Hypobranchials are the most medial of the bilaterally paired elements of the gill arches. Hypobranchial ossifications 1-3 (of 4) develop in the small hypobranchial cartilages that lie between the medial tips of the ceratobranchials and copula 2. The hypobranchials articulate anteromedially with the basibranchials. [ GOC:mh ORCiD:0000-0001-9114-8737 ]