I. READ ALL the assigned Introductory Chapter Essays
You WILL be given one intro essay question/chapter.
Ch 18 lecture topics ~
1.7 species known, 1.3 are animals. Duck-billed platypus who has hair and milk is a mammal due to hat trait even
though it looks like a duck and lays eggs. Platypus’ bill has a larger purpose as a sensory organ to find locate food while
the duck uses it only to dig. Marsupials, where the young grows up in the pouch used to live in other continents but could
not compete with other mammals except in Australia.
Animalia is 35 phyla.
1. Taxonomic groups covered on this exam include [know major traits and phylogenetic relationships among the
2. Make sure you remember analogy versus homology and be able to apply the use of these words:=D
Homology - reflects common ancestry. Birds share with crocodilians and some extinct dinosaurs nest building,
acoustic communication among parents and young, and other aspects of complex parental care… homologies
Analogy – convergent evolution
and function—think wings of birds and bats, white fur of some cats and bears.
3. Know the key characteristics of the above groups [e.g. what makes a tetrapod a tetrapod, what & who is an
amniote? What do chordates share in common?
Tetrapods are four limbed bony creatures
Amniotes are reptiles and mammals, have a terrestrially adapted shelled egg, internal fertilization, and an
integument that is less leaky than that of amphibians
Chordates all share dorsal hollow nerve, a notochord, pharyngeal slit, post-anal tail, and body segmentation.
4. What is ectothermy?
What is endothermy?
Which groups have which?
What traits evolved as tetrapods gained more independence from an aquatic life-style? Which group(s) do you see
the transition of traits supporting life on land?
Ectothermy- cold-blooded, get heat externally- non-bird reptiles
Endothermy- metabolically produce body heat- dinosaurs, birds and mammals
Early Tetrapods- plementing gills for gas exchange, and sturdy muscular fins supporting extension of the skeleton
for paddling and crawling through dense vegetation at water’s end, definitive tongue, metamorphis to adulthood
on land, and larvae has to be born in water from early lungfish
Frogs show a transition of traits supporting life on land.
5. What are the definitive characteristics of early tetrapods and modern amphibians?
Early tetrapods had plementing gills for gas exchange, and sturdy muscular fins supporting extension of the
skeleton for paddling and crawling through dense vegetation at water’s end.
Amphibians were specialized in their land environment, four legs, air-breathing lungs
6. Know examples from major placental mammal groups “ orders” that were given during lecture [see ppt &
Rodentia, 2025 species of rats, squirrels, etc. . Woodchuck, porcupine, beaver, racoon and Prairie dog