Haikouichthys ercaicunensis (Luo, Hu & Shu 1997; Shu et al.1999; HZf-12-127; 2.5cm) is an Early Cambrian fish basal to sturgeons in the LRT.

Turinia pagei (originally Thelodus pagei Traquair 1896, 1898, Powrie 1870, Donoghue and Smith 2001; Early Devonian, 410mya; 33cm length, 16.4cm width) nests with Thelodus in the LRT. This ventral view preserves soft tissue with an open stomach cavity and a simple gut extending to the cloaca. The gill chamber was enormous. The pectoral fins were nearly immobile. The gill openings were ventral to the large pectoral fins. Tiny pelvic fins were just developing.

Thelodus parvidens (Agassiz 1839; GLAHM–V8304, Early Silurian; 5–15cm in length) this specimen was published in a popular book, Long 1995. Soft tissue is preserved. This specimen nests basal to sturgeons.

Acipenser brevistrostrum (Lesueur 1818 non Heckel 1836, Hilton 2005; 1m length) is the extant short-nosed sturgeon, with fossils going back to the Late Cretaceous (70mya). In the LRT it is the most primitive tested sturgeon. The short rostrum is retained in Chondrosteus and Isurus. The dorsal scutes are low as in Osteostraci. Younger shortnose sturgeons tend to have longer snouts compared to their older counterparts, but that is not shown in the skull. Adult sturgeons have bony plates along their esophagus that help them crush hard items instead of having teeth.

Shortnose sturgeons are cartilaginous with bones only in the skull, jaw and pectoral girdle. The swim bladder is connected to the intestinal tract by a special duct. This taxon gives us our clearest view into the soft tissue of ancestral Osteostraci.

Pseudoscaphirhychus kaufmanni (Nikolskii 1900) is the extant amu darya sturgeon. Distinct from traditional cladograms, the LRT nests this sturgeon between the osteostracan, Hemicyclaspis and the last common ancestor of sharks and bony fish, Chondrosteus. All have weak ventral jaws, no teeth and a shark-like heterocercal tail.

The lacrimal and mandible support a bottom-feeding extendable tube disconnected from the quadrate. Breathing is hampered whenever the mouth is in the mud, so water enters the top of the operculum, then exits laterally.

Yanosteus longidorsalis (originally Peipiaosteus pani Liu and Zho 1965; Late Jurassic, Early Cretaceous, China) is smaller and earlier than Pseudoscaphirhynchus with less ossification. The 'quadratojugal' occurs much earlier than in other taxa, so this may just be the posterior jugal. Jaws are absent here.