Below, you see a list with possible ichnogenera for a U- and bow-shaped, unlined, actively filled, (sub)vertical, unbranched burrow. Click on them to get detailed descriptions of the ichnogenus and a list of its ichnospecies. (Please allow for pop-up windows):

• Alectorurus (Taxonomical status unclear, use not recommended)
• Diplocraterion
• Polarichnus (Ichnogenus includes ornamented ichnospecies)