Why do Gonorynchiformes lack a true Weberian apparatus?

The superorder Ostariophysi is divided into two series based on the presence or absence of a complex Weberian apparatus: the series Otophysi and the series Anotophysi.1

The order Gonorynchiformes, which comprises the series Anotophysi, lacks a "true" Weberian apparatus because it does not possess the complex, specialized chain of four paired bones (ossicles) that characterizes the Otophysi. Instead, Gonorynchiformes exhibit only a rudimentary version of this structure, which involves the first three vertebrae and one or more ribs. While these anterior vertebrae and ribs show affinities with the rest of the superorder, they do not form the fully developed, functional bony connection between the swim bladder and the inner ear found in other ostariophysans.12