Phylum: Mollusca
Class: Bivalvia
Order: Trigonioda
Family: Lyrodesmatidae Ulrich, 1894
Cincinnatian Genera: Lyrodesma

Geologic Range
Middle Ordovician – Late Ordovician

Common Paleoecology
Lyrodesmatidae is an extinct family of facultatively mobile shallow infaunal suspension feeders

Description of the Family

  • Small shell
  • Subtrigonal shell shape
  • Rounded toward anterior
  • Obliquely truncate
  • Hinge plate semicircular

Published Descriptions

Treatise on Invertebrate Paleontology, Part N, Mollusca 6(1 of 3) (1969):

  • Shell small, subtrigonal, rounded in front, acuminate posteriorly and commonly obliquely truncate; umbonal fold rounded or carinate; beaks small; hinge plate semicircular, with several angular, crenulated teeth radiating more or less symmetrically from beneath the beak.