Sturgeon is the common name for the 27 species of fish belonging to the family acipenseridae. the earliest sturgeon fossils date to the late cretaceous, and are descended from other, earlier acipenseriform fish, which date back to the early jurassic period, some 174 to 201 million years ago. the family is grouped into four genera: acipenser, huso, scaphirhynchus, and pseudoscaphirhynchus. two species (a. naccarii and a. dabryanus) may be extinct in the wild, and one (p. fedtschenkoi) may be entirely extinct. two closely related species, polyodon spathula (american paddlefish) and psephurus gladius (chinese paddlefish, extinct) are of the same order, acipenseriformes, but are in the family...

Source: Wikipedia