Paleontologists have uncovered new dinosaur fossils near the Bulgarian town of Tran during the Eighth Paleontological Expedition organized by the National Museum of Natural History (NPM-BAS), which took place from July 28 to August 5. The excavation focused on a site rich in Late Cretaceous vertebrate remains, originally discovered on August 16, 2017, by Assoc. Prof. Latinka Hristova and Ralitsa Bogdanova. Since its discovery, the site has yielded a wealth of valuable fossils, proving far more diverse and significant than initially expected.

One of the expedition’s highlights was the discovery of an almost fully preserved dinosaur rib by Assoc. Prof. Hristova, who leads the team. The rib measures approximately 50 centimeters in length, according to reports from NPM-BAS, cited by BTA. The team for the expedition included Prof. Marlena Yaneva (Strashimir Dimitrov Geological Institute – BAS), Assoc. Prof. Docho Dochev (Sofia University “St. Kliment Ohridski”), Asst. Prof. Vladimir Nikolov (NPM-BAS), students Georgi Sevov and Martin Chavdarov, and PhD student Gergana Velyanova from the Institute of Mineralogy and Crystallography of BAS.

The eighth expedition proved highly productive, with roughly 30 new fossil vertebrate specimens recovered. Finds included bones of various sizes - some possibly belonging to dinosaurs - larger fragments of turtle shells, teeth from at least two crocodile species, a vertebra and scales from armored pike, a tooth, and fragments of amphibian bones. In addition, the team collected fossilized seeds and nuts, which could provide insights into the local flora of the Late Cretaceous period.

Alongside excavations at the main site, Hristova’s team conducted field surveys across Upper Cretaceous rock sequences between Tran and Breznik. While no vertebrate remains were found during these surveys, the collection of rare fossilized leaves from the Late Campanian suggests these sites may yield terrestrial animal bones in the future. The NPM-BAS highlighted that similar-aged rocks in neighboring Serbia have recently produced fossils of dinosaurs, crocodiles, and mammals, indicating the potential for further discoveries in Bulgaria.

The Tran collection now comprises roughly 300 fossil specimens, representing at least seven to ten vertebrate groups that inhabited the area around 83 million years ago. Among the discoveries are two groups of dinosaurs: titanosaurs, the large long-necked herbivores, and ornithischian dinosaurs, also herbivorous, which may include hadrosaurs, known for their duck-like beaks. Additionally, remains of at least two crocodile species, two turtle species, and frogs - the first amphibians from the dinosaur era discovered in Bulgaria - have been documented at the site, according to Vladimir Nikolov.

Further unusual finds include armored pikes, a type of fish now found only in regions such as the southeastern United States, Central and Latin America, and Cuba, as well as several shark teeth. These discoveries highlight the Tran site as one of Bulgaria’s richest fossil deposits from the Late Cretaceous, offering a unique window into the region’s ancient biodiversity and the ecosystems in which dinosaurs lived.