''Alphacrinus'' is an extinct genus of

crinoid Crinoids are marine invertebrates that make up the class Crinoidea. Crinoids that remain attached to the sea floor by a stalk in their adult form are commonly called sea lilies, while the unstalked forms, called feather stars or comatulids, are ...

s which existed during the early Ibexian period. It was named by Thomas E. Guensburg in 2010, and placed into its own family, Alphacrinidae. The type species is ''Alphacrinus mansfieldi''.

References

Prehistoric crinoid genera Fossil taxa described in 2010 {{paleo-crinoidea-stub