Section 31.4 (Exam 3) Flashcards
Tetrapods Diversified Rapidly in Terrestrial Environments
What was necessary for the fish to evolve into land animals?
The ability to breath air; lung-like sacs (lungfishes)
What resulted in the ability to walk on land in lobe-limbed vertebrates?
paired pelvic and pectoral fins became more muscular, joined to the body by an enlarged bone
When were coelacanths thought to have become extinct?
65 mya
Where were living coelacanths found and when?
Off the coast of South Africa in 1938
What is a derived feature of coelacanths?
cartilaginous skeleton
Why is a cartilaginous skeleton a derived feature of coelacanths?
Because its ancestors had bony skeletons
What are some characteristics of lungfishes?
They have lungs and gills
They can burrow in mud when ponds dry up and survive many months in an inactive state while breathing air
What was the first step that aquatic lobe-limbed vertebrates took to evolve into ancestral tetrapods?
Using terrestrial food sources and became adapted to life on land
Which two groups make up tetrapods?
Amphibians and amniotes
What are some characteristics of amphibians?
Most remain tied to moist habitats; they lose water easily through the skin; eggs dry out if exposed to air.
Some species are entirely aquatic, and in others adults live on land, but must return to water to lay eggs; larvae develop in the water.
What are the three groups of amphibians?
Caecilians
Anurans
Salamanders
What are caecilians?
A major amphibian group
Wormlike, limbless, tropical burrowing animals
What are some characteristics of anurans, a major amphibian group?
Some have tough skins and other adaptations for dry habitats.
Many are arboreal; some completely aquatic.
All have a short vertical column and pelvic region modified for hopping/leaping or kicking in the water.
What are some characteristics of salamanders, a major amphibian group?
Many live in moist soil and rotting logs.
One major group has lost the lungs and relies on gas exchange through skin and mouth lining.
Completely aquatic species – they develop through neoteny.
What is neoteny?
retention of juvenile characteristics
Many amphibians have complex social behaviors. What are some examples of these?
Male anurans call to attract females and defend territories.
Some species lay a few eggs and guard the nest or carry the eggs on the body
What are some characteristics of amniotes that enable them to conserve water and exploit terrestrial habitats?
Amniote egg
Adult amniotes have a tough skin with scales, feathers, or hair to prevent drying.
Kidneys allow excretion of concentrated urine
How do kidneys in amniotes prevent water loss?
Kidneys allow excretion of concentrated urine, allowing excretion of nitrogen wastes without losing a lot of water
What are some characteristics of the amniote egg?
Relatively impermeable to water; the embryo develops in a contained aqueous environment
Leathery or brittle shells
Yolk
Extraembryonic membranes
What are some characteristics of the leathery/brittle shells of amniote eggs?
Retard water evaporation
Allow gas exchange
What is the function of a yolk in amniote eggs?
storing food
What is the function of extraembryonic membranes in the amniote egg?
protect the embryo from drying and assist gas exchange and excretion of nitrogen
Name some ways in which the amniote egg was modified for different organisms.
In several groups, modification of the egg allowed the embryo to develop inside its mother’s body
In mammals the egg lost its shell entirely; functions of the extraembryonic membranes were retained and expanded.
What are the two major groups of animals that amniotes split into?
Reptiles and mammals
What are the 4 groups of reptiles?
Squamates
Turtles
Crocodilians
Birds
What are some examples of squamates?
lizards or snakes
What are some characteristics of squamates?
Skin covered with horny scales.
Gas exchange is only through the lungs.
What is the lizard feeding type?
Most lizards are insectivores, some are herbivores and predators
Name some characteristics of snakes.
Snakes are limbless squamates; all are carnivorous.
Many have venom glands.
How has the turtle changed over time?
very little since the early Mesozoic
Name some characteristics of turtles.
Dorsal and ventral bony plates form a shell.
Dorsal shell is a modification of the ribs.
What are 4 examples of crocodilians?
Crocodiles, caimans, gharials, and alligators
What are some characteristics of crocodilians?
Carnivores; mostly stay in water in tropical and warm temperate regions.
Build nests on land or floating piles of vegetation—heat from decaying organic matter warms the eggs.
Describe some classifying characteristics of birds.
They are a specialized group of theropods
They fall into two groups: flying and flightless
Describe some physical characteristics of birds.
Feathers
Bones
Beaks and no teeth
What are theropods?
a group of predatory dinosaurs
What are the three traits that birds shared with theropods?
Bipedal stance
Hollow bones
A Furcula
What is a furcula?
a wishbone
Name some flightless birds.
Tinamou, rhea, emu, kiwi, cassowary, ostrich
What are some characteristics of bird feathers?
lightweight, but strong
provides flying surfaces
insulation
attracts mates
What are some characteristics of bird bones?
Hollow with internal struts; lightweight, but strong
Why do birds have beaks with no teeth?
Birds may consume many different types of food.
Since they eat fruits and seeds, what roles do birds play in the environment?
Birds are important agents of plant dispersal
What are some fun facts about mammals?
They coexisted with dinosaurs
Range in size from tiny shrews to blue whales
Highly differentiated teeth represent their varied diets
What are some key physical features of the mammals?
Sweat glands
Mammary glands
Hair
4-chambered heart
What is the function of a 4-chambered heart?
completely separates oxygenated from deoxygenated blood (a convergent trait with groups like dinosaurs, birds and crocodiles)
What is a convergent trait?
Similar selective pressures led to the evolution of a certain trait; unrelated to genetic similarities
Describe the eggs of mammals.
Fertilized internally
Embryos develop in female uterus
Embryo is contained in an amniotic sac
Placenta connects embryo and uterus wall
What is the purpose of the placenta in mammals?
nutrient/gas exchange
waste elimination
both happen via the female’s circulatory system
Describe hair in mammals.
Hair (fur) is thick in some species, and greatly reduced in others
How do mammals that have greatly reduced fur insulate themselves?
In cetaceans (whales and dolphins) – a thick layer of fat (blubber)
Humans learned to use clothing
What are the two groups of living mammals?
Prototherians and Therians
What are 2 prototherians?
duck-billed platypus and echidna
What are some characteristics of prototherians?
lay shelled eggs
provide milk to their young
What are some characteristics of marsupials?
Carry and feed young in a ventral pouch. Young are born early, and crawl into pouch for further development.
Most are in Australia and South America.
Marsupials are herbivores, insectivores, and carnivores.
None can fly, but some arboreal species are gliders.
What is the name of the only marsupial in North America north of Mexico?
Virginia opossum
What are some characteristics of eutherians?
Have well-developed placentas; young are more developed at birth than marsupials.
Almost 2/3 of all eutherians are rodents and bats
What did several groups do that transformed the landscape?
grazing and browsing
What did plants do in response to grazing and browsing?
Evolved to create harsh chemical compounds, plant spines, tough leaves, and larger size.
How did herbivores respond to plants evolving to create harsh chemical compounds, plant spines, tough leaves, and larger size?
Herbivores in turn evolved adaptations to the teeth and digestive systems, and many grew larger
How did carnivores evolve in response to herbivores growing larger?
Carnivores also grew larger so they were able to prey on the large herbivores.
Which eutherian lineage returned to an aquatic habitats?
Cetaceans
What are cetaceans?
whales and dolphins
What did cetaceans evolve from?
hoofed ancestors
