Comparison: Skulls and Feeding Styles
Chondrichthyes Osteichthyes Tetrapods
Chondocranium Does not ossify. Partly or completely ossified.
Also forms walls and roof of braincase. Enveloped in dermatocranium.
Dermatocranium Extra set of opercular bones covering
Splanchnocranium Spiracle (reduced gill opening) remain Splanchnocranium partially or completely replaced by dermal bone.
between hyoid and mandibular arches. Hyomandibula -> stapes
Fish: Arches I and II form jaws. Synapsids: (Allowed muscles to insert closer to teeth.)
× Articular -> Dentary bone
× Quadrate -> Squamosal bone
Quadrate -> Incus
Articular -> Malleus
Feeding Type Paleostyly – Agnathans Euautostyly – Fish Modified Hyostyly Metautostyly – Amphibians, Reptiles,
× No jaws; branchial arches used × Mandible articulates with × Articular and Quadrate bone
to support gills instead. unsupported palatoquadrate. × Main attachment of jaw to × Jaw attached to braincase
Amphistyly – Ancient sharks hyomandibula. through quadrate bone.
× Jaw supported by both the × Symplectic bone helps suspend Craniostyly – Mammals
hyomandibula and the jaws. × Upper jaw merged with floor of
Hyostyly – Modern sharks
× Jaws supported by
× Complex loose and dynamic.
Feeding Bottom feeding, sucking, mud Hyostyly - Suction feeders. Mammal