Figure 3. Phylogenetic framework of GIT morphology and spiral valve turn counts of actinopterygians, including †Saurichthys paucitrichus.

Phylogenetic hypothesis based on refs ⁵,²⁰. Interpretative drawings of GITs of Polypterus, Polyodon spathula, Lepisosteus osseus and the teleost Alosa redrawn and modified from ref 27. The interpretative drawing of the Amia calva GIT is redrawn and modified from ref 7. The drawings of the Acipenser baerii and †S. paucitrichus GITs are based on our observations. All drawings depict the GIT in ventral view with foregut to the left and hindgut to the right.