natural history of (terrestrial) vertebrates chapter # 1 – the diversity, classification, and...
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Natural History of (Terrestrial) Vertebrates
Chapter #1 – The Diversity, Classification, and Evolution of
Vertebrates
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Introduction to Vertebrates
What is a Vertebrate?Answer:
Classification of organisms that share similar derived characteristics
CommonAncestor
Domain: Eukarya (Eukaryotic cells = “true nucleus”)
Kingdom: Animalia (Multi-cellular heterotrophs)
Phylum: Chordata
• Notochord (Flexible rod; skeletal support)
• Dorsal, hollow nerve cord (Brain / spinal column)
• Pharyngeal slits (openings in throat; water passage)
• Muscular, post-anal tail (Balance / propulsion)
Subphylum: Urochordata• Tunicates (sea squirts)
Subphylum: Cephalochordata• Lancelets
Phylogeneticsystematics
(cladistics)
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What is a Vertebrate?Answer:
Classification of organisms that share similar derived characteristics
CommonAncestor
Domain: Eukarya (Eukaryotic cells = “true nucleus”)
Kingdom: Animalia (Multi-cellular heterotrophs)
Phylum: Chordata
• Notochord (Flexible rod; skeletal support)
• Dorsal, hollow nerve cord (Brain / spinal column)
• Pharyngeal slits (openings in throat; water passage)
• Muscular, post-anal tail (Balance / propulsion)
Phylogeneticsystematics
(cladistics)
Subphylum:
Vertebrata
• Vertebral column present (bone / cartilage)• High degree of cephalization
• Cranium; tripartite brain; multi-cellular sense organs• Specialized organ systems
• e.g., closed circulatory system; specialized kidneys
Increased body sizeand activity level
Introduction to Vertebrates
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Classification ofVertebrates:
• 57,000 species (100x extinct)
• New discoveries weekly
Introduction to Vertebrates
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Giant Forest Hog(Kenya – 1904)
Komodo Dragon(Komodo - 1912)
Bonobo(Congo – 1929)
Giant Panda(China – 1932)
Saola(Vietnam - 1992)
Megamouth(Deep Sea - 1976)
Coelocanth(Deep Sea – 1998)
Introduction to Vertebrates
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Earth History Critical for Understanding Natural History of Vertebrates:
Precambrian~ 4,600 mya
~ 540 mya
ERA PERIOD
Pale
ozo
ic
Cambrian
Ordovician
Silurian
Devonian
Carboniferous
Permian
~ 490 mya
~ 440 mya
~ 420 mya
~ 350 mya
~ 290 mya
~ 250 mya
Meso
zoic
~ 205 myaTriassic
Jurassic
Cretaceous~ 145 mya
Cen
ozo
ic
~ 65 mya
~ 5 myaTertiary
QuaternaryPresent
Introduction to Vertebrates
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Cen
ozo
icM
eso
zoic
Pale
ozo
ic
Precambrian
~ 65 mya
ERA
~ 540 mya
PERIOD
Cambrian
Ordovician
Silurian
Devonian
Carboniferous
Permian
Triassic
Jurassic
Cretaceous
Tertiary
Quaternary
~ 250 mya
Present
The Paleozoic world very different from the one we currently know:
• 6 major land masses including Laurentia (North America) and Gondwana (Current Southern Hemisphere countries)
Climate:• Sea levels at / near all-time high; high levels of CO2
• Greenhouse Effect: hot & dry climate
Terrestrial Ecosystem (unsuitable conditions…):• Wet habitat = algae / lichens / fungi• Land = green algae
Continental Geography:
Introduction to Vertebrates
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Cen
ozo
icM
eso
zoic
Pale
ozo
ic
Precambrian
~ 65 mya
ERA
~ 540 mya
PERIOD
Cambrian
Ordovician
Silurian
Devonian
Carboniferous
Permian
Triassic
Jurassic
Cretaceous
Tertiary
Quaternary
~ 250 mya
Present
The Paleozoic world very different from the one we currently know:
• Cooler, moister conditions than Cambrian
• Major glaciations; falling CO2 levels
Terrestrial Ecosystem:• Stratified forest communities of vascular plants (wet places…)
• Terrestrial animals = millipedes / springtails / mites• No terrestrial vertebrates
Continental Geography:
Continents beginningto drift together
Gondwana(south pole)
Laurasia:Laurentia + Baltica + Siberia
(along equator)
Climate:
Introduction to Vertebrates
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Cen
ozo
icM
eso
zoic
Pale
ozo
ic
Precambrian
~ 65 mya
ERA
~ 540 mya
PERIOD
Cambrian
Ordovician
Silurian
Devonian
Carboniferous
Permian
Triassic
Jurassic
Cretaceous
Tertiary
Quaternary
~ 250 mya
Present
The Paleozoic world very different from the one we currently know:
Continental Geography:
Continents drift together to form Pangaea (Permian)
(36% of Earth’s surface)
Climate:• Climate highly differentiated across super-continent
• Due to glaciations (also oscillated sea levels)
Terrestrial Ecosystem:• Broadleaf forests appear (similar in appearance to those today)
• Gymnosperms – not angiosperms• Arthropods flourished (Detritivores / herbivores / carnivores)
• Terrestrial vertebrates appear / diversify (non-amniotes / amniotes)
Figure 7.4
Introduction to Vertebrates
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Earth History Critical for Understanding Natural History of Vertebrates:
Precambrian~ 4,600 mya
~ 540 mya
ERA PERIOD
Pale
ozo
ic
Cambrian
Ordovician
Silurian
Devonian
Carboniferous
Permian
~ 490 mya
~ 440 mya
~ 420 mya
~ 350 mya
~ 290 mya
~ 250 mya
Meso
zoic
~ 205 myaTriassic
Jurassic
Cretaceous~ 145 mya
Cen
ozo
ic
~ 65 mya
~ 5 myaTertiary
QuaternaryPresent
Diversification of fish (~ 420 mya)
First amphibians (~ 370 mya)
First reptiles (~ 300 mya)
Diversification of mammals and birds (~ 57 mya)
Age of Dinosaurs
Introduction to Vertebrates
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Earth History Critical for Understanding Natural History of Vertebrates:Continued continental drift strong influence on vertebrate evolution:
Introduction to Vertebrates
• Location of land masses (Mesozoic = tropical / Cenozoic = temperate)
• Ocean circulation (e.g., arctic ocean isolated = lack of warm currents)
• Sea level (epicontinental seas = maritime climate inland)
1) Climate:
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Western InteriorSea
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Earth History Critical for Understanding Natural History of Vertebrates:
2) Land Bridges
1) Climate:• Location of land masses (Mesozoic = tropical / Cenozoic = temperate)
• Ocean circulation (e.g., arctic ocean isolated = lack of warm currents)
• Sea level (epicontinental seas = maritime climate inland)
Marsupial Migration
Bering Land Bridge(e.g., human migration)
Introduction to Vertebrates
• Connections of land between continents (attach / detach)
Continued continental drift strong influence on vertebrate evolution:
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Earth History Critical for Understanding Natural History of Vertebrates:
ERA
Precambrian~ 4,600 mya
~ 540 mya
PERIOD
Pale
ozo
ic
Cambrian
Ordovician
Silurian
Devonian
Carboniferous
Permian
~ 490 mya
~ 440 mya
~ 420 mya
~ 350 mya
~ 290 mya
~ 250 mya
Meso
zoic
~ 205 myaTriassic
Jurassic
Cretaceous~ 145 mya
Cen
ozo
ic
~ 65 mya
~ 5 myaTertiary
QuaternaryPresent History of life punctuated by mass extinctions:
MassExtinction
ExtensiveDiversification
Introduction to Vertebrates
• 90% marine species
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• Massive volcanic eruptions in Siberia (lava flows = ½ area of United States)
Permian Mass Extinction
Underwater Methyl hydrate melting
Methane release
PositiveFeedback
Global environment disrupted (100,000’s years)
• Gas release = Global warming (~ 6º C)
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Earth History Critical for Understanding Natural History of Vertebrates:
ERA
Precambrian~ 4,600 mya
~ 540 mya
PERIOD
Pale
ozo
ic
Cambrian
Ordovician
Silurian
Devonian
Carboniferous
Permian
~ 490 mya
~ 440 mya
~ 420 mya
~ 350 mya
~ 290 mya
~ 250 mya
Meso
zoic
~ 205 myaTriassic
Jurassic
Cretaceous~ 145 mya
Cen
ozo
ic
~ 65 mya
~ 5 myaTertiary
QuaternaryPresent History of life punctuated by mass extinctions:
MassExtinction
ExtensiveDiversification
• 90% marine species
• 50% marine species; dinosaurs
Introduction to Vertebrates
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• Massive volcanic eruptions in Siberia (lava flows = ½ area of United States)
• Gas release = Global warming (~ 6º C)
Permian Mass Extinction
Underwater hydrate melting
Methane release
Global environment disrupted (100,000’s years)
The K - T Meteorite:
If a 10km diameter object impacted at the point at which it struck it would have a velocity of roughly 100,000 km/h. At this velocity there would have been an initial blast which would have destroyed everything within a radius of between 400 and 500 km. At the same time large fires would have been started by the intense shock wave which would have traveled long distances. Trillions of tons of debris (dust, gases and water vapour) would have been thrown into the atmosphere when the object vaporized. Many enormous tidal waves would be started. Along with the tidal waves the blast would also start a chain reaction of earthquakes and volcanic activity. There would have also been very high winds caused by the blast. In the days and weeks following the impact the cloud of debris would have been carried over large distances by the post blast high winds. This will have caused months of darkness and a decrease in global temperatures. After this there would have been an increase in temperatures caused by the large amounts of CO2 released by what would have been global fires. Eventually this would cause chemical reactions that would result in the formation of acid rains.
“A dinosaur’s worst nightmare…”
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Early vertebrates believed to have evolved in marine environment:
• Earliest vertebrate fossils located in marine sediment• All non-vertebrate chordates / other deuterostomes exclusively marine
1st Vertebrates(early Cambrian period)
Gnathostomes (“jawed mouth”)(mid Ordovician period)
Ag
nath
an
s (“
jaw
less
” ve
rteb
rate
s)
Retains primitive vertebrate features (e.g., [body fluid] similar to [seawater])
Hagfish (Myxinoidea)(Carboniferous* period)
Life History:• Entirely marine• Bottom-dwelling scavengers
Morphology:• Round, jawless mouth• Elongated, scale-less• Degenerate eyes; tentacles
Introduction to Vertebrates
• Slime glands (flanks)
• Anti-predator (gels H2O)
Feed via tearingoff tidbits…
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Yummmm…
Introduction to Vertebrates
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Early vertebrates believed to have evolved in marine environment:
• Earliest vertebrate fossils located in marine sediment• All non-vertebrate chordates / other deuterostomes exclusively marine
1st Vertebrates(early Cambrian period)
Gnathostomes (“jawed mouth”)(mid Ordovician period)
Ag
nath
an
s (“
jaw
less
” ve
rteb
rate
s)
Retains primitive vertebrate features (e.g., [body fluid] similar to [seawater])
Table 3.1 – Vertebrate Life
Hagfish (Myxinoidea)(Carboniferous* period)
Life History:• Entirely marine• Bottom-dwelling scavengers
Harvested for skin (“eel-skin” leather)
Morphology:• Round, jawless mouth• Elongated, scale-less
• Cartilaginous skeleton• Lack vertebrae
Feed via tearingoff tidbits…
Morphology:• Round, jawless mouth• Elongated, scale-less• Degenerate eyes; tentacles
• Slime glands (flanks)
• Anti-predator (gels H2O)
Introduction to Vertebrates
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Early vertebrates believed to have evolved in marine environment:
• Earliest vertebrate fossils located in marine sediment• All non-vertebrate chordates / other deuterostomes exclusively marine
1st Vertebrates(early Cambrian period)
Gnathostomes (“jawed mouth”)(mid Ordovician period)
Ag
nath
an
s (“
jaw
less
” ve
rteb
rate
s)
Hagfish (Myxinoidea)(Carboniferous* period)
Lamprey (Petromyzontoidea)(Carboniferous* period)
Life History:• Marine / Freshwater (anadromous)
• Parasites (fluid-feeders)
Introduction to Vertebrates
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Early vertebrates believed to have evolved in marine environment:
• Earliest vertebrate fossils located in marine sediment• All non-vertebrate chordates / other deuterostomes exclusively marine
1st Vertebrates(early Cambrian period)
Gnathostomes (“jawed mouth”)(mid Ordovician period)
Ag
nath
an
s (“
jaw
less
” ve
rteb
rate
s)
Hagfish (Myxinoidea)(Carboniferous* period)
Lamprey (Petromyzontoidea)(Carboniferous* period)
Morphology:• Round, jawless mouth• Elongated, scale-less• Cartilaginous skeleton
• Vertebral elements presentLife History:
• Marine / Freshwater (anadromous)
• Parasites (fluid-feeders)
Devastated Great Lakes fisheries
Introduction to Vertebrates
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Derived Features of Gnathostomes:
• Derived from anterior branchial arches (gill supports)
1) Jaws:
2) Paired Appendages:• Benefits: 1) Control of body position (primarily pitch) in water (active, predatory fish…)
2) Defense (spines); Behavior (e.g., reproductive)
Suspension feeders / Parasites
Raptorial feeders
Expansion of pharynx;Mouth closure to prevent food escape
• Benefits: 1) New feeding behaviors (e.g., grasping / biting / tearing)
Introduction to Vertebrates
Stonefish
2) New food resources (e.g. herbivory)
3) Manipulation of environment (e.g., digging holes / carrying objects)
4) Improved gill ventilation (primary driving force?)
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Gnathostomes (“jawed mouth”)(mid Ordovician period)
Tetrapods (“jawed mouth”)(late Devonian period)
Introduction to Vertebrates
Early vertebrates believed to have evolved in marine environment:
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Early vertebrates believed to have evolved in marine environment:
Gnathostomes (“jawed mouth”)(mid Ordovician period)
Tetrapods (“jawed mouth”)(late Devonian period)
Chondricthyes (“Cartilage fish”)(late Silurian period)
Life History:• Primarily marine• Suspension feeders / carnivores• Internal fertilization
Morphology:• Cartilaginous endoskeleton (derived)
• Scales (Placoid)
• Well developed jaws / paired fins
1) Sharks
Introduction to Vertebrates
• Fusiform (powerful; maneuverability)
• Acute vision / smell
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Early vertebrates believed to have evolved in marine environment:
Gnathostomes (“jawed mouth”)(mid Ordovician period)
Tetrapods (“jawed mouth”)(late Devonian period)
Chondricthyes (“Cartilage fish”)(late Silurian period)
Life History:• Primarily marine• Suspension feeders / carnivores• Internal fertilization
Morphology:• Cartilaginous endoskeleton (derived)
• Scales (Placoid)
• Well developed jaws / paired fins
2) Skates / Rays• Flattened, bottom dwellers
• Enlarged pectoral fins (“fly” through H2O)
Skate Ray
Introduction to Vertebrates
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Early vertebrates believed to have evolved in marine environment:
Gnathostomes (“jawed mouth”)(mid Ordovician period)
Tetrapods (“jawed mouth”)(late Devonian period)
Chondricthyes (“Cartilage fish”)(late Silurian period)
Life History:• Primarily marine• Suspension feeders / carnivores• Internal fertilization
Morphology:• Cartilaginous endoskeleton (derived)
• Scales (Placoid)
• Well developed jaws / paired fins
3) Ratfish (Chimera)• Deep water dwellers• Little known of natural history
Introduction to Vertebrates
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Early vertebrates believed to have evolved in marine environment:
Gnathostomes (“jawed mouth”)(mid Ordovician period)
Tetrapods (“jawed mouth”)(late Devonian period)
Chondricthyes (“Cartilage fish”)(late Silurian period)
Osteichthyes (“Bony fish”)(late Silurian period)
Introduction to Vertebrates
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Early vertebrates believed to have evolved in marine environment:
Gnathostomes (“jawed mouth”)(mid Ordovician period)
Tetrapods (“jawed mouth”)(late Devonian period)
Osteichthyes (“Bony fish”)(late Silurian period)
Life History:• Marine / Freshwater• Diverse feeding strategies• External / Internal fertilization
Most diverse vertebrategroup (~ 30,000 species)
Morphology:• Ossified endoskeleton (Calcium phosphate)
• Flattened, bony scales• Mucus glands (drag reduction / protection)
• Operculum (gill covering – stationary breathing)
• Swim bladder (motionless buoyancy)
1) Ray-finned Fish (actinopterygii)• Fins supported by flexible rods
• Increased maneuverability
1) Lobe-finned Fish (Sarcopterygii)• Fleshy fins supported by bone
• “Walking” underwater
Introduction to Vertebrates
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Demands of terrestrial life different than aquatic life…
Introduction to Vertebrates
1) Density: H2O is 800x denser than air (Ramification = support systems)
Fish:
• Remain neutrally buoyant (same density as H2O)
A) Swim bladder (Bony fish)
B) Store oils in liver (cartilaginous fish)
C) Store oils / lipids in swim bladder / body (Deep sea fishes)
Terrestrial Vertebrates:
1) Bones designed for strength (compact bone) and weight (spongy bone)
2) Axial skeleton modifications (fish = flexibility)
• Vertebral processes (zygaphophyses) resist twisting & bending
• Distinct vertebral regions (e.g., lumbar = support vertebrae) • Ribs stout and prominently developed
3) Axial muscles differentiated and enlarged (postural support)
4) Limb girdles enlarged; limb location shifted (e.g., under body)
• Require modified skeleton / musculature (counter gravity)
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Demands of terrestrial life different than aquatic life…
Introduction to Vertebrates
Fish:
2) Viscosity: H2O has 18x viscosity of air (Ramification = locomotion)
• Have stream-lined shape (minimize drag)
• Small scales / loss of scales; mucus production• Utilize undulations of body / tail to “push” against viscous water
1) Anguilliform
Majority of body undulates
2) Carangiform
Caudal region undulates
3) Ostraciiform
Caudal fin undulates
Paired fins used for steering, braking, and providing lift
• Friction must be generated between limbs and ground:• Primitive mode = axial flexion with limbs acting as holdfasts
• Lateral Sequence Gait: 3 of 4 limbs in contact with ground (tripod)
Terrestrial Vertebrates:
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Demands of terrestrial life different than aquatic life…
Introduction to Vertebrates
2) Viscosity: H2O has 18x viscosity of air (Ramification = locomotion)
• Friction must be generated between limbs and ground:• Derived mode = limbs held underneath body (limb flexion)
Avoid tangling of long limbs
Keeps line of supportunder center of gravity
Excellent stability;Excellent clearance
Amble / Pace
Fore- and hind feet on sameside swung in unison
Trot
Feet diagonally oppositemove in unison
Bound
All four limbs strike ground in unison
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Demands of terrestrial life different than aquatic life…
Introduction to Vertebrates
2) Viscosity: H2O has 18x viscosity of air (Ramification = locomotion)
• Friction must be generated between limbs and ground:• Derived mode = limbs held underneath body (limb flexion)
Ricochet
Two limbs strike groundin unison
Gallop / Canter
Fore / hind feet show lead / trail pattern
(asymmetrical)
Half Bound
Hind legs strike
together;forelegs = lead / trail
pattern
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Demands of terrestrial life different than aquatic life…
Introduction to Vertebrates
3) Oxygen Content: H2O contains ¼ [O2] of air (Ramification = respiratory systems)
Fish:
• Lungs / Accessory Structures: ([O2] very low)
• Facultative Air Breathers = supplement gills as necessary• Obligatory Air Breathers = must supplement gills or drown
• Gills: Specialized respiratory structures for capturing O2
Flow of water unidirectional(viscosity issues…)
• Buccal Pumping• Ram Ventilation
Counter-current exchange ( efficiency)
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Demands of terrestrial life different than aquatic life…
Introduction to Vertebrates
3) Oxygen Content: H2O contains ¼ [O2] of air (Ramification = respiratory systems)
• Air easier medium for respiration than water:
1) Low density / low viscosity = energetically feasible tidal ventilation
2) High [O2] = reduced volume of air needed to supply O2
• Ventilation strategies:
1) Positive Pressure: Air “swallowed”; pushed into lungs (shrink oral cavity)
Terrestrial Vertebrates:
2) Negative Pressure: Thoracic cavity expanded; air “pulled” into lungs
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Sensory Systems:
B
ATetrapod
Fish
Vision Smell / Taste Mechanical
A
A
B
B
Tetrapods cansee further withless distortion
Receptors in head region detect
dissolved / volatilizedchemicals
Lateral lineSystem
AuditorySystem
Left Right
Introduction to Vertebrates
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Introduction to Vertebrates
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Sensory Systems:
Tetrapod
Fish
Vision
B
A
Smell / Taste
B
Mechanical
A
AB
Tetrapods canSee further withless distortion
Receptors in head region detect
dissolved / volatilizedchemicals
Rely on hair cellsto detect vibrations
in water / air
Electroreception
A
D
Water conductselectricity – air
does not
Function:Prey Location
Mate Identification
Introduction to Vertebrates
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Origin and Radiation of Tetrapods:
Stem Tetrapod (“four limbs”)(late devonian period)
• Related to lobe-finned fish (sarcopterygians – lung fish)• Anatomy suggests that early tetrapods were aquatic (e.g., internal, fish-like gills)
How does a terrestrial animal evolve in water?
Thoughts of foresight not an option!
Acanthostega Ichthyostega
Introduction to Vertebrates
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Origin and Radiation of Tetrapods:
Stem Tetrapod (“four limbs”)(late devonian period)
• Related to lobe-finned fish (sarcopterygians – lung fish)• Anatomy suggests that early tetrapods were aquatic (e.g., internal, fish-like gills)
How does a terrestrial animal evolve in water?
Classic Theory:
MigrationDries up
Problems: 1) Current lung fish cope with problem by estivating
2) New pond = continuation in aquatic lifestyle
Current Theory = Juvenile lob-finned fish aggregated in shallow-water habitats• Limbs with digits / ankle / wrists = navigation / manipulation of bottom vegetation
• Strengthening of girdles = predatory lunges under water• Development of distinct neck = lift snout out of water
Acanthostega Ichthyostega
Introduction to Vertebrates
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Origin and Radiation of Tetrapods:
Stem Tetrapod (“four limbs”)(late devonian period)
Batrachomorphs (“Frog form”) Reptilomorph (“Reptile form”)
(V) Table 9.1
Pages 206 - 211
Lissamphibians (extant amphibians)
Lepospondyl
Anthracosaur(Terrestrial)
Temnospondyl(aquatic)
??
??
Majority extinct by mid Persian
Amniotes(early Carboniferous period) (major radiation = Permian)
Introduction to Vertebrates
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