33
Deuterostome
Animals
33 Deuterostome Animals
• 33.1 What is a Deuterostome?
• 33.2 What Are the Major Groups of
Echinoderms and Hemichordates?
• 33.3 What New Features Evolved in the
Chordates?
• 33.4 How Did Vertebrates Colonize the
Land?
• 33.5 What Traits Characterize the
Primates?
33.1 What is a Deuterostome?
Deuterostomes
characterized by early
developmental patterns:
 Radial cleavage
 Bilateral symmetry
 Mouth forms opposite
blastopore – blastopore
forms anus
 Coelom develops from
mesodermal pockets that
bud off from gastrula’s cavity
http://kentsimmons.uwinnipeg.ca/16cm05/1116/32-07-ProtoDeuterostDev-L.gif
33.1 What is a Deuterostome?
First two (radial cleavage,
bilateral symm.) are
ancestral states for all
bilaterian animals
 Evidence from DNA
sequencing supports
monophyly of
deuterostomes
 Fewer species of
deuterostomes than
protostomes
33.1 What Is a Deuterostome?
Living deuterostomes comprise three major
clades:
 Echinoderms — sea stars, sea urchins, &
relatives
 Hemichordates — acorn worms & pterobranchs
 Chordates — sea squirts, lancelets, &
vertebrates
Figure 31.1 The Phylogeny of Animals
Figure 33.1 Phylogeny of the Deuterostomes
33.1 What is a Deuterostome?
Deuterostomes are
 triploblastic,…
 coelomate animals…
 with internal skeletons
www.sci.nu.ac.th/biology/elearning/picture5
http://images.encarta.msn.com/xrefmedi
a/aencmed/targets/illus/ilt/T014598A.gif
33.1 What is a Deuterostome?
Recently discovered fossils
of early deuterostomes in
China:
 They had skeletons
similar to
echinoderms,
 but also bilateral
symmetry and
pharyngeal gill slits
http://www.mcz.harvard.edu/Departments/Invert
Paleo/Trenton/Intro/PaleoPage/TrentonFauna/Ec
hinodermata/EchinoImages/MCZ128266.jpg
Homalozoan
33.1 What is a Deuterostome?
 Yunnanozoans (fossils from Yunnan, China)
 Large mouth
 Six pairs of external gills
 Segmented posterior section
Figure 33.2 Ancestral Deuterostomes Had External Gills
33.1 What is a Deuterostome?
Bilateral symmetry is
ancestral condition
 Echinoderms evolved
unique pentaradial
symmetry
 Other deuterostomes
retained bilateral
symmetry
33.2 What Are the Major Groups of Echinoderms
and Hemichordates?
Together echinoderms &
hemichordates are known as
ambulacrarians
 Only six of 23 groups of
echinoderms known from fossils
survive today – nearly all are
marine – ~7000 species
 Hemichordates – 100 living
species
33.2 What Are the Major Groups of Echinoderms
and Hemichordates?
Both echinoderm and hemichordates
 Ciliated larvae have bilateral symmetry
 in echinoderms, larvae develop into adults 
changes to pentaradial symmetry (in fives
or multiples of fives)
 Hemichordate adults retain bilateral symm.
Paracentrotus urchin: pentaradial adult and test, and
bilateral echinopluteus larva
www.smiley.cy.net/basspro
http://www.snv.jussieu.fr/bmedia/oursinMDC/coursours3/
Figure 33.3 Echinoderms Are Bilaterally Symmetrical as Larvae but Radially
Symmetrical as Adults (Part 1)
Bipinnarian
larvae of sea
star, Pisaster
33.2 What Are the Major Groups of Echinoderms
and Hemichordates?
http://www.oceanexplorer.noaa.gov/explorations/islands01/log/aug30/media/brittlestar_450.jpg
Echinoderm derived
characters
(synapomorphies)
 Lack head  move
equally well in multiple
directions
 Have oral side containing
mouth, & aboral side
containing anus
Ophioderma brittlestar
http://www.tolweb.org/tree/ToLimages/diagram5a1.gif
Figure 33.3 Echinoderms Are Bilaterally Symmetrical as Larvae but Radially
Symmetrical as Adults (Part 2)
33.2 What Are the Major Groups of Echinoderms and
Hemichordates?
Echinoderms have an endoskeleton
 System of internal calcified plates
 Covered by thin layers of skin and some muscle
 Plates fuse to form internal skeleton
Neognathostomata
Fossilized, early
“sea biscuits”
www.nhm.ac.uk/research-curation/departments/palaeontology/echinoids/GENERA/CASSIDULOID/72gif
33.2 What Are the Major Groups of Echinoderms and
Hemichordates?
Water vascular system
 Network of water-filled canals leading to tube feet
 Water enters through madreporite,


Connected to ring canal around esophagus
Other canals radiate out from ring canal
 Functions in locomotion, feeding and gas exchange
www.vsf.cape.com/~jdale/science
www.ptpleasantbch.k12.nj.us/bridge/genbio/bioimages/
Figure 33.3 Echinoderms Are Bilaterally Symmetrical as Larvae but Radially
Symmetrical as Adults (Part 3)
33.2 What Are the Major Groups of Echinoderms and
Hemichordates?
Crinoids
 Sea lilies & feather stars
 More abundant 300–500 mya
 Sea lilies
Metacrinus rotundus,
lives at relatively
shallow depths of 100150 m off Japan
attach to substrate by stalk
consisting of stack of
calcareous discs
 five to several hundred arms

http://www.phschool.com/science/science_news/articles/images/stalking_larvae_01.jpg
33.2 What Are the Major Groups of Echinoderms and
Hemichordates?
 Feather stars

Grasp substratum with flexible appendages that
allow limited movement
Florometra serratissima
http://www.reefs.org/library/aquarium_net/1296/images/fig3.jpg
Figure 33.4 Diversity among the Echinoderms (A, B)
33.2 What Are the Major Groups of Echinoderms
and Hemichordates?
Echinoids
 Sea urchins, sand dollars,
sea biscuits
 Lack arms & covered
Photo 33.7 Purple sea urchin
with spines
(Strongylocentrotus
Spines attached to
underlying skeleton by
ball-and-socket joints
 Spines moveable, and
some produce toxins

purpuratus)
33.2 What Are the Major Groups of Echinoderms
and Hemichordates?
 Sand dollars are flattened relatives of sea
urchins
Photo 33.9 Sand dollars (Dendraster excentricus)
showing tube feet.
Figure 33.4 Diversity among the Echinoderms (C)
33.2 What Are the Major Groups of Echinoderms
and Hemichordates?
Holothuroideans
 Sea cucumbers
 Lack arms
 Oriented with mouth anterior & anus posterior
 Anterior tube feet modified into feeding tentacles
 Tube feet are used to anchor to substrate
Photo 33.12 Synapted sea
cucumber (Euapta godeffroyi);
Sea of Cortez, Mexico.
Figure 33.4 Diversity among the Echinoderms (D)
33.2 What Are the Major Groups of Echinoderms
and Hemichordates?
http://biodidac.bio.uottawa.ca/thumbnails/images/ECHI002B.gif
Asteroids
 Sea stars
 Gonads & digestive organs located in arms
 Tube feet for locomotion, gas exchange,
and attachment

Each foot consists of internal ampulla
connected to external suction cup
Photo 34.4 Crown-of thorns
(Acanthaster ellisii) feeding
on a gorgonian; Sea of
Cortez, Mexico.
33.2 What Are the Major Groups of Echinoderms
and Hemichordates?
Ophiuroids
 Brittle stars, basket stars
 Flexible arms composed of jointed plates
 Most ingest particles from sediment surface
Photo 34.6 Brittle star
(Ophiothrix swensoni)
on a sponge; Bonaire,
Netherland Antilles.
33.2 What Are the Major Groups of Echinoderms
and Hemichordates?
http://www.ucmp.berkeley.edu/echinodermata/comatulid.gif
Tube feet used in variety
of ways to capture prey
 Sea lilies use tube feet
on arms for filter feeding
 In sea cucumbers,
anterior tube feet are
modified into feathery,
sticky tentacles that
protrude from mouth
Photo 33.10 Tropical sea
cucumber (Cucumaria sp.),
retracting a feeding tentacle.
33.2 What Are the Major Groups of Echinoderms
and Hemichordates?
http://www.dkimages.com/discover/previews/878/20092474.JPG
 Sea stars use tube
feet to capture large
prey
Clamp onto bivalve
and exhaust the
muscles bivalves
use to hold shells
closed
 Stomach everts
through mouth and
space between
shells
 Enzymes secreted to
digest bivalve

http://img263.imageshack.us/img263/7307/stomach2oq5.jpg
33.2 What Are the Major Groups of Echinoderms
http://www.botany.hawaii.edu/basch/uhnpscesu
and Hemichordates?
/htms/kahoinvr/images/toxopn/colurchlb7.jpg
 Sea urchins eat algae
that they scrape from
rocks

Collector urchin
Aristotle’s lantern to
scrape
Urchin with tube
feet extended
Echinoid with
light-purple
spines and darkpink tube feet
http://www.nhm.ac.uk/research-curation/research/projects/echinoiddirectory/morphology/JPEG/LANTERN.jpg
http://www.discoveringfossils.co.uk/echinoid
33.2 What Are the Major Groups of Echinoderms
and Hemichordates?
Hemichordates
 Acorn worms & pterobranchs
 Three-part body plan:
Proboscis
 Collar
 Trunk

33.2 What Are the Major Groups of Echinoderms
and Hemichordates?
Acorn worms – about 70 species
 Burrow in soft sediments
 Digestive tract is a mouth, pharynx, & intestine
Pharynx opens to outside via pharyngeal slits
 Vascularized tissue around slits serve as gas
exchange surface

www.cals.ncsu.edu/course/zo150/mozley/fall/
Figure 33.5 Hemichordates (Part 1)
33.2 What Are the Major Groups of Echinoderms
and Hemichordates?
 Prey captured with large proboscis which is
covered in sticky mucus

cilia moves mucus/food  mouth
Some acorn worms swim
freely near ocean bottom
and feed on floating
particles of organic
matter.
http://dsc.discovery.com/convergence/blueplanet/photo/gallery2
33.2 What Are the Major Groups of Echinoderms
and Hemichordates?
Pterobranchs
 20 living species,
sedentary marine
animals
 live in tubes secreted
by proboscis
 Some are solitary,
others form colonies
 Collar has 1–9 pairs of
arms with tentacles for
prey capture and gas
exchange
www.iwu.edu/iwunews/Antarctica/Photos
Figure 33.5 Hemichordates (Part 2)
33.3 What New Features Evolved in the Chordates?
Evolutionary relationships among chordate
groups are most evident in early
developmental stages
Three chordate clades
 Urochordates
 Cephalochordates
 Vertebrates
33.3 What New Features Evolved in the Chordates?
Pharyngeal gill slits (ancestral character – also in
hemichordates)
All chordates have following derived characteristics:
 Dorsal, hollow nerve cord
 Tail extending beyond anus (post-anal tail)
 Notochord – most distinctive
 Ventral heart
http://faculty.baruch.cuny.edu/jwahlert/bio1003/images
33.3 What New Features Evolved in the Chordates?
Notochord
 Core of large cells with
fluid-filled vacuoles  rigid
but flexible
 In urochordates, notochord
is lost in metamorphosis to
adult stage
 In vertebrates, it is
replaced by skeletal
structures (vertebrae)
Figure 33.6 The Key Features of Chordates Are Most Apparent in Early
Developmental Stages (Part 1)
33.3 What New Features Evolved in the Chordates?
Ancestral pharyngeal slits
 Present at some developmental stage in all
chordates
 Often lost in adults
 Pharynx develops around
pharyngeal slits
Amphioxis Crosssection (10x)
In chordate ancestors,
functioned in gas exchange
 Enlarged in some chordates
and lost in others

http://www.umanitoba.ca/faculties/science/biological_sciences/lab13/images/amphioxx10.jpeg
33.3 What New Features Evolved in the Chordates?
Cephalochordates (lancelets, amphioxus)
 Very small, less than 5 cm
 Notochord retained throughout life  used in
burrowing
 Extract prey from water with pharyngeal basket
www.saudeanimal.com.br/imagens/
Figure 33.6 The Key Features of Chordates Are Most Apparent in Early
Developmental Stages (Part 2)
Figure 34.7 Lancelets (Part 1)
Lancelets typically live in sediment, tail first, with head
exposed at surface to bring in water for feeding, gas
exchange and waste removal
33.3 What New Features Evolved in the Chordates?
Three urochordate groups (ascidians,
thaliaceans, larvaceans)
 All marine
 90% are ascidians
33.3 What New Features Evolved in the Chordates?
Ascidians (sea squirts)
 Solitary or may form colonies by budding
from single founder
 Colonies may be meters across
Diplosoma listerianum
Rhopalaea sp.
http://space.mit.edu/home/kenton/M
icronesia_2004/pohnpei/images
http://massbay.mit.edu/exoticspecies/exoticmaps/images/diplosoma.jpg
33.3 What New Features Evolved in the Chordates?
 Adults are typically sessile

Adult body is bag-like
 enclosed in ―tunic‖ of proteins and complex
polysaccharides
 secreted by epidermis
Photo 34.13 Colony of light-bulb
tunicates (Clavelina huntsmani).
Figure 33.7 Adult Urochordates (A)
33.3 What New Features Evolved in the Chordates?

Pharynx is enlarged into a pharyngeal
basket that filters prey from water
http://www.coastal.ca.gov/publiced/photos/2006/1-Bradford-tunicates.jpg
33.3 What New Features Evolved in the Chordates?
 Ascidian larvae
have pharyngeal slits,
a hollow nerve cord,
and notochord that is
in the tail region
 All but pharyngeal slits
degenerate in adult
 Swimming, tadpole-like
larvae suggest
relationship between
ascidians and
vertebrates

Diplosoma larvae and adult colony
http://www.mba.ac.uk/Fellows/pemberton/images/
Figure 22.6 The Evolutionary Relationship Between Sea Squirts
and Vertebrates
33.3 What New Features Evolved in the Chordates?
Thaliaceans (salps)
 live singly or in chain-like colonies
 float in tropical oceans
 retain notochord & nerve cords throughout lives
Pegea confoederata
Thaliacea
www.amonline.net.au/exhibitions/beyond/images/400
http://jellieszone.com/Output/Gelatino
us%20Zooplankton
Figure 33.7 Adult Urochordates (B)
33.3 What New Features Evolved in the Chordates?
Larvaceans
 solitary, planktonic animals
 retain notochord throughout life
 Most are less than 5 mm long
 some build mucus ―house‖ of sticky slime to trap organic
particles
Oikopleura
labradoriensis
http://oceanexplorer.noaa.gov/explorations
/02arctic/background/fauna
Bathochordaeus with mucus “house”
http://dsc.discovery.com/news/briefs/20050613/gallery
33.3 What New Features Evolved in the Chordates?
Vertebrates
 Jointed, dorsal vertebral column replaces notochord
early in development
 In early forms, enlarged pharyngeal basket used to
extract prey from mud
 Radiated in marine, freshwater, & terrestrial habitats.
www.fisheries.org/education/fisheries_techniques/Chapter5
33.3 What New Features Evolved in the Chordates?
Vertebrate derived characteristics
 Rigid endoskeleton supported by vertebral column
 Anterior skull with large brain
 Internal organs suspended in coelom by mesentaries
 Well-developed circulatory system with ventral heart
Figure 33.10 The Vertebrate Body Plan (Part 1)
Figure 33.10 The Vertebrate Body Plan (Part 2)
Look for
mesentaries
in your pig
in lab
33.3 What New Features Evolved in the Chordates?
Jawless fishes (Agnathans)
 Common in Devonian
 Filter-feeding ancestral
vertebrates lacked jaws and
gave rise to jawless fishes
 Ostracoderms
 Mostly extinct group of
jawless fishes
 Bony external armor for
predator protection
 Only hagfishes and
lampreys survive today
(extant)
http://io.uwinnipeg.ca/~simmons/16cm05/1116
Figure 33.8 Phylogeny of the Living Vertebrates
33.3 What New Features Evolved in the Chordates?
Hagfishes
 Sister group to other verts?
 Partial cranium
 Lack jaws

Have specialized structure
with keratinized teeth to
capture prey and tear up
dead organisms
Eptatretus cirrhatus
New Zealand Hagfish
http://www.geol.umd.edu/~tholtz/G331/lectures/331grapt.html
33.3 What New Features Evolved in the Chordates?
 Skeleton is cartilage
 Lack vertebrae

Some biologists do not
consider them to be
vertebrates
Eptatretus cirrhatus
New Zealand Hagfish
http://www.ryanphotographic.com/images/JPEGS/Eptatretis%20cirrhatus%20New%20Zealand%20hagfish.jpg
33.3 What New Features Evolved in the Chordates?
 Weak circulatory system
with 3-4 small hearts
 Lack stomach
 Lack eyes
Eptatretus cirrhatus
New Zealand Hagfish
http://www.ryanphotographic.com/images/JPEGS/Eptatretis%20cirrhatus%20New%20Zealand%20hagfish.jpg
33.3 What New Features Evolved in the Chordates?
 Produce large amounts of
slime as defense against gillbreathing predators
Slime video
Knot behavior video
 Development is direct
 Hermaphroditic adults can
change sex from year to year
Hagfish slime is similar in
composition to egg whites, and
may be used in cooking.
http://www.jyi.org/volumes/volume5/issue7/images/lee_2.jpg
33.3 What New Features Evolved in the Chordates?
Lampreys
 Complete cranium
 Cartilaginous vertebrae
 Lack paired appendages
 Complete metamorphosis
from filter feeding larvae
(ammocoetes – similar to
lanceolet) to adult form
Ammocoetes larvae
http://io.uwinnipeg.ca/~simmons/16cm05/1116
http://www.wiscfish.org/fishid/images/
large_images/1025.jpg
33.3 What New Features Evolved in the Chordates?
 Adults of many are parasitic
 Round mouth and keratinized ―teeth‖ for
attaching to fish
 Keratinized tongue to rasp at host’s flesh
http://dnr.wi.gov/org/caer/ce/eek/critter/invert/lamprey.htm
http://floridafisheries.com/images/fish-pic
Figure 33.9 Modern Jawless Fishes
33.3 What New Features Evolved in the Chordates?
 Gene sequences suggest hagfishes may be more
closely related to lampreys
If so, then hagfishes must have secondarily lost many
vertebrate features
 Together, they are called cyclostomes (―circle mouths‖) or
agnathan (jawless fishes)

?
XXX
http://bio.slu.edu/mayden/lamprey/index.html
?
Chordates: New Ways of Feeding
• Many kinds of fishes
evolved during Devonian
(―age of fishes‖)
http://www.devoniantimes.org/opportunity/images/p-vertebrates.gif
http://www.karencarr.com/Images/
Gallery/2004_gallery_devonian.jpg
33.3 What New Features Evolved in the Chordates?
Gnathostomes (―jaw
mouths‖)
 Evolved from anterior
skeletal arches that
supported gills
 Jaws improve feeding
efficiency and prey
capture
Figure 33.8 Phylogeny of the Living Vertebrates
33.3 What New Features Evolved in the Chordates?
There is evidence that HOX
genes may be involved in gill
arch and jaw development
showing homology and
evolutionary links between
agnathan and jawed
vertebrates that supports
fossil record
Hypothesized role of Dlx genes in Branchial Arches patterning. (A) Diagram of a protognathostome neurocranium (Nc) and associated BA (1 to 7) skeletal derivatives. Gnathostome
BA are metameric structures within which develop a proximodistal series of skeletal elements.
Inter-BA identity is regulated by Hox, Pbx, and Otx genes. It is hypothesized that the nested
expression of Dlx genes regulates intra-BA identity. (B) In situ hybridization of Dlx2 and Dlx5
(E10.5) and diagram highlighting the nested Dlx expression within BA mesenchyme. AP,
anteroposterior; BA, branchial arch; BA1, first branchial arch; BA2, second branchial arch; Bb,
basibranchial; Cb, ceratobranchial; Eb, epibranchial; Hb, hypobranchial; hy, hyoid arch; md,
mdBA1; mx, mxBA1; ; Pb, pharyngeobranchial; PD, proximodistal. From Michael J. Depew, M.
J. et al., Specification of Jaw Subdivisions by Dlx Genes. Science, 298 (5592) :381-385, October
http://hometown.aol.com/darwinpage/
11, 2002
Figure 33.11 Jaws and Teeth Increased Feeding Efficiency (Part 1)
33.3 What New Features Evolved in the Chordates?
 Evolution of teeth made predators even more
effective
 Teeth function in both grasping and breaking
up prey
 Chewing also aids chemical digestion and
improves ability to extract nutrients from food
Placoderms –
heavily armored,
jawed fishes were
dominant early in
Devonian
http://cas.bellarmine.edu/tietjen/images/
Figure 33.11 Jaws and Teeth Increased Feeding Efficiency (Part 2)
placoderms
www.emc.maricopa.edu/faculty/farabee/BIOBK/
33.3 What New Features Evolved in the Chordates?
 Jawed fishes move through water using their fins
Median dorsal and anal fins stabilize the fish
 Caudal fins help propel the fish forward, and turn
rapidly
 Pectoral and pelvic (paired fins) for control, precise
movement

Four Eyed
Butterfly
(Chaetodon
capistratus)
http://toons.artie.com/20010301/arg-goldfish-url.html
33.3 What New Features Evolved in the Chordates?
Chondrichthyes –
cartilaginous fishes
 finned fishes with
skeletons of cartilage
 firm but pliable material
 Secondarily lost –
ancestors had bony
skeleton
Skeleton of porbeagle shark
(Lamna nasus)
www.marinebiodiversity.ca/shark/english/images/
Chordates: New Ways of Feeding
 Skin is flexible and
leathery
 Loss of external
armor increased
mobility and ability
to escape from
predators

Placoid scales
www.usm.maine.edu/bio/courses/bio205
Figure 33.12 Cartilaginous Fishes (Part 2)
 Nearly all cartilaginous fishes live in the
oceans

Chimeras live in deep sea, cold waters
33.3 What New Features Evolved in the Chordates?
http://www.whale-shark.org/images/whale_shark_research.jpg
 Most sharks are
predators, some strain
plankton from the
water
 Skates and rays
(most) live on the
ocean floor and feed
on animals in the
sediments.
Rhincodon typus
Figure 33.12 Chondrichthyans
Chordates: New Ways of Feeding
http://www.oceanoasis.org/fieldguide/images/mantaray.jpg
 Pairs of unjointed fins control
swimming
Pectoral, pelvic, dorsal, caudal, anal fins
 Sharks create thrust using caudal fin
 Skates and rays propel themselves by
undulating movements of enlarged
pectoral fins

Reef shark
Manta ray
Figure 33.12 Chondrichthyans
33.3 What New Features Evolved in the Chordates?
Some early bony fishes had gas-filled sacs
 Supplemented gills in gas exchange in some
(early ―lungs‖) 
 Allowed fish to live in shallow, low O2 waters
 Evolved into swim bladders in ray-finned fishes
 organs of buoyancy…
 maintain position at specific depths
www.biology.iastate.edu/Courses/201L/Deuterostomes
33.3 What New Features Evolved in the Chordates?
Ray-finned fishes
 Calcified bones
 Most are covered by thin, lightweight scales
 Provide some protection
 Improves hydrodynamics
www.fisheries.org/education/fisheries_techniques/Chapter5
www.amonline.net.au/fishes/what/scales/images
33.3 What New Features Evolved in the Chordates?
 Gills open to a chamber covered by operculum

Movement of operculum enhances water flow over
gills for gas exchange
www.rhul.ac.uk/ElectronMicroscopy-Unit/images
www.taxidermy.net/reference/fish/lmbass/art/
Figure 33.13 Diverse Ray-Finned Fishes (Part 1)
 Radiated during Tertiary into diversity of
lifestyles
 Wide diversity of sizes, shapes and lifestyles
 About 24,000 extant species
Barracuda
Damselfish
Figure 33.13 Diverse Ray-Finned Fishes
Wrasse
Moray eel
Grouper
Anglerfish luring prey
Diversity of Ray-Finned Fishes
Anglerfish
Sea dragon sea horse
33.3 What New Features Evolved in the Chordates?
Ray-finned fishes exploit nearly all
types of food in aquatic habitats:
 filtering plankton
 digging animals from sediments
 rasping algae from rocks
Parrotfish rasping at rock
 eating corals
for algae
 predation
http://farm1.static.flickr.com/116/314781762_6b559c5f16.jpg?v=0
33.3 What New Features Evolved in the Chordates?
Many species form aggregations called
schools
Photo 34.30 Family
Engraulididae:
northern anchovy
(Engraulis mordax);
Monterey Bay, CA.
33.3 What New Features Evolved in the Chordates?
Most marine fish move to shallow water to
release eggs
 coastal waters & estuaries are extremely
important for many marine species
Click on image above to
connect to YouTube video
http://www.nmfs.noaa.gov/habitat/ead/EADimages/spwanaggNemeth.png
33.3 What New Features Evolved in the Chordates?
Some fish, such as salmon, return to
freshwater rivers and lakes to lay eggs in
redds or nests
Pair of sockeye salmon
spawning on a beach in
Iliamna Lake (Alaska).
http://biology.mcgill.ca/faculty/hendry/pic_files/image008.jpg
33.4 How Did Vertebrates Colonize the Land?
Evolution of lung-like sacs set stage for evolution of
land animals
 Some supplemented gills with lung sacs in low-O2 water
 Allowed them to breathe in air & leave water temporarily
Changes in fin structure
 Jointed fins allowed
some fish to support
themselves in shallow
water  later move onto
land
www.mines.utah.edu/geo/courses/UOnline/E&V_figs/evol&fossils
33.4 How Did Vertebrates Colonize the Land?
Jointed fins evolved in the ancestor of
sarcopterygians (coelacanths, lungfishes,
and tetrapods)
33.4 How Did Vertebrates Colonize the Land?
http://www.biologycorner.com/resources/fin.gif
Coelocanths
 thought to have gone
extinct 65 million years
ago, but living ones
were found off South
Africa in 1938
 Cartilaginous skeleton
that is derived feature
Bones in fins
homologous to those
in tetrapod limbs
Coelocanth
Figure 33.14 The Closest Relatives of Tetrapods (A)
http://www.biologycorner.com/resources/fin.gif
Bones in fins
homologous to those
in tetrapod limbs
Coelocanth
Figure 33.14 The Closest Relatives of Tetrapods (A)
33.4 How Did Vertebrates Colonize the Land?
Lungfishes
 Important in Devonian
 Six species survive in tropical swamps
 Lungs and gills for gas exchange
 Burrow in mud when ponds dry up,
and survive many months in inactive
state while breathing air
Australian lungfish
Lungfish
pectoral fin
http://www.usm.maine.edu/bio/co
urses/bio205/sarcop_fins.jpg
Figure 33.14 The Closest Relatives of Tetrapods (B)
West African lungfish
33.4 How Did Vertebrates Colonize the Land?
http://www.naturescornermagazine.com/NaturesBlog/images/missing%20link.jpg
Some sarcopterygians may have
used terrestrial food sources 
evolved into tetrapods – 4-legged
vertebrates
 Devonian fossil found in 2004 may
represent an transition between fins
and the limbs of terrestrial tetrapods
http://afarensis.blogsome.com/category/vertebrates/amphibians/
3-Tiktaalik, discovered in 2004
Figure 33.14 The Closest Relatives of Tetrapods (C)
Pectoral fins show
some skeletal elements
of tetrapods
Colonizing the Land:
Obtaining Oxygen from the Air
Class Amphibia – amphibians
 Arose during Devonian period
 Ancestral jointed fins  legs used to ―walk‖ on bottom



Amphibian transition was NOT from water to land, BUT from
fins to feet that took place in the water
Finlike legs probably allowed ancestors to crawl from one body
of water to another
Eventually evolved ability to live on dry land
Rhipidistian fish  ancestral amphibian transition
http://homepage.mac.com/wis/Personal/lectures/limb-evolution
Colonizing the Land:
Obtaining Oxygen from the Air
Rhipidistian fish  ancestral amphibian transition
Tetrapod legs evolved
from jointed fins
Bones in fins
homologous to those
in tetrapod limbs
http://homepage.mac.com/wis/Pers
onal/lectures/limb-evolution
33.4 How Did Vertebrates Colonize the Land?
Most modern amphibians have small lungs and
exchange gases via skin
 Confined to moist habitats
 Skin loses water easily
 Eggs dry out if exposed to air
http://animals.howstuffworks.com/amphibians/amphibian-info.htm
33.4 How Did Vertebrates Colonize the Land?
http://www.ct.gov/dep/cwp/view.asp?a=2723&q=325818
 Some species are
entirely aquatic
 In temperate zones,
many adults live on dry
land but must return to
water to lay eggs
 larvae develop in
water
Fully aquatic adult
mudpuppy (Necturus
maculatus)
Figure 33.15 In and Out of the Water
33.4 How Did Vertebrates Colonize the Land?
Other amphibians have
other modes of
reproduction
 Internal fertilization
evolved several times
 Some species have
direct development –
i.e. no larval form
As in most salmanders, male
Ambystoma maculatum
produce a spermatophore that
transfers sperm to females
http://www.herpnet.net/Minnesota-Herpetology/salamanders/images/SalamanderSpotted_3.jpg
33.4 How Did Vertebrates Colonize the Land?
About 6,000 species in three groups:
 Caecilians: wormlike, limbless, tropical
burrowing animals
33.4 How Did Vertebrates Colonize the Land?
 Anurans
 frogs and toads; most species of amphibians
33.4 How Did Vertebrates Colonize the Land?
Endangered Yosemite toad (Bufo canorus, male).
Some anurans have
tough skins and other
adaptations that allow
them to live in dry
habitats
 Many are arboreal (treedwelling)
 Some are completely
aquatic

Tree frog (Hyla sp.), vocalizing
33.4 How Did Vertebrates Colonize the Land?
http://www.dkimages.com/discover/previews/813/80002383.JPG

All have short vertebral
column and pelvic region
modified for hopping or
kicking in water
http://www.frogtrans.com/hopping_frog.gif
http://scienceblogs.com/tetrapodzoology/2007/10/fr
ogs_toads_sheer_untold_awesomeness.php
33.4 How Did Vertebrates Colonize the Land?
 Urodeles (Salamanders)

Most are terrestrial as adults
 Many live in moist soil and rotting logs
Barred Tiger Salamander
(Ambystoma tigrinum mavortium),
http://www.statesymbolsusa.org/IMAGES/Kansas/tiger_salamander_380.jpg
33.4 How Did Vertebrates Colonize the Land?

One group has lost lungs and relies on gas
exchange through skin and mouth lining
Photo 33.62 Red salamander
(Pseudotriton ruber), a
lungless salamander
33.4 How Did Vertebrates Colonize the Land?

Necturus (mudpuppy) is entirely aquatic
 Completely
aquatic species have evolved several times
through paedomorphosis — retention of juvenile
characteristics (e.g. gills) in adult form
33.4 How Did Vertebrates Colonize the Land?
 Most salamanders
have internal
fertilization

sperm is transferred
in small capsule –
spermatophore
Plethodon shermani delivering
courtship pheromone (above, male
on left) with a slap on her nares.
Deposition of spermatophore
(below). Female (left) will straddle
spermatophore and take it up in her
cloaca.
33.4 How Did Vertebrates Colonize the Land?
http://allaboutfrogs.org/weird/general/songs.html
http://ist-socrates.berkeley.edu/~schovill/pictures/l_dumerilii.jpg
 Many amphibians have
complex social behaviors

Male anurans call to attract
females and defend territories
Video
Southern Bullfrog
Video
Green Tree Frog
http://ccrm.vims.edu/Teaching_Marsh/images/green_treefrog.jpg
White’s Tree Frog
http://www.frogsonice.com/froggy/images/tfrog.gif
33.4 How Did Vertebrates Colonize the Land?
http://www.coquipr.com/anf/dorfws.gif
Some species lay only a few eggs
and guard the nest; or are carried
on the body
 A few are viviparous — give birth
to live young

Male Archey's Frog (Leiopelma archeyi) guarding eggs; the Midwife Toad
(Alytes obstetricans) carrying its eggs; and the Golden coqui (Eleutherodactylus
jasperi), a viviparous frog
http://www.nzfrogs.org/site/nzfrog/images/Fr
og_photos/archeyfrogRM.gif
http://scienceblogs.com/tetrapodzoology/2007/10/frogs_toads_sheer_
untold_awesomeness.php
33.4 How Did Vertebrates Colonize the Land?
Many populations of
amphibians are declining.
Blue poison dart frog
(Dendrobates azureus)
Several hypotheses are
being researched
 habitat destruction,
 increased UV radiation,
 pesticide pollution, and
 a pathogenic chytrid
fungus and other parasites
http://weblog.pell.portland.or.us/~orc/images/BlueFrog.jpg
33.4 How Did Vertebrates Colonize the Land?
Amniote clade evolved
several features that
contributed to success
on dry land
 Skin impermeable to
water
 Kidneys excrete
concentrated urine
 Amniotic egg
Snapping turtle (Chelydra
serpentina ) laying eggs
http://www.naturealmanac.com/archive/snappers/sn_eggs.jpg
33.4 How Did Vertebrates Colonize the Land?
 Amniotic egg is impermeable
to water
Allows embryo to develop in a
protected aqueous environment
 Leathery or brittle shell retards
water evaporation but allows
passage of gasses
 Yolk sac stores food – embryos
develop using energy from yolk
and are hatched at an advanced
stage

ww.bargarainn.com.au/Images
33.4 How Did Vertebrates Colonize the Land?

Several extra-embryonic membranes within
shell that…
 Protect
embryo from desiccation (amion),
 Assist in gas exchange (chorion & allantois)
 Excretion of nitrogen (allantois)
 Nutrient storage (yolk sac)
http://www.sanovoeng.com/images/7
47_Broken%20egg.jpg
Figure 33.17 An Egg for Dry Places
33.4 How Did Vertebrates Colonize the Land?
 Adult amniotes have a tough
skin with scales and other
modifications to prevent
desiccation
 Excretory organs allow
excretion of concentrated urine

allows excretion of nitrogen
wastes without losing a lot of
water
Photo 33.68 Yellow-headed
collared lizard (Crotaphytus
collaris auriceps).
33.4 How Did Vertebrates Colonize the Land?
During Carboniferous
amniotes split into two
major groups – reptiles
and mammals
Reptiles
 half of living species are
birds
 Birds are only living
descendents of dinosaurs
 Classically, reptiles are
paraphyletic (unless birds
are included)
www.emc.maricopa.edu/faculty/farabee/BIOBK/
Figure 33.18 Phylogeny of Amniotes
www.emc.maricopa.edu/faculty/farabee/BIOBK/
33.4 How Did Vertebrates Colonize the Land?
Turtles (Testudines)
 Changed very little in past 250 my
 Dorsal and ventral bony plates
form a shell – dorsal shell is
expansion of ribs
Gopher Tortoise
(Gopherus polyphemus)
http://media.duc.auburn.edu/media
http://www.dkimages.com/discover/previews/960/5015030.JPG
33.4 How Did Vertebrates Colonize the Land?
 Most are aquatic, some terrestrial

Sea turtles come ashore to lay eggs
 Human exploitation has resulted in
declining populations — sea turtles
are endangered
Loggerhead turtle laying eggs on beach
http://www.brandoncole.com/profileseaturtles.htm
Figure 33.19 Reptilian Diversity (A)
Green turtle
33.4 How Did Vertebrates Colonize the Land?
Lepidosaurs:
 Tuataras – resemble lizards; only two species
survive
 Squamates – lizards, snakes, and
amphisbaenians
Tuatara
33.4 How Did Vertebrates Colonize the Land?
Lepidosaur characters…
 Skin covered with horny scales
 Gas exchange is only through lungs  move to
more terrestrial habits
 Heart divided into chambers that partially
separates oxygenated from deoxygenated blood
Generates high blood pressure
 Sustains relatively high metabolism

Photo 33.66 Sphenodon
punctatus, tuatara endemic to
New Zealand
33.4 How Did Vertebrates Colonize the Land?
Squamates
 Most lizards are insectivores, some herbivores, some
predators – largest lizard is Komodo dragon of East
Indies
 Snakes are limbless squamates and all are
carnivorous – many evolved venom glands
World's largest monitor
lizard, Varanus komodoensis
Sumatran pit viper
Trimeresurus sumatranus
Figure 33.19 Reptilian Diversity (C, D)
33.4 How Did Vertebrates Colonize the Land?
Squamates
 Amphisbaenians (legless burrowing lizards)
Worm lizard (Amphisbaena angustifrons)
33.4 How Did Vertebrates Colonize the Land?
Archosaurs
 Crocodilians
 Pterosaurs
 ―Dinosaurs‖
 Birds
33.4 How Did Vertebrates Colonize the Land?
Modern crocodilians
 Crocodiles, caimans, gharials, and alligators
 Spend much of their time in water
 All are carnivorous
Grarial – Gavialis
gangeticus
Crocodylus niloticus
http://www.madrascrocodilebank.org/images/Thump/Gharial.jpg
http://www.dinosoria.com/reptil_prehi/nile_croco
dile07.jpg
Figure 33.20 Archosaurs (A)
33.4 How Did Vertebrates Colonize the Land?
 Maternal care
Females build nest on land or floating piles of
vegetation
 Heat from decaying organic matter warms eggs
 Protects eggs and young

www.cpet.ufl.edu/true/TRUE1997/parts/hough/Images
www.southalley.com/misc
Colonizing the Land:
Obtaining Oxygen from the Air
 Pterosaurs branched off
before dinosaurs

Sister group to dinosaurs
www.bindonart.com
www.ucmp.berkeley.edu/diapsids/ornithischia
33.4 How Did Vertebrates Colonize the Land?
Dinosaurs
 Dominated terrestrial
environments for 150
million years
 During Mesozoic, most
large animals were
dinosaurs
www.emc.maricopa.edu/faculty/farabee/BIOBK/
Figure 33.18 Phylogeny of Amniotes
Colonizing the Land:
Obtaining Oxygen from the Air
 Dinosaurs have two main
lineages
 Ornithischia
www.ucmp.berkeley.edu/diapsids/ornithischia
Colonizing the Land:
Obtaining Oxygen from the Air
Saurischia
www.ucmp.berkeley.edu/diapsids/saurischia
Colonizing the Land:
Obtaining Oxygen from the Air
http://www.watauga.k12.nc.us/staff/felkera/Willo_heart_info.JPG
 Dinosaurs possessed traits in
common with other land vertebrates
Convergent with mammals
 Ability to breathe and run
simultaneously – major innovation in
terrestrial vertebrates
 Muscles enabled lungs to be filled
and emptied while limbs moved

Colonizing the Land:
Obtaining Oxygen from the Air

Legs assumed vertical position in
lineages leading to mammals,
dinosaurs, and birds


present in living birds and mammals, and
dinosaurs (inferred from fossils)
Endothermy (―warm-bloodedness‖)??


Recent evidence suggests that most, if
not all, dinosaurs were endotherms
which helped make them dominant
Still controversial
"Willo", only dinosaur fossil
ever found with fossilized heart
http://www.watauga.k12.nc.us/staff/felkera/Willo_heart_info.JPG
33.4 How Did Vertebrates Colonize the Land?
Dinosaurs
 Mass extinction at end of
Cretaceous – probably from
a meteorite hitting Earth
near the Yucatan 65 mya
 Only dinosaurs that
survived where birds
www.emc.maricopa.edu/faculty/farabee/BIOBK/
http://funstoo.blogspot.com/2010/10/realreason-why-dinosaurs-became.html
33.4 How Did Vertebrates Colonize the Land?
Birds are thought to have
emerged among the
theropods (Saurichians)
 Predatory dinosaurs
 Bipedal
 Hollow bones
 Furcula (or wishbone)
 Three-fingered feet and hands
 Pelvis points backwards
http://www.geologyrocks.co.uk/system/files/u3/birdcompl.gif
http://www.wired.com/wiredscience/2011/09/dinosaur-feathers-amber/
33.4 How Did Vertebrates Colonize the Land?
Jurassic fossils (~155 mya) indicate
some predatory dinosaurs had scales
modified into colorful feathers before
birds evolved
 Microraptor gui (a theropod dinosaur) had
feathers on all four limbs, very similar in
structure to modern bird feathers
http://pterosauria.wordpress.com/tag/protofeathers/
Dinosaur feathers in amber
indicated many were colorful
Figure 33.21 Mesozoic Bird Fossils
 Archaeopteryx
 Oldest known fossil bird (150 million years)
 Feathers nearly identical to modern birds
 Clawed fingers on forelimbs probably assisted in
clambering over tree branches
http://www.dinosaur-world.com/feathered_dinosaurs/species/archaeopteryx_lithographica.gif
33.4 How Did Vertebrates Colonize the Land?
http://farm1.static.flickr.com/32/98573929_1f958dda60.jpg
Living bird species fall into two
groups that diverged in late
Cretaceous:
Great Tinamou, Tinamus major
 Palaeognaths
 secondarily flightless or weak
flyers
 Tinamou, rhea, emu, kiwi,
cassowary, ostrich
 Neognaths — most retained ability
to fly and have many more species
Cassin’s Vireo
(Vireo cassinii)
http://nrs.ucdavis.edu/Quail/Images/Birds/Cassin's_vireo.jpg
Figure 33.20 Archosaurs (B)
33.4 How Did Vertebrates Colonize the Land?
Evolution of feathers was
major force for avian
diversification
 Lightweight but strong
 Provide flying surfaces and
insulation
 Bones of theropods are
hollow with internal struts –
lightweight but strong
http://uk.dk.com/static/cs/uk/11/clipart/sci_animal/img
Figure 33.22 Feathers Represent a Major Evolutionary Innovation
Birds: More Feathers and Better Flight
 Feathers probably developed for insulation or
display in theropods

eventually able to become airborne for short distances
– probably early gliders
Cardinals
Lesser Bird-of-Paradise
http://k41.pbase.com/u44/r53lanc/upload
http://animals.timduru.org/dirlist/bird/misc/
Birds: More Feathers and Better Flight
 Sternum (breastbone)
Has expanded ―keel― – attachment for flight muscles
 Muscles pull wings downward during propulsive
movement in flight

Keeled
sternum
Large fan-shaped pectoralis
muscle attached to humerus,
and smaller supracoracoideus
(dashed line) deep to
pectoralis, attaches to top of
humerus via a tendon passing
through the foramen triosseum
http://academic.emporia.edu/sievertl/verstruc
www.nurseminerva.co.uk/adapt/prepics/
33.4 How Did Vertebrates Colonize the Land?
http://www.birdsinflight.net/galleries/gal_3/th/lrg/gal3_6.jpg
Flight is metabolically
expensive
 High metabolic rates
generate a lot of heat
 Birds control heat loss by
holding feathers close to
body, or elevating them
 Bird lungs allow air to flow
through lungs in one
direction, instead of
in-and-out

http://www.staff.ncl.ac.uk/candy.rowe/snow_bird.jpg
Also in crocodilians…so
this is either convergent or
an ancestral trait
33.4 How Did Vertebrates Colonize the Land?
Living birds: 9,600 species.
 ranging in size from 2-gram bee hummingbird to
150-kilogram ostrich
Mellisuga helenae
www.mangoverde.com/birdsound/images
33.4 How Did Vertebrates Colonize the Land?
 Teeth were secondarily lost, but birds consume
many different types of food

Because they eat fruits and seeds, birds are important
agents of plant dispersal
Cedar waxwing
Kingfisher
www.schmoker.org/BirdPics/Photos/Waxwings
www.treknature.com/images/photos/1396
Figure 33.23 Diversity among the Birds
33.4 How Did Vertebrates Colonize the Land?
Class Mammalia – Mammals
 Appeared in early part of
Mesozoic era
 Small mammals coexisted
with reptiles & dinosaurs for
at least 150 million years
 Mammals increased in size
and diversity after extinction
of dinosaurs
www.emc.maricopa.edu/faculty/farabee/BIOBK/
33.4 How Did Vertebrates Colonize the Land?
Characteristics of mammals:
 Mammary glands provide
young with milk
 Sweat glands
 Four-chambered heart
completely separates
oxygenated from deO2 blood
 also in birds & crocodilians
West Indian Manatee (Trichechus
manatus) calf nursing on single
teat, present in skin fold at base
of each flipper
Dog dentition
 Heterodont dentition
(differentiated teeth)
  diversity in diet &
capture/processing food
http://dentals.me/canine-dental-formula.asp
33.4 How Did Vertebrates Colonize the Land?
 Hair

greatly reduced in cetaceans (whales and
dolphins) and humans
 cetaceans
have fat layer for insulation
 humans learned to use clothing
http://www.freedolphin.com/wp-content/uploads/2007/03/dolphin1.jpg
33.4 How Did Vertebrates Colonize the Land?
 Mammal eggs are fertilized internally

embryos undergo a development period
(gestation) in uterus of female
Less than 17-day old
Sugar Glider (marsupial)
fetus (Petaurus breviceps)
http://bmxglider.tripod.com
9-10 week human fetus (Homo sapiens)
http://betweenthespecies.org
The Origin and Diversity of Mammals
 Approximately 5,000 species of living mammals
 Two major clades:
 Prototheria
 Theria
http://webpages.charter.net/teefile/biognomen/tree
33.4 How Did Vertebrates Colonize the Land?
Prototherians
 duck-billed platypus and echidnas
 lack a placenta
 lay eggs
 have legs out to sides
Platypus (Ornithorhynchus anatinus)
www.rpdc.tas.gov.au/soer/image/559/ilw
Short-beaked echidna
(Tachyglossus
aculeatus).
Figure 33.24 Prototherians
33.4 How Did Vertebrates Colonize the Land?
 Therian clade has two subdivisions:
Marsupials
 Eutherians

http://webpages.charter.net/teefile/biognomen/tree
33.4 How Did Vertebrates Colonize the Land?

Marsupials
 Carry and feed young in a ventral pouch
 Young born early, and crawl into pouch
for further development
 Most species are in Australia and South
America
Kangaroo young in
pouch and hairynosed wombat
(Lasiorhinus krefftii)
http://teachit.acreekps.vic.edu.au/animals/images
http://condor.depaul.edu/~gandrus/jpg/pics
Figure 33.25 Marsupials
33.4 How Did Vertebrates Colonize the Land?

Bonnet Macaque Mother and Infant
Eutherians
Placental mammals
Young are more
developed at birth
 Actually, all mammals
have a placenta (even
monotremes) of
varying complexity

http://lh5.google.com/traverseindia/RnpYq69DbdI/AAAAAAAAA9Q/1pxhsp_yJkQ/Monkey.jpg
33.4 How Did Vertebrates Colonize the Land?
 Eutherians
are extremely varied
Extinction of non-avian dinosaurs allowed radiation
into a large number of ecological niches
 Some species assumed the role of dominant terrestrial
predators

Figure 33.26 Diversity among the Eutherians (Part 2)
Table 33.1 Major Groups of Living Eutherian Mammals (Part 1)
Table 33.1 Major Groups of Living Eutherian Mammals (Part 2)
33.4 How Did Vertebrates Colonize the Land?
Herbivore-plant coevolution
 Herbivores influenced
evolution of plant spines,
tough leaves, toxic
compounds, and difficult-toeat growth
 Herbivores in turn evolved
adaptations to teeth and
digestive systems
• Large size evolved independently
in several herbivorous lineages,
probably as anti-predator trait
http://www.imagesofanthropology.com/images/Feeding_giraffe_Masai_Mara_Kenya.jpg
An interordinal mammalian phylogeny reconstructed by our retroposon insertion analysis.
Eutherian
mammal
phylogeny
Marsupials are
the outgroup
Nishihara H et al. PNAS 2006;103:9929-9934
©2006 by National Academy of Sciences
http://www.pnas.org/content/103/26/9929.full
33.4 How Did Vertebrates Colonize the Land?
Several eutherian
lineages returned to
aquatic habitats
  limbs became modified
as flippers
 Cetaceans evolved from
artiodactyls (ancestors of
pigs, deer, cattle)
 Seals from carnivores
(ancestors of cats, dogs)
http://palaeo.gly.bris.ac.uk/Palaeofiles/whales/pictures/clad.jpg
33.5 What Traits Characterize the Primates?
www-personal.umich.edu/~carpo/CV_files
Eutherian primates
radiated from a small,
arboreal insectivorous
mammals
 From ancestors of rodents,
tree shrews, flying lemurs
 Grasping limbs and
opposable digits were major
adaptation to arboreal life
 Two main clades
 Prosimians
 Anthropoids
An ancient
primate,
Carpolestes, 56
mya
Figure 33.27 A Current Phylogenetic Tree of the Primates
33.5 What Traits Characterize the Primates?
Prosimians
 Lemurs, pottos, and lorises
 Now restricted to Africa, Madagascar, & tropical Asia
 Mainland prosimians are arboreal and nocturnal
 On Madagascar, there was a radiation of lemurs –
some are terrestrial and diurnal
Golden potto
(Arctocebus
calabarensis)
http://homepage.mac.com/w
ildlifeweb/primate/photos
Jump to
Slide 197
Slow loris
(Nycticebus
coucang)
www.primates.com
Figure 33.28 A Prosimian
33.5 What Traits Characterize the Primates?
Anthropoids
 Tarsiers, Old World monkeys,
New World monkeys, apes, and
humans
 Evolved from early primate
lineage about 55 mya in Africa
or Asia
Philippine Tarsier
(Tarsuis syrichta)
www.ninme.com/photos
33.5 What Traits Characterize the Primates?
 New World monkeys
Probably reached South America from Africa
when continents were still connected
 All arboreal (live in trees)
 Many having long, prehensile tails

Black Howler Monkey (Alouatta caraya)
www.treknature.com/images/photos/2550
Silvery marmoset
(Callithrix argentata)
www.primates.com/marmosets
33.5 What Traits Characterize the Primates?
 Old World monkeys
more arboreal, others are terrestrial
 lack prehensile tails
 Often live in social groups

Mandrill (Papio sphinx)
Black and White Colobus
(Colobus guereza)
www.geometer.org/beginner
Figure 33.29 Monkeys
33.5 What Traits Characterize the Primates?
Lineage leading to modern apes split from Old
World monkeys about 35 mya
 Asian apes (gibbons & orangutans) descended from
two of ape lineages
Gray Gibbon
Orangutan
Figure 33.30 Apes (Part 1)
33.5 What Traits Characterize the Primates?
Third clade (African apes) split
 Led to chimpanzee/bonobo &
hominid clades about 6 mya
Bonobo (Pygmy Chimpanzee)
Pan paniscus
http://homepage.mac.com/wildlifeweb/prim
ate/new/Grundmann/bonobo.html
http://williamcalvin.com/teaching/bonobo.htm
Figure 33.30 Apes (Part 2)
33.5 What Traits Characterize the Primates?
Earliest protohominids, a.k.a. ardipithecines
 Bipedal locomotion is more energetically economical
 Forelimbs are free to manipulate and carry objects
 Eyes are elevated to look for prey
 But had ancestral traits – grasping big toe, small
bonobo-sized brain – a transitional species??
Ardipithecus ramidus – a 4.4-millionyear-old human ancestor found in
Ethiopia in 1992, but recently
described in 2011
http://news.bbc.co.uk/2/hi/8285180.stm
33.5 What Traits Characterize the Primates?
Australopithecines
 Descended from ardipithecines
~3.5 mya
 ―Lucy‖ (Australopithecus
afarensis) is most complete
skeleton found to date from
Ethiopia
www.skullsunlimited.com/graphics
“Lucy”
www.achievement.org/achievers/joh1/large
http://www.amnh.org/exhibitions/permanent/humanorigins/history/humans6.php
33.5 What Traits Characterize the Primates?
Two types of australopithicines lived in eastern
Africa about 4–5 million years ago:
 Paranthropus – lineage extinct ~1.2 mya
 A. africanus – probably gave rise to genus Homo,
but not directly??
Paranthropus boisei
https://www.msu.edu/~heslipst/contents/ANP440/boisei.htm
Figure 33.31 A Current Phylogenetic Tree of Homo sapiens and Our Close Extinct Relatives
Homonid evolution was
not linear, but branched
with many extinctions.
This is one hypothesis;
others can be made
depending on data
interpretations.
“Lucy”
www.amonline.net.au/human_evolution/images
Primates and the Origin of Humans
 Early hominids — of genus Homo —
Lived at same time as australopithecines for ~0.5
million years
 Homo habilis
 Oldest fossils of Homo
 Estimated to have lived about 2 mya

www.evolutionnyc.com/ImgUpload
www.avph.hpg.ig.com.br/jpg
33.5 What Traits Characterize the Primates?
http://www.science.mcmaster.ca/geo/research/age/Images/skull01.JPG
Homo erectus used tools and fire for cooking
 Survived in Eurasia until about 250 mya
 Fossils of descendent of H. erectus were found on an
Indonesian island in 2004 – these H. floresiensis
fossils were only 18,000 years old
http://www.realhistoryww.com/world_history/ancient/images_eman/erectus.jpg
33.5 What Traits Characterize the Primates?
In lineage leading to Homo sapiens
 Brain size increased rapidly while jaw muscles
decreased in size
 Enlargement of brain relative to body size was
probably favored by increasingly complex social life
 access to fat-rich food may have been key factor
 Features that increased communication between
individuals would have been favored
Chimpanzee,
Homo erectus,
Homo sapiens
33.5 What Traits Characterize the Primates?
Several Homo species existed in mid-Pleistocene
 All hunted large mammals and made variety of tools
 Rituals and a concept of life after death emerged.
 Homo neanderthalensis was widespread in Europe
and Asia
 May have been exterminated by H. sapiens known
as Cro-Magnons
33.5 What Traits Characterize the Primates?
Cro-Magnons (early Homo sapiens )
 Used sophisticated tools and created remarkable
cave paintings
 Spread across Asia and reached North America
about 20,000 years ago, quickly spreading
through the Americas
http://leseyziesdetayac.info/articles/discovery-of-the-cro-magnon
33.5 What Traits Characterize the Primates?
Our recent ancestors evolved large brains,
complex social behaviors, and language
 Complex cultures developed
 Knowledge and traditions passed from one generation
to the next
 Facilitated development of agriculture & pastoralism
  led to sedentary lives, cities, and occupational
specialization
http://www.mc.maricopa.edu/dept/d10/asb/anthro2003/lifeways/hg_ag/hunt-gath-pg4b.jpeg
Deuterostomes and Protostomes:
Shared Evolutionary Themes
Deuterostome evolution paralleled
protostome evolution in several ways:
 Both exploited abundant food in soft marine sediments
attached to rock or suspended in water
 Bodies became compartmentalized
 Planktonic larval stages evolved in both groups
 Both colonized land
 Internal skeletons of deuterostomes were able to
support much larger animals
 Terrestrial deuterostomes recolonized aquatic
environments several times