What is "praenuculinae"

Praenuculinae is an extinct subfamily of prehistoric bivalves in the family Praenuculidae. Praenuculinae species lived from the middle Ordovician through the late Devonian. Praenuculinae fossils are found in Europe, Africa, North America and South America, and species are though to have been stationary attached to substrate in shallow infaunal marine water environments where they formed shells of an aragonite composition. The subfamily Praenuculinae was named by Teresa M. Sánchez in 1999.