Presentation 6: The Skeleton Continued

Question 1

Ostracoderm

Answer 1

fossil that shows external dermal exoskeleton that improves conduction of electrical signals - oldest fossil

Question 2

Splanchnocranium

Answer 2

visceral arches and jaw bone, part of the head skeleton, composed of Mandibular, Hyoid, and Branchial arches

Question 3

Branchial arches

Answer 3

aka gill arches in fish, consisting of
Pharyngobranchial,
Epibranchial
Ceratobranchial
Hypobranchial
Basibranchial (connects 2 sides of the head ventrally)

Question 4

Mandibular arch

Answer 4

epibranchial of 1st -> palatoquadrate
ceratobranchial of 1st -> Meckle’s cartilage aka mandible
pharyngo, hypo, and basibrancial arches are lost

Together palatoquadrate and mandible form jaw

Question 5

Hyoid Arch

Answer 5

epibranchial of 2nd -> hyomandibula
ceratobranchial of 2nd -> ceratohyal
hypo + basibranchial -> hypohyal and basihyal

Pharyngobranchial is lost

Question 6

Ossification of visceral skeleton (JAW and EAR CAPSULE)

Answer 6

palatoquadrate -> quadrate bone (fish)
Mandible -> Articular bone (fish)
hyomandibular arch -> hyomandibular bone (homologous to stapes in mammals and columella of frogs)

Quadrate -> incus (mammals)
Articular -> malleus (mammals
Hyomandibular bone -> stapes (mammals)

amphibians only have columella

Question 7

Quadrate Bone

Answer 7

part of jaw in fish that comes from palatoquadrate

Question 8

Articular Bone

Answer 8

part of jaw in fish that comes from mandible

Question 9

Hyomandibular bone

Answer 9

part of jaw in fish that comes from hyomandibular arch

Question 10

Incus

Answer 10

part of ear capsule in mammals derived from quadrate bone

Question 11

Malleus

Answer 11

part of ear capsule in mammals derived from articular bone

Question 12

Stepes

Answer 12

part of ear capsule in mammals derived from hyomandibular bone (part in contact with inner ear)

Question 13

Columella

Answer 13

homologous to stepes, only ear bone in amphibians

Question 14

Jaw Suspension

Answer 14

1. Amphisyli (palatoquadrate fused to neurocranium, hyomandibula supports jaw)
2. Hyostyli (palatoquadrate NOT fused to neurocranium, hyomandibula supports the jaw)
3. Autostyli ( palatoquadrate fused to neurocranium, hyomandibula DOES NOT support jaw)

Question 15

Amphistyli

Answer 15

palatoquadrate fused to neurocranium, hyomandibula supports jaw

Found in fossils, bony fishes, and early tetrapods

Question 16

Hyostyli

Answer 16

palatoquadrate NOT fused to neurocranium, hyomandibula supports the jaw

found in cartilaginous fishes, sharks, and fossil gnathostomes

Question 17

Autostyli

Answer 17

palatoquadrate fused to neurocranium, hyomandibula DOES NOT support jaw

Found in cartilaginous fishes and early tetrapods

Question 18

Skull Fenestration

Answer 18

1. Anapsida (no fenestra)
2. Synapsid (only lower fenestra)
3. Diapsida (2 temporal fenestra)
4. Eurypsida (only upper fenestra)

Question 19

Anapsida

Answer 19

no fenestra, found in turtles

Question 20

Synapsid

Answer 20

only lower temporal fenestra - found in mammals

Question 21

Diapsida

Answer 21

both temporal fenestra - found in crocodylia, birds, and squamates (snakes and lizards)

Question 22

Eurypsida

Answer 22

only upper temporal fenestra - found in plesiosaurs and icthyosaurs

Question 23

Secondary Pallate

Answer 23

YES - mammals, crocodilia, turtles
NO - amphibia