Table 1:

Features and structures of cartilaginous fish jaw skeletons. Blank spaces indicate that homologous element has not been reported. Elements that may be lost secondarily are indicated as “absent”.

		Cartilaginous fishes
		Placodermii (Carr et al., 2009; Hu et al., 2017; Rücklin et al., 2012; Young, 1986; Zhu et al., 2013)	Acanthodii (Brazeau, 2009; Brazeau & de Winter, 2015; Friedman & Brazeau, 2010; Gardiner, 1984)	Chondrichthyes (Gillis, Modrell, et al., 2012; Kent & Carr, 2001; Patterson, 1982)
Feature/structure	Element
Mineralization of cartilage		Present	Perichondral	Prismatic
Dermal bone		Present	Present	Absent
First pharyngeal arch	Anguloarticular or angular			Absent
	Meckelian			Absent
	Dentary	Present		Absent
	Ectopterygoid			Absent
	Entopterygoid			Absent
	Maxilla	Present		Absent
	Meckel’s cartilage	Present	Present	Present
	Metapterygoid			Absent
	Palatoquadrate	Present	Present	Present
	Palatine			Absent
	Premaxilla	Present		Absent
	Quadrate			Absent
	Retroarticular			Absent
Second pharyngeal arch	Branchiostegal ray		Hyoid gill cover	Absent
	Ceratohyal	Present	Present	Present
	Epihyal	Present		Absent
	Hyomandibula	Present	Present	Present
	Symplectic			Absent
	Interhyal	Present	Limited evidence	Absent
	Interopercle			Absent
	Opercle	Present	Hyoid gill cover	Absent
	Opercular cartilage	Present		Absent
	Preopercle			Absent
	Subopercle			Absent
Ventral and branchial arch structures	Basibranchial	Present	Present	Present
	Basihyal	Present	Present	Present
	Ceratobranchials		Present	Present
	Epibranchials		Present	Present
	Hypohyals		Present	Absent
	Hypobranchials		Present	Present
	Urohyal	Present		Absent