Romer hesitated from designating Proterogyrinus as a true embolomere, because its intercentra (the forward portion of each vertebra) were smaller than its pleurocentra (the rear portion). He used the group Anthracosauria to encompass embolomeres and their close relatives such as Proterogyrinus. However, other sources prefer a wider definition of Embolomeri similar in usage to Romer's Anthracosauria, thus counting Proterogyrinus as an embolomere.
