This is the right side middle hand bone (metacarpale) of an Aurocheros Bos primigenius. The Fossiil comes from the Pleistocene sediments of a gravel pit near Stockstadt am Main in Germany.
The bone is perfectly preserved and unbroken, it measures about 28 cm. The piece is highly mineralized and weighs more than one kilogram.
Fossils of aurochs are quite sought after by collectors, they are much rarer than those of bison priscus.