1. CHAPTER 34
VERTEBRATE EVOLUTION
AND DIVERSITY

2. Phylum Chordata Deuterostomes Some Invertebrates Notochord (disks)
-longitudinal, flexible rod between
digestive tube and nerve cord
-large, fluid filled cells/ stiff fibrous tissue
-support
-most vertebrates – only remains as “disks”
2. Dorsal, Hollow Nerve Cord
-develops from ectoderm that rolls into a
tube/ dorsally from notochord
-develops into the Central nervous system:
the brain and spinal cord
3. Pharyngeal Slits
-region of digestive tract posterior to mouth “ “pharynx”/ pouches
-filter food for invertebrate chordates
-modified for gas exchange (in aquatic
vertebrates), jaw support, hearing, and
other functions
4. Muscular, Postanal Tail

3. Subphylum Urochordata (Tunicates/ Sea Squirt)
Sessile or Planktonic
Tunic (cellulose-like carbohydrate)
Larva

4. Subphylum Cephalochordata (Lancelet)
“Idealized” chordates
Small (few cm long)
Live in the sand
Swim like fish
Gas exchange mainly across regions of the external body surface
Suspension feeders

5. Subphylum Vertebrata Endoskeleton
Axial skeleton (cranium, vertebrae, ribs)
Appendicular skeleton (support appendages)
Living/ Grows
Larger size
Active lifestyle
Ventral, chambered heart (blood, arteries, capillaries)
Neural crest (form skeletal elements/braincase)
Pronounced cephalization
Vertebral column
Closed circulatory system
Gills or lungs
*Adaptations for feeding, digestion, and nutrient absorption
Jaws/ 2 sets of paired appendages
Contribute to formation
of certain skeletal elements
(cranium/ vertebral column)
4 footed
shelled, water-retaining egg
Dorsal, hollow
Nerve cord

6. Class Myxini: Hagfishes
Agnathans
Jawless vertebrates
eel-like in shape
Class Myxini: Hagfishes
Most primitive living "vertebrates"
Bottom-dwelling scavengers
Slime producing glands
predate the origin of
paired fins, teeth, and
bones hardened by
mineralization
(ossification)
Cartilage (connective tissue)
Serpentine swimming

7. Class Cephalaspidomorphi:
Lampreys
larvae for years in freshwater streams
 migrate to the sea/lakes streams (anadromous)
Cartilaginous pipe surrounding the rodlike notochord
Toothlike structures (keratin)

8. Gnathostomes YouTube - Evolution Of Jaws 1of5
Jaws evolved by modification of the skeletal rods
that had previously supported the anterior
pharyngeal (gill) slits
Jaws
Paired fins
Tail
Active predators
remaining gill slits =
respiratory gas exchange
YouTube - Evolution Of Jaws 1of5
YouTube - Evolution Of Jaws 2of5
YouTube - Evolution Of Jaws 3of5
YouTube - Evolution Of Jaws 4of5
YouTube - Evolution Of Jaws 5of5

9. Class Chondrichthyes: Sharks and rays
Cartilaginous skeletons
Sharp Bony teeth
Streamlined bodies
Powerful swimming muscles
Buoyancy by storing a large amount of oil in its huge liver
Animal is still denser than water, and it sinks if it stops swimming
Use muscles of the jaws and pharynx to pump water over the gills
Suspension feeders and Carnivores
Short digestive tract (spiral valve)
Acute senses (predation)
Sight good (no color)
Smell (nostrils)
Lateral line system (detect water pressure changes
Detect electrical fields generated by muscle contractions of animals
Entire body transmits sound to hearing organs of inner ear (no eardrum)
Internal fertilization (cloaca/ male claspers near pelvic fin)
Oviparous; they lay eggs that hatch outside the mother’s body.
Ovoviviparous; they retain the fertilized eggs in the oviduct.
Viviparous; the young develop within the uterus, nourished by placenta

11. Class Osteichthyes: The bony fishes
Ray-finned fishes, lobe-finned fishes, and the lungfishes
Ray-finned fishes
Bass, trout, perch, tuna, herring, etc.
Fins supported by long flexible rays
Lungfishes
Lungs connected to the pharynx
of the digestive tract
Gills (main organs for gas exchange)
Aestivate (state of torpor).
Most numerous vertebrates
Ossified endoskeleton (calcium phosphate)
Flattened, bony scales
Mucous glands
Lateral line system
Four or five pairs of gills
Operculum (muscle movement)
Swim bladder
Flexible fins
Most oviparous
Lobe-finned fishes
Coelacanth
Muscular pectoral and pelvic fins
supported by extensions of the bony skeleton

12. Tetrapods

13. Tetrapod Evolution
Coelacanth

14. Tetrapods Class Amphibia Adaptations to shallow water
Buccal pumping/ mouth breathing (lungfishes and frogs)
Leglike appendages
Acanthostega
Class Amphibia
Salamanders, frogs, and caecilians
Moist skin to carry out gas exchange
Eggs lack a shell (dehydrate)
External fertilization (most)
Complex and diverse social behavior
Rapid and alarming population decline (worldwide)

15. Order Urodela "tailed ones"
Salamanders
Aquatic and Terrestrial (as adults)
Walk with a side-to-side bending
swagger (resembling early tetrapods)

16. Order Anura "tail-less ones"
Powerful hind legs
Long sticky tongue
Camouflage
Skin glands (distasteful/poison mucus)
Brightly colored (poisonous)
Metamorphosis

17. Class: Reptilia (lizards, snakes, turtles, crocodiles)
Amniotes
reptiles, birds, and mammals
Adaptations to land (terrestrial)
Amniotic egg (shell)
Extra embryonic membranes
Waterproof skin
Increasing use of the rib cage to ventilate the lungs
Class: Reptilia (lizards, snakes, turtles, crocodiles)
Scales (protein keratin)
Lungs
Shelled amniotic eggs (land/ leather)
Internal fertilization
Viviparous (some lizards and snakes)
“Cold blooded”
Ectothermic (basking)
Dominant terrestrial vertebrates for
+200 million years
Dinosaurs and Pterosaurs
Social behavior and parental care
Endothermic?
key differences between the three
groups in their skull anatomy

19. Order Testudines (turtles) Order Squamata (lizards and snakes)
Most numerous and diverse reptiles
Relatively small
Hard shell
Lay eggs on land
Snakes
Descendants of lizards that adapted
to a burrowing lifestyle (vestigial limbs)
Limbless
Carnivorous
Acute chemical sensors
Lack eardrums but sensitive to ground vibrations
Heat-detecting organs between the eyes and nostrils of pit vipers
Toxin through a pair of sharp hollow or grooved teeth
Tongue (olfactory organs on the roof of the mouth)
Loosely articulated jaws
Order Crocodilia (alligators and crocodiles)
Among the largest living reptiles
Upturned nostrils

20. Class: Reptilia (lizards, snakes, turtles, crocodiles)
Order Testudines (turtles)

21. Order Squamata (lizards and snakes)

23. Order Crocodilia (alligators and crocodiles)

24. Class: Aves (birds)
Amniotic eggs and scales on the legs (reptilian features)
Flight
Bones are honeycombed (light)
Absence of some organs (one ovary)
Toothless
Gizzard grinds food (crocodiles/dinosaurs)
Beak of keratin (adaptations)
Active metabolism
Endothermic
Feathers (retain heat)
Advanced circulatory (4 chambered heart)
Advanced respiratory
Acute senses
Sight (possibly the best)
Motor skills/ coordination
Social behavior
Internal fertilization
Archaeopteryx
Large pectoral (breast) muscles anchored to a keel
on the sternum (breastbone)
Feathers (endothermy and flight)
Carinates (keels)
Ratites (no keel)
Passeriformes
“perching”

25. Class: Mammalia Platypus Spiny Anteater
Differentiation of dentition (teeth)
Inner ear (from jaw bones)
Mammary glands
Hair (keratin)
Endothermic
Circulatory-4 chambered heart
Respiratory-diaphragm
Fat (retain heat)
Internal fertilization
Birth (some placenta)
Large brains
Cognitive abilities
Extended parental care
Monotremes (platypuses spiny anteaters)
Egg laying (reptilian like)
Milk and hair
No nipples (just glands)
Therapsids
Eutherians (Placental)
Longer gestation (pregnancy)
Marsupials (Opossums, kangaroos, koalas)
Early birth
Pouch (marsupium)
Austraila
Platypus
Spiny Anteater

27. Order: Primates Prosimians New World Monkeys Old World Monkeys Lemurs
Grasping hands
Opposable thumb (big toe)
Larger brain
Flattened face
Stereoscopic vision
Nails
Finger skin ridges (prints)
Extended parental care
Complex social behavior
Coordination
Flexible joints
Prosimians
New World
Monkeys
Lemurs
Old World
Monkeys
Bushbaby
Tarsier

28. Hominoids Orangutan Great Apes/ Humans Gorilla Chimpanzee
Bonobo chimpanzee

29. Hominids “Lucy” Australopithecines ~5 – 2 mya Homo sapiens
Homo habilis
Homo erectus
~400,000 – 100,000 ya
~2 – 1.5 mya
~1.6 mya
Bipedalism
Larger brain (~400 cm3  1300 cm3)
Shorter jaws
Dentition
Sexual dimorphism (male size to female)
Extended parental care
Family structure
Learning
“Lucy”

30. ~5 million years of Evolution
Pan troglodytes
Homo sapiens

31. Human
Diversity
Homo sapiens