PLATY LIMESTONES
(OR THE STORY OF ROCKY
FISH AND REPTILES)
A very interesting facies that extends along the Adriatic carbonate platform for the Cretaceous period is the very recognisable platy limestones. Exposed platy limestones of varying lithological properties can be seen at a number of localities along the Adriatic coastal belt. These deposits have been the subject of intensive study by scientists and laypersons for more than 200 years, primarily due to the relatively common finds of highly attractive fossil vertebrates, especially fish. Therefore, the Adriatic coastal region is considered a classic locality for Cretaceous vertebrates, and is noted as such in the global palaeontological literature (such as Romer, 1966). The platy limestone facies is a prime area of very valuable and beautiful specimens of fossil fish, that have since become scattered amongst private collections, monasteries, and global scientific institutions and museums. The Geology and Palaeontology Department of the Croatian Natural History Museum also holds a unique collection of fossil fish that primarily originated from the platy limestones of the island of Hvar. They were collected for the museum and determined at the end of the 19th century by the great Croatian palaeontologist, Dragutin Gorjanović-Kramberger.
The fish fossil deposits of the island of Hvar (called ichthyofern deposits), according to the global palaeontology literature, are considered to be classic fossil deposits from the Upper Cretaceous that bear witness to the development of the living world nearly 100 million years ago. Though since ancient times and widely promoted by writer Alberto Fortis in the 18th century, they would only become a part of the global literature after the systematic research of Dragutin Gorjanović-Kramberger. He studied them, describing the Cretaceous fish of the Dalmatian islands (Hvar, Brač and Šolta), and the fossil fish of the karst rock surrounding Trieste (Komen and Mrzlek), describing many new species and genera of extinct taxa of the past. His detailed descriptions, morphological analysis and comparison with similar finds continue to be fundamental knowledge of contemporary palaeontology of the vertebrates, contained within many textbooks.
Platy limestones on the island of Hvar
However, fossil fish are not such a common find, and cannot be found just anywhere. On the island of Hvar, deposits containing fossil fish have been discovered in the middle of the island, in the area between Vrbanj and Vrbosko, in the facies of the platy limestones. The facies is defined by the overall rock properties: lithological, palaeontological, mineralogical, and structural. The facies of the platy limestones is easily recognisable, and extends broadly along the Adriatic carbonate platform. Exposed thin layers of these platy limestones of varying lithological properties have been identified at numerous localities along the Adriatic coastal belt.
NEXT