In situ finds of aptychi in the Barremian of the Alpine Lower Cretaceous (Northern Calcareous Alps, Upper Austria)

Lower Barremian deposits (KB1-B) of Upper Austria yield some extraordinarily preserved ammonoids withLamellaptychus -type lower jaws in their body chambers. The ammonoids with in situ lower jaws are referable toKarsteniceras ternbergense sp. nov. This new occurrence was detected during palaeoecological and sedimentological studies at an outcrop in the Ternberg Nappe in Upper Austria. The jaw apparatuses are found in situ or in an isolated condition but are associated with a mass-occurrence of the genus Karsteniceras, which contributes 91% of the total ammonite fauna. Most of the lower jaws are flattened, but their characteristic mode of occurrence with conchs of the Tethyan ammonoidKarsteniceras allows their use as indicators of palaeobiogeography, palaeobathymetry and palaeoecology.