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Geological structure of the Vrátna dolina Valley in the Krivánska Malá Fatra Mts. is composed of two main Western Carpathian tectonic units – Tatricum and Fatricum (Krížna nappe). Tatricum is represented by almost all common lithostratigraphic members, although mainly the Jurassic and Cretaceous sediments are either strongly reduced, or completely missing. Based on our field observation, sedimentary cover is thrusted over its own crystalline basement accompanied by the reduction of lowermost sedimentary formation – Lúžna Fm. Situation in the Krížna nappe rock sequence is even more extremly reduced. Radiolarian limestone of the Ždiar Fm. (Oxfordian) is the oldest lithostratigraphic unit. This causes considerable problems in defining the stratigraphic range of the particular units. We have defined the individual rock members into tectonic units on the basis of lithological character, because tectonic repetition or superposition of sedimentary sequences was not observed. All rock members form one apparently continuous sequence with stratigraphic range from the Paleozoic to the Early Cretaceous. We present different interpretation of the geological setting on the ridge under the Vrátna ropeway. Chaotic configuration and/or repetition of the Triassic members were documented in the older maps, which could indicate assumed folding or duplex structures. However, we suppose that these complications are the result of younger slope deformation, rather than the older tectonic deformations.

An eosauropterygian skeleton found in the Middle Triassic (upper Anisian) Gutenstein Formation of the Fatric Unit (Demänovská dolina Valley, Low Tatra Mountains, Slovakia) represents the earliest known occurrence of marine tetrapods in the Western Carpathians. The specimen represents a partly articulated portion of the postcranial skeleton (nine dorsal vertebrae, coracoid, ribs, gastral ribs, pelvic girdle, femur and one zeugopodial element). It is assigned to the Pachypleurosauria, more precisely to theSerpianosaurus–Neusticosaurusclade based on the following combination of features: (1) small body size; (2) morphology of vertebrae, ribs and femur; (3) tripartite gastral ribs; and (4) microanatomy of the femur as revealed by μCT. Members of this clade were described from the epicontinental Germanic Basin and the Alpine Triassic (now southern Germany, Switzerland, Italy), and possibly from Spain. This finding shows that pachypleurosaur reptiles attained a broader geographical distribution during the Middle Triassic, with their geographical range reaching to the Central Western Carpathians. Pachypleurosaurs are often found in sediments formed in shallow, hypersaline carbonate-platform environments. The specimen found here occurs in a succession with vermicular limestones in a shallow subtidal zone and stromatolitic limestones in a peritidal zone, indicating that pachypleurosaurs inhabited hypersaline, restricted carbonate ramps in the Western Carpathians.