1. Are humans among the descendants of this ancient organism?
Figure 34.1 Are humans among the descendants of this ancient organism?

2. Phylogeny of living chordates
Echinodermata
(sister group to chordates)
Cephalochordata
(lancelets)
ANCESTRAL
DEUTERO-
STOME
Chordates
Urochordata
(tunicates)
Notochord
Myxini
(hagfishes)
Common
ancestor of
chordates
Craniates
Petromyzontida
(lampreys)
Head
Chondrichthyes
(sharks, rays, chimaeras)
Vertebrates
Vertebral column
Actinopterygii
(ray-finned fishes)
Gnathostomes
Jaws, mineralized skeleton
Actinistia
(coelacanths)
Osteichthyans
Lungs or lung derivatives
Figure 34.2 Phylogeny of living chordates
Lobe-fins
Dipnoi
(lungfishes)
Lobed fins
Amphibia (frogs,
salamanders)
Legs
Reptilia
(turtles, snakes,
crocodiles, birds)
Tetrapods
Amniotes
Amniotic egg
Mammalia
(mammals)
Milk

3. Dorsal, hollow nerve cord Pharyngeal slits or clefts Muscular,
Chordate characteristics
Dorsal,
hollow
nerve cord
Muscle
segments
Notochord
Mouth
Figure 34.3 Chordate characteristics
Anus
Pharyngeal
slits or clefts
Muscular,
post-anal tail

4. Lancelets are named for their bladelike shape
Lancelets are named for their bladelike shape. They are marine suspension feeders. Adults retain characteristics of chordate body plan.
Cirri
2 cm
Mouth
Pharyngeal slits
Atrium
Notochord
Digestive tract
Atriopore
Dorsal, hollow
nerve cord
Segmental
muscles
Figure 34.4 The lancelet Branchiostoma, a cephalochordate
Anus
Tail

5. Tunicates (Urochordata) are more closely related to other chordates than are lancelets. They are marine suspension feeders commonly called sea squirts. As an adult, a tunicate draws in water through an incurrent siphon, filtering food particles. Juveniles, not adults, have a notochord.
Incurrent
siphon
to mouth
Water flow
Notochord
Dorsal, hollow
nerve cord
Excurrent
siphon
Excurrent
siphon
Excurrent
siphon
Tail
Atrium
Muscle
segments
Incurrent
siphon
Pharynx
with
slits
Intestine
Anus
Stomach
Tunic
Intestine
Atrium
Figure 34.5 A tunicate, a urochordate
Esophagus
Pharynx with slits
Stomach
An adult tunicate
A tunicate larva

6. Fossil of an early Chordate
5 mm
Figure 34.8 Fossil of an early chordate
Segmented muscles
Pharyngeal slits

7. Hagfishes have a cartilaginous skull and axial rod of cartilage derived from the notochord, but lack jaws and vertebrae
Slime glands
Figure 34.9 A hagfish

8. Lampreys represent the oldest living lineage of vertebrates
Lampreys represent the oldest living lineage of vertebrates. They are jawless vertebrates inhabiting various marine and freshwater habitats.
Figure A sea lamprey

9. Hypothesis for the evolution of vertebrate jaws
Gill slits
Cranium
Mouth
Skeletal rods
Figure Hypothesis for the evolution of vertebrate jaws

10. Chondrichthyans Figure 34.15 Chondrichthyans Pelvic fins Pectoral fins
(a) Blacktip reef shark (Carcharhinus
      melanopterus)
Figure Chondrichthyans
(b) Southern stingray (Dasyatis americana)
(c) Spotted ratfish (Hydrolagus colliei)

11. Anatomy of a trout - bony fish - Osteichthyes
Swim
bladder
Dorsal fin
Adipose fin
(characteristic
of trout)
Caudal
fin
Spinal cord
Brain
Nostril
Cut edge
of operculum
Anal fin
Liver
Lateral
line
Figure Anatomy of a trout, a ray-finned fish
Gills
Anus
Heart
Gonad
Stomach
Urinary
bladder
Pelvic
fin
Kidney
Intestine

12. A Devonian era relative of tetrapods
Bones
supporting
gills
Figure Acanthostega, a Devonian relative of tetrapods
Tetrapod
limb
skeleton

13. Origin of Tetrapods Figure 34.20 The origin of tetrapods 430 415 400
Ray-finned fishes
Coelacanths
Lungfishes
Eusthenopteron
Panderichthys
Tiktaalik
Elginerpeton
Metaxygnathus
Acanthostega
Ichthyostega
Hynerpeton
Figure The origin of tetrapods
Greerpeton
Amphibians
Amniotes
PALEOZOIC
Silurian
Devonian
Carboniferous
Permian
430
415
400
385
370
355
340
325
310
295
280
265
Time (millions of years ago)

14. Amphibians (a) Order Urodela (b) Order Anura (c) Order Apoda
Figure Amphibians
(c) Order Apoda

15. The “dual life” of a frog
(a) Tadpole
Figure The “dual life” of a frog (Rana temporaria)
(b) During
metamorphosis
(c) Mating adults

16. The amniotic egg Chorion Allantois Amnion Yolk sac Embryo Amniotic
cavity
with
amniotic
fluid
Yolk
(nutrients)
Figure The amniotic egg
Shell
Albumen

17. Hatching reptiles
Figure Hatching reptiles

18. Extant reptiles (other than birds).
(a) Tuatara (Sphenodon punctatus)
(b) Australian thorny devil
lizard (Moloch horridus)
Figure Extant reptiles (other than birds)
(c) Wagler’s pit viper
(Tropidolaemus wagleri)
(d) Eastern box turtle (Terrapene carolina carolina)
(e) American alligator
(Alligator mississippiensis)

19. Form fits function: the avian wing and feather
Finger 1
(b) Bone structure
Palm
(a) Wing
Finger 2
Finger 3
Forearm
Wrist
Figure Form fits function: the avian wing and feather
Shaft
Shaft
Barb
Vane
Barbule
Hook
(c) Feather structure

20. Archaeopteryx, the earliest known bird
Toothed beak
Wing claw
Figure Artist’s reconstruction of Archaeopteryx, the earliest known bird
Airfoil wing
with contour
feathers
Long tail with
many vertebrae

21. Diversity among living birds
(a) Emu - flightless
(b) Mallards - web feet
Figure A small sample of living birds
(c) Laysan albatrosses
(d) Barn swallows

22. evolution of the mammalian ear bones
Key
Temporal
fenestra
Articular
Quadrate
Jaw joint
Dentary
Squamosal
(a) In Biarmosuchus, an early synapsid, the articular and
quadrate bones formed the jaw joint.
Middle ear
Eardrum
Middle ear
Eardrum
Stapes
Inner ear
Inner ear
Stapes
Figure The evolution of the mammalian ear bones
Incus (quadrate)
Sound
Sound
Malleus (articular)
Present-day reptile
Present-day mammal
(b) In mammals, the articular and quadrate bones are incorporated into the middle ear.

23. an Australian monotreme
Figure Short-beaked echidna (Tachyglossus aculeatus), an Australian monotreme

24. Australian marsupials
(a) A young brushtail possum
Figure Australian marsupials
(b) Long-nosed bandicoot

25. Evolutionary convergence of marsupials and placental mammals
Eutherian
mammals
Marsupial
mammals
Eutherian
mammals
Plantigale
Deer mouse
Wombat
Woodchuck
Marsupial mole
Mole
Wolverine
Tasmanian devil
Sugar glider
Flying squirrel
Figure Evolutionary convergence of marsupials and eutherians (placental mammals)
Patagonian cavy
Kangaroo

26. Mammalian Diversity (5 species) Monotremes Monotremata ANCESTRAL
Marsupialia
Marsupials
(324 species)
Proboscidea
Sirenia
Tubulidentata
Hyracoidea
Afrosoricida (golden
moles and tenrecs)
Macroscelidea (elephant
shrews)
Eutherians
(5,010 species)
Xenarthra
Figure Mammalian diversity
Rodentia
Lagomorpha
Primates
Dermoptera (flying lemurs)
Scandentia (tree shrews)
Carnivora
Cetartiodactyla
Perissodactyla
Chiroptera
Eulipotyphla
Pholidota (pangolins)

27. Mammalian diversity
Figure Mammalian diversity

28. Lemurs
Figure Coquerel’s sifakas (Propithecus verreauxi coquereli), a type of lemur

29. A phylogenetic tree of primates
Lemurs, lorises,
and pottos
ANCESTRAL
PRIMATE
Tarsiers
New World monkeys
Anthropoids
Old World monkeys
Gibbons
Orangutans
Gorillas
Figure A phylogenetic tree of primates
Chimpanzees
and bonobos
Humans 60 50 40 30 20 10
Time (millions of years ago)

30. New World monkeys and Old World monkeys
Figure New World monkeys and Old World monkeys
(a) New World monkey
(b) Old World monkey

31. Nonhuman apes (a) Gibbon (b) Orangutan (c) Gorilla (d) Chimpanzees
Figure Nonhuman apes
(e) Bonobos

32. A timeline for some selected hominin species
Paranthropus
robustus
Homo
neanderthalensis
Homo
sapiens
Paranthropus
boisei
Homo
ergaster ?
0.5
1.0
1.5
Australopithecus
africanus
2.0
Kenyanthropus
platyops
2.5
Australo-
pithecus
anamensis
Australopithecus
garhi
Homo
erectus
3.0
Millions of years ago
3.5
Homo
habilis
Homo
rudolfensis
4.0
4.5
Ardipithecus
ramidus
Australopithecus
afarensis
Figure A timeline for some selected hominin species
5.0
5.5
Orrorin tugenensis
6.0
6.5
Sahelanthropus
tchadensis
7.0

33. Upright posture predates an enlarged brain in human evolution
(a) Australopithecus
afarensis skeleton
(b) The Laetoli footprints
Figure Upright posture predates an enlarged brain in human evolution
(c) An artist’s reconstruction of what A. afarensis may have looked like

34. 160,000-year-old fossil of Homo sapiens
Figure A 160,000-year-old fossil of Homo sapiens

35. You should now be able to:
List the derived traits for: chordates, craniates, vertebrates, gnathostomes, tetrapods, amniotes, birds, mammals, primates, humans.
Describe the trends in mineralized structures in early vertebrates.
Describe and distinguish between Chondrichthyes and Osteichthyes.
Describe an amniotic egg and explain its significance in the evolution of reptiles and mammals.
Explain why the reptile clade includes birds.

36. 6. Distinguish among monotreme, marsupial, and eutherian mammals.
7. Define the term hominin.
8. Describe the evolution of Homo sapiens from australopith ancestors, and clarify the order in which distinctive human traits arose.
9. Explain the significance of the FOXP2 gene.