Late Cretaceous dinosaur remains and other tetrapod fauna from the vicinity of Tran town (Western Srednogorie)

Abstract

Brief conference report on a new Late Cretaceous tetrapod fossil site near the town of Tran (Western Srednogorie), Western Bulgaria, with notes on its dating and palaeoecology. Collected fossil material indicates presence of at least two groups of non-avian dinosaurs, crocodylomorph, and testudines.

Palynostratigraphy of dinosaur bone-bearing deposits from the Upper Cretaceous of Western Bulgaria

“…The preliminary taxonomic evaluation of the fossil assemblage at the Vrabchov dol locality indicates a rich late Santonian-early Campanian vertebrate fauna (Nikolov et al 2018), potentially one of the best found in Europe so far. Future comparisons with the Santonian vertebrate fauna of Hungary are of major interest, because they may reveal a lot about the isolated Late Cretaceous insular faunas, their composition and differences in between, and eventually elucidate the palaeobiogeography and migration history of some tetrapod groups.…”

“…The sedimentary sequences of the formation are deposited predominantly in shallow marine palaeoenvironments, but sediments deposited in foreshore to lagoonal depositional environments also occur. The studied section has a total thickness of 8 m and is composed of grey to light grey marls, silicified marls, coal and coaly shales (Nikolov et al 2018;Text-fig. 2).…”

“…2). The relationship to the underlying and overlying rock successions is unclear in the outcrop since the boundaries are covered by shrubs, grass and soil (Nikolov et al 2018). Thus, the early Campanian age of the Rezhantsi Formation accounts only for the shallow marine sediments of this formation and is not suitable for the entire section studied.…”

“…The Upper Cretaceous Western Srednogorie sedimentary rock succession at Vrabchov dol, a gully exposed between the villages of Bankya and Vrabcha in Western Bulgaria, has recently revealed a diverse tetrapod fauna, including fragmentary dinosaur bones. On the basis of osteohistological features, the dino-saur bones, attributed to the clade Titanosauria, represent the first documented occurrence of this group in Bulgaria (Nikolov et al 2018). The sediments hosting the bones are represented by fine-grained terrigenous rocks and thin coal layers assigned to the Rezhantsi Formation and, based on calcareous nannofossils, so far dated to the early Campanian (Sinnyovsky et al 2013).…”

“…Remains of non-avian dinosaurs in Bulgaria are exceedingly rare, with all of the dinosaur material known so far being derived from the upper Maastrichtian bioclastic limestones recognised as the Kajlâka Formation (Jolkičev 1986) from north-western Bulgaria (Godefroit and Motchurova-Dekova 2010;Mateus et al 2010;Nikolov et al 2018). The recent age assessment of the Kajlâka Formation is based mainly on late Maastrichtian echinoids and rare ammonite species (Jolkičev 1986(Jolkičev , 2006 but lacks palynological data.…”