Below, you see a list with possible ichnogenera for an unlined (sub)horizontal, unbranched burrow with a cylindrical cross section or a ridge-like appearance 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):

• Archaeonassa (May also occur as surface trace (track, trail, impression, etc.))
• Belonidopsisichnium (May also occur as surface trace (track, trail, impression, etc.))
• Halimedides (May be branched or unbranched; ichnogenus includes ornamented ichnospecies)
• Hormosiroidea (May be branched or unbranched)
• Katarrhedrites (Ichnogenus includes ornamented ichnospecies)
• Katbergia (Ichnogenus includes ornamented ichnospecies)
• Megaplanolites (May also occur as surface trace (track, trail, impression, etc.))
• Oravaichnium (May also occur as surface trace (track, trail, impression, etc.))
• Paramargaritichnus (May also occur as surface trace (track, trail, impression, etc.))
• Platicytes
• Tuberculichnus (May also occur as surface trace (track, trail, impression, etc.))