A COMPLEX RECONSTRUCTION OF THE PALEO-ECOLOGICAL CONDITIONS FOR A BARTONIAN-AGE FISH FAUNA FROM THE TRANSYLVANIAN BASIN OF ROMANIA

Eocene-age fossil vertebrates of Romania are poorly known and have been overlooked by researchers until recently. This is particularly true with respect to marine fishes. Here, we report preliminary findings on the Bartonian age species-rich fish fauna from Romania’s Transylvanian Basin, including its faunal composition and paleo-ecological conditions. The Floresti site in this basin is associated with the Ciuleni Member of the middle Eocene-age Mortănușa Formation, a marine deposit in an outer, open marine facies.

Shark remains from the Floresti site represent four orders and include Hemiscyllium sp., Pseudabdounia claibornensis and P. recticona, Scoliodon conecuhensis, Squatina prima, and Jaekelotodus trigonalis. Batoid remains from this site represent two orders and include Acroteriobatus sp., Pristis sp., Jacquhermania duponti, Aktaua kizylkumensis, Rhinoptera sp. and Archaeomanta hermani. Teleost remains represent at least seven orders and include Acanthuridae, Ariidae, cf. Balistes sp., Albula oweni, and Sphyraena sp. Many of the fish taxa recovered from this site represent first records for the Eocene of Romania.

In addition to the fish faunal elements recovered, macroinvertebrates were also well represented and included echinoid, cirripede, mollusk, and decapod crustacean taxa. Foraminifera and calcareous nannoplankton were also collected from this site and studied. The overall integrative approach to the study of the Floresti site allowed for an improved picture of the ecological conditions present when the vertebrates lived at this site.

The combined preliminary data from the microfossils and fishes document a middle-late Bartonian (NP17) marine fauna. This fauna appears to have occurred in a low-energy, muddy, marine shelf complex having tropical temperatures. Sortation and some high-energy laminations indicate possible storm-grade layers. The paleoecology and food web of the Floresti site is inferred from already established paleo-associations and reinforced by the corresponding ecology of modern taxa. The results of this paleontological study have the potential to help advance the knowledge of marine faunas of the Paleogene.