natural history of (terrestrial) vertebrates chapter # 1 – the diversity, classification, and...

Natural History of (Terrestrial) Vertebrates

Chapter #1 – The Diversity, Classification, and Evolution of

Vertebrates

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)

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


Classification ofVertebrates:

• 57,000 species (100x extinct)

• New discoveries weekly


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)


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


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:


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


• 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


Continents beginningto drift together

Gondwana(south pole)

Laurasia:Laurentia + Baltica + Siberia

(along equator)

Climate:


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



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




~ 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


Earth History Critical for Understanding Natural History of Vertebrates:Continued continental drift strong influence on vertebrate evolution:


• 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:

Western InteriorSea


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)


• Connections of land between continents (attach / detach)

Continued continental drift strong influence on vertebrate evolution:


ERA


~ 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

• 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)


ERA


~ 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


• 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…”

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


• Slime glands (flanks)

• Anti-predator (gels H2O)

Feed via tearingoff tidbits…

Yummmm…






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


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)






Ag

nath

an

s (“

jaw

less

” ve

rteb

rate

s)


Lamprey (Petromyzontoidea)(Carboniferous* period)

Life History:• Marine / Freshwater (anadromous)

• Parasites (fluid-feeders)






Ag

nath

an

s (“

jaw

less

” ve

rteb

rate

s)


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


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)


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?)


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


• Fusiform (powerful; maneuverability)

• Acute vision / smell









2) Skates / Rays• Flattened, bottom dwellers

• Enlarged pectoral fins (“fly” through H2O)

Skate Ray










3) Ratfish (Chimera)• Deep water dwellers• Little known of natural history






Osteichthyes (“Bony fish”)(late Silurian 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


Demands of terrestrial life different than aquatic life…


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)



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)





• 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




• 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



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)



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)


2) Negative Pressure: Thoracic cavity expanded; air “pulled” into lungs

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


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


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




• 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




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)


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natural history of (terrestrial) vertebrates chapter # 1 – the diversity, classification, and...

Documents

mya mesozoic

mya cenozoic

classification of vertebrates

evolution of vertebrates

natural history of vertebrates

sea levels

paleozoic world

deep sea