Lecture 10 - 2.0

Question 1

Three Extant Living Groups of Amphibians:

Answer 1

1. Urodela (caudata): Salamanders and newts
2. Salientia (Anura): frogs and toads
3. Gymnophonia (Apoda): caecilians

Question 2

Amphibian Shin (Integument( Major Features (2):

Answer 2

1. Musouc glands
2. Granular glands

Question 3

Significance of Mucus Glands:

Answer 3

secrete musuc to help with cutaneous respiration

Question 4

Significance of Granular Glands:

Answer 4

Secrete poisonous alkaloid compounds for defense

Question 5

Aspects of Amphibian Skin (Integument) (3):

Answer 5

1. Increased compared to fishes but thinner overall to facilitate gas exchange
2. Most terrestrial forms have more keratin (waterproofing)
3. Some caecilians and toads have bone elements (osteoderms) in the dermis for defense

Question 6

What is Metamorphosis in Amphibians:

Answer 6

Indirect development from egg to larval form to adult

Question 7

What is Paedomorphosis in Metamorphosis:

Answer 7

Retention of larval characters into ‘adulthood’

Question 8

What are Pedicellate Teeth:

Answer 8

Each tooth crown sits on a base (pedicel) separated from tip (crown) by a fibrous connection (suture)

Question 9

Anurans (Frogs and Toads) Main Characteristics (5):

Answer 9

1. Paired limbs
2. Absence of tails (adults)
3. Jumpers
4. Tympanum usually present to transmit sound to inner ear
5. Fertilization external, except in Ascaphus (extension of male cloaca

Question 10

Anurans (Frogs and Toads) - Skull (3):

Answer 10

1. Flattened, open, with big jaws
2. Palate is highly reduced - allows eyeballs to drop into oral cavity when swallowing prey
3. Hyomandibula becomes the stapes (first ear bone)
   - splanchocranium, chondrocranium, dermatocranium all present

Question 11

Anurans (Frogs and Toads) Skeleton - Axial Skeleton (4):

Answer 11

1. Highly specialized to support muscular jumping hindlimb
2. Shortened vertebral column with 9 or fewer vertebrae
3. Atlas (cervical vertebrae) - skull junction forms a moveable joint through two condyles
4. Post-sacral vertebrae fused into a rod-shaped urostyle lying between the two elongated ilium bones of pelvis girdle

Question 12

What do the Condyles do:

Answer 12

Improved mobility of head in dorsoventral axis

Question 13

Anurans (Frogs and Toads) Skeleton - Appendicular Skeleton (3):

Answer 13

1. Robust pectoral girdle and fused radius/ulna are used to absorb the shock of landing
2. Tibi/fibula and ankle bones also fused for sturdiness
3. increased in length of hindlimbs (jumpers)

Question 14

Salamanders (Order Caudata): (Main Characteristics) (4):

Answer 14

1. Paired limbs and a long tail
2. Suction feeding in water and projectile tongue on land
3. No tympanum present
4. Fertilization can be external or internal transfer by means of spermatophore transfer

Question 15

Salamander Skeleton - Skull (4):

Answer 15

1. Flattened, open skull with large orbits
2. Poor ossification, reduction and loss of bones are common
3. Floor of the throat is rapidly expanded, and the jaws parted during suction feeding
4. Splanchocranium, chondocranium, dermatocranium all present

Question 16

Salamander Skeleton - Axial and Appendicular Skeleton (2):

Answer 16

1. Use short walking limbs are swimming tail
2. Walking and swimming are distinct modes of locomotion controlled by distinct set of neurons in the brainstem

Question 17

Caecilians (Main Characteristics) (3):

Answer 17

1. No limbs or girdles, skull is often solid and compact for burrowing
2. Ristricted to tropical habitats
3. Internal fertilization; hatchlings are aquatic or terrestrial

Question 18

Origins: Competing Theories (Temnospondyl Hypothesis) (2):

Answer 18

1. Modern amphibians form a monophyletic clade
2. Derived from Temnospondyl amphibian ancestors

Question 19

Origins: Competing Theories (Lepospondyl Hypothesis) (2):

Answer 19

1. Modern amphibians form a monophyletic clade
2. Derived from Lepospondyl amphibian ancestors

Question 20

Origins: Competing Theories (Polyphyletic Hypothesis) (3):

Answer 20

1. Lissamphibia from a polyphyletic clade
2. Frogs and salamanders are derived from Temnospondyl amphibian ancestors
3. Caeilians are derived from Lepospondyl amphibian ancestors

Question 21

Why the Conflicting Answers: Heterochrony:

Answer 21

Changes in the rate and timing of developmental events between ancestors and descendants