Practice Qs

Question 1

Using diagrams, show the main patterns of skull fenestration in aminotes and give an example for each.

Answer 1

Anapsid - Turtle
Synapsid - Human
Diapsid - Lizard

Question 1

What are pharyngeal jaws? Give an example

Answer 1

• Second set of jaws within an animals pharynx
• Branchial arches modified
• E.g Moray Eel has highly specialised raptorial jaws

Question 2

Other than the aminotic egg, what are some dervied features of the aminotes?

Answer 2

• Thick, waterproof skin
• Costal ventilation (by ribs and diaphram)
• Temporal fenestration
• Skin elaborations (Scales, hair, feathers,

Question 3

How do cartilaginous fish sense their prey?

Answer 3

• Mechanoreceptors: neuromast cells detect vibrations
• Chemoreceptors: Olfactory bulbs, acute sense of smell
• Electroreceptors: electric impulses sensed by ampullary organs
• Vision: low light

Question 4

Key features of mammals

Answer 4

• Diaphragm
• Mammary glands = lactation
• Hair
• Lower jaw made from single bone (Dentary) - strong articulation
• Endothermy

Question 5

Illustrate covergent evolution in marsupial and placental mammals

Answer 5

Flying squirrel (placental) and flying phalanger (marsupial)

Or

Marsupial mole and placental mole

Question 6

How and why did the jaw evolve?

Answer 6

• Muscularised pharynx (branchial arches) - formed jaw
• Mandibular arch
• Gnathostomes were able to suck in prey - selected jaw to be large for feeding
• Duplication of Hox gene complex

Question 7

What features distinguish the vertebrates from the invertebrate chordates?

Answer 7

• Vertebrae (replaces notochord)
• Endoskeleton made from cartilage or bone
• Invert chordates have 1 hox gene complex, verts have 2
• Larger brain with 3 parts (fore,mid, hind)

Question 8

Why is Tiktaalik considered a transitional form between the early
tetrapodomorph fishes and the early tetrapods?

Answer 8

Fish like features:
- Scales
- Fins
- Gills

Tetrapod features:
- Neck
- Flattened head with eyes on top
- Lungs!

Question 9

Explain why Archaeopteryx can be considered as an intermediate
between birds and dinosaurs.

Answer 9

Reptillian features:
- Strong thick bones
- No fusion of vertebrae
- Toothed Jaw

Bird features:
- Well developed feathers
- Reduction in digits (3)
- S shaped neck

Question 10

Discuss the importance of hip structure in the phylogeny of Dinosauria.

Answer 10

Semi-erect to erect posture
- Open hip socket (acetabulum)

Divides into clades: Saurischians, Ornithischians:
- Saurischians ‘lizard hipped’ bone points down and forwards (modern birds)
- Orthiischians ‘bird hipped’ bone points down and backwards

Question 11

What are the main hypotheses explaining the evolution of flight? Discuss
using examples.

Answer 11

1. Arboreal ‘tree down’ e.g Extant Hoatzin chicks use claw to help climb trees
2. Cursorial ‘ground up’ e.g Archaeopteryx may have used wings for balance while running
3. WAIR ‘wing assisted incline running
4. Pouncing Proavis

Question 12

Briefly detail the unique features of marsupial reproduction and discuss
the associated costs and benefits

Answer 12

• 2 vaginas and bifuricate penis! so preg can follow immediately after one another
• Short gestation
• Extended lactation & development

Benefits
- Less gestation risk for mother
- Rapid repro cycle
- Post-birth flexibility

Costs:
- Low fitness of young
- High parental care

Question 13

Providing one example, discuss the diversity of sociality in primates.

Answer 13

Very diverse:
- Male transfer
- Female transfer
- Monogamy
- E.g organutans are solitary but due to undefendable ranges display scramble competition polygyny