In an abandoned limestone quarry (Kamenjak) near Arandjelovac (central Serbia), a fossiliferous fissure filling rich in vertebrate remains has been discovered. The quarry Kamenjak is situated on a ridge of the Venčac Mountains, 500 meters to the west of the top. The fissure is approximately 8 meters long with a maximum width of 70 centimeters, trending in north-south direction. It cuts the layers of weakly metamorphized slates and marbles of the Late Cretaceous age (Turonian-Sennonian). The fissure is filled with bone breccia full of bone fragments in reddish matrix of clay, carbonates and limonite.
In this site several samples of bone breccia were collected in 1980 and 1989. Some bones of large and small mammals were extracted from these samples and preliminary described. In this work remains of the following species of rodents have been identified: Spermophilus citelloides (Kormos, 1916), Microtus nivaloides Forsyth Major, 1902, Microtus (Terricola) arvalidens Kretzoi, 1958, Arvicola sp. (cf. cantiana-terrestri), Clethrionomys glareolus (Schreber, 1780), Lagurus sp., Cricetus cricetus Linnaeus, 1758, Mesocricetus newtoni Nehring, 1898, Cricetulus migratorius (Pallas, 1773), Apodemus sylvaticus (Linnaeus, 1758), Apodemus microps (van Kolfschoten, 1985)/A. maastrichtensis (Kratochvil & Rossicky, 1952), Mus cf. musculus Linnaeus, 1758, and Myoxus sackdilligensis (Heller, 1930). Some other small vertebrates (insectivores, lagomorphs, amphibians, reptiles) have also been found in this site. The fossil collections are stored at the Museum of Natural History in Belgrade.
The absolute predominance (about 75% of all rodent remains) of only one species (Microtus nivaloides) suggests relatively harsh conditions during a cold (glacial) period. This species probably preferred open areas, so it can be concluded that such type of environment prevailed in the vicinity of the site. But some forest inhabitants were also present, as well as indicators of more humid conditions (such as shrews).
On the basis of fossil evidence a Middle Pleistocene age has been proposed for this site. The rodent fauna has been compared with the faunas of some neighbouring countries and it has been concluded that it shows most similarity to the Saalian localities from Hungary (Nagyharsanyhegy-6 and Solymar) and Bulgaria (Morovitsa).
This locality is very interesting because it is the first “fissure filling” site of the Pleistocene age in Serbia with small mammal remains. The second important thing is its Middle Pleistocene age – there are many occurrences of Late Pleistocene mammals in Serbia, but remains of Early and Middle Pleistocene age are rare and usually confined to isolated teeth. Many of the mentioned species are reported in Serbia for the first time. So the investigation of this locality will provide us with a better understanding of this period of Pleistocene.
In the preliminary investigations, the age of the fauna from Venčac has been considered as Late Pleistocene, because of morphological similarity between some extant species and their ancestors. An older age can also be rejected, because there are no Mimomys remains, while the genus Arvicola – a characteristic element of Middle and Late Pleistocene rodent faunas – is present. Unfortunately, remains of this genus are very scarce and poorly preserved, so they could not been precisely identified and assigned to a species. The future investigations will hopefully reveal more about this very interesting and rich Middle Pleistocene locality.