Skull

chondrocranium

• neurocranium

• elasmobranchs (sharks)

• cartilage / endochondral bone

  → brain floor

  → sensory (nasal, otic, optic)

1. basal and ethmoid plate

2. optic and otic capsules

splanchnocranium

visceral portion

→ gill support

→ respiratory muscle attachment

→ jaw, hyoid apparatus

• serial theory: 1&2nd arch → mandibular and hyoid

  → mandibular: auditory region

  → hyoid arch: hyoid apparatus

• composite: series of losses and fusions to form jaw

dermatocranium

arise from ostracoderms

• predominant portion of amniotes skulls

  → encase brain

  → dentary

  → roof of braincase

cranial bones

• frontal

• parietal

• temporal

• occipital

• maxilla

• mandible

• zygomatic

• foramen magnum

• hard and soft plate

mandible mental foramen

nerves and blood vesselsdentry

mandible body

holds dentry

skull phylogeny

• reflect feeding style

• reduce bone numbers

• composite structure of skull portions

chondrichthyes

chondrocranium is prominent

• cartilaginous fish

lissamphibia

• broad, flat braincase

• bone loss associated with metamorphosis lifestyle

• lingual feeding

snake

dislocates mandible

avian

• fused bones

• sclerotic bone (eye sensory)

• mandible and maxilla = beak

  • shaped determined through diet

ear

tympanic membrane and auditory tube

horse optic nerve blocks

useful for eye exams

• supraorbital

• palpebral

• auriculopalpebral

nasal turbinates

filter and warm air

• size allows for nasal tubing