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208 Cards in this Set

  • Front
  • Back

What is the oldest authenticated bird?

Archaeopteryx lithographica

Skeleton first found in 1861

Approximate, what percentage of rocks can preserve fossils?


What percentage of fossils are of aquatic origin?


What is the name of our current eon and when did it begin?

the Phanerozoic eon and it began with the Cambrian, around 540 million years ago - it was the origins of hard bodied invertebrates.

Who developed phylogenetic systematics, also known as cladistics?

Wili Hennig in the 1960s


The same organ...under a variety of form and function.

Evidence of a common ancestry.


A part or organ that has the same form or function.

Evidence of convergent evolution to a similar form, fromdissimilar ancestry.

Hennig's influential ideas.

1. A definition of relationship, using recency of common ancestry.

2. A method of detecting relationship, using shared, derived characters.

3. A method of depicting relationships (dichotomous, branching diagrams = cladograms).

4. A clear research program (the hunt for the sister group).

Ray-finned fish


Lobe-finned fish


Cartilaginous fish



The formation of the eye, ear, olfactory organs and lateral line during embryonic development, as well as associated sensory neurons.

The neural crests.

Specialized migratory cells that contribute to a diversity of different cell types.

Brain elaboration

Forebrain, midbrain and hindbrain.

Vertebrate innovations - Mineralised tissues.

Most vertebrates have three skeletons:

1. Craniofacial - neural crest-derived

2. Axial - formed from the somites

3. Appendicular - formed from lateral plate mesoderm

How are vertebrates distinguished from the invertebrate relatives?

Through innovations linked to the evolution of a predatory lifestyle.

What characterizes vertebrate evolution?

A decrease in armor, increase in mobility and the change from a cartilaginous to a bony skeleton.

What percentage of vertebrates are fish?

About half.

Crown group

Consists of the last common ancestor of all living forms in the phylum and all of its descendants.

Stem group

Consists of a series of extinct organisms leading up to the crown group, away from the last common ancestor of this phylum and the most closely related phylum.

E.g. Dinosaurs are stem birds

What are Agnathans?

Jawless fish

Myxiniformes - Hagfish

Elongate, no paired fins, cartilaginous skeleton.

"Teeth" composed of Keratin.

Body fluids iso-osmotic with water.

78 species.

Marine scavengers.

Produce slime - probably defensive.

Petromyzontiformes - Lampreys

Elongate, no paired fins, cartilaginous skeleton.

Filter feeding larvae (ammocoete).

Parasitic or non parasitic.


First known from Ordovician, around 480 million years ago.

Externally armored with bony plates.

Plates show evidence of sensory canals and gill openings.

Fresh water species, probably could osmoregulate.

Jawless, but some had bony mouth plates.

Typically heterocercal caudal fin.

Origins of paired fins, but only pectoral.

What are jawed fish called?


What is so good about jaws?

Active predation - can capture food and bite.

Manipulate food - improves digestion.

Herbivory - grazing becomes possible.

Mating - nest building, mate grasping, mouth brooding.

Improved gill ventilation (forceful).

Where do jaws originate from?

The first gill arch.


Early Silurian - 440 million years ago.

Pectoral and pelvic fins.



Head-trunk joint.

Primarily benthic.


1. Holocephalii

- Chimeras, ratfish,

- Deep-water, few species.

2. Elasmobranchii

- Sharks, skates and rays

- Widespread, >500 species.

Hyostylic jaw suspension.

Osteichthyes - Bony fish

1. Actinopterygii

- Around 26,000 species,

- Teleosts are the most diverse group.

2. Sarcopterygii

- Around 8 species, excluding tetrapods.

- Lungfish and Coelacanths


Generally more active, fast swimmers.

Radiation began in the Cretaceous.

Around 96% of all "fish".

But majority of diversity in two main groups:

1. Ostariophysi

2. Acanthopterygii

Teleost feeding

Ram feeding - Mackerel, herring.

Suction feeding - evolved independently in several lineages. Jaw bones are pushed forwards and the buccal cavity expands.

Fish movement

Typically, fish swimming depends on the oscillation of a flexible body with a fin at one end.

Main body muscles are arranged as segments (myotomes).

Blocks separated by myosepta.

Fish muscles

Myotomes lie alongside a flexible but incompressible column - the vertebral column.

The myosepta focus the contractile force to the vertebral column (and the skin) and away from neighboring blocks.

The skin may also store elastic energy.

Bulk of myotome (and therefore a large amount of muscle mass) is set aside for occasional use.

Muscle and lifestyle

Amount and distribution of fibres can provide insights to lifestyle.

Red fish - lots of cruising

White fish - sluggish, ambush predators.

Roughly how much heat loss occurs at gills?


Retia mirabilia

Complexes of closely associated arteries and veins.

Cruising speed is generally unaffected, but bursts of speed much faster.

Can extend range, able to cruise into cooler waters.

What is a carangiform motion?

Swim by undulating mainly their caudal fin.

What is a anguilliform motion?

Swim by undulating their whole body.

Ostraciiform motion.

Body rigid

Tail oscillates

Rajiform motion

Vertical undulations along large pectoral fins (e.g. rays).

Total drag is the sum of...

1. Pressure drag - pressure at the nose is greater than at the tail due to velocity.

2. Skin friction.

Methods of reducing skin friction.

1. Reduction of wetted area (utilizing finlets, cut away caudal fins and collapsible fins).

2. Boundary layer control (turbulence at the body-water later can affect drag).

3. Mucus, long chain polymers at the boundary layer.

Dynamic lift

Fins exert downwards force on the water.

Have to keep swimming.

No hovering.

No swimming backwards.

Static lift.

Gas or oil swim bladders

typically 5-7% of body

Physostome gas bladder

Arises from diverticulum in roof of foregut. Adult retains pneumatic gut.

Fills by gulping air.

Empties by burping.

Physoclist gas bladder

Young may have open duct, adults are closed with secreting gas gland and re-absorption gland.

Gas comes from oxygen in water, passed via blood.

Production of gas

Specialized region called the gas gland produces lactic acid and carbon dioxide.

Lowering the pH causes haemoglobin to lose oxygen.

Countercurrent multiplication system raises the partial pressure of gases.


Antarctic ice fish

inhabits water -2 - 4 degrees C

Reduced bone density and lipid storage for buoyancy

Little hemoglobin


Low oxygen in water so a large surface area is required for gas exchange.

Viscosity of water means that unidirectional flow is the most energy efficient.


Oldest method is buccal pumping.

Gill arches

Derived from pharyngeal arches during embryonic development.

Typically for filter or suspension feeders.

Gill rakers

Mechanical sieving:

Gill rakers cause a vortex to form in the roof of the mouth, food particles accumulate and get stuck to mucus lining the mouth.

Mucus and food then swallowed.

Hydrosol filtration

Mucus covering the rakers acts as a filter, the gaps between rakers allows water to pass through.

Crossflow filtration

Only liquid is drawn though, particles moved along.

Osmoregulation - marine teleosts

Ionic concentrations of the blood lower than the surrounding water.

Drink large volumes to replace lost water.

Solving the salt problem.

Chloride cells (mitochondria-rich cells) in thegills

Osmoregulation - freshwater teleosts

Ionic concentration of blood higher than thesurrounding water

– Produce large amounts of dilute urine (saltsreabsorbed by the kidney)

– Gills take up salts

Osmoregulation - chondrichthyes

Blood contains high amounts of urea (CH4N2O)

– Urea + ions creates blood of similarosmolarity to seawater

– Kidney and gills act to conserve urea


Absorbs around 76% of the water…

…but 99% of the Na+ and 96% of the Cl-

• Between 8-17% of resting metabolic rateis dedicated to pumping ions

Gills summary

Gas exchange, osmoregulation

– Feeding (gill rakers, teeth, extra jaws)

– Locomotion (ram ventilation and dragreduction)

– Adaptability (evolution of jaws, operculum,later modifications in tetrapods)

Locomotion summary

Muscles (myotomes, myosepta), backbone

– Fins – median and paired, rays and lobes,limbs

– Lift (gas, oil) and drag reduction

– Respiration (gills, swim bladders, lungs),ram ventilation

– Senses, heads and tails, predation

Feeding summary

Jaws and teeth, gill rakers, pharyngealjaws, suction feeding

– Senses, camouflage

– Swimming, directionality

– Defense

– predator detection, armour,defensive structures/behaviour

Fish take home messages

Gills have a diversity of roles

– gas exchange,feeding, osmoregulation

• Gas exchange depends on a unidirectional flowof water and countercurrent exchangemechanism

• Gills are ventilated by buccal pumping or ramventilation

• Freshwater and marine species have to contendwith different osmoregulatory problems


Newts and salamnders




Frogs and toads








Snakes, lizards and amphisbaenians

What is the sacrum?

A large wedge shaped vertebra at the inferior end of the spine (forms the solid base of the spinal column made up of fused sacral vertebrae)

Adults that retain larval gill forms are?


What are melanophores?

The deepest level of chromatophores

What are guanophores?

Intermediate level of chromatophores that contains many granules and produce blue-green colors.

What are lipophores?

Produce yellow colours and make up the most superficial layer.

Scales are made from?

Keratin, from the epidermis.

What are the bony plates that underlay reptile scales?


What is the armor of crocs and turtles made from?

The dermis layer (deeper than epidermis and not homologous to squamate scales).

Properly called scutes.

What is the purpose of the mucus secreted onto an amphibians skin?

To protect it from desiccation when on land.

To maintain salt and water balance in the internal organs when submerged.

Amphibian eggs are 'non-cleidoic' what does this mean?

They are not closed.

What is the order of structures in an amphibian egg?

Jelly capsule

Vitelline membrane

Perivitelline fluid

Yolk plug


What is the function of the jelly capsule?

Protects the embryo from the outside environment and prevents the egg from drying out.

What does the vitelline membrane do?

Surrounds the egg and upon fertilization it splits off from the surface of the egg and the space is filled with perivitelline fluid.

What does the perivitelline fluid do?

Surrounds the embryo and yolk plug.

What are 3 ways the primitive mode of amphibian reproduction can be modified?

1. Loss of larval stage (e.g. Whistling frog - E. martinicensis).

2. Loss of adult stage (neoteny or paedomorphis) - almost exclusively in salamanders, e.g. Axolotl.

3. Addition of a non-reproductive terrestrial stage in North American Notophthalmus.

What are the 3 main modes of amphibian reproduction?

1. Aquatic egg

2. Egg laid on land

3. Eggs retained within the female

MoR: Aquatic eggs - what is an example of an amphibian that lays its eggs in still freshwater?

Leopard frog (Rana sphenocephala)

MoR: Aquatic eggs - what is an example of an amphibian that lays eggs in brackish water?

Green toad (Bufo viridis)

MoR: Aquatic eggs - what is an example of an amphibian that lays eggs in flowing water?

Tailed frog (Ascaphus)

MoR: Aquatic eggs - where does the Trinidad golden tree frog lay its eggs?

In small collections of water. Bromeliad tanks.

MoR: Eggs on land - Caribbean whistling tree frogs (Eleutherodactylus sp.)

Under stones or other cover: nutrition provided by yolk.

MoR: Eggs on land - Salamander , Desmognathus sp.

Under stones or other cover: tadpoles make their own way to water.

Or develop on land (non-feeding) or direct development.

MoR: Eggs on land - what is an example of an amphibian that uses a foam nest over water?

Asian brown tree frog (Polypedates leucomystax)

MoR: Eggs on land - what is an example of an amphibian that uses foam nests in burrows?


The hourglass tree frog can...

Lay eggs both on land and in water

MoR: Eggs in oviducts. Ovoviviparous means...

Nutrition provided by yolk (e.g. some salamanders, a few anurans).

MoR: Eggs in oviducts. Viviparous means...

Nutrition provided by oviducal secretions (e.g. African toad, Nectophrynoides sp.).

Specialized lining of oviduct (matrotrophy) in some caecilians with special teeth that are shed after birth.

What were the two innovations that allowed reptiles to reproduce on land?

Amniotic egg and penis.

The heavily mineralised, hard shell (95% Ca) is a shared characteristic of who?

The archosaurs

In squamates a hatchling possesses what?

An egg tooth.

A horny caruncle is a feature of hatchling...

Turtles, sphenodon, crocs, birds and monotremes.

What does the amnion do?

Surrounds the embryo and creates a fluid filled vanities in which the embryo develops.

What does the chorion do?

Forms a protective membrane around the egg, adheres closely to the shell and provides for gas exchange.

What is the allantois?

It is closely applied against the chorion where it performs gas exchange and stores metabolic waste. Develops into a large sac which becomes the urinary bladder in the adult.

Nightjars (Caprimulgiformes?)

Are crepuscular to night time hunters.

Large eyes and visual predators.

Only avian hibernator.

Lunar cycle - usually only feeds at dawn and dusk (around 1 hour) but during full moon will feed during middle of night.

Oilbirds (Steatornis caripensis)

Most sensitive eyes in bird world.

Named by Alexander Humboldt (1799).

Light gathering power of f=1.07 with 9 mm pupil on only 16 mm deep eye.

Small rods in 3 tier design.

1,000,000 rods per mm2 (highest in vertebrates).

Sensitive but low resolution so echolocation used to detect large objects and olfactory senses are important.

Eats palm nuts and figs by hawking.

Hummingbirds (Apodiformes)

Important plant pollinators.

Trochilinis (90%) & Topaz and Hermits.

Hermits use male leks and heliconia flowers.






Wing-beats between 15 & 80 Hz.

Breathing rate 300-500 bpm.

50% of body mass in nectar per day.

Smallest = bee hummingbird <2 g.

Wings give lift on upstroke.

Water intake 160% of body mass.

Needs dilute urine and 10% salt intake per day.

Commonly use torpor.

Aggressive & resource territorial.

Head can shake at 34 g and dive at 9 g.

Hummingbird breeding

Serially polygamous.

Females do all the work.

Lay 2 eggs.

Hatch blind and naked.

Long nesting period (23-40 days).

Cuckoos (Cuculiformes)

Zygodactly feet.

Very diverse.

57 sp. in 2 sub-families parasites to warblers and crows.

European cuckoo takes 10 secs to deposit egg.

Mimics host egg (region specific), gape and call.

Short incubation (11 days shortest).

Ejects host eggs.

Induces equivalent feeding rate of 3-4 host young.

Hoatzin (Cuculiformes)

Foregut 25% of body mass.

Food retained 1-2 days.

Helpers at nest.

Liquids food with microbes.

Juvenile wing claw.

Woodpeckers (Piciformes)

Golden-fronted woodpecker.

8 inch diameter hole, 2 feet deep.

Hits tree 12,000 times a day.

Decelerates at 1200 g.

Needs to protect brain & retina.

Bill muscles contract to take force to base of skull.

Thickened nictitating membrane to protect eye.

Thick spongy skull and cartilage base to bill.

Small brain, little spinal fluid.

Toucans (Piciformes) (Ramphastidae)

Massive bill but hollow and light.

Gives reach to fruit but eats most thing except leaves.

Mainly lowland, warm forests.

Bill heat exchanger.

25-400% of resting heat production.

Respiration (birds)

6-12 air sacs.

Air passes through fine parabronchial tubes and air capillaries in one direction (almost counter current to blood).

What are flight feathers called?


What are tail feathers called?


Body feathers are mostly...

Contour feathers

Reptilian features retained by birds, skull...

Avian skull articulates with first neck vertebra by a single ball and socket - like growth (the occipital condyle) - mammals have 2.

Cervical vertebrae...

birds have 14 mammals have 7.

Kiwi eggs

One of largest eggs for body mass (around 18-25%).

Which were the 'mammal-like' reptiles?

The synapsids (320 mya). Dominant land vertebrates before the dinosaurs.

Neocortex (defining mammal feature)

Part of the cerebral cortex.

Responsible for:

- Sensory perception.

- Generation of motor commands.

- Spacial reasoning.

- Conscious thought.

- Language in humans.

Lactation allows...

Delay in development of teeth.

Less burdening of mother.

Independence from environment resource availability.

Vision in nocturnal mammals

Greater sensitivity.

Larger eyes.

More rods (cones may be absent).

Many to one connection between photoreceptors and interneurones.

DNA in nuclei is packaged differently making them light focusing rather than scattering.

Mirrors add sensitivity.

Sound production in whales

Produced throughout dive despite decreasing air volume with depth.

Sound pressure levels can be independently regulated.

Right nasal passage and/or associated air sacs can form a closed system in which air can be recycled.

Sound production in sperm whales

Spermaceti oil conducts sound at same speed as water.


Flat foot (humans)


Walk on toes (dogs)



Ambulatory mammals

Adapted to walking (amble).

Most primitive.

Mobile joint.

Can rotate hand.

5 digits (opposable thumb/big toe).

Plantigrade to semi-plantigrade posture.

Length of 3 limb segments approximately equal.

e.g. Armadillo, Racoon


Adapted to running.

Elongation of intermediate and distal limb elements.

Extreme digigrade or unguligrade.

Muscle mass concentrates close to body.

Reduction of digits (especially outer ones).

Spinal flexion.

Cursorial adaptations

Crucial change in action of axial skeleton appeared in therapsid lineage.

Shift from lateral to vertical flexion (increase stride length).

Hooves often present.

Restricted mobility at shoulder and hip joints.

Long, thin, vertically positioned scapular.

Loss of clavicle.

Tendons and ligaments act as a spring (increased in size).


Adapted to climbing.

Usually plantigrade.

Long digits on grasping appendages.

Often with elongated claws.

Low centre of gravity.

Shoulder/limb joints very mobile.

Tail long/prehensile.

Which scansorial mammals can hyper invert their hind feet?

Procyonids (racoons) and Sciurids (squirrels).


Arm swinging.

Gibbons, spider monkeys.

Clavicle prominent.

Upright posture.

Bipedal mammals

Humans only habitual non-jumping bipeds.


Vertically orientated pelvis.

Short/absent tails.

Human bipedal adaptations

Short flared pelvis.

Extremely long femur.

Down-turned heel.

Large, elongated pollux (big toe).

Fossorial mammals

Adaptation to burrowing.

Forelimb or teeth digging.

Both have evolved independently many times.

- Old world porcupines.

- Mole rats.

Degree of specialization varies.

Forelimb digging is energetically expensive.

Fossorial burrowing adaptations

- Eyes degenerate.

- Depigmentation.

- Robust skeletons.

- Claws enlarged.

- Tail reduced.

- Wedge shaped skulls, large incisors.

- High oxygen affinity haemoglobin.

Graviportal mammals

Open mixed woodland/savanna.

Evolved in late Eocene but grass not common until Miocene.

Straight column limbs.

Thick limb bones.

Intermediate limb segments are short.

Vertical pelvis.

Ankle & knee joints nearly vertical.

Digigrade or semi-digigrade, short broad digits.

Broad nails or hooves.

Saltatory/Ricochetal mammals


Usually propelled by hind limbs.

Metatarsals usually very long and tibia/fibula fused.

Forelimbs usually short and unspecialized.

Tail acts as counterbalance.

Tridactyl feet for stability and weight support.

Volant/Glissant mammals


Earliest gliding lineage extinct (125 mya).

Gliding evolved independently at least 7 times.

Gliding = energetically cheap and morphologically simple.

Powered flight only once in bats (51 mya).

Flying still energetically more efficient than quadrapedism.

Natatorial mammals.


Streamlining (fusiform).

Short neck & fusion of cervical vertebrae (whales).

Retraction/extension of neck possible in seals.

Forelimbs short & flipper-like or webbed.

Triangular scapular and large muscle attachment point for strong adduction of front limb.

Digits elongated.

Hindlimbs modified, reduced or absent.

Restricted limb joint mobility.

Sea lions: front limb propulsion.

True seals/walruses: sinus side-side motion.

Marine habitats

Fossils show that mammals have re-invaded the sea 7 times (5 still extant).

- Cetacea (Eocene, 56-34 mya).

- Sirenia ( Early Eocene)

- Pinnepedia (late Oligocene, 34-23 mya).

Aquatic adaptations: Respiration

Blowholes, terminal nostrils.

Avoid bends by collapsing lungs during deep dives.

Extensive vasculature in air spaces in head (middle ear, sinus) help equilibrate pressure.

During diving; reduced blood flow to lungs, digestive tract, skeletal muscles & reduced heartbeat.

Very efficient lungs at surface.

Elevated levels of myoglobin in skeletal muscles.

Other aquatic adaptations.

Hair only useful at shallow depths.

Replaced by sub-cutaneous fat (blubber).

Reduction of volume:surface area ratio (increase in size).

Counter-current blood flow.

Arboreal habitat adaptations

Large eyes.

Optical convergence (stereoscopic vision).

- Helps judge distances.

- Relatively large brain size.

Open habitat adaptions

Feeding specializations for herbivory.

Large high-crowned cheek teeth (hypsodonty).

Ever growing teeth (hypselodonty).

High risk of predation:

- Large, lateral eyes.

Good smell.

Defensive structures.


Open habitat thermal adaptations

Behavioral (wallowing).

Morphological ( well-vasculated, large ears, thick skin).

Physiological (water conservation).

Arial habitat adaptations: Gliders

Elongated limbs.

Presence of patagium.

Expanded tail flume.

Dorso-ventral flattening.


Accurate vision.


Best adapted gliders.

Up to 70 m (little height loss).

Excellent vision.

Unique comb-like lower incisors.

Marsupial-like reproduction (2-3 yrs).


Early offshoot to primates.

True flight: Bats

Flexible wings, elastic membranes supported by greatly elongated metacarpal bones.

- over 24 independent joints.

Can beat up to 17/sec.

Great agility.

Active flight using "unsteady" aerodynamics.

More similar to insects than birds.

Echolocation: Bats

Pulses from larynx.

11-212 KHz (mostly 20-60 KHz).

Evolved at least twice.

3 sp. of megabat produce tongue clicks (lingual).

Megabat sister group (horseshoe) produce dominant consistent frequency calls (nasal).

Most microbats produce multiharmonic calls (laryngeal).

Bats: Change in skull orientation for echolocation

Laryngeal - same as non-echolocating bats.

Nasal - nostrils face forward, not mouth.

Bats: Sound reception

Muscular mechanism & neural attenuation avoid "self deafening".

Bony otic separated from skull.

Specialized outer hair cells in organ of corti mechanically amplify sound.



Egg layers.

Lactate but have no nipples.

Reptilian limb orientation.

Ribs on cervical vertebrae.

Lack penis and extended testes.

Bird-like skull.

Unique facial electroreceptor arrays.

Adults lack teeth.

Juveniles have tribosphenic molars.

External ear opening at base of jaw.



Testes descended into scrotal sack.

Bifid penis, posterior to scrotum.

Paired, lateral vaginas.

Cloaca present.

Skeleton very similar to placentals.

Dental formula differs:

- More incisors.

- different number on top and bottom.



Fetus nourished by placenta.

Protected from mother's immune system.

Degree of development from birth varies greatly.



Also known as Subungulata.

A group of animals with broad, flat nails that could be viewed as intermediates between hooves and claws.


Proboscidea (Elephants).

Hyracoidea (Hyrax).

Sirenia (Manatees).

Tetrapod origins: Limbs before terrestriality

Acanthostega, early aquatic tetrapod, 365 mya.


Mostly aquatic.

Retained gills (and lungs).

Forelimbs stronger than hindlimbs.

Vertebral column articulated dorsoventrally, not laterally.

Terrestrial locomotion likely restricted to "push ups".

Why be a tetrapod and stay in the water?

Late Devonian environment:

Development of land plants.

Increased nutrient flow into seas.

Increased microbial activity -> decreased oxygen levels.

Advantageous to breathe atmospheric oxygen.

Post-Devonian trends

Reduction of digit numbers to 5.

Evolution of fully terrestrial forms.

- Diversification of insects in Carboniferous -> food source for terrestrial predators.

Return to fully aquatic life.

Evolution of diverse morhpologies.

Evolution of amniotes.

What was the first evidence for pentadactyl foot?


End of early tetrapod lineages

Most amniotic lineages extinct at end of Permian.

Permian-Triassic mass extinction.

Most severe mass extinction event.

98% of all marine and 70% of terrestrial vertebrates went extinct.

Origin of amniotes

All living tetrapods (except amphibians) are amniotes.

Great majority of Mesozoic tetrapods.

Originated in early Carboniferous -> 20 my after first tetrapods.

First stem amniotes were small, lizard like creatures.

Earliest known amniote reproduction: Viviparous

Mesosauria: aquatic.

Were the earliest amniotes viviparous?


Probably leathery shell, poor fossilization.

Early amniote diversity


Extensive diversity.

First herbivores.

First radiation of major groups;

- Synapsids

- Sauropsids

Two major lineages: Synapsids and Sauropsids

Diverged late carboniferous.

Very soon after origin of amniotes.

Synapsids = 'Mammal-like' reptiles and mammals.

Sauropsids = Diapsids

Why skull fenestration?

Room for muscle bulging.

Addition muscle attachment points.

Lightening of skull.

Trend to increasing fenestration across amniote lineages.

Major Diapsid liineages

Lepidosauria ("scaly lizards"):

Plesiosauria - marine.

Ichthyosauria - marine.

Extant Lepidosauria = mostly terrestrial, squamata & tuatara.

Archosauria ("Ruling lizards"):

Crocodylmorphia - terrestrial, freshwater, marine.

Dinosauria (inc. birds) - terrestrial, flying.

Pterosauria - flying.

Pterosaur adaptations for flight

Wings formed from membrane stretched over arm and extended by 4th finger.

1st-3rd fingers retained as claws.


Tooth loss in later forms.

Lungs developed unidirectional flow.

Pterosaur biology


Diverse ecology, morphology and diet.

Largest ever flying animal (Quetzalcoatlus northropi).

Successful group - persisted for 160 MY.

Dinosaur diversity

Primitively bipedal.

Over 1000 species known.

Major Dino lineages

Ornithischia - "bird-hipped dinosaurs".

Saurischia - "lizard-hipped dinosaurs":

- Sauropoda.

- Theropoda


All herbivores.

Very diverse body forms.

Complex social behaviors (horns, sexual dimorphism, frills etc...).


Two major groups:

Sauropods - quadrupedal, herbivores.

Theropods - Bipedal, carnivores (inc. birds).





Long necks and tails.

Likely gregarious, herd living.

Sauropods - why so big?

Increased digestion of poor quality plant material.

Likely through hind gut fermentation.

Likely interspecific competition -> reaching tall trees.


Bipedal carnivores, includes T. Rex and Velociraptor.

Some later lineages feathered.

Birds descended from withing Theropoda.

Dino social behavior

Displayed extensive parental care.

Use of vocalism and color.

Role for sexual dimorphism.

Evolution of mammals

First mammals evolved in late Triassic.

First Eutherian mammals in Jurassic.

Stayed small until end of Cretaceous.

Early Squamata

Diversification of main lineages since early Jurassic.

Mostly small but...

Giant marine lizards, relatives of Varanid lizards.

Occupied niches of extinct Ichthyosaurs.

Many large snakes.

It was good while it lasted

Dinosaurs and other large Diapsids were highly diverse.

Dominant large vertebrates for >160 my (Mammals 65 my).

What are Therian mammals?

Eutheria (Placental mammals).


Metatherians (Marsupials).


Even-toed Ungulates.







Odd-toed Ungulates.





Indicates sexual selection, has a horny beak. 120 myo.


Four wings.



Chinese fossil, 140 myo.

Toothed, sparrow-like bird.

Advanced and primitive features.

Reduced tail, large sternum (small keel) but still had unfused digits and pelvic bones.

Origin of flight theories

The Cursorial theory (running).

The arboreal theory.

The pouncing proavis model.

Wing assisted incline running.

Concept of sustained and burst power output

Pmax = Maximum anaerobic (burst) power output.

Pms = Maximum aerobic (sustainable) power output.

Flight summary

Low cost of transport.

Speed of flight proportional to square root of wing loading (body mass/wind area).

Angle of flight related to lift to drag ratio.

Long thin wings have a high aspect ratio and high lift to drag ratio.

Liftis result of suction from above, pushing from below and direction of airdownwards.

Fertilization and development: Caecilians

Internal - phallodeum.

Few yolky eggs.

Aquaticeggs and larvae, terrestrial eggs and direct dev.,or retain eggs in oviducts

Fertilization and development: Newts

Internalfertilization with spermatophore in most.

someprimitive groups have external fertilization.

Eggs laid singly or in small groups.

larvae similar to adults in morphology anddiet.

Amnion (simplified).


Allantois (simplified)

Wastes, gas exchange.

Chorion (simplified)

Gas exchange.


•Egg laying,

eggs develop outside mother’sbody, nutrients from yolk.


•Eggs retained by mother untilhatching,

nutrients from yolk sac.


•embryos develop inside mother, derivenutrients directly from mother through placenta (uncommon in reptiles).

Viviparity in Squamates

•Evolved over 100 times independently indifferent lineages

•Variable at low taxonomic levels

•Several species have both oviparous andviviparous populations (e.g., Lacerta vivipara,Leristabougainvillii).

Types of viviparity: Lecithotrophy

Retain shell-less eggs in uterus,very simple placenta and little nutrient uptake from the mother duringpregnancy, embryo sustained mostly or wholly by yolk.

Commonest form, no newstructures or processes. E.g. horned toads and all boas (here red-tailed boa).

Types of viviparity: Placantotrophy

Small eggs, most nutrients areprovided across the complex placenta during development. Relatively rare:caecilians, Therian mammals, skinks (eg Mabuya, Chalcides); involves more complex changes.

Parental care in squamates

•Known in approx. 100 species

•More common and highly developed inegg-laying species; live-bearing species may stay near their young for a fewdays/weeks until they disperse.