Lissamphibia (Lec 12)

Question 1

Lissamphibia SYNAPOMORPHIES

Answer 1

2 occipital condylles

Loss of skull bones (compare to sarcopterygian ancestors)

Short STRAIGHT ribs (when present) do NOT encircle visceral cavity = NO rib cage:
–Implies lung ventilation

Levator bulbi muscles to elevate the eyes

Naked moist skin with mucous and poison glands

Pedicellate teeth with suture

Gas exchange:

• -Cutaneous
• -Buccopharyngeal air pump (positive pressure pump)

Question 2

Lissamphibia ANCESTRAL CHARACTERISTICS

Answer 2

Gills and/or lungs (larval and/or adult stage) = gas exchange in adults can be via GILLS, LUNGS, SKIN, or some COMBO

3 chambered heart (2 atria + 1 ventricle) = double circulation pattern (tetrapod synap)

Ectothermic

Undergo metamorphosis (i.e., larval and adult stages)

Question 3

Diversity of Lissamphibia

Answer 3

Number of described species has doubled since 1985: “race” to discover new species before they go extinct

Question 4

Number of Species: Caudata

Answer 4

738

Question 5

Number of Species: Anura

Answer 5

7145

Question 6

Number of Species: Gymnophiona

Answer 6

213

Question 7

Caudata

Answer 7

SALAMANDERS

Occur in Northern temperate regions (Holoarctic)

Greatest deep lineage diversity in Appalachian region of USA (7 of 10 families)

ONE family (PLETHODONTIDAE) accounts for 2/3 of all species

One lineage of plethodontids has diversigied in Central and norther S. America into ~300 species (40% of all salamander species)

Most species are small (but Andrias reaches >1m)

USUALLY have forelimbs and hind limbs

ALWAYS have a tail

Carniverous both as larvae and as adults

Very LOW metabolic rates

Metamorphic condition: ANCESTRAL

Some paedomorphic (heterochrony): DERIVED
--Attain sexual maturity but retain larval characteristics (external gills, tailfin, aquatic habit, etc.)