PROBABLE CONNECTIONS OF THE MESOZOIC ADRIATIC CARBONATE PLATFORM WITH SURROUNDING CONTINENTAL AREAS AS INDICATED BY DINOSAUR TRACKWAYS

The Adriatic Carbonate Platform (AdCP) is one of the best preserved Perimediterranean platforms. During the Paleogene collision of the Adria microplate and the Eurasian continental plate the disintegrated AdCP became part of the Dinarides, the mountain chain connecting the Alps with the Hellenides along the NE Adriatic coast of Slovenia, Croatia and Montenegro, known as locus typicus of karst.

An almost continuous existence of vertebrates, mostly dinosaur trackways, has been confirmed in the NW part of the AdCP (NW Croatia, NW Slovenia, NE Italy) as well as in one locality in Dalmatia (S Croatia) from the latest Jurassic (or earlier?) to the end-Cretaceous. The older tracks belong to large dinosaurs of African affinity, the Mid-Cretaceous ones to smaller endemic animals indicating temporary isolation, and the Late Cretaceous tracks belong to larger dinosaurs including hadrosaurids confirming their Eurasian affinity.

Numerous trackway findings in the NW part of the AdCP revised the traditional paleogeographic interpretation of the AdCP as an isolated carbonate platform. Furthermore, the previously documented paleoisland in Istria could not provide enough food and fresh-water to support such rich assemblages, while numerous levels with dinosaur tracks and their predominantly Gondwanan and Eurasian origin indicate the existence of more or less continuous land bridges to these large continental areas except during a temporary isolation in Mid-Cretaceous.

The exact position of such land bridges is unknown, but outcrops on the Adriatic islands and hinterland indicate more or less continuous inner platform carbonate deposition, while seismic profiles along the SW AdCP margin indicate aggradational architecture with continuous deposition along the platform margins. Therefore, the land bridges probably existed along the NE platform margin, which is supported by a long-lasting stratigraphic hiatus recorded in central Slovenia, Croatia and Bosnia and Herzegovina. Bridges may have been enabled by the Late Jurassic compressional tectonics in the area, while during temporary emergences of the AdCP (Aptian/Albian emergence recorded on the entire platform and Late Cretaceous emergences of various blocks due to the beginning of platform disintegration) large animals migrated across different parts of the AdCP.