You will be given a definition of a task first, then some input of the task.
Generate a correct and concise answer for the question based on the words in the context.

Context : 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.
Question : Is the taxon rank of Birkenia species or genus?
Output:
genus