1. Biology, 9th ed, Sylvia Mader
Chapter 31
Chapter 31
The Vertebrates
The Vertebrates

2. Lancelet, Branchiostoma

3. Outline Chordates Non-vertebrate Chordates Vertebrates Fishes
Amphibians
Reptiles
Birds
Mammals

4. Chordates Phylum Chordata Four Main Characteristics Notochord
Dorsal Tubular Nerve Cord
Pharyngeal Pouches
Postnatal Tail

5. Invertebrate Chordates
Notochord persists and is never replaced by a vertebral column
Lancets (Subphylum Cephalochordata)
Sea Squirts (Subphylum Urochordata)

6. Sea squirt, Halocynthia

7. Vertebrates Subphylum Vertebrata
Internal jointed skeleton of vertebrates is living tissue that grows with the animal
Main axis of skeleton consists of vertebral columns and a skull that encloses the brain
Cephalization is accompanied by sense organs
Evolution of jaws and predation
Amnion allows reproduction on land

8. Phylogenetic Tree of the Chordates
Biology, 9th ed, Sylvia Mader
Phylogenetic Tree of the Chordates
Chapter 31
The Vertebrates
1.B.2: chordate development

9. Vertebrate Features
Living endoskeleton with vertebral column
Closed circulatory system
Paired appendages
Efficient respiration and excretion
High degree of cephalization
Adapted to active lifestyles

10. Biology, 9th ed, Sylvia Mader
Ectotherms
Chapter 31
The Vertebrates
Ectotherms – depend on the environment to regulate body temperature.
Fish
Amphibians – able to live in environments where the temperature fluctuates greatly
Most reptiles – allows them to survive on a fraction of the food per body weight required by birds and mammals; behaviorally adapted to maintain warm body temperature by basking in the sun
2.A.1: Ectothermy is the use of external thermal energy to help regulate and maintain body temperature.

11. Biology, 9th ed, Sylvia Mader
Endotherms
Chapter 31
The Vertebrates
Endotherms – can use metabolic heat to maintain a constant internal temperature; endothermy may be associated with their efficient nervous, respiratory, and circulatory systems.
Birds – unlike, other reptiles, generate internal heat
Mammals
2.A.1: Endothermy is the use of thermal energy generated by metabolism to maintain homeostatic body temperatures.

12. Jawless fishes (agnathans) Fishes with jaws
Cartilaginous (chondrichthyes)
Bony (osteichthyes)

13. Amphibians
Modern amphibians include three groups:
salamanders and newts
frogs and toads
caecilians

14. Evolution of the amniotes
The amniotes consist of three lineages: a. The turtles, in which the skull has no openings behind the orbit—eye socket (anapsid). b. All the other reptiles, in which the skull has two openings behind the orbit (diapsid). c. The mammals, in which the skull has one opening behind the orbit (synapsid)

15. Timeline of the evolution of the amniotes
Biology, 9th ed, Sylvia Mader
Timeline of the evolution of the amniotes
Chapter 31
The Vertebrates
4.B.4: Meteor Impact on Dinosaurs
Dinosaurs dominated Earth for about 170 million years before they died out at the end of the Cretaceous period, 65 mya. One hypothesis for this mass extinction – a massive meteorite struck the Earth near the Yucatan Peninsula; this disrupted existing ecosystems and destroyed many living things. The hypothesis is supported by a layer of the mineral iridium, which is rare on Earth but common in meteorites.

16. Reptiles
Most reptiles today live in the tropics or subtropics
lizards and snakes live on soil
turtles, crocodiles, and alligators live in water

17. Birds
Bird classification is based on beak and foot types, and some on habitats and behaviors.
Birds of prey have notched beaks and sharp talons.
Shorebirds have long slender bills and long legs.
Waterfowl have webbed toes and broad bills

18. Mammals
Monotremes are mammals that have a cloaca and lay hard-shelled amniote eggs (duckbill platypus and two species of spiny anteaters).
Marsupials begin development inside the mother’s body but are then born in a very immature state.
Placental Mammals are dependent on a placenta, an organ of exchange between maternal and fetal blood.

20. Major Orders of Mammals
Perissodactyla
Horses
Artiodactyla
Deer
Carnivora
Cats
Primates
Monkeys
Cetacea
Whales
Chiroptera
Bats
Rodentia
Mice
Proboscidea
Elephants
Lagomorpha
Rabbits

21. Biology, 9th ed, Sylvia Mader
Chapter 31
Ending Slide Chapter 31
The Vertebrates
The Vertebrates