24. CLASSIFICATION: Animalia (Vertebrates -- "Craniata"{)


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Students are required to read the textbook for the instructor to be able to teach the concepts the course encompasses. (From FOUNDATION SKILLS in the Biology Department Master Syllabus.)
Students, do not just read these notes, to succeed in this class -- at least if you wish to have a high grade, you MUST use your textbook as a LEARNING TOOL!



MAIN TOPICS OUTLINE

24.1 General Characteristics
24.2 Vertebrate Classification
24.3 Human Evolution




LECTURE OBJECTIVES

1. Discuss the characteristics of the Phylum Chordata, and some criteria used in classifying vertebrate (craniates) animals.
2. List the major classes of the subphylum Vertebrata (the craniates), and give some examples of each.
3. List the major sub classes of the class Mammalia, and give some examples of each.
4. Define selected key terms.




Key Terms:

def. Amniotic cavity: Cavity within the blastocyst that eventually becoms a fluid-filled sac in which the embryo will float during development.
def. Amniotic egg: An egg with an amnion in reptiles, birds and mammals.
def. Amnion: Extraembryonic membrane of reptiles, birds, and mammals that forms an enclosing, fluid filled sac.
def. Exoskeleton: Protective external skeleton, as in arthropods..
def. Endoskeleton: Protective internal skeleton, as in vertebrates.
def. Feather: A modified scale that form the external covering of the body of birds.
def. Gill slits: see pharyngeal pouches.
def. Hair: A modified scale that form the external covering of the body of mammals.
def. Homeothermic: Maintenance of a uniform body temperature independent of the environmental temperature.
def. Mammary gland: Milk producing gland in female mammas.
def. Notochord: Supporting rod in at least some life stages in all chordates. (During development modified to the vertebral column in vertebrates.)
def. Nerve cord: A centrally placed cord of nervous tissue that receives sensory information and exercises motor control.
def. Parasites: Ecological relationship between two organisms where only one organism benefits, by deriving nourishment from the other, without killing it (at least not immediately) but usually doing harm to it.
def. Pharyngeal pouches (gill slits): Embryonic structures present in all chordates embryos that becomes functioning gills in fishes and larvae amphibians.
def. Placenta: The partly fetal and partly maternal organ whereby materials are exchanged between fetus and mother in the uterus of placental mammals.
def. Poikilothermic: Maintenance of a uniform body temperature dependent of the environmental temperature.
def. Postanal tail: Posterior part of an animal, extending beyond the anus.
def. Scale: A flake covering the body and offering protection in fishes and reptiles.
def. Tadpole: Aquatic larva of frogs and toads.



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Big Picture -- Animal Evolution



24.1 General Characteristics


Phylum Chordata ("Vertebrates". Animals with a backbone.)

Characters in common (at least part of their life cycle -- sometimes secondarily lost):

1. gill slits
2. dorsal nerve cord
3. dorsal notochord (backbone supporting the nerve cord)
4. postanal tail



Subphylum Urochordata
-- tunicates, sea squirts

Subphylum Cephalochordata
-- lancelets

Subphylum Vertebrata
-- vertebrates




24.2 Vertebrate Classification


Subphylum Vertebrata
-- vertebrates (craniates)


Class Jawless fishes (Agnatha) lamprey, hagfish
Note: Newer research remove the hagfishes from the vertebrates but include them in a new group called "craniates". This nullifies the name Agnatha for the lampreys. The lampreys (have a cranium and vertebrae) instead become the class Cephalaspidomorphi. Hagfishes (have a cranium but no vertebrae) become class Myxini. This classification is followed below.
Class Cartilaginous fishes (Chondrichthyes) sharks, rays
Class Bony fishes (Osteichthyes) all fishes with bony skeleton
Class Amphibians (Amphibia) frogs, toads, salamanders
Class Reptiles (Reptilia) snakes, lizards, turtles
Class Birds (Aves) all organisms with feathers
Class Mammals (Mammalia) Platypus, Marsupials, Placentals


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Subphylum Vertebrata (Vertebrates -- "Craniates"))


- evolutionary step 1: Cranium (bony frame work protecting the brain)
-- previous: no cranium

Class Hagfishes (Myxini -- previously Agnatha -- jawless fishes)
hagfishes
Photo of the hagfish by C. Ortlepp, found at URL: http://www.zoology.ubc.ca/labs/biomaterials/slime.html, used for educational purposes by Dr. Jan A. Nilsson, STCC.

1. no jaws
2. Cartilaginous skeleton (no true skeleton -- no vertebrae -- notochord only)
3. Aquatic
4. "cold blooded" Poikilothermic
Hagfish on the web



- evolutionary step 2: Vertebrae (notochord modified to a vertebral column)
-- previous: notochord only

Class Lampreys (Cephalaspidomorphi -- previously Agnatha -- jawless fishes)
lampreys

1. no jaws
2. Cartilaginous skeleton
3. Aquatic
4. "cold blooded" Poikilothermic

Parasites

def. Parasites: Ecological relationship between two organisms where only one organism benefits, by deriving nourishment from the other, without killing it (at least not immediately) but usually doing harm to it.



- evolutionary step 3: Jaws
-- previous: no jaws

Class Cartilaginous Fish (Chondrichthyes)
sharks, rays

1. Jaws
2. Cartilaginous skeleton
3. Aquatic
4. "cold blooded" Poikilothermic




- evolutionary step 4: Bony vertebrae (skeleton)
-- previous: cartilaginous skeleton

Class Bony Fish (Osteichthyes)
All other fish


1. Jaws
2. Bony skeleton
3. Aquatic
4. "cold blooded" Poikilothermic




- evolutionary step 5: Limbs (living on land)
-- previous: no limbs and living in water

See: Movement to land – problems which needed to be overcome

Class Amphibians (Amphibia)
Salamanders, Frogs, Toads


1. Jaws
2. Bony skeleton
3. Terrestrial (near water)
4. "cold blooded" Poikilothermic

-- permeable skin
– must live close to water to avoid water loss


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CNN:
Frogs as Indicator Species



- evolutionary step 6: Amnion (improved land adaptation)
-- previous: living near water

Class Reptiles (Reptilia)
Snakes, Lizards, Turtles


1. Jaws
2. Bony skeleton
3. Terrestrial
4. Poikilothermic

less permeable skin (scales)
– do not have to live close to water to avoid water loss
(egg & body can be away from water)
amniotic egg


- evolutionary step 7a: Feathers (Body temp. regulation -- improved land adaptation)
-- previous: cold blooded -- temperature as the environment

Class Birds (Aves)


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1. Jaws
2. Bony skeleton
3. Terrestrial
4. "warm blooded" Homeothermic (feathers)


• -- body temperature: Homeothermic organisms vs. Poikilothermic organisms
– insulating material: feathers
– the circulatory system regulate body temperature


• -- Flight evolved independently in 3 groups of Animalia
1. Insects (Arthropoda)
2. Birds (Chordata)
3. Bats (Chordata)

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CNN:
Bird Evolution



- evolutionary step 7b: Hair (Body temp. regulation -- improved land adaptation)
-- previous: cold blooded -- temperature as the environment

Class Mammals (Mammalia)
Platypus, Marsupials, Placental mammals


1. Jaws
2. Bony skeleton
3. Terrestrial
4. "warm blooded" Homeothermic (hair)


• -- body temperature: evolved independently in 2 groups of Animalia
1. Birds: – insulating material: feathers
2. Mammals: – insulating material: hair -- the circulatory system regulate body temperature


• -- mammary glands
-- for feeding of newborn

• -- placenta
– for feeding and assisting the fetus


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CNN:
Fossil Horses of Florida






i. Subclass Monotremes (Holotheria)
-- duck-billed platypus
(females lay eggs)

ii. Subclass Marsupials (Metatheria)
-- koala bear, kangaroo, opossum
(females have pouches)

iii. Subclass Placental mammals (Eutheria)
Placental mammal page, fr. Biology, 7th. ed., Solomon, et.al., Brooks/Cole, Thomson Learn. Used f. educ. purposes by Dr. J.A. Nilsson, STCC. Placental mammal page, fr. Biology, 5th. ed., Raven, et.al., WBC/McGraw-Hill. Used f. educ. purposes by Dr. J.A. Nilsson, STCC.

-- bats, primates, rodents, whales, carnivores, elephants, horses, pigs, deer, giraffes, rabbits
(females have placenta)






Order Primates (“Monkeys”: lemurs, monkeys, apes, humans)



Suborder 1: Prosimians (Prosimii: tarsiers. lemurs, treeshrews, lorises)
Suborder 2: Anthropoids (Anthropoidea)


Infraorder 1: New World Monkeys (tail -- some prehensile tail)
Infraorder 2: Old World Monkeys (rather short tail, some no tail)


Superfamily: Hominoids (Hominoidea -- Apes)

-----
One potential family classification:

FAMILY Hylobatidae -- gibbons (Lesser Apes)
FAMILY Pongidae -- orangutan, gorilla, chimpanzee, pygmy chimpanzee (Greater Apes)
FAMILY Hominidae -- humans (Hominids)

-----
Another potential family classification?:

FAMILY Hylobatidae -- gibbons (Lesser Apes)
FAMILY Pongidae -- orangutan (Asian Greater Apes)
FAMILY Hominidae -- gorilla, chimpanzee, pygmy chimpanzee, humans (African Greater Apes)



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CNN:
Mystery Ape



24.3 Human Evolution (incl. Origin and Evolution of Life)

Continental Drift & Plate Tectonics
-- the map of the Earth has not always been the same -- the continents have moved and continue to move

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Continental Drift
Plate Tectonics


Evolutionary Timetable
-- for the formation of the solar system, earth, & life



1. Start of CHEMICAL EVOLUTION


15 billion yrsa

SOLAR SYSTEM BEGINS TO FORM

4.5 billion yrsa

EARTH FORMED
-- no oxygen
-- too hot for life (and water)
-- the crust cooled slowly and hardened
-- water vapor in the atmosphere condensed >>> rain

OCEANS FORMED

-- water erosion of rocks (chemicals for chemical reactions)
-- lightning, volcanic heat, & UV radiation (energy for reactions)

ORGANIC MOLECULES FORMED



2. Start of BIOLOGICAL EVOLUTION


3.8 billion yrsa


PROKARYOTIC ORGANISMS (oldest known fossils)
-- anaerobic (no oxygen)
-- heterotrophs (used an organic source of energy – "eating")


3.5 billion yrsa

PHOTOSYNTHETIC BACTERIA
-- anaerobic (no oxygen)
-- autotrophic (used sunlight energy, produced oxygen - waste)


OXYGEN FORMED

2.5 billion yrsa

AEROBIC BACTERIA (mitochondrial-like bacteria)

-- used oxygen (aerobic, prokaryotic)
-- used energy more efficiently (Krebs cycle)


ENDOSYMBIOTIC RELATIONSHIPS (organisms start to interact)

1.8 billion yrsa

EUKARYOTIC ORGANISMS (Protistans)

0.75 billion yrsa (750 mya)

MULTICELLULAR ORGANISMS -- incl. the FIRST ANIMALS

0.55 billion yrsa (550 mya)

“Cambrian Explosion” -- all modern phyla formed

0.45 billion yrsa (450 mya)

first fishes (jawless)
first plants (nonvascular)
first insects
first amphibians

0.4 billion yrsa (400 mya)

first vascular plants
first gymnosperms

0.35 billion yrsa (350 mya)

amphibians decline
first reptiles
0.25 billion yrsa (250 mya)
Pangaea
first dinosaurs
first mammals


0.15 billion yrsa (150 mya)
Gondwanaland / Laurasia
first birds
first flowering plants (angiosperms)
first placental mammals


0.066 billion yrsa (66 mya)
Earth when the dinosaurs went extinct

last dinosaur, mammals diversify

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CNN: Evidence of Asteroid Impact
CNN: Measuring Time


0.060 billion yrsa (60 mya)

first primates (prosimians)

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Binocular Vision

0.035 billion yrsa (35 mya)

first anthropoids (monkeylike primates)

0.024 billion yrsa (24 mya)

first hominoids (apelike primates)

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Ape Skulls

0.018 billion yrsa (18 mya)

Asian ape evolutionary line separates from the African ape line
-- gibbon line
-- orangutan line


0.010 billion yrsa (10 mya)

African ape evolutionary lines diverge
-- gorilla line
-- chimpanzee line

-- pygmy chimpanzee line

0.005 billion yrsa (5 mya)

Pygmy chimpanzee line separates from the human line

0.0045 billion yrsa (4.5 mya)

OLDEST HOMINID FOSSILS
-- Australopithecus sp.

0.003 billion yrsa (3 mya)

FIRST HOMO sp.
-- Homo habilis
-- Homo erectus
-- Homo sapiens

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CNN:
Fossil Humans


3. Start of CULTURAL EVOLUTION

0.00004 billion yrsa (40,000 yrsa)
Earth today
AGRICULTURE



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Big Picture -- Animal Evolution




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