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Chapter 24

1. Phylogeny and characteristics of classes in the subphylum vertebrata a. Agnatha ---cartilagineous skeleton and lacks a functional

jaw

b. Chondrichthyes --- jaws present but no true bonec. Osteichthyes most modern fish are representative of this group (gills

, lung, and bladder )

d. Amphibia metamorphosis during development; juveniles areaquatic but adults are terrestrial

e. Reptilia produces an amniotic (land) egg

2. 4 major milestones that mark evolution of the vertebrate choradatesa. The evolution of bony vertebrae around the hollow dorsal nerve cord .

b. Evolution of a bony cranium to protect the brain (related to 1a)..

c. The evolution of jaws (gnathostomes) .

d. The evolution of tetrapody (4 appendages )-- vertebrate animals with four limbs

e. Evolution of the amniotic (terrestrial) egg.

3. What is the main line of evidence to suggest that the first terrestrial amphibians evolvedfrom lobefin fish? Hint: the coelacanth is a modern representative of this group- This is the origin of tetrapody in vertebrates- Evidence comes from the homology in limb structures(the homology in bone structure suggests that lobe fin fish gave rise to primitiveamphibian tetraphods)

4. The vertebrate lung first appeared in amphibians

5. All chordates have 3 structures in common during some point in development: Notochord

, hollow dorsal nerve cord , and pharngyl slits

6. In the most primitive chordates (urochordates ), only the larval form mayhave bilateral symmetry and all of the distinctive chordate characteristics (e.g.notochord, dorsal nerve).

7. List 3 tissue that are only found in vertebrate chordates

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a. Epithelium cells -- important lining tissue. b. Connective tissue -- includes collagen, elastic fibers, and cartilage . Alsoincludes blood and lymph cells .c. Bone -- Higher vertebrates have calcareous bone tissue as well as cartilage.

8. What do endothermy (being warm blooded) and activity level have to do with theevolution of the 4 chambered heart in birds and mammals?Double ventricles effectively separate the deoxygenated and oxygenated blood whichleads to much higher blood oxygen levels (compared to amphibians and reptiles). Thisallows for the much higher metabolism of birds (and mammals-- see below)necessary to support endothermy and high levels of physical activity. Notice the degreeof lethargy of amphibians and reptiles compared to birds and mammals.