Opisthomyzon glaronensis (Friedman et al. 2013; early Oligocene) is a small prehistoric remora with only a small posterior sucker. This specimen indicates that the adhesion disc originated in a postcranial position, and that other specializations (including the origin of pectination, subdivision of median fin spines into paired lamellae, increase in segment count and migration to a supracranial position) took place later in the evolutionary history of remoras. This phylogenetic sequence of transformation finds some parallels in the order of ontogenetic changes to the disc documented for living remoras. Note the elevated origin of the pectoral elements.

Remora remora (Rafinesque 1810; Britz and Johnson 2012; 75cm) is the extant remora or shark-sucker. A flexible membrane rises due to blood flow atop the skull to produce suction. Like its phylogenetic sister, the barracuda, the skull roof is otherwise flat. Remoras eat the ectoparasites and feces of their host.

At 3cm Remora a fully formed 2mm sucking disc is present. It still has the basalmost components found in the dorsal fin with everything tiny and nothing transformed into a fin: the tiny fin spines, spine bases and supporting bones, but the spine bases have greatly expanded.

Echeneis naucrates (Linneaus 1758; 110cm) is the extant live sharksucker, a type of remora. Note the high placement of the pectoral fins and prognathus jaws. The Gregory 1933 diagram provides insight to the dorsal skull bones. The dorsal sucker begins as laterally expanded dorsal neural spines that never break the surface, but expanded anteriorly over the skull.