Transcript You Light Up My Life

Vertebrates
Old and New
• Every animal is a
combination of traits
• Some traits come
from ancestors
• Other traits are
unique
Chordate Characteristics
• All share four features:
– Notochord -> vertebrae
– Dorsal tubular nerve cord
– Pharynx with gill slits
– Post-anal tail
LE 17-30
Muscle segments
Notochord
Dorsal,
hollow
nerve cord
Brain
Mouth
Anus
Post-anal
tail
Pharyngeal
slits
Invertebrate Chordates
• Two subphyla
• Sea squirts
– Larval stage
• Lancelet
– All characteristics
Figure 17.31
LE 17-32
Chordates
Vertebrates
Tetrapods
Amniotes
0
65
145
200
251
299
Hair and mammary glands
Amniotic egg
359
Four legs
416
444
Lungs or lung derivatives
488
Jaws
Vertebrae
542
Ancestral chordate
Fishes
• Lampreys
• Cartilaginous fishes
• Bony fishes
Lampreys
• Jawless
• Blood suckers
• 2 paired fins
• Few remaining species
Hagfish
tentacles
gill slits (twelve pairs)
mucous glands
Do not post
photos on
Internet
Figure 26.6
Page 449
Slide 9
Evolution of
Jaws
supporting structures
Early
jawless
fish
(agnathan)
gill slit
• Modifications of
gill supports
Early jawed
fish
(placoderm)
jaw
spiracle jaw
support
Modern
jawed fish
(shark)
jaw
Jawed Fishes
• Large diverse group
– Powerful tails
– Streamlined body
– Swimbladder
• Two classes:
– Cartilaginous fishes (Chondrichthyes)
– Bony fishes (Osteichthyes)
Cartilaginous Fishes:
(Chondrichthyes)
• Most are marine predators
• Cartilaginous skeleton
• Streamline body
• Powerful tail
• Lateral line system
Cartilaginous Fishes
Bony Fishes:
(Osteichthyes)
• 96% of living fish species
• Operculum covers gills
• Swim bladder
• Good sense of smell
• Good eyesight
Body Plan of a Bony Fish
fin supports
muscle
segments
brain
olfactory
bulb
urinary
bladder
heart
anus
kidney
swim bladder
liver
gallbladder
stomach
intestine
Ray-finned Fishes
Unarmored Stickleback - Endangered
Green Sunfish
•
•
•
•
Lobe-Finned Fishes
Lung fish
Coelocanths
Lunglike sacs
“Walk” on fins
Lungfishes
• Have gills and one lungs
• Surface to gulp air
Invasion of Land
• Water
availability
• Temperature
Variation
• Skeletal support
• New habitats
• Food
Invasion of Land
Lobe-finned fish
Early amphibian
Amphibians
• Require water; most
lay eggs in water
• Lungs are inefficient
• Skin works as
respiratory organ
Amphibian Groups
Reptiles
Amniotes: Amniotic egg
• No more water
– Tough, scaly skin
– Internal fertilization
– Water-conserving kidneys
• Ectotherms
Evolutionary History of Amniotes
snakes
lizards
stem
reptiles
tuataras
ichthyosaurs
pterosaurs
birds
dinosaurs
plesiosaurs
archosaurs
crocodilians
turtles
anapsids
therapsids
synapsids
Carboniferous
Paleozoic era
(mammals)
Permian
Triassic
Jurassic
Mesozoic era
Cretaceous
Turtles
• Armorlike shell
• Horny plates instead
of teeth
• Lay eggs on land
Lizards and Snakes
Coast Horned Lizard
Crocodilians
Birds
• Evolved from reptiles
• Endotherms
• Feathers
– Derived from reptilian scales
– Serve in insulation and flight
Adapted for Flight
• Four-chambered heart
• Highly efficient
respiratory system
• Lightweight bones with
air spaces
• Powerful muscles
attach to the keel
Adapted for Flight
Birds
Mammals: (Mammalia)
• Hair
• Mammary glands
• Distinctive teeth
• Highly developed brain
• Extended care for the young
Three Mammalian Lineages
• Monotremes
– Egg-laying mammals
• Marsupials
– Pouched mammals
• Eutherians
– Placental mammals
Role of Geologic Change
PLACENTAL
MAMMALS
EVOLVE;
ADAPTIVE
RADIATIONS
BEGIN
Isolation of the early
monotremes, marsupials
on this land mass
Between 100 million and 85 million years ago, during the Cretaceous
Figure 26.20b
Monotremes
• Three species
– Duck-billed platypus
– Two kinds of spiny
anteater
• Lay eggs and suckle
Marsupials
• Development in a
permanent pouch
Placental Mammals
• Young develop in mother’s uterus
• Placenta composed of maternal and
fetal tissues
• Placental mammals develop more quickly
than marsupials
Placental Mammals
Trends in the Evolution
of Vertebrates
• Shift from notochord to vertebral column
• Nerve cord expanded into brain
• Cranium
• Evolution of jaws
• Paired fins evolved, gave rise to limbs
• Gills evolved, gave rise to lungs