Llandovery genus first appearances

Birkenia is a genus of extinct anaspid fish from Middle Silurian strata of Northern Europe, and Middle Silurian to possibly Earliest Devonian strata of Arctic Canada. Birkeniid anaspids are covered by a series of small plates on the head and rod-shaped scales in a cheveron-like pattern on the trunk.

Cyathocrinites is an extinct genus of crinoids that lived from the Early Silurian to the Late Permian in Europe and North America.