Exam II – Ch. 34 – Sheet 6
Chapter 34 – Vertebrates
1. What are unique characteristics of amphibians?
 3 chambered heart
 Closed circulatory system (all craniates)
 Have lungs and moist skin
 External fertilization in water and on land (spermatophores)
2. Amphibians undergo Metamorphosis as they transition from juveniles to adults. Some adult
newts retain gills from their juvenile state which is an example of Paedomorphism.
3. What are unique characteristics of reptiles?
 3 chambered heart (except for crocodiles which have 4)
 Keratinized skin (waterproof)
 Internal fertilization
 Exothermic
 Amniotic Egg
4. Name and describe the four amniotic membranes mentioned in class.
 Amnion – keeps embryo moist
 Chorion – aids in gas exchange
 Yolk - provides nutrients for the embryo
 Allantois – aids in disposal of metabolic waste
5. What ancestral species is believed to be a bridge between reptile and bird evolution? Why?
 Archaeopteryx
 Reptile characteristics: teeth, claws, scales, and vertebral tail
 Bird characteristics: feathers (derived from scales; both keratinized)
6. Birds exhibit Sexual Dimorphism, which distinguishes males from females.
7. What are the defining characteristics of mammals?
 Hair made of keratin (did not derive from scales)
 Mammary glands – modified sweat gland
 Tooth differentiation – based on food
 Brain – highly developed with a large cerebral hemisphere
 Nervous system
 Lungs
 4 chambered heart
 3 ear bones – stapes (only in reptiles), incus, and malleus
8. Name and describe the three groups of mammals.
 Monotremes – egg laying
primitive
milk disperses like sweat (no nipples)
example: Platypus and Echidna
 Marsupials - give birth to embryo
embryo develops inside pouch
embryos have very developed forelimbs for climbing
Exam II – Ch. 34 – Sheet 6

Placentals -
nourishes embryo via placenta
advanced mammals (group with greatest number of species)
9. Many marsupials resemble placental animals in similar ecological roles in other parts of the
world, which is an example of Convergent Evolution.
10. If you were given a description of a monkey, what characteristics would help you distinguish if it
was an old world or new world monkey?
 New World – long slender arms
prehensile tail (able to grasp)
live predominantly in trees
nostrils open to the side
 Old World - lack prehensile tail
colored buttocks
tough seat pads
nostrils open downward
11. What is the difference between a Hominoid and a Hominid?
 Hominoid – describes humans, ancestral species, and great apes
 Hominid – describes only humans and ancestors
12. Describe these early human.
 Australopithecus –
Afarensis
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“Lucy”
walked upright
450 cc brain
Homo habilis –
“handy man”
made tools
660-750 cc brain
Homo erectus first to leave Africa
controlled fire
1100 cc brain
Homo neaderthalensis – not related to humans
larger than humans
lived in cold climates
Homo sapiens evolved from Homo erectus in Africa, NOT in various places
13. Which gene is responsible for our ability to speak?
 Fox P-2 gene