The bones of a prehistoric mammal were found during the ongoing construction of the second subway line at a station in the Wola district of Warsaw.
The creature, probably a mammoth, or a prehistoric forest elephant, lived around 100,000-120,000 years ago.
The pelvis bone and fragments of skeleton were found by the workers, six meters under the surface while working on the construction of the station ventilation room. The construction works were stopped to enable a search for artefacts, e.g. flint tools.
"The remains found were extracted and cleaned by us and will be the subject of further research to determine the exact species of this animal, its age and the circumstances of death", the director of the State Archaeological Museum in Warsaw Wojciech Brzeziński said.
Preliminary information indicates that the bones may belong to a mammoth or prehistoric forest elephant that lived in Poland during the Pleistocene period (often called the Ice Age). The largest could grow up to 4.5 meters high and could weigh up to seven tons.
During the Pleistocene period, in the present day Wola district area of construction, there was a lake.
"It is possible that this mammal entered the frozen lake, and the ice collapsed under its weight, which caused the death of the creature," Mr Brzeziński added.
Earlier during the underground construction work, items related to the everyday life of the residents of pre-war Warsaw and the remains of a former tram track were found, as well as bayonets, a rifle butt and a cannon grenade from the time of the November Uprising.
So far, the oldest find was a 300-year old well, which was found nine meters below the surface.