Palaeobiology of Schaubcylindrichnus heberti comb. nov. from the Lower Jurassic of Northeast England

• Palaeophycus heberti is synonymised with Schaubcylindrichnus to create S. heberti.
• Burrows are U-shaped, may be closely clustered or occur as isolated single burrows.
• The burrow walls of S. heberti are composed of clay and sand-rich annular rings.
• Burrows of S. heberti are passively filled and may contain sedimentary laminae.
• Rare meniscate backfill of S. heberti is recorded.

The distinctive species of Palaeophycus known as Palaeophycus heberti is characterised by its thick burrow wall and passive burrow fill. This species is typically associated with intensely bioturbated, heterolithic sandstones and mudstones deposited in shoreface to offshore marine palaeoenvironments. Three-dimensional analysis of specimens attributed to P. heberti based on closely-spaced serially ground surfaces has revealed a number of hitherto unknown morphological elements more comparable to the ichnogenus Schaubcylindrichnus, thereby creating Schaubcylindrichnus heberti comb. nov. Schaubcylindrichnus burrows are typically passively filled, and have a thick burrow wall composed of sand-rich annular rings. The three-dimensional reconstructions importantly demonstrate that the gross morphology is a broad-open U-shape, which is inconsistent with the ichnogeneric diagnosis of Palaeophycus. S. heberti differs from all other species of Schaubcylindrichnus in that the burrow wall is mineralogically heterogeneous rather than purely quartzose; the ichnogeneric diagnosis is thus emended to accommodate S. heberti.