Sturgeons outlived dinosaurs—then met the caviar market
Twenty-seven Acipenseridae species descend from Early Jurassic acipenseriforms some 174–201 million years ago, with true sturgeon fossils by the Late Cretaceous. Sister to paddlefish, they include giants like an 1827 Volga beluga 7.2 meters long and 1,571 kilograms.
Sturgeons have barely changed shape in a very long time. Their order, the Acipenseriformes, appears in rocks 174 to 201 million years old, making it one of the oldest surviving groups of ray-finned fish. The split from paddlefish, their only living relatives, happened no later than 125 to 120 million years ago, and one of the oldest true sturgeon fossils is a partial skull from Alberta dated 100 to 94 million years old. They keep a shark-like tail with a longer upper lobe, and a Maastrichtian fossil from Morocco shows they once lived in Africa too.
That conservatism has made them hard to classify. Lineages separated since the Cretaceous can look almost identical, individuals vary in snout shape, bony scutes and length across their ranges, and sturgeons can produce fertile hybrids even across genera. Earlier researchers proposed more than 40 species that were later rejected, and molecular studies since the 1990s overturned the old two-subfamily scheme. In 2025, Brownstein and Near combined DNA and anatomy to settle on five genera, reviving Sinosturio for species such as the kaluga.
Most of the 27 species feed on river bottoms in deltas and estuaries and swim upstream to spawn, though some never leave fresh water and others range into the open sea. They live long and mature late, and several reach 2 to 3.5 metres. The biggest ever measured was a beluga caught in the Volga Delta in 1827, 7.2 metres long and 1,571 kilograms.
Demand for caviar has driven most species to critical endangerment. The Adriatic sturgeon, feared extinct in the wild from 2011, was reassessed as critically endangered in 2022.
Source: Sturgeon
