[N] 2005 Late Jurassic dinosaurs of Istria
Mezga, A., Bajraktarevic, Z., Tetovic, C.B. & Gusic, I. (2005) First record of the dinosaurs in the Late Jurassic sediments of Istria, Croatia (preliminary report) 1st Meeting of the EAVP Natural History Museum Basel
All fossil remains of dinosaurs on the Adriatic carbonate platform (which is now outcropping along the eastern coast of the Adriatic Sea) came from the Cretaceous sediments. Recently, a new locality with the Upper Tithonian dinosaur footprints have been discovered. The site is situated in an active quarry front near the village Kirmenjak in the central Istria
The site consists of the peritidal limestones and the Upper Tithonian age was proved by microfossil assemblage found in stylolitised mudstones: Clypeina jurassica FAVRE, Salpingoporella annulata CAROZZI, Campbelliella striata (CAROZZI) and Favreina sp. The footprints are situated on the top of a fenestral mudstone layer that could be interpreted as an emersion surface. The intertidal environment and influence of meteoric water are indicated not only by fenestral fabrics but also by geopetal infillings of cavities, desiccation cracks and the presence of dinosaur footprints.
The site is very rich in footprints, some few hundreds of them have been found on the outcrop. The majority of the footprints show an oval or horse-shoed shape without clearly visible digit impressions and are relatively shallow (10-20 mm). Although the state of preservation is far from ideal, it is concluded that the prints, regarding morphology, belong to the sauropod dinosaurs. The oval prints would respond to the pes prints and the horse-shoe shaped ones to the manus prints. The footprints are of various dimensions; manus prints show the length range between 100 – 250 mm, pes prints between 350 – 500 mm. The calculated height at the hip ranged between 2.06 - 2.95 m.
Dozens of trackways can be observed on the outcrop and they frequently overlapp. There are also some areas which are heavily trampled by sauropod foots. The main direction of dinosaur movements was toward E-NE and because there are a number of parallel trackways it could be concluded that some of the individuals were moving together (indication of gregarious behavior). A large number of the trackways disappeared below the quarry surface and probably extend further. Some of the trackways show characteristics of a narrow-gauge type, some of them are slightly wider but none shows the wide-gauge character. The pace and stride lengths indicate slow walk of the individuals. The ichnocoenosis from this outcrop could be assigned to the Brontopodus ichnofacies.
The presence of the large sauropod dinosaurs on the Adriatic carbonate platform during the Upper Jurassic could be explained by its connection with the African continent via its southern margins. The sauropods could have migrated into the area during an emersion phase when the platform was exposed to subaeric conditions. There had to be a widespread continental area in the hinterland in order to support the survival of such large terrestrial herbivores as were the sauropod dinosaurs.