Download like dinosaur - Southwest High School

• 18.16 Lampreys are vertebrates that lack
hinged jaws
– Lampreys represent the oldest living lineage of
vertebrates
• Suspension feeders in freshwater streams
• Have jawless mouth with rasping tongue
– The vast majority of living vertebrates have
two-part jaws connected by a hinge
– Jaws likely evolved from anterior pharyngeal slits
•18.17 Jawed vertebrates with gills and paired fins
include sharks, ray-finned fishes, and lobe-fins
– Three lineages of jawed vertebrates with gills and
paired fins are commonly called fishes
– Chondrichthyans have changed little in 300 million
years
• Include sharks and rays
• Flexible skeleton made of cartilage
• Lateral line system of sensory organs
– The ray-finned fishes include familiar fishes
such as tuna, trout, and goldfish
• Skeleton reinforced with a hard matrix of calcium
phosphate
• Operculi that move water over the gills
• Buoyant swim bladder
– Lobe-finned fishes have muscular fins
supported by bones
• Three surviving lineages including one that gave
rise to terrestrial vertebrates
•18.18 Amphibians were the first tetrapods—
vertebrates with two pairs of limbs
– Amphibians were the first tetrapods with limbs
allowing movement on land
• Possibly evolved from lobe-fins during the
Devonian period
• Became very widespread during the Carboniferous
period
• Include salamanders, frogs, and caecilians
– The “double life” of amphibians refers to the
metamorphosis of many frogs
• Larval stage (tadpole): a legless, aquatic algae-eater
with gills, a lateral line system, and a long, finned tail
• Adult: a terrestrial insect eater with four legs and airbreathing lungs
– Most amphibians are found in damp habitats,
where their skin functions in gas exchange
– Amphibian skin usually contains poison glands
that function in defense
• 18.19 Reptiles are amniotes—tetrapods with a
terrestrially adapted egg
– Reptiles include lizards, snakes, turtles, crocodiles,
birds, and a number of extinct groups such as dinosaurs
– The major derived characteristic of the clade containing
reptiles and mammals is the amniotic egg
• Embryo develops with a protective, fluid-filled sac
• Enabled reptiles to complete their life cycles on land
– Reptile adaptations for terrestrial life in addition to the
amniotic egg include
• Scaly, waterproof skin that keeps body from drying out
• Lungs for obtaining oxygen
• Ecothermic metabolism (in nonbirds)
– Dinosaurs, the most diverse reptiles, included some of
the largest animals ever to inhabit land
• May have been endothermic
• Died out 65 million years ago but left birds as descendants
•18.20 Birds are feathered reptiles with
adaptations for flight
– Birds likely evolved from a lineage of small,
two-legged dinosaurs called theropods
• Evidence from fossils such as Archaeopteryx
LE 18-20a
Wing claw
(like dinosaur)
Teeth
(like dinosaur)
Feathers
Long tail with
many vertebrae
(like dinosaur)
– Nearly every part of the body of most birds
reflects adaptations that enhance flight
• Weight-reducing features such as few teeth, strong
but light bones
• Feathers
• Large, powerful breast muscles
• Endothermic metabolism, highly efficient circulatory
system
• Acute vision
– Birds have relatively large brains and complex
behaviors
• Male and female cooperation in raising young
• Migration
– A few flightless species of birds exist (example:
emu)
•18.21 Mammals are amniotes that have hair and produce
milk
– Main adaptive features of mammals
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Hair, which provides insulation
Mammary glands, which produce milk
Endothermic metabolism
Efficient respiratory and circulatory systems
Differentiation of teeth for different foods
Large brain, long period of parental care allowing for learning
– There are three main groups of living mammals
• Monotremes lay eggs
– Examples: echidna, duck-billed platypus
• The embryos of marsupials and eutherians are nurtured
by the placenta within the uterus
– Marsupials complete development outside the mother’s
body
– Eutherians (placental mammals) complete development
before birth