The first Polish find of Lower Paleocene crocodile Thoracosaurus Leidy, 1852: geological and palaeontological description

Abstract

Skeletal remains of a crocodile of the genus Thoracosaurus Leidy, 1852 were discovered by M. Żarski in Lower Paleocene gaizes in the neighbourhood of Kazimierz Dolny. They consist of a part of the vertebral column containing the last dorsal vertebra, the sacrum and eight caudal vertebrae. The age of the deposits was determined by means of micro- and macrofauna; they were dated as middle Danian. In the absolute chronological scale it was the period between 64.5 and 62.5 m.y. ago. The study of pelecypods and gastropods makes it possible to assume that the sea in which the crocodilian lived was shallow basin with water temperature of about 18°C. The presence of tree trunks in the layer containing the crocodilian skeleton suggests closeness to land. The foraminifers occurring in the Greenland, the hard limestone "hardground" and the opokas were also studied.