Hagfish from the Cretaceous Tethys Sea and a reconciliation of the morphological–molecular conflict in early vertebrate phylogeny

The Cretaceous hagfish Tethymyxine preserves barbel cartilages, a branchial apparatus behind the skull and chemical traces interpreted as slime glands. These fossil features document similarities to living hagfish, not directly observed slime production or a universal description of every Myxini species.

The complete body fossil Tethymyxine tapirostrum holotype BHI 6445 from the Cenomanian Hâdjoula Lagerstätte of Lebanon, displayed as 100.5–93.9 Ma, was recovered within crown Myxini; this specimen supports a crown-hagfish fossil bound but not a global FAD, and the older stem hagfish Myxinikela is excluded from the crown range.

Tethymyxine tapirostrum holotype BHI 6445 was recovered within crown Myxini in the published morphology analysis, while its exact branch position remains matrix-dependent.

BHI 6445 comes from the Cenomanian Hâdjoula Lagerstätte of Lebanon in the eastern Tethys; the locality does not establish a global crown-hagfish distribution.

The marine depositional context is documented, but the fossil does not directly establish diet, scavenging behaviour, depth preference or modern hagfish ecology.

BHI 6445 preserves a complete soft-bodied hagfish with character information from the feeding apparatus and body used in the published phylogenetic matrix.

The displayed 100.5–93.9 Ma interval is the Cenomanian envelope for BHI 6445 and supplies a crown-Myxini fossil bound, not a global FAD.

The Cyclostome fossil evidence route navigation entity is source-linked only to the named specimen, dataset and analysis dossiers already cited by its range ledger. Its displayed span is a study-bounded route or sample envelope, not a biological taxon, ancestor sequence, global FAD/LAD or exact origin interval.