Below, you see a list with possible ichnogenera for an unlined (sub)horizontal, unbranched burrow with a bilobate cross section and passive filling. Click on them to get detailed descriptions of the ichnogenus and a list of its ichnospecies. (Please allow for pop-up windows):

• Aglaspidichnus (Ichnogenus includes ornamented ichnospecies)
• Carpatichnis (Ichnogenus includes ornamented ichnospecies)
• Cruziana (May also occur as surface trace (track, trail, impression, etc.); ichnogenus includes ornamented ichnospecies)
• Didymaulichnus (May also occur as surface trace (track, trail, impression, etc.))
• Didymaulyponomos (Ichnogenus includes ornamented ichnospecies)
• Isopodichnus (Taxonomic status unclear, use not recommended; may also occur as surface trace (track, trail, impression, etc.); ichnogenus includes ornamented ichnospecies)
• Raaschichnus (Ichnogenus includes ornamented ichnospecies)
• Rusophycus (Ichnogenus includes ornamented ichnospecies)
• Tumblagoodichnus (May also occur as surface trace (track, trail, impression, etc.); ichnogenus includes ornamented ichnospecies)
• Tylichnus (Ichnogenus includes ornamented ichnospecies)