Considered as holectypoid (Gnathostomata) Pygaster microstoma Lambert, 1933 from the Toarcian of Morocco is actually the most primitive galeropygid (Atelostomata) for which the new genus Eogaleropygus is proposed. Incipient "irregular" position of the periproct and very shallow anal groove are in sharp contrast with much more advanced evolutionary changes such as small size and unnotched peristome (external manifestations of the loss of dental apparatus and gills) as well as dense and unordered tuberculation. The morphology of Eogaleropygus suggests that galeropygids became atelostomate probably long before they became bilateral.