Volga River, Ulyanovsk Region, Russia 10x1.5x4.5cmA striking fossil specimen featuring a pliosaur bone transformed by pyrite replacement, creating a metallic luster and distinctive golden-bronze surface. Sourced from the Volga River region in Ulyanovsk, Russia, this piece captures the intersection of paleontology and mineralogy—where ancient marine reptile remains have been chemically altered by iron sulfide mineralization over millions of years. The specimen measures 10 x 1.5 x 4.5 cm, offering substantial presence for display or study. Pyrite replacement specimens are prized by collectors for their rarity, visual contrast, and the geological narrative they tell about diagenetic processes in fossil-bearing formations. An excellent addition to paleontology or mineral collections seeking museum-quality character and scientific interest.