1 - Ruban, Dmitry A.; 2 - Nielsen, Jan K.; 3 - Zayats, Pavel P. 

1 - Department of Tourism, Higher School of Business, Southern Federal University, 23-ja linija Street 43, Rostov-na-Donu, 344019, Russia E-mail: ruban-d@mail.ru
2 - Department of Geological Engineering, Süleyman Demirel University, 32260 Isparta, Turkey E-mail: bioerosion@yahoo.dk
3 - Camp for Practice and Educational Tourism 'Belaja Retchka', Southern Federal University, Nikel', Majkop District, Republic of Adygeja, 385792, Russia

The Lower-Middle Jurassic deposits of the Western Caucasus are of interest to study the development of palaeoecosystems under dysoxic conditions. These deposits were studied in the lengthy section between the town of Guzeripl' and the Partisan Glade (Republic of Adygeja, southwestern Russia), where Upper Toarcian-Middle Aalenian shales with siderite concretions and sandstone interlayers represent the axial part of the Greater Caucasus sedimentary basin. Trace fossils named ? Chondrites isp. were found there. They are evidence of behavioural activity of animals (either endobenthic bivalves or deep-marine nematodes) on the dysoxic bottom of the Caucasian Sea. Difference in the Tubinskaja Formation by the trace fossils and the character of bioturbation between the new and earlier found trace fossil localities imply changes in the bottom ecosystems that were probably related to palaeoenvironmental changes and, particularly, shifts in the water oxygenation.

Keywords: trace fossil, sedimentary basin, oxygen deficiency, Greater Caucasus, Jurassic