1. Phylum Chordata Subphylum Vertebrata Class Mammalia: US!
Biology 11
Phylum Chordata
Subphylum Vertebrata
Class Mammalia: US!

2. Class Mammalia Mammalian Evolution:
Also evolved from the reptiles in late Mesozoic
Existed as small rodent-like animals that burrowed in the ground
Were able to survive end of Mesozoic and were pre-adapted to the new cool dry reality
Completed the vertebrate evolution to land
Class Mammalia

3. Mammalia Objectives General characteristics
6 body systems: circulatory, respiratory, integumentary, reproductive, nervous, skeletal
3 subclasses and example animals
Mammalia Objectives

4. Mammalian Characteristics
4 chambered heart
Hair or fur
Diaphragm for breathing
Amniotic egg
Mammary glands for nursing young
Extensive post natal care
Learning and reasoning levels of behavior
Mammalian Characteristics

5. Class Mammalia Advances and Characteristics: 1. Circulatory System
Complete four chamber heart and circulatory pattern (same as Aves except for the whole air sac business )
2. Respiratory System
Highly efficient lungs with muscular diaphragm
Class Mammalia

8. Class Mammalia 3. Body Covering
Covered with hair for insulation (modified scales) and sensing
All mammals are endothermic
Have a layer of subcutaneous fat for insulation and food storage
Class Mammalia

9. Class Mammalia 4. Reproduction Internal fertilization & development
Amniotic egg: modified to include placenta
Nurse young with mammary glands
Young born very immature - require extensive post natal care (18yrs worth! )
Class Mammalia

10. Class Mammalia 5. Nervous System
Most advanced nervous system in the animal kingdom
Great increase in cerebrum (convoluted)
Very well developed senses
Behavior reaches learning and reasoning levels – infant care, mating & societies
Class Mammalia

11. Brain Regions and Functions
Frontal Lobe thinking, planning, & central executive functions; motor execution. Parietal Lobe somatosensory perception, integration of visual & somatospatial information. Temporal Lobe language function and auditory perception involved in long term memory and emotion. Occipital Lobe visual perception and processing.
Brain Regions and Functions

12. Class Mammalia 6. Skeletal
Limbs are well adapted for land and water & allow very rapid movement
Class Mammalia

13. Class Mammalia Classification 1. Subclass Prototheria (the monotremes)
The mammals are placed into three Orders:
1. Subclass Prototheria (the monotremes)
Have fur & nurse young
Have a bird bill & lay eggs which they incubate outside body
Today represented only by Duck Billed Platypus and the two species of Anteater
An evolutionary dead end

14. Class Mammalia 2. Subclass Metatheria (the marsupials)
Do not have a uterus (but do have a short lived placenta!) complete development in the pouch fused to mammary gland
First major group of mammals to evolve – spread all over Earth – adaptive radiation
Became reduced globally due to competition from placental mammals
Class Mammalia

15. Class Mammalia Example Marsupials:
The North American marsupial is the opossum – an omnivore
The Australian marsupials are represented by kangaroos, wallabies, possums and koala bears among many others – all herbivores

16. Possum (Australian)
Opossum (American)

17. Class Mammalia 3. Subclass Eutheria
(the placental mammals) Complete internal development due to placenta – an organ of exchange between mother & fetus
Most common order of mammals today - includes us!
Dominant land vertebrate - adaptive radiation!
Class Mammalia