Lab 4 - Skeleton

What does is a cartilaginous fish skull made of?

1. Chondrocranium

2. Splanchonocranium

What is the chondrocranium?

A solid, singular cartilaginous structure that encloses the brain and inner ears.

What is the splanochonocranium?

It consists of 7-9 visceral arches of cartilaginous elements and is located ventral/posterior to the chondrocranium.

What are the first two visceral arches of the splanchnocranium?

• mandibular and hyoid

• both of which of below the chondrocranium

Define the Mandibular Arch.

• the first visceral arch that forms the jaws

• consists of the palatoquadrate cartilage (upper jaw) and the Meckel’s cartilage (lower jaw)

What forms the upper jaw of a cartilaginous fish?

The palatoquadrate cartilage

What forms the lower jaw of a cartilaginous fish?

Meckel’s cartilage.

What is the function of the hyoid arch?

It suspends the jaws and forms the mouth floor and tongue.

What is the hyomandibular cartilage?

The dorsal hyoid element connecting the jaws to the neurocranium.

What are the main gill-arch cartilages?

1. Pharyngobranchial

2. Epibranchial

3. Ceratobranchial

4. Hypobranchial

5. Basibranchials

What are radii branchiales?

Structures supporting the interbranchial septum between gill filaments.

What are processus rastriformes?

Extension of gill-arch cartilages analogous, but not homologous, to gill rakers.

What is endoskeletal bone?

Bone that develops from a cartilaginous precursor.

What is exoskeletal bone?

Dermal bone that develops within the dermis without a cartilage precursor.

What is the dermatocranium?

The dermal-bone component surrounding the chondrocranium and splanchnocranium.

What is the neurocranium?

The part of the skull protecting the brain and sense organs.

What is the suspensorium?

Elements of the first two visceral arches plus associated dermal bones.

How can dermal bones often be distinguished from endoskeletal bones?

Dermal bones commonly contain a sensory canal.

What are the four regions of the bony fish neurocranium?

1. Ethmoid

2. Orbital

3. Otic

4. Occipital

What is the ethmoid region?

The anteriormost region of the neurocranium.

What bones comprise the ethmoid region?

1. Ethmoid

2. Lateral ethmoid

3. Nasal

4. Vomer

What is the orbital region?

The region of the neurocranium that rims the orbit.

What bones comprise the orbital region?

1. Frontal

2. Basisphenoid

3. Orbitosphenoid

4. Parasphenoid

5. Pterosphenoid

What is the otic region?

The region posterior to the orbit that houses part of the inner ear.

What bones comprise the otic region?

1. Parietal

2. Prootic

3. Pterotic

4. Sphenotic

5. Intercalar

What is the occipital region?

The posterior skull region connecting the skull to the vertebral column.

What are the three occipital condyles?

Paired exoccipital condyles and a median basioccipital condyle.

What is the ethmoid bone composed of?

Mesethmoid (endoskeletal) and dermethmoid (exoskeletal) components.

What is the nasal bone?

A paired exoskeletal bone supporting the supraorbital sensory canal.

What is the vomer?

A median exoskeletal bone that bears teeth in some taxa.

What is the frontal bone?

A paired exoskeletal bone supporting the supraorbital sensory canal.

What is the parasphenoid?

A median exoskeletal bone that bears teeth in some taxa.

What is the pterotic?

A compound bone of endoskeletal autopterotic and exoskeletal dermopterotic.

What is the sphenotic?

A compound bone connecting the supraorbital, infraorbital, and otic sensory canals.

What is the supraoccipital?

A median endoskeletal bone forming a large posterior cranial crest.

What does the mandibular arch form in adult bony fishes?

The upper and lower jaws.

What are the major upper-jaw bones?

1. Premaxilla

2. Maxilla

3. Palatine

4. Quadrate

5. Metapterygoid

6. Ectopterygoid

7. Endopterygoid

What is the premaxilla?

A paired exoskeletal upper-jaw bone that bears teeth.

What is the maxilla?

A paired exoskeletal upper-jaw bone that bears teeth in some taxa.

What is the palatine?

A compound upper-jaw bone with endoskeletal and exoskeletal components.

What are the major lower-jaw bones?

1. Dentary

2. Angulo-articular

3. Retroarticular

4. Coronomekelian

What is the dentary?

A paired exoskeletal lower-jaw bone that bears teeth and supports the sensory canal.

What is the anglo-articular?

A compound bone made of angular and articular components.

What is the hyoid arch?

The second visceral arch, involved in jaw suspension and expansion of the pharyngeal cavity.

What are the upper hyoid arch elements?

Hyomandibular and symplectic, plus associated opercular bones.

What is the hyomandibular bone?

An endoskeletal bone articulating dorsally with the neurocranium.

What is the symplectic?

A paired endoskeletal bone of the upper hyoid arch.

What bones make up the opercular series?

1. Interopercle

2. Preopercle

3. Opercle

4. Subopercle

What is the preopercle?

An exoskeletal bone supporting the preopercular-mandibular canal.

What is the opercle?

An exoskeletal bone contributing to the operculum.

What are the lower hyoid arch elements?

1. Interhyal

2. Anterior/posterior ceratohyals

3. Dorsal/ventral hypohyals

4. Basihyal

What are branchiostegal rays?

Paired exoskeletal bones associated with the lower hyoid arch.

What is the suspensorium?

All first- and second-arch elements except the lower hyoid portion.

What is the hyopalatine arch?

The suspensorium minus specified upper/lower jaw elements.

What is the hyoid bar?

The lower hyoid portion minus the basihyal.

What do visceral arches 3-7 form?

The gill or branchial arches

Which bony fish gill arches have the full complement of elements?

The first three gill arches

What is the characteristic of the 5th gill arch?

It consists solely of ceratobranchial.

What are toothplates?

Exoskeletal elements associated with the gill arches that often bear teeth.

What are gill rakers?

Exoskeletal elements associated with gill arches.

What is the infraorbital series?

Bones rimming the ventral orbit in teleost fishes.

How many infraorbital bones typically occur in teleosts?

Five, designated IO1-5

What does the infraorbital series suppport?

The infraorbital sensory canal.

What are the two major divisions of the postcranial skeleton?

1. Axial

2. Appendicular

What does the axial skeleton include?

• vertebral column

• median fins/supports

• intermuscular bones

• supraneurals

What does the appendicular skeleton include?

paired fins and their girdles

What is the centrum?

The cylindrical central part of a vertebra surrounding the notochord.

What is the neural arch?

The dorsal vertebral arch surrounding the neural canal.

What is the neural canal?

The canal through which the dorsal nerve/spinal cord passes.

What are neural spines?

Spines extending from the tips of neural arches.

What are hemal arches?

Ventral arches protecting caudal blood vessels.

What is the hemal canal?

The canal containing the caudal blood vessels.

What are transverse processes/basipophyses?

Lateral abdominal vertebral projections where ribs articulate.

What is a parapophysis?

A small ossification on abdominal centra where actinopterygian ribs articulate.

What are prezygapophyses and postzygapophyses?

Processes forming intervertebral articulations on the anterior/posterior centrum.

What is the 1st preural centrum?

The centrum marking the transition between preural and ural vertebrae.

What are epineurals?

Intermuscular bones dorsal to the horizontal septum.

What are epipleurals?

Intermuscular bones ventral to the horizontal septum.

What are epicentrals?

Intermuscular bones located in the horizontal septum.

What are myorhabdoi?

Intermuscular bones lacking a ligamentous connection to the vertebral column.

What are radials?

Endoskeletal elements supporting the median fins.

What are pterygiophores?

Bony radials supporting dorsal and anal fins in ray-finned fishes.

What are supraneurals?

Small plate-like bones between neural spines anterior to dorsal-fin pterygiophores.

What are hypurals?

Radials supporting the caudal fin of bony fishes.

What is a urostyle?

A compound centrum formed by fusion of multiple ural centra and 1st preural centrum.

What are epurals?

Remnant neural spines separated from their associated ural centra.

What are uroneurals?

Remnant neural arches of the ural centra.

What is the scapulocoracoid cartilage?

The largest element of the cartilaginous fish pectoral girdle.

What are the main cartilages of the shark pectoral girdle?

1. Scapulocoracoid

2. Suprascapular

3. Proterygium

4. Mesopterygium

5. Metapterygium

6. Radials

What are the endoskeletal bones of the bony fish pectoral girdle?

1. Scapula

2. Coracoid

3. Mesocoracoid

4. Pectoral radials

What are the exoskeletal bones of the bony fish pectoral girdle?

1. Posttemporal

2. Supracleithrum

3. Cleithrum

4. postcleithra

What is the cleithrum?

The largest bony-fish pectoral-girdle bone; supports muscles and rims the opercular opening.

What is the posttemporal?

A bone connecting the pectoral girdle to the skull.

What is the pubic bar?

The transverse/cylindrical cartialge forming the elasmobranch pelvic girdle.

What are basipterygia?

Paired wedge-shaped endoskeletal bones forming the bony fish pelvic girdle.

What happens to pelvic radials in derived acanthomorphs?

They may be absent; fin rays articulate directly with the basipteryfia.

How are pelvic fins positioned in basal bony fishes?

Typically abdominally, without connection to the pectoral girdle.