middle Triassic coleoids from Alpine-Carpathian system: A new records from Slovakia and their significance

Abstract

Abstract The two stratigraphically well constrained (by ammonites and conodonts) coleoid remains have been recorded in the Triassic (Anisian) dark-grey organodetritic limestones (Ráztoky Limestone) of Western Carpathians (Hronic Nappe). The facies originated between carbonate ramp and basinal development. It yields highly diversificated cephalopod fauna including nautiloids (2 taxa), ammonoids (7 taxa) and indetermined aulacoceratids. Two unusual coleoid specimens are referred to genus Mojsisovicsteuthis (M. boeckhi) and probably to a new taxon (described as Breviconoteuthis aff. breviconus herein) possessing similar morphological features of genus Breviconoteuthis (Phragmoteuthida) and/or Zugmontites. Based on index ammonites and conodonts, both records are of the uppermost Trinodosus through the lowermost Reitzi zones (Anisian – lower Illyrian). While the genus Mojsisovicsteuthis has been widely dispersed (however its records are rare), the occurrence of Breviconoteuthis and Zugmontites is strictly limited to the Alpine-Carpathian region. Compare to the holotype and additional specimens stored in the Hungarian Natural History Museum, the overal shell of Mojsisovicsteuthis and its size has been reconstructed. Its relationship to aulacoceratids and phragmoteuthids is briefly discussed. Geochemical record provided a relevant signal of the existence of algal meadows which may represent an analogy with later sea-grasses.