1. Axial Skeleton - Skull
Neurocranium
Dermatocranium
Splanchnocranium

2. Dermatocranium
Phylogeny – membrane bone which evolved from dermal armor
Roofing bones
Along side and above brain

3. Roofing Bones Nasal Frontal Parietal Orbital Squamosal Lacrimal
Jugal = Infraorbital = Zygomatic
Squamosal

7. Look at the Skull & Lower Jaw components page
Look at the Skull & Lower Jaw components page. Examine the roofing bones.

8. Upper jaw
Premaxilla
Maxilla

11. Lower Jaw Dentary - largest Splenial – small, dorsomedial
Surangular - lateral
Angular – medial, becomes typanic bulla
Coronoid – medial
Prearticular – medial & caudal – becomes anterior malleus in mammals

15. Key Points
Look at upper and lower jaw dermatocranium bones on Skull & Lower Jaw Components page
Give an example of homology.
What trend do you see in lower jaw evolution?

16. Primary Palate Bones Roof of oropharyngeal cavity in fish, amphibians
Roof of nasal cavity in amniotes

18. Primary Palate
Vomer
Palatine
Pterygoid

21. Primary Palate
Examine Skull & Lower Jaw Components page

22. Dermatocranium
Operculum

23. Key Point
Describe dermatocranium bones in the shark…

24. Axial Skeleton - Skull Neurocranium Dermatocranium
Splanchnocranium – Visceral skeleton

25. Splanchnocranium Supports & allows movement of jaws, gill, tongue
Associated with hearing
Ancient in evolution
Replacement bone

26. Splanchnocranium Typically 6 gill slits between Visceral arches
A typical visceral arch that is gill in function has five segments
Pharyngobranchial
Epibranchial
Ceratobranchial
Hypobranchial
Basibranchial

29. Splanchnocranium Mandibular arch = Visceral Arch I Palatoquadrate
Mandibular = Meckel’s Cartilage

32. Splanchnocranium Hyoid arch = Visceral arch II Hyomandibula Ceratohyal
Basihyal

34. Interrelationships
The neurocranium, dermatocranium and splanchnocranium eventually becomes intimately associated to form one single, firm skull

35. Key Point Describe the origin of jaws from this picture

36. Key Point
The three main components of the cranium are: