Download VERTEBRATE EVOLUTION AND DIVERSITY

Vertebrate Evolution and
Diversity
Chapter 34
• Vertebrates belong to phylum
Chordata.
• Includes 3 subphyla, vertebrates
and 2 phyla of invertebrates,
urochordates and
cephalochordates.
• 4 characteristics: notochord;
dorsal, hollow nerve cord;
pharyngeal slits; and muscular,
postanal tail.
• Notochord, present in all chordate
embryos - flexible rod between
digestive tube and nerve cord.
• Dorsal, hollow nerve cord develops
in vertebrate embryo from plate of
ectoderm that rolls into tube dorsal
to notochord - can develop into
spinal cord.
http://www-biol.paisley.ac.uk/courses/tatner/biomedia/jpegs/hypchrdb.jpg
• Pharyngeal gill slits connect
pharynx, just posterior to mouth,
to outside of animal.
• Most chordates have muscular tail
extending posterior to anus.
http://science.kennesaw.edu/biophys/biodiversity/animalia/cephal.gif
Tunicates
• Sessile marine animals that adhere
to rocks, docks, and boats.
• Invertebrates - urochordates.
• Chordate characteristics are
present as larva.
• Suspension-feeders.
http://www.aboututila.com/Reviews/Charlie-Johnson/Photos/Bluebell-Tunicates.jpg
Lancets
• Cephalochordates - have chordate
characteristics in adult.
• Suspension-feeders.
Lancet
Vertebrates
• Neural crest, pronounced
cephalization, vertebral column,
closed circulatory system subphylum Vertebrata.
• Neural crests start of formation of
cranium; cephalization - collection
of nervous tissue that forms brain.
http://bio1151.nicerweb.com/doc/class/bio1151/Locked/media/ch34/34_07NeuralCrest_L.jpg
• Have appendicular skeleton,
supporting 2 pairs of appendages
(fins, legs, or arms).
• Can be made of either bone,
cartilage, or both.
http://sciencecity.oupchina.com.hk/biology/student/glossary/img/appendicular_skeleton.jpg
Jawless vertebrate
• 2 classes of jawless vertebrates
still living: Class Myxini (hagfish)
and Class Cephalaspidomorphi
(lampreys).
• Hagfish - skeletons made of
cartilage making them flexible, but
no backbone.
Hagfish
• Lampreys - parasites with cartilage
skeletons.
• Lack backbone - have notochord.
Jawed fish
• Jawed fish broken into 2 classes
(extant).
• Chondrichthyes (cartilaginous
fishes: sharks, rays), Osteichthyes
(bony fishes: ray-finned fishes,
lobe-finned fishes, lungfishes).
http://palaeo.gly.bris.ac.uk/Palaeofiles/Fossilgroups/Chondrichthyes/megalodon.jpg
• Chondrichthyes - skeleton made of
cartilage.
• Cartilaginous skeleton usually
replaced by bone; chondrichthyes process prevented.
• Fertilize internally; some lay eggs
(oviparous), few give birth to live
young (viviparous)
• Osteichthyes - bony fish endoskeleton made of bone.
• Bony fish have swim bladder not
found in cartilaginous fish - helps
control buoyancy of fish.
• Bony fish actually broken down into
3 groups: ray-finned fishes, lobefinned fishes, lungfishes.
Ray-finned fishes
Lobe-finned
fish
http://www.cartage.org.lb/en/themes/Sciences/Zoology/Biologicaldiverstity/AnimalsIII/coelacanth.jpg
Lungfish
Tetrapods
• Tetrapods -land animals - walk on all
fours - transition from water
animals to land animals amphibians.
• Class Amphibia - amphibians salamanders, frogs, caecilians
(legless animals that burrow)
• Fertilization external - lay eggs.
• Most amphibians rely heavily on
moist skin to carry out gas
exchange with environment - still
tied to water.
• Some adult frogs have lungs.
Caecilian
Amniotes
• Mammals, birds, reptiles, including
turtles, lizards, snakes, crocodiles.
• Transition to land - adaptations
were needed: amniotic egg,
waterproof skin, increasing use of
rib cage to ventilate lungs.
http://content.answers.com/main/content/wp/en-commons/thumb/f/fc/250px-Tortoise-Hatchling.jpg
• Amniotic eggs of most amniotes
have shell that retains water - can
be laid in dry place.
• Inside shell of amniotic egg several extraembryonic membranes
that function in gas exchange,
waste storage, and transfer of
stored nutrients to embryo.
Reptiles
• Class Reptilia divided into 4 orders.
• Reptiles - several adaptations for
terrestrial life not found in
amphibians - leathery skin to
prevent dehydration, lungs.
• Fertilization internal, eggs laid
(amniotic eggs)
http://www.dnr.state.wi.us/org/caer/ce/eek/critter/reptile/images/turtleHatching.jpg
• Reptiles - ectotherms - cannot
maintain own internal temperature
(cold-blooded).
• Turtles return to water to lay eggs;
have not evolved since 1st
appearance.
• Lizards - most numerous reptiles.
• Snakes - limbless reptiles - still
have pelvic bones - evidence that
they evolved from reptiles with
legs.
• Crocodiles and alligators - largest
living reptiles.
• Breathe through their nostrils that
are pointed upward out of water.
Birds
• Birds - class Aves - broken down
into 28 orders (few flightless
birds)
• Birds evolved to have hollow bones
to allow for flight and feathers.
• Modern birds - toothless - grind
food in muscular gizzard near
stomach.
• Large brains of birds
(proportionately larger than
reptiles or amphibians) support
very complex behavior.
• Birds - endotherms - metabolism
allows them to regulate internal
temperature.
Mammals
• Mammals - class Mammalia identified by mammary glands.
• Most mammals give birth to live
young after internal fertilization.
• Nutrition done via placenta.
• Most mammals capable of learning
due to larger brains.
• Monotremes - duck-billed platypus
and echindas - lay eggs that have
yolks to support embryo.
• Marsupials - born early in
development crawl into pouch in
mother to complete development.
• Eutherians - placental mammals.
http://cache.eb.com/eb/image?id=94548&rendTypeId=4
Echinda
http://marsupials.org/koalaalb.jpg
Opposum
http://www.ucmp.berkeley.edu/mammal/eutheria/rat.jpg
• Primates - most advanced of
eutherians.
• Opposable thumb characteristic of
most advanced primates.
• Divided into 2 groups: prosimians
(lemurs), anthropoids (apes,
humans).
http://www.dumondconservancy.org/dc2005/images/web/troy%20originals/lemur8.jpg
http://www.dkimages.com/discover/previews/920/55048736.JPG
• New World monkeys - arboreal (live
in trees) - tails used for grasping.
• Hominoid - great apes and humans
collectively.
• Hominid - group closely related to
humans.
• Human evolution included many
adaptations - larger brains, ability
to stand upright.
http://www.nhc.ed.ac.uk/images/vertebrates/primates/HominoidSkulls.jpg