Lectures 3 & 4 Outline Fall 2025 Study Material: The Diversity of Fishes 'Skeleton, Skin, and Scales'

Vocabulary flashcards covering the major terms and concepts from the skeletal osteology, skull regions, gill arches, postcranial skeleton, and scales as presented in the notes.

chondrocranium

The original cartilaginous braincase of fishes.

dermatocranium

The part of the skull made of dermal bones (dermal skull).

agnathan

A jawless fish type lacking biting jaws.

chondrichthyan skull type

Skull type composed of a single cartilaginous structure.

bony fish skull type

Skull type composed of ossified dermal bones.

Ethmoid region

Anterior skull region providing support for biting; includes vomer, ethmoid, and related bones.

lateral ethmoids

Ethmoid region bones located laterally to the ethmoid.

median vomer (dentigerous)

Median facial bone bearing teeth (dentigerous) in the Ethmoid region.

nasals

Bones located lateral to the ethmoid in the skull.

Orbital region

Skull region surrounding the eyes; includes sphenoids, frontals, and infraorbital bones.

sphenoids

Bones in the orbital region; include paired pterosphenoids and other sphenoid elements.

pterosphenoids

Cartilaginous bones in the orbital region of some fishes.

basisphenoid

Cartilaginous bone in the orbital region; part of the basicranium.

parasphenoid

Cartilaginous bone in the orbital region; part of the skull base.

frontals

Dermal bones in the orbital region forming part of the skull roof.

infraorbital (suborbital) bones

Bones beneath the orbit; advanced teleosts typically have five infraorbital bones.

Otic region

Skull region enclosing the otic (ear) chamber; contains several paired bones.

sphenotics

Cartilaginous bones in the otic region (one of the ear-related bones).

pterotics

Cartilaginous bones in the otic region (ear region).

prootics

Cartilaginous bones in the otic region near the ear canal.

epiotics

Cartilaginous bones in the otic region (near the ear).

Basicranial region

Braincase area; formed by three sets of cartilaginous bones.

exoccipitals

Pair of bones surrounding the foramen magnum in the basicranium.

basioccipital

Most posteroventral neurocranial bone in the basicranial region.

supraoccipital

Dorsal midline bone of the skull in the basicranial region.

Mandibular arch

Upper and lower jaw arch; first visceral arch forming jaws.

premaxillary

Anterior upper jaw bone; often dentigerous.

maxillary

Upper jaw bone; may bear teeth in some teleosts.

dentary

Main lower jaw bone; dentigerous in many fishes.

supramaxilla

Upper jaw bone present in some teleosts; may be dentigerous.

angular (cartilaginous)

Lower jaw bone linking jaw elements; cartilaginous in some fishes.

Palatine arch

Roof-of-mouth arch containing palatines and pterygoids.

palatines

Palatine bones in the roof of the mouth.

mesopterygoids

Midline pterygoid bones in the palate.

ectopterygoid

Ecto- (lateral) pterygoid in the palatine arch.

mesopterygoids

Middle series of pterygoid bones in the palate.

metapterygoid

Quadrangular cartilaginous/dermal bone in the pterygoid series.

quadrate

Bone connecting the palatoquadrate/mandible region to the skull; articulation with hyomandibula.

hyomandibula

Part of the jaw suspensorium linking the jaw to the skull.

Hyoid arch (suspensorium)

Second visceral arch attaching the lower jaw and opercular apparatus to the skull.

hyomandibular

Bone in the hyoid arch; part of suspensorium.

symplectic

Bone in the suspensorium of the hyoid arch.

quadrate (in hyoid arch context)

Bone in the jaw suspension system; different usage than in palatoquadrate context.

hypohyals

Hyoid arch bones located medially in the hyobranchial system.

ceratohyals

Hyoid arch bones medial to the hyomandibula; part of the hyobranchial apparatus.

epihyal

Hyoid arch element near the tongue region.

interhyal

Hyoid arch bone between hyomandibular and ceratohyals.

glossohyal

Hyoid arch element associated with the tongue muscles.

Opercular arch

Series of gill-covering bones in the gill cover apparatus.

opercles

Largest and heaviest bone in the opercular arch; forms the operculum.

preopercle

Anterior bone of the opercular arch.

interopercle

Ventrolateral bone of the opercular arch.

subopercle

Posterior bone of the opercular arch.

Branchial arch

Gill arches; series of arches supporting gills and pharyngeal apparatus.

basibranchials

Lowermost pair of cartilaginous/osseous elements in the branchial arches.

hypobranchials

Lower elements of the branchial arches near the jaw region.

ceratobranchials

Carilaginous/osseous elements of the branchial arches bearing teeth on some species.

epibranchials

Elements of the branchial arches above the ceratobranchials.

pharyngobranchials

Pharyngeal elements forming the upper arch structures; often four pharyngobranchials.

glossohyal (branchial context)

Hyobranchial element associated with the tongue/pharyngeal region.

Branchial arches (summary)

Gill arches and their components enabling breathing and prey processing.

Postcranial skeleton

Skeleton behind the skull, including the vertebral column and girdles.

Vertebrae

Structural units of the backbone; include precaudal and caudal regions.

precaudal vertebrae

Vertebrae extending to the posterior end of the body cavity bearing ribs.

caudal vertebrae

Vertebrae starting with the first vertebra bearing a haemal spine toward the tail.

Neural spine

Dorsal projection of a vertebra for muscle attachment and protection of the spinal cord.

neural arch

Part of the vertebra surrounding the neural canal for the spinal cord.

haemal canal

Ventral canal through which blood vessels run; begins at the posterior end of vertebrae.

epineurals

Intra-muscular bones associated with the vertebral column.

epicentals

Intra-muscular bones relating to the vertebral column (paired with epineurals).

epipleurals

Intra-muscular bones located dorsally along the rib area.

Caudal complex

Structures supporting the tail fin, including haemal and neural spines, hypurals, uroneurals, and rays.

hypural bones

Enlarged haemal spines forming part of the tail support system.

uroneurals

Bones associated with the dorsal aspect of the caudal fin in some fishes.

hypural plate

Girdle-like plate supporting hypurals at the base of the tail fin.

principal caudal rays

Main fin rays attached to the hypurals at the tail end.

procurrent rays

Rays extending forward from the tail fin rays.

Pectoral girdle

Girdle attaching the pectoral fins to the axial skeleton; lacks direct vertebral attachment.

supratemporal

Pectoral girdle bone situated above the temporal region.

supracleithrum

Pectoral girdle bone near the shoulder region.

cleithrum

Bone in the pectoral girdle forming part of the shoulder arch.

coracoid

Shoulder girdle bone connecting the girdle to the sternum or body wall.

scapula

Shoulder blade bone part of the pectoral girdle.

radials

Segmental bones in the fin base contributing to fin support.

Fins (general)

Appendages using soft rays, spines, and pterygiophores for locomotion and steering.

soft rays

Flexible fin rays used in soft-bodied fins.

spines

Stiff, pointed fin rays providing stiffness in fins.

pterygiophores

Supportive elements linking fin membranes to the fin skeleton.

Placoid scales

Dermal denticles typical of chondrichthyans; consist of a basal plate with a posterior spine and enamel-like outer layer called vitrodentine.

Vitrodentine

Enamel-like outer layer of placoid scales.

cosmoid scales

Scales with cosmine and two basal bone layers (isopedine and cancellous bone).

cosmine

Dentinoid substance that coats cosmoid scales beneath the outer layer.

isopedine

Dense bone layer in cosmoid scales.

ganoine

Calcified, non-cellular outer layer replacing cosmine in ganoid scales.

ganoine (definition)

Calcified, non-cellular outer layer on ganoid scales; lacks canals.

cycloid scales

Dermal scales with no enamel-like layer; derived from ganoids after ganoine loss.

ctenoid scales

Dermal scales with a rounded posterior edge; derived from ganoids after ganoine loss.

dermal denticles

Another term for placoid scales.