Four Key Chordate Characteristics

Invertebrate Chordates• Cephalochordata

-Lancelets/Amphioxus• Urochordata

–Tunicates/Sea Squirts• Vertebrates may have

evolved from a sexually mature larval urochordate

• Metamorphosis is eliminated

Subphylum Cephalochordata: the Lancelet Branchiostoma

Lancelet Anatomy

Subphylum UrochordataTunicate Anatomy

Subphylum: Vertebrata

• Cephalization (Craniates are chordates with a head)

• Vertebrate skeleton

• Brain protected by skull

• Closed circulatory system

• Gills or lungs

• Kidneys for excretion

Fishes• Very successful vertebrates–Fast streamlined body plan–Excellent sensory organs,

lateral line system–Highly developed organs for

osmoregulation–Complex behavior–2 chambered heart–Swim bladder

Fish

A Sea Lamprey (Class Cephalospidomorphi)

A Hagfish (Class Myxini)

Hypothesis for the evolution of vertebrate jaws from two pairs of skeletal rods

Gnathostomes Are Vertebrates That Have Jaws

Class Chondrichthyes

Ray-finned Fishes; Yellow Perch; Have thin bony spines connected by a layer of skin to form the fins

Ray-finned Fishes (Class Actinopterygii): long-snouted sea horse

A coelocanth (Class Actinistia), a Lobe-finned Fish, has rod-shaped bones and few bones in its fin bases

Coelacanth at the Field Museum - Chicago

Fossilized and modern

coelocanths

Life on LandProblems:

• No support on land

• Gills stick together

• Ammonia no longer a good source of excretory waste

• Dehydration

• Sound/light /smell is perceived differently on land

Solutions• cartilage bone• Lungs• Excrete

concentrated urea uric acid

• Skin and scales• Adapt ability to

perceive sound, smell and light differently

Skeleton of Acanthostega, a Devonian tetrapod fish

Class Amphibia• Shoulder hip and girdles act to

strengthen limbs for life on land• Heart with 3 chambers• They are not completely free from

water–Reproduction–Dessication (skin must stay wet)

                                                                

Amphibian Orders: Newt (left) Order Urodela, frog (right) Order Anura

Frogs

“Dual life” of a frog (Rana temporaria)

Class Reptilia

• Completely free from water• Amniotic egg• Scaly skin• 3-4 chambered heart• Uric acid as nitrogenous waste• Ectothermic

                                      

                           

                  

Extant Reptiles: Desert tortoise (top left), lizard (top right), king snake (bottom left),

alligators (bottom right)

Banded Gecko, Coleonyx varigatus

Emerald Tree Boa

Sea Turtle

Archaeopteryx

Archaeopteryx

Cretaceous theropod dinosaurs with putative feathers from Chinese

sediments: Caudipteryx

Class Aves• Evolved from reptiles• Flying dinosaurs• Bones and feathers are

adapted for flight• 4 chambered heart• Endothermic• Efficient 1 way lungs• Excrete uric acid

A small sample of birds: Blue-footed boobies (top left), male peacock (top right), penguins (bottom left), perching bird (bottom right)

Class Mammalia• Hair• Mammary glands• Placenta connects fetus to mom

(missing in marsupials)• Diaphragm for ventilation of

lungs• 4 chambered heart• Endothermic• Large brains• Diverged from reptilian

ancestors earlier than the birds

Major Groups of Mammals• Monotremes:

–Platypuses, spiny anteater - lay eggs

–Mixture of reptilian and mammalian traits

• Marsupials–Non-placental – Kangaroo, opossum –Young born early and complete

development within pouch• Placental Mammals – bats, dogs, us!

Major Orders of Mammals (Monotremata-Sirenia)

Major Orders of Mammals (Edentata-Primates)

Major Orders of Mammals (Carnivora-Cetaceans)

Major Orders of Mammals (Perissodactyla-Insectivora)

Hypothetical Cladogram of Mammals

A Phylogenetic Tree of Primates

Primate Diversity

Prosimians: Lemurs

A Capuchin, a New World Monkey (left), and a Vervet, an Old World Monkey (rt)

Arboreal, no sitting pads or estrus swelling, prehensile tail

Sitting pads, estrus swelling, generally larger

Others: squirrel monkey, spider monkey, howler monkey

Others: baboon, macaque,Colobus, Rhesus

Apes: Gibbon (top left), orangutan (top right), gorilla (bottom left), chimpanzee (bottom right)

Bonobo with Infant

Jane Goodall, well known for her studiesof chimpanzees

Major Orders of Mammals (Edentata-Primates)

Major Orders of Mammals (Edentata-Primates)

Major Orders of Mammals (Carnivora-Cetaceans)

Major Orders of Mammals (Perissodactyla-Insectivora)

HumanPlace the following organisms on the

phylogenetic tree in terms of theirrelationship to the human:spider monkey, bush baby,orangutan, baboon, siamang.

Chimp

1) Name two Anthropoids.

2) What behavior in chimpanzees was Jane Goodall the first to document?

3) Name one animal from which Ken Miller showed several transitional fossils.

4) What two things are necessary for speciation to occur?

5) The Kaibab and Abert squirrel live on either side of the Grand Canyon and over 10,000 years ago were one species. This demonstrates…

6) If many species evolve from one common ancestor such as occurred with Darwin’s finches this demonstrates the concept of:

7) Other than the chimpanzee, name one other Great Ape.

8) All of the great apes have ______ chromosomes in each of their cells.