Lecture 3

Question 1

Name the 7 Pleisomorphic characters of Vertebrata

Answer 1

1) Deuterostomate (all deuterostomata)
2) pharyngeal slits (Ambulacraria + Chordata)
3) patterning inversion (all Chordata)
4) endostyle (all Chordata)
5) post-anal tail, metamerism, swimming (all Chordata)
6) dorsal nerve tube, notochord (all Chordata)
7) migratory neural crest cells (all Olfactores)

Question 2

Name the Synapomorphic characteristics within Vertebrata

Answer 2

1) Vertebral column

2) cranium

Question 3

Changes in skeletal system during chordate phylogeny

Answer 3

• skeleton to support muscular pump
• distinct cartilage & bone tissues
• body support changed from 
 notochord to vertebral column
• jaws  (predatory life style)
• complex system 
 in head region, sensory more complex 
  brain, protection by a skull
• appendages & eventual aquatic to 
 terrestrial lifestyle transition

Question 4

Endochondral bone develops from—

Answer 4

a cartilage template

Question 5

Adult long bones exhibit what type of growth in mammals?

Answer 5

Determinate

Question 6

Adult long bones exhibit what type of growth in fish?

Answer 6

indeterminate

Question 7

Membranous bones form—

Answer 7

without a cartilage template

Question 8

What are dermal bones?

Answer 8

Bones within dermis

Question 9

Sasamoid bones are—

Answer 9

bones within tendons

Question 10

What is the chemistry of bone?

Answer 10

70% mineral, 30% protein (mostly collagen)

Question 11

What is the chemistry of tooth enamel?

Answer 11

100% mineral

Question 12

What happens in Chondrichthyes (including Elasmobranchii) in regards to bone?

Answer 12

A secondary loss of bone

Question 13

Why are bones continually remodelled?

Answer 13

to repair stress microfractures/fractures and respond to mechanical loading

Question 14

What are the three components of the composite cranium?

Answer 14

Splanchnocranium, Chondrocranium, and Dermatocranium

Question 15

The Composite skull arrases embryologically from—

Answer 15

Mesoderm and Neural Crest Cells

Question 16

The chondrocranium section of the skull includes what?

Answer 16

• form the base & back of braincase,
surround sensory capsules
• develop at anterior end of notochord
includes otic capsule, parachordal, Ethmoid plate

Question 17

Chondrocranium is present in all of what group?

Answer 17

The Vertebrates

Question 18

Why is there no chondrocranium in agnathans or chondrycthyes?

Answer 18

There’s no dermal bone in those groups

Question 19

What does splanchnocranium form?

Answer 19

Derivatives of the pharyngeal arches

Question 20

What does the splanchnocranium do?

Answer 20

• support the gills, respiratory 
muscle attachments
• contribute to the jaws, hyoid 
 apparatus & middle ear bones
• a lot of bones are available for
reorganization during evolution

Question 21

Splanchnocranium is present in all of what group

Answer 21

Vertebrates

Question 22

Dermatocranium is what type of bone?

Answer 22

Dermal

Question 23

What does Dermatocranium form?

Answer 23

• the vault and sides of skull, the face
• also part of the roof of the mouth
• often replace bones of the chondro-
& splanchnocranium in adults.

Question 24

What else develops from Dermatocranium?

Answer 24

teeth

Question 25

What 2 groups don’t have Dermatocranium?

Answer 25

Cyclostomes and chondrycthyes