This striking Soviet stamp from the 1990 “Extinct Animals” series features Thyestes, an ancient prehistoric fish known from fossil discoveries. The realistic scientific illustration highlights the armored head and elongated body characteristic of early vertebrate species, reflecting the USSR’s strong tradition of scientific-themed philately. Issued shortly before the dissolution of the Soviet Union, this stamp represents one of the final scientific commemoratives of the era, making it particularly attractive to both thematic collectors of paleontology and late-period USSR philately specialists.