Transcript Vertebrates

Vertebrates
Which of these is most
closely related to you?
Which of these is most
closely related to you?
Vertebrates
Echinoderms and Chordates are the
only two phyla of deuterostomes.
Chordata
fish, amphibians, reptiles, birds, mammals
Deuterostome coelomates
Notochord serves as axis of body
Dorsal, hollow nerve cord
Tails. Human coccyx is vestigial tail.
Birds & mammals = homeotherms (constant
body temperature)
All others are poikilotherms (cold-blooded)
though some reptiles are endothermic.
Mammals
class
Nurse their young with milk
Have hair or fur made of keratin
Homeotherms
•
Placental = develops in womb
•
Marsupial = born early, develops in
pouch
•
Monotreme = egg-laying (duck-billed
platypus and spiny anteater).
Primates
order
Hands with opposable thumbs
Claws have become nails
Eyes are in front and close together for
binocular vision
Nurture their young for a long time.
Chordate Characteristics
Chordate Characteristics
Notochord
•A flexible rod between the nerve
cord and the digestive tube
•All chordates have this as embryos
•Most develop later into complex,
jointed skeleton.
Chordate Characteristics
Dorsal, hollow nerve cord
•Develops from a plate of ectoderm
that rolls into a tube
•Unique to chordates. (Other phyla
have solid, ventral nerve cords)
•Develops into central nervous
system, spinal cord, and brain.
Chordate Characteristics
Pharyngeal slits or clefts
•Just posterior to the mouth
•Used for suspension feeding and
gas exchange (gills)
•In land animals, they develop into
parts of the ear.
Chordate Characteristics
Muscular, post-anal tail
•Lost during embryonic development
in many species
•Provides propulsion for many
aquatic species.
Classes of Chordates
Classes of Chordates
Tunicates
Classes of Chordates
Tunicates
Classes of Chordates
Tunicates
Classes of Chordates
Tunicates
Classes of Chordates
Lancelets
Classes of Chordates
Lancelets
Classes of Chordates
Hagfish
•Craniate (has brain and skull)
•No jaws
•No vertebrae
Classes of Chordates
Hagfish
Classes of Chordates
Hagfish
Classes of Chordates
Hagfish
Classes of Chordates
Lamprey
•Vertebrate (has backbone)
•Still no jaws
Classes of Chordates
Lamprey
Classes of Chordates
Lamprey
Classes of Chordates
Lamprey
Classes of Chordates
Sharks and Rays
•Gnathostomes (“jaw-mouths”)
•Bones have some mineralization
but are still mostly cartilage
•Acute senses (lateral line, nostrils,
black-and-white vision)
•Oviparous, ovoviviparous, or
viviparous.
Classes of Chordates
Sharks and Rays
Classes of Chordates
Sharks and Rays
Classes of Chordates
Sharks and Rays
Classes of Chordates
Ray-Finned Fishes
Classes of Chordates
Lobe-Finned Fishes
Classes of Chordates
Lungfishes
Tetrapods
Classes of Tetrapods
Amphibians
Urodela (“tailed ones”)
Salamanders
Anura (“tailless ones”)
Frogs and toads
Apoda (“legless ones”)
Caecilians
Classes of Tetrapods
Amphibians
Adaptations:
•Camouflage
•Poison
•Metamorphosis / paedomorphosis
•Complex social behavior
•Eggs lack shells, dehydrate quickly
•Gas exchange through moist skin
Amniotes
Amniotes
•Amniotic egg may be laid on land.
•Contains extra-embryonic
membrane
•May be calcified (birds) or leathery
(reptiles) or may implant in the
uterus (mammals)
Phylogeny of Amniotes
Synapsidia
Anapsidia
Ancestral
amniote
Diapsidia
Phylogeny of Amniotes
Synapsidia
Mammals
Anapsidia
Turtles
Lizards &
Snakes
Ancestral
amniote
Crocodiles
Diapsidia
Dinosaurs
Birds
Phylogeny of Amniotes
Synapsidia
Mammals
Anapsidia
Turtles
Lizards &
Snakes
Ancestral
amniote
Crocodiles
Diapsidia
Dinosaurs
Birds
Reptiles
Adaptations:
•Keratinized skin
•Lungs
•Leathery shells on eggs
•Ectotherms.
Birds began as feathered reptiles
Adaptations:
•Feathers
•Honeycombed bones
•Missing some organs
•Gizzard instead of teeth
•Endothermic
•Four-chambered heart
•Good vision
•Relatively large brains.
Mammals diversified in the wake of
the Cretaceous extinctions
Adaptations:
•Mammary glands
•Hair
•Four-chambered heart
•Endothermic
•Placenta / live birth
•Large brains
•Differentiated teeth.
Primates
and Human Evolution
Adaptations:
•Brain size
•Jaw shape
•Bipedal posture
•Size difference between sexes
•Long-term pair bonding
•Long-term infant dependency.
Multiregional Hypothesis
African European
Asian
interbreeding
1-2 million
years ago
Homo erectus
In Africa
Austalasian
Replacement Hypothesis
African European
Asian
100,000
years ago
1-2 million
years ago
Homo erectus
In Africa
Austalasian