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1:​ ​INTRODUCTION

2

2:​ ​HEMICHORDATA

2

2:​ ​CHORDATA

3

3:​ ​EARLY​ ​VERTEBRATES​ ​(PRIMITIVE​ ​FISH)

6

4:​ ​CHONDRICHTHYES

12

5:​ ​OSTEICHTHYES

16

6:​ ​EVOLUTION​ ​OF​ ​THE​ ​TETRAPODS

24

7:​ ​AMPHIBIA

29

8,9&10:​ ​REPTILIA

33

11:​ ​ECTOTHERMY​ ​AND​ ​ENDOTHERMY

33

12,13,14&15:​ ​BIRDS

33

16&17:​ ​MAMMALS

48

18:​ ​HOMININ​ ​EVOLUTION

54

Joanna​ ​Griffith​ ​(2017)

1:​ ​INTRODUCTION
--------------------------------------------------------------------------------------------------------------------------2:​ ​HEMICHORDATA
Used​ ​to​ ​be​ ​a​ ​subphylum​ ​of​ ​the​ ​chordates,​ ​but​ ​molecular​ ​advances​ ​put​ ​them​ ​into​ ​a
phylum​ ​of​ ​their​ ​own
● Acorn​ ​worms​ ​and​ ​pterobranchs
● Very​ ​fragile,​ ​so​ ​difficult​ ​to​ ​study​ ​extensively
● Marine​ ​and​ ​intertidal
● Live​ ​in​ ​tubes​ ​and​ ​burrows
● Feed​ ​using​ ​a​ ​proboscis
● Mostly​ ​gonochoristic​ ​(dioecious)
Body​ ​plan
● Gill​ ​pores
● Dorsal​ ​nerve​ ​cord
○ Links​ ​the​ ​central​ ​nervous​ ​system​ ​(like​ ​the​ ​nerves​ ​inside​ ​the​ ​spines​ ​of
chordates)
● Notochord
○ Not​ ​homologous​ ​with​ ​chordate​ ​notochords
● Buccal​ ​diverticulum
○ The​ ​notochord​ ​is​ ​an​ ​extension​ ​of​ ​the​ ​mouth​ ​cavity
● Open​ ​circulatory​ ​system
● Glomerulus
○ Unique​ ​to​ ​hemichordates
○ Function​ ​is​ ​still​ ​debated,​ ​but​ ​may​ ​be​ ​similar​ ​to​ ​kidneys
■ Fingerlike​ ​projections​ ​extract​ ​metabolic​ ​waste​ ​and​ ​reclaim​ ​essential
nutrients​ ​and​ ​ions
Enteropneusta
● Class​ ​of​ ​hemichordates
● Acorn​ ​worms
● deposit/suspension​ ​feeders
● Both​ ​asexual​ ​and​ ​sexual​ ​reproduction
● Some​ ​species​ ​have​ ​a​ ​tornaria​ ​larva​ ​stage
○ Similar​ ​to​ ​the​ ​bipinnaria​ ​larval​ ​stage​ ​of​ ​echinoderms
○ Free-swimming,​ ​settles​ ​on​ ​the​ ​substrate​ ​to​ ​develop​ ​into​ ​an​ ​adult
Pterobranchia
● Class​ ​of​ ​hemichordates
● Pterobranchs
● Small,​ ​colonial
● Filter​ ​food​ ​particles​ ​from​ ​the​ ​water​ ​using​ ​a​ ​lophophore-like​ ​feeding​ ​structure
● Most​ ​species​ ​reproduce​ ​asexually
--------------------------------------------------------------------------------------------------------------------------●

Joanna​ ​Griffith​ ​(2017)

2:​ ​CHORDATA
Evolution​ ​of​ ​the​ ​chordates
● The​ ​origins​ ​of​ ​chordates​ ​is​ ​still​ ​a​ ​major​ ​unsolved​ ​problem
● Chordates​ ​evolved​ ​from​ ​an​ ​ancestral​ ​deuterostome
○ Developed​ ​a​ ​brain,​ ​skull,​ ​and​ ​paired​ ​sensory​ ​organs
Body​ ​plan
● Notochord
○ Used​ ​for​ ​structural​ ​support
○ Muscles​ ​contract​ ​against​ ​it
● Dorsal​ ​hollow​ ​nerve​ ​cord
○ Runs​ ​the​ ​length​ ​of​ ​the​ ​body
● Post-anal​ ​tail
○ Muscular,​ ​contains​ ​skeletal​ ​elements
○ Used​ ​for​ ​propulsion​ ​in​ ​aquatic​ ​forms
● Pharynx​ ​with​ ​gill​ ​slits
○ Allows​ ​water​ ​entering​ ​the​ ​mouth​ ​to​ ​leave​ ​the​ ​body
○ Lots​ ​of​ ​different​ ​roles
● Cephalisation​ ​(brain)
● Segmented​ ​and​ ​regionally​ ​different
● Bilateral​ ​symmetry
● Ventral​ ​heart,​ ​closed​ ​circulation
○ Blood​ ​flows​ ​from​ ​heart​ ​to​ ​anterior,​ ​ventrally
● Generally​ ​active
● Major​ ​defining​ ​characteristics​ ​of​ ​chordates​ ​may​ ​only​ ​be​ ​present​ ​at​ ​one​ ​stage​ ​of​ ​the
individual’s​ ​life​ ​cycle,​ ​not​ ​necessarily​ ​in​ ​its​ ​adult​ ​form
Urochordata
● Tunicates​ ​(sea​ ​squirts)
○ Name​ ​means​ ​‘tail​ ​chordates’
● About​ ​2000​ ​species
● All​ ​marine
● Most​ ​sessile,​ ​few​ ​free-living
● Mainly​ ​colonial,​ ​few​ ​solitary
● Filter​ ​food​ ​from​ ​water
● Have​ ​a​ ​mucus-secreting​ ​gland​ ​called​ ​an​ ​endostyle
○ Possible​ ​precursor​ ​to​ ​the​ ​thyroid​ ​gland
● Larval​ ​stage​ ​bears​ ​chordate​ ​characteristics
○ Larvae​ ​settle,​ ​release​ ​adhesive,​ ​and​ ​undergo​ ​rapid​ ​metamorphosis
■ Tail​ ​and​ ​notochord​ ​reabsorbed,​ ​outer​ ​layer​ ​of​ ​cuticle​ ​shed,​ ​nervous
system​ ​degenerates,​ ​organs​ ​rotate​ ​90°
● Ascidiacea
○ Found​ ​in​ ​all​ ​oceans,​ ​at​ ​all​ ​depths
○ Can​ ​be​ ​solitary​ ​or​ ​colonial
● Larvacea
○ Solitary
Joanna​ ​Griffith​ ​(2017)

○ Luminescent
○ Planktonic
○ Certain​ ​larval​ ​features​ ​(paedomorphosis)
● Thaliacea
○ Includes​ ​free-floating​ ​salps
■ Make​ ​chains​ ​and​ ​float​ ​through​ ​water
○ Mainly​ ​found​ ​in​ ​tropical/subtropical​ ​waters
○ No​ ​free-swimming​ ​larval​ ​stage
○ Eg
...
​ ​fewest​ ​steps,​ ​fewest​ ​base​ ​changes
■ Distinguishing​ ​homologous​ ​characters​ ​(shared​ ​ancestry)​ ​from
analogous​ ​characters​ ​(similar​ ​function,​ ​but​ ​evolved​ ​independently
Joanna​ ​Griffith​ ​(2017)

Eg
...
​ ​all​ ​have​ ​the​ ​same​ ​“arm”
bones
■ Learning​ ​from​ ​geology,​ ​paleontology,​ ​fossils,​ ​‘living​ ​fossils’,​ ​extant
organisms,​ ​anatomy,​ ​and​ ​comparative​ ​(statistical)​ ​analysis
● Eg
...
​ ​in​ ​Bolivia​ ​and​ ​Australia
■ Eg
...
​ ​a​ ​notochord)
■ Lacked​ ​gills​ ​slits
● May​ ​have​ ​used​ ​diffusion​ ​for​ ​respiration
■ Earliest-known​ ​vertebrates​ ​with​ ​bonelike​ ​structures
● Origin​ ​of​ ​bone​ ​and​ ​mineralised​ ​tissues
○ Made​ ​up​ ​of​ ​CaCO​3​​ ​and​ ​Ca​5​(PO​4​)​3
○ Link​ ​to​ ​Ostracoderm​ ​armour
○ Complex​ ​origin
■ Teeth​ ​evolved​ ​multiple​ ​times
● For​ ​protection,​ ​electroreception,​ ​mineral​ ​storage?
Joanna​ ​Griffith​ ​(2017)

Initially​ ​evolved​ ​as​ ​odontodes
● Toothlike​ ​elements​ ​found​ ​in​ ​skin
● Some​ ​extant​ ​sharks​ ​still​ ​have​ ​them
● Aggregations​ ​of​ ​odontodes​ ​formed​ ​head​ ​shields
○ Ostracoderms
■ Paraphyletic​ ​group
● Contains​ ​fish​ ​with​ ​mineralised​ ​tissues
○ All​ ​extinct,​ ​except​ ​for​ ​more​ ​derived,​ ​extant​ ​Agnathans
■ Most​ ​went​ ​extinct​ ​in​ ​the​ ​late​ ​Devonian,​ ​likely
due​ ​to​ ​the​ ​loss​ ​of​ ​warm,​ ​shallow​ ​coastal​ ​seas
■ Body​ ​plan
● 10-50cm
● Cerebellum
● Two​ ​semi-circular​ ​canals​ ​(“ears”)
● Lacked​ ​jaws,​ ​moveable​ ​mouth​ ​plates​ ​instead
● Midline​ ​dorsal​ ​fins,​ ​some​ ​had​ ​pectoral​ ​fins
○ For​ ​axial​ ​support
● Had​ ​carapaces
■ Filter-feeders,​ ​or​ ​ate​ ​soft-bodied​ ​prey
■ Three​ ​main​ ​groups
● Heterostracans,​ ​Osteostracans,​ ​Anaspids
● Heavily​ ​argued​ ​relationships
○ Some​ ​are​ ​more​ ​derived​ ​than​ ​others
Jawless​ ​to​ ​jaws
○ Agnathans​ ​(jawless)​ ​to​ ​Gnathostomes​ ​(jaws)
○ Major​ ​evolutionary​ ​step
■ Enabled​ ​new​ ​behaviours,​ ​new​ ​use​ ​of​ ​resources,​ ​new​ ​habitats
○ Evolved​ ​jaws​ ​are​ ​homologous​ ​with​ ​branchial​ ​arches​ ​(evolved​ ​from​ ​gill
openings)
■ Primary​ ​ventilatory​ ​function,​ ​helped​ ​to​ ​pump​ ​water​ ​over​ ​the​ ​gills,
increasing​ ​respiratory​ ​efficiency
■ Secondary​ ​feeding​ ​function,​ ​increased​ ​ability​ ​to​ ​grasp​ ​prey
● Increased​ ​jaw​ ​size​ ​=​ ​increased​ ​mouth​ ​size​ ​=​ ​increased​ ​prey
size
○ Agnatha
■ Jawless​ ​fish
■ Body​ ​plan
● Slender,​ ​eel-like​ ​bodies
● Naked​ ​skin,​ ​no​ ​scales
● Cartilaginous​ ​skeleton/cranium
● Persistent​ ​notochord​ ​(not​ ​replaced​ ​by​ ​a​ ​spinal​ ​cord)
● No​ ​vertebrae
● No​ ​jaws
● Distinct​ ​brain
● No​ ​distinct​ ​stomach
● 5-16​ ​pairs​ ​of​ ​gills
■

●

Joanna​ ​Griffith​ ​(2017)

■

■

Myxinoidea​ ​(hagfish)
● About​ ​65​ ​described​ ​species
● All​ ​marine
● colonial/semi-colonial
○ Can​ ​occur​ ​at​ ​high​ ​densities​ ​(eg
...
​ ​coelacanths
● Actinopterygii
○ Ray-finned​ ​fish,​ ​eg
...
​ ​megamouth​ ​sharks,​ ​basking​ ​sharks
○ Live​ ​in​ ​deep,​ ​cold​ ​water
○ Named​ ​for​ ​squalene,​ ​found​ ​in​ ​the​ ​liver
Galeoids
○ About​ ​280​ ​species
○ Eg
...
​ ​lemon​ ​sharks
Viviparous​ ​species
● Produce​ ​live​ ​young​ ​within​ ​the​ ​uterus
○ Nutrition​ ​is​ ​often​ ​through​ ​an​ ​umbilical​ ​cord,​ ​or​ ​the
mother​ ​may​ ​secrete​ ​substances​ ​from​ ​the​ ​walls​ ​of​ ​the
reproductive​ ​tract​ ​(matrotrophy)
■ Eg
...
​ ​the​ ​Rajidae​ ​family​ ​can​ ​generate​ ​weak​ ​electrical​ ​discharges
■ Have​ ​ampullae​ ​of​ ​lorenzini
■ Sexual​ ​dimorphism​ ​present​ ​in​ ​teeth
Holocephali
● Ratfish,​ ​chimaeras​ ​and​ ​ghost​ ​sharks
● About​ ​35​ ​species
● Very​ ​primitive
○ Anatomically​ ​odd​ ​mix
■ Both​ ​shark/ray​ ​and​ ​bony​ ​fish​ ​features
○ Diverged​ ​from​ ​sharks​ ​360​ ​million​ ​years​ ​ago
● Tend​ ​to​ ​live​ ​on​ ​the​ ​ground​ ​in​ ​deep​ ​water
Joanna​ ​Griffith​ ​(2017)

○ Many​ ​have​ ​huge​ ​eyes​ ​to​ ​maximise​ ​light​ ​use
● Autostylic​ ​jaw
○ Upper​ ​jaw​ ​fused​ ​to​ ​cranium
○ Primitive​ ​characteristics
○ Tend​ ​to​ ​have​ ​small​ ​mouths​ ​as​ ​a​ ​result
● Poisonous​ ​spines
● Mixed​ ​diet
○ Mouth​ ​contains​ ​toothy​ ​crushing​ ​plates
● Cephalic​ ​claspers​ ​suggest​ ​internal​ ​fertilisation
● oviparous
Conservation
● Elasmobranchs​ ​have​ ​life​ ​history​ ​characteristics​ ​that​ ​put​ ​them​ ​more​ ​at​ ​risk
○ Long-lived,​ ​slow-growing,​ ​delayed​ ​maturity,​ ​few​ ​young
● Consumption
○ Lamna​ ​catch​ ​has​ ​decreased​ ​from​ ​8060​ ​tons​ ​per​ ​year​ ​to​ ​50-80​ ​tons​ ​per​ ​year,
with​ ​0​ ​tons​ ​caught​ ​in​ ​2010​ ​in​ ​the​ ​EU
■ Suggests​ ​declining​ ​populations
○ Dogfish​ ​consumption​ ​is​ ​unregulated,​ ​resulting​ ​in​ ​populations​ ​decreasing​ ​by
95%
○ Shark​ ​finning
■ Worth​ ​£200​ ​per​ ​kilo,​ ​£70-100​ ​per​ ​bowl​ ​of​ ​soup
■ In​ ​2003,​ ​the​ ​UN​ ​was​ ​asked​ ​to​ ​ban​ ​finning,​ ​but​ ​all​ ​they​ ​could​ ​do​ ​was
introduce​ ​legislation​ ​to​ ​make​ ​finners​ ​land​ ​the​ ​whole​ ​shark​ ​instead​ ​of
throwing​ ​the​ ​de-finned​ ​shark​ ​back
○ There​ ​are​ ​100​ ​million​ ​longline​ ​hooks​ ​in​ ​a​ ​single​ ​fishery
■ In​ ​the​ ​US,​ ​98
...
​ ​deep​ ​sea​ ​fish,​ ​bottom-dwellers,​ ​tuna
● In​ ​the​ ​mid-Devonian,​ ​the​ ​ancestral​ ​group​ ​radiated​ ​into​ ​two​ ​major​ ​clades
○ Sarcopterygii
■ Lobe-finned​ ​fish​ ​(vertebrae​ ​extend​ ​into​ ​the​ ​fin,​ ​creating​ ​leaflike​ ​fins)
○ Actinopterygii
■ Ray-finned​ ​fish​ ​(vertebrae​ ​stop​ ​at​ ​the​ ​base​ ​of​ ​the​ ​fin,​ ​and​ ​then​ ​rays
extending​ ​into​ ​the​ ​fin​ ​create​ ​fanlike​ ​fins)
Body​ ​plan
● Bony​ ​endoskeleton​ ​made​ ​up​ ​of​ ​a​ ​calcium​ ​phosphate​ ​matrix
● Operculum
○ Bony​ ​plate​ ​covering​ ​gills,​ ​with​ ​muscle​ ​attachments​ ​for​ ​pumping​ ​water​ ​over​ ​the
gills
● Gas-filled​ ​pouch​ ​off​ ​the​ ​oesophagus​ ​(lungs,​ ​swimbladder)
● Progressive​ ​specialisation​ ​of​ ​the​ ​jaw,​ ​eg
...
3-0
...
001-0
...
​ ​cod
● Some​ ​species​ ​have​ ​larval​ ​stages​ ​that​ ​then​ ​undergo​ ​metamorphosis
○ Eg
...
​ ​sticklebacks,​ ​salmon
■
■

Joanna​ ​Griffith​ ​(2017)

Varying​ ​degrees​ ​of​ ​parental​ ​care
○ No​ ​care
○ Female​ ​care
■ Eg
...
​ ​seahorses
○ Male​ ​and​ ​female​ ​care
■ Eg
...
​ ​indigo​ ​hamlets
● Some​ ​species​ ​are​ ​sequential​ ​hermaphrodites
○ Protandrous​ ​hermaphroditism
■ Reproduction​ ​is​ ​limited​ ​by​ ​egg​ ​production,​ ​so​ ​all​ ​but​ ​the​ ​male​ ​at​ ​the
top​ ​of​ ​the​ ​social​ ​hierarchy​ ​will​ ​become​ ​female​ ​-​ ​the​ ​most​ ​socially
elevated​ ​male​ ​remains​ ​male​ ​(all​ ​individuals​ ​are​ ​born​ ​male,​ ​become
female​ ​based​ ​on​ ​demand)
■ Eg
...
​ ​Thalassoma​ ​bifasciatum
Neutral​ ​buoyancy​ ​and​ ​the​ ​swimbladder
● Gas-filled​ ​space
● Takes​ ​up​ ​different​ ​volumes​ ​of​ ​space​ ​in​ ​marine​ ​and​ ​freshwater​ ​fish
● Both​ ​marine​ ​and​ ​freshwater​ ​fish​ ​have:
○ Gas​ ​gland
■ Releases​ ​lactic​ ​acid​ ​to​ ​promote​ ​oxygen​ ​release​ ​from​ ​the​ ​swimbladder
○ Rete​ ​mirabile
■ Capillary​ ​network
● Physostomous​ ​fish
○ Have​ ​a​ ​pneumatic​ ​duct
■ Gulp​ ​in​ ​air,​ ​swim​ ​bladder​ ​filled​ ​with​ ​gas
■ Air​ ​is​ ​also​ ​released​ ​through​ ​the​ ​pneumatic​ ​duct
● Physoclistous​ ​fish
○ Don’t​ ​have​ ​a​ ​pneumatic​ ​duct,​ ​have​ ​an​ ​ovale​ ​valve​ ​instead
■ When​ ​it​ ​is​ ​open,​ ​oxygen​ ​moves​ ​into​ ​the​ ​blood
Migration
● Eg
...
​ ​Atlantic​ ​salmon,​ ​Salmo​ ​salar
○ Anadromous:​ ​swim​ ​up​ ​rivers​ ​to​ ​breed
○ Smolts​ ​return​ ​to​ ​the​ ​sea​ ​and​ ​spend​ ​3-4​ ​years​ ​maturing​ ​at​ ​sea​ ​before​ ​returning
to​ ​rivers​ ​to​ ​spawn
○ Iteroparous:​ ​do​ ​not​ ​die​ ​after​ ​spawning
Sarcopterygii
● Lobe-finned​ ​fish​ ​(vertebrae​ ​extend​ ​into​ ​lobe)
● Abundant​ ​in​ ​the​ ​Devonian
● Considered​ ​to​ ​be​ ​the​ ​ancestors​ ​of​ ​the​ ​tetrapods
● Body​ ​plan
○ Early​ ​forms​ ​were​ ​long​ ​and​ ​cylindrical​ ​(like​ ​eels)
○ Bony​ ​axis
○ Fleshy,​ ​paired​ ​fins,​ ​two​ ​dorsal​ ​fins,​ ​epicercal​ ​lobe​ ​on​ ​tail
■ Fins​ ​may​ ​have​ ​become​ ​fused​ ​together​ ​over​ ​time
○ Massive​ ​jaw​ ​muscles,​ ​attached​ ​to​ ​skull
■ Suggests​ ​that​ ​prey​ ​are/were​ ​predominantly​ ​made​ ​up​ ​of​ ​hard​ ​body
parts
○ Contain​ ​cosmine
■ Similar​ ​to​ ​dentine
■ Tends​ ​to​ ​be​ ​associated​ ​with​ ​skull​ ​structure
■ Not​ ​found​ ​in​ ​any​ ​modern​ ​forms,​ ​lost​ ​over​ ​the​ ​course​ ​of​ ​evolution
through​ ​changes​ ​in​ ​the​ ​skull​ ​and​ ​dentition
● Dipnoi
○ Lungfish
○ 6​ ​extant​ ​species
○ Found​ ​in​ ​freshwater​ ​only
○ Body​ ​plan
■ Autostylic​ ​jaws​ ​(attached​ ​to​ ​skull)
■ Durophagous​ ​jaw​ ​muscles
● Adapted​ ​to​ ​eat​ ​hard​ ​prey
■ Lack​ ​premaxillary​ ​and​ ​maxillary​ ​teeth,​ ​have​ ​a​ ​toothy​ ​palate​ ​instead
■ Lack​ ​cosmine
■ Dorsal,​ ​caudal,​ ​and​ ​anal​ ​fins​ ​are​ ​fused
■ Most​ ​lungfish​ ​have​ ​a​ ​lung
● Attached​ ​to​ ​the​ ​back​ ​of​ ​the​ ​pharynx,​ ​no​ ​trachea
● Have​ ​many​ ​air​ ​sacs
● Will​ ​drown​ ​without​ ​air
● Eg
...
​ ​forsteri​ ​exclusively​ ​have​ ​gills,​ ​Protopterus​ ​and
Lepidosiren​ ​have​ ​weak​ ​gills
○ Can​ ​go​ ​into​ ​estivation​ ​is​ ​environmental​ ​conditions​ ​are​ ​bad
■ State​ ​of​ ​torpor,​ ​like​ ​hibernation
■ Produce​ ​a​ ​slimy​ ​“cocoon”​ ​inside​ ​their​ ​burrow
■ Live​ ​off​ ​of​ ​reserves
● Shut​ ​off​ ​metabolism​ ​to​ ​reduce​ ​energy​ ​use
■

Joanna​ ​Griffith​ ​(2017)

■

●

Change​ ​of​ ​waste​ ​products
● Normally​ ​produce​ ​ammonia,​ ​which​ ​is​ ​toxic​ ​but​ ​cheap​ ​to
produce,​ ​and​ ​can​ ​be​ ​flushed​ ​out​ ​with​ ​water
● Produce​ ​urea​ ​in​ ​estivation,​ ​which​ ​is​ ​less​ ​toxic​ ​but​ ​requires
more​ ​energy​ ​to​ ​produce

Actinistia
○ Coelacanths
○ Two​ ​extant​ ​species
○ Originated​ ​in​ ​the​ ​mid​ ​Devonian
■ Thought​ ​to​ ​have​ ​gone​ ​extinct​ ​until​ ​1938,​ ​when​ ​a​ ​specimen​ ​was​ ​found
in​ ​the​ ​Comoro​ ​Islands
○ Marine,​ ​live​ ​in​ ​deep​ ​water
○ Very​ ​aggressive
○ Body​ ​plan
■ Have​ ​three-lobed​ ​tails​ ​with​ ​fin​ ​rays​ ​from​ ​the​ ​lobes
■ Have​ ​a​ ​rostral​ ​organ,​ ​like​ ​sharks
● Pits​ ​in​ ​front​ ​of​ ​the​ ​mouth,​ ​filled​ ​with​ ​glycoprotein
● Used​ ​for​ ​detecting​ ​electrical​ ​signals​ ​in​ ​the​ ​water
■ Have​ ​a​ ​tapetum​ ​lucidum​ ​in​ ​the​ ​back​ ​of​ ​each​ ​eye​ ​to​ ​reflect​ ​light
■ Have​ ​a​ ​fat-filled​ ​swimbladder​ ​with​ ​ossified​ ​walls
○ Reproduction/development
■ Ovoviviparous
● 9cm​ ​eggs
● Gestation​ ​period​ ​of​ ​13​ ​months,​ ​30-40cm​ ​pups​ ​are​ ​born
■ Males​ ​don’t​ ​have​ ​claspers,​ ​but​ ​eggs​ ​must​ ​be​ ​internally​ ​fertilised​ ​for
ovoviviparity
Actinopterygii
● Ray-finned​ ​fish​ ​(vertebrae​ ​do​ ​not​ ​extend​ ​into​ ​the​ ​fin,​ ​fin​ ​is​ ​fully​ ​composed​ ​of​ ​fin​ ​rays)
● Early​ ​Actinopterygians
○ Full​ ​fossils​ ​date​ ​to​ ​the​ ​mid​ ​Devonian
○ Body​ ​plan
■ Small​ ​(5-25cm)
■ Small​ ​changes​ ​in​ ​locomotion​ ​and​ ​feeding​ ​over​ ​time
■ Heterocercal​ ​tails​ ​(vertebral​ ​column​ ​goes​ ​upwards​ ​into​ ​tail​ ​fin,​ ​dorsal
lobe​ ​likely​ ​to​ ​be​ ​larger)
■ Paired​ ​fins​ ​with​ ​long​ ​bases
■ Interlocking​ ​scales,​ ​made​ ​from​ ​ganoine
■ Non-solid​ ​cheek
● Increased​ ​orobranchial​ ​chamber
● More​ ​jaw​ ​muscles,​ ​could​ ​tackle​ ​larger​ ​prey​ ​and​ ​swallow​ ​them
more​ ​easily
■ Coronoid​ ​process
● Bone​ ​projection
● Allows​ ​the​ ​attachment​ ​of​ ​more​ ​jaw​ ​muscle,​ ​increasing​ ​bite
strength
● Chondrosteans
Joanna​ ​Griffith​ ​(2017)

Paraphyletic​ ​group
Polypteriformes
■ Eg
...
​ ​sturgeons,​ ​paddlefish
■ 30​ ​extant​ ​species
● Most​ ​are​ ​endangered
■ Acipenseridae
● Sturgeons
● Only​ ​found​ ​in​ ​the​ ​northern​ ​hemisphere
● Freshwater​ ​and​ ​marine
○ All​ ​breed​ ​in​ ​freshwater
● Lack​ ​endochondral​ ​bone,​ ​decreased​ ​dermal​ ​bone
● Heterocercal​ ​tail
● Protrusible​ ​jaws,​ ​used​ ​for​ ​suction
● 5​ ​rows​ ​of​ ​enlarged​ ​scales
● Main​ ​source​ ​of​ ​caviar
■ Polyodontidae
● Paddlefish
● Only​ ​2​ ​extant​ ​species
● Found​ ​in​ ​freshwater
● Very​ ​little​ ​dermal​ ​ossification
● Large​ ​rostrum,​ ​contains​ ​ampullary​ ​organs
● Filter​ ​feeders
Neopterygians
○ Lepisteiformes
■ Gars
■ 7​ ​extant​ ​species
■ Found​ ​in​ ​freshwater​ ​and​ ​estuaries​ ​in​ ​warm​ ​and​ ​temperate​ ​regions
■ Grow​ ​1-4m​ ​long
■ Body​ ​covered​ ​in​ ​interlocking,​ ​multi-layered​ ​scales
■ Piscivorous​ ​(eat​ ​fish)
○ Amiiformes
■ Bowfin
■ One​ ​extant​ ​species
■ Asymmetrical​ ​caudal​ ​fin
■ Single​ ​layer​ ​of​ ​scales​ ​over​ ​body
■ Jaw​ ​modified​ ​for​ ​suction
● Will​ ​eat​ ​anything
○ Teleostei
■ 96%​ ​of​ ​all​ ​fish​ ​types
○
○

●

Joanna​ ​Griffith​ ​(2017)

■

■

■

■

■

● 27,000​ ​species,​ ​4​ ​clades
Osteoglossomorpha
● About​ ​220​ ​species
● Dominated​ ​Jurassic​ ​seas
● Found​ ​in​ ​tropical​ ​freshwater​ ​environments
● Bony​ ​mouths
Elopomorpha
● About​ ​800​ ​species
● Originated​ ​in​ ​the​ ​late​ ​Jurassic
● Found​ ​in​ ​marine​ ​environments
● Develop​ ​from​ ​Leptocephalus​ ​larvae
Clupeomorpha
● Between​ ​360​ ​and​ ​400​ ​species
● Eat​ ​plankton​ ​using​ ​mouth​ ​and​ ​gill​ ​straining​ ​apparatus
● Highly​ ​valuable
Eusteolostei
● Contains​ ​those​ ​that​ ​do​ ​not​ ​fit​ ​into​ ​the​ ​other​ ​groups
● Originated​ ​in​ ​the​ ​mid-to-late​ ​Cretaceous
● Commonly​ ​form​ ​shoals
● Use​ ​ostariophysi
○ Weberian​ ​apparatus
■ Bones​ ​connect​ ​ear​ ​to​ ​swim​ ​bladder,​ ​swim
bladder​ ​used​ ​as​ ​an​ ​amplifier​ ​to​ ​detect​ ​sound
waves​ ​in​ ​water
○ Can​ ​release​ ​alarm​ ​chemicals​ ​from​ ​skin
■ Promotes​ ​shoal​ ​behaviour
Why​ ​are​ ​teleosts​ ​more​ ​successful​ ​than​ ​other​ ​groups​ ​of​ ​fish?
● Have​ ​cycloid​ ​and​ ​ctenoid​ ​scales
○ Overlapping,​ ​rather​ ​than​ ​interlocking
■ Promotes​ ​flexibility​ ​and​ ​speed
● Homocercal​ ​tails
● Elaborate​ ​fins
○ Can​ ​be​ ​adapted​ ​for​ ​different​ ​roles
○ Used​ ​more​ ​for​ ​stability​ ​than​ ​for​ ​swimming
● Increased​ ​gas​ ​absorption​ ​and​ ​secretion​ ​efficiency
● Changes​ ​in​ ​jaw​ ​suspension
○ Allows​ ​a​ ​larger​ ​mouth​ ​cavity,​ ​creating​ ​greater​ ​negative
pressure,​ ​which​ ​causes​ ​food​ ​items​ ​and​ ​water​ ​to​ ​be
sucked​ ​into​ ​the​ ​mouth
● Operculum
○ Bony​ ​plate​ ​covering​ ​the​ ​gills,​ ​can​ ​be​ ​used​ ​to​ ​pump
water​ ​into​ ​the​ ​gills
● Swim​ ​bladder
○ Used​ ​for​ ​buoyancy,​ ​helps​ ​to​ ​save​ ​energy

Conservation
● Fish​ ​are​ ​of​ ​economic​ ​importance

Joanna​ ​Griffith​ ​(2017)

● Threat​ ​from​ ​habitat​ ​degradation​ ​and​ ​overexploitation
● Common​ ​Fisheries​ ​Policy
--------------------------------------------------------------------------------------------------------------------------6:​ ​EVOLUTION​ ​OF​ ​THE​ ​TETRAPODS
Tetrapod:​ ​a​ ​gnathostome​ ​(jawed)​ ​with​ ​limbs
○ Includes​ ​amphibians,​ ​reptiles,​ ​birds​ ​and​ ​mammals
○ Appeared​ ​in​ ​the​ ​early​ ​Devonian​ ​(400​ ​million​ ​years​ ​ago)
■ Underwent​ ​four​ ​major​ ​changes​ ​(duplication​ ​of​ ​the​ ​Hox​ ​gene​ ​complex)
Difficulties​ ​of​ ​moving​ ​onto​ ​land
● What​ ​was​ ​the​ ​drive​ ​to​ ​move​ ​onto​ ​land?
○ Higher​ ​oxygen​ ​content​ ​in​ ​air,​ ​if​ ​you​ ​have​ ​the​ ​lungs​ ​to​ ​harness​ ​it
○ Larger​ ​diversity​ ​of​ ​habitats
■ Shelter​ ​for​ ​eggs​ ​and​ ​young​ ​more​ ​readily​ ​found
● Air​ ​density
○ Air​ ​is​ ​1000x​ ​less​ ​buoyant​ ​and​ ​50x​ ​less​ ​viscous​ ​than​ ​water,​ ​so​ ​land​ ​organisms
have​ ​to​ ​be​ ​better​ ​able​ ​to​ ​bear​ ​their​ ​own​ ​weight
● Gravity
○ Stronger​ ​influence​ ​on​ ​support​ ​and​ ​locomotion
● Bone
○ Needed​ ​to​ ​resist​ ​gravity​ ​and​ ​generated​ ​forces
○ Haversian​ ​systems
■ Bone​ ​does​ ​not​ ​have​ ​a​ ​uniform​ ​structure
● Internal​ ​part​ ​made​ ​up​ ​of​ ​cancellous​ ​bone,​ ​which​ ​is​ ​light​ ​and
spongy
● External​ ​layers​ ​are​ ​arranged​ ​concentrically,​ ​and​ ​are​ ​dense​ ​and
compact
○ Articular​ ​joints​ ​made​ ​up​ ​of​ ​cartilage​ ​and​ ​encased​ ​in​ ​synovial​ ​fluid
● Axial​ ​skeleton
○ Vertebrae​ ​and​ ​ribs
○ Used​ ​for​ ​support​ ​and​ ​breathing​ ​in​ ​tetrapods
■ In​ ​fish,​ ​the​ ​axial​ ​muscles​ ​contract​ ​to​ ​bend​ ​the​ ​body​ ​and​ ​allow​ ​the​ ​fish
to​ ​swim
○ Zygapophyses
■ Sticky-out​ ​points​ ​on​ ​vertebrae​ ​that​ ​lock​ ​together​ ​and​ ​resist​ ​torsion
■ Amphibians​ ​and​ ​reptiles​ ​still​ ​have​ ​some​ ​lateral​ ​movement​ ​(smaller
zygapophyses),​ ​but​ ​in​ ​birds​ ​and​ ​mammals,​ ​this​ ​has​ ​been​ ​replaced​ ​by
limb​ ​movement
● Changes​ ​to​ ​the​ ​appendicular​ ​skeleton​ ​(limbs)
● Changes​ ​to​ ​and​ ​in​ ​the​ ​skull
○ Different​ ​modes​ ​of​ ​food​ ​intake​ ​(fish​ ​just​ ​suck​ ​food​ ​into​ ​their​ ​mouths,​ ​this
doesn’t​ ​work​ ​on​ ​land)
○ Muscular​ ​tongue
○ Salivary​ ​glands
● Oxygen​ ​content​ ​is​ ​20x​ ​greater​ ​on​ ​land​ ​than​ ​it​ ​is​ ​in​ ​water
●

Joanna​ ​Griffith​ ​(2017)

Lungs​ ​evolved​ ​to​ ​extract​ ​that​ ​oxygen​ ​(negative​ ​pressure​ ​aspiration​ ​pump)
■ Wet​ ​internal​ ​surface​ ​needed
○ At​ ​the​ ​time​ ​of​ ​the​ ​evolution​ ​of​ ​the​ ​tetrapods,​ ​temperatures​ ​were​ ​mild,​ ​with
many​ ​floods​ ​and​ ​droughts
■ Most​ ​of​ ​the​ ​freshwater​ ​fish​ ​that​ ​survived​ ​this​ ​had​ ​a​ ​lung​ ​(outgrowth​ ​of
the​ ​pharynx)
○ Having​ ​lungs​ ​increased​ ​efficiency,​ ​and​ ​increased​ ​the​ ​size​ ​of​ ​the​ ​capillary
network​ ​to​ ​supply​ ​arterial​ ​blood​ ​to​ ​organs
■ Need​ ​for​ ​a​ ​pulmonary​ ​vein​ ​to​ ​send​ ​oxygen-rich​ ​blood​ ​from​ ​the​ ​lungs​ ​to
the​ ​heart
● Beginnings​ ​of​ ​the​ ​double​ ​circulatory​ ​system
Sensory​ ​systems​ ​in​ ​air
○ Vision
■ Easier​ ​on​ ​land,​ ​better​ ​light​ ​transfer​ ​(no​ ​refraction)
■ Fish​ ​move​ ​the​ ​whole​ ​lens​ ​around​ ​to​ ​focus​ ​an​ ​image​ ​on​ ​the​ ​retina,
whereas​ ​tetrapods​ ​change​ ​the​ ​shape​ ​of​ ​the​ ​lens
■ Eyelids,​ ​lacrimal​ ​glands,​ ​and​ ​nasolacrimal​ ​glands​ ​needed​ ​to​ ​protect
and​ ​keep​ ​eyes​ ​moist
○ Hearing
■ Middle​ ​ear​ ​developed​ ​to​ ​amplify​ ​sound
■ Eardrum​ ​to​ ​middle​ ​ear​ ​to​ ​oval​ ​window​ ​to​ ​otic​ ​capsule​ ​to​ ​organ​ ​of​ ​corti
■ Flak-shaped​ ​lagena​ ​(cochlea​ ​in​ ​mammals)
○ Olfaction
■ Olfactory​ ​epithelium​ ​and​ ​sensory​ ​cells​ ​in​ ​the​ ​nasal​ ​passage
■ Turbinate​ ​bones​ ​(thin​ ​partition​ ​between​ ​nostrils)
● The​ ​larger​ ​the​ ​turbinate​ ​bone,​ ​the​ ​better​ ​the​ ​sense​ ​of​ ​smell
■ Vomeronasal​ ​organ​ ​in​ ​the​ ​roof​ ​of​ ​the​ ​mouth
● Contains​ ​chemical​ ​receptors
● Jacobsen’s​ ​organ​ ​in​ ​snakes
● Flehmen​ ​allows​ ​scents​ ​to​ ​enter​ ​the​ ​mouth
○ Proprioception
■ Knowing​ ​where​ ​your​ ​body​ ​parts​ ​are
■ Muscle​ ​spindles​ ​detect​ ​stretch,​ ​feedback​ ​sent​ ​to​ ​brain
Conserving​ ​water​ ​and​ ​controlling​ ​body​ ​temperature
○ Aquatic​ ​environments​ ​are​ ​more​ ​stable​ ​than​ ​air
○ It​ ​takes​ ​more​ ​energy​ ​to​ ​heat​ ​water​ ​than​ ​to​ ​heat​ ​air
○ Early​ ​tetrapods​ ​had​ ​scaly,​ ​abrasive​ ​skin​ ​filled​ ​with​ ​lipids​ ​to​ ​reduce​ ​evaporative
loss
■ Stratum​ ​corneum
● Thick,​ ​keratinised​ ​layer​ ​of​ ​skin
○ Bladder​ ​adapted​ ​for​ ​water​ ​recovery
○ Maintenance​ ​of​ ​body​ ​temperature​ ​evolved​ ​in​ ​different​ ​ways​ ​for​ ​different
environments
■ Ectothermy,​ ​endothermy
■ Behavioural​ ​and​ ​physiological​ ​strategies
● Eg
...
5m​ ​long
○ Paired​ ​limbs​ ​at​ ​right​ ​angles​ ​to​ ​the​ ​body
■ Fore​ ​and​ ​hind​ ​limbs​ ​are​ ​equally-sized
○ Lack​ ​ribs
■ May​ ​be​ ​related​ ​to​ ​the​ ​use​ ​of​ ​body​ ​wall​ ​muscles​ ​for​ ​breathing
● Carnivorous​ ​at​ ​all​ ​life​ ​stages
● Reproduction
○ Elaborate​ ​courtship​ ​rituals
■ Wafting​ ​of​ ​pheromones​ ​from​ ​the​ ​hedonic​ ​and​ ​mental​ ​glands
○ Some​ ​families​ ​undergo​ ​external​ ​fertilisation
○ Others​ ​undergo​ ​internal​ ​fertilisation
■ Male​ ​passes​ ​the​ ​female​ ​a​ ​spermatophore​ ​with​ ​a​ ​sperm​ ​cap​ ​and
gelatinous​ ​base​ ​into​ ​her​ ​cloaca
● The​ ​cap​ ​dissolves,​ ​sperm​ ​is​ ​released,​ ​and​ ​fertilisation​ ​occurs
in​ ​the​ ​oviducts
○ Most​ ​species​ ​are​ ​oviparous,​ ​but​ ​some​ ​are​ ​viviparous
○ Typically,​ ​larvae​ ​have​ ​gills,​ ​which​ ​are​ ​lost​ ​in​ ​adult​ ​forms
■ In​ ​aquatic​ ​species,​ ​larvae​ ​have​ ​external​ ​gills​ ​and​ ​a​ ​fin-like​ ​tail
■ Some​ ​adult​ ​forms​ ​may​ ​retain​ ​gills
● Some​ ​species​ ​(eg
...
​ ​Plethodontidae​ ​have​ ​modified​ ​tongues​ ​to​ ​catch
food,​ ​but​ ​as​ ​a​ ​result,​ ​they​ ​can​ ​no​ ​longer​ ​use​ ​positive
pressure​ ​breathing,​ ​so​ ​rely​ ​on​ ​moist​ ​habitats​ ​for​ ​gas
exchange​ ​through​ ​the​ ​skin
○ Rely​ ​on​ ​cutaneous​ ​respiration​ ​and​ ​buccopharyngeal
breathing​ ​(gas​ ​exchange​ ​over​ ​mouth​ ​membranes)
○ Some​ ​species​ ​retain​ ​gills​ ​for​ ​their​ ​entire​ ​lives​ ​(eg
...
​ ​mud​ ​puppies​ ​and​ ​axolotl),​ ​and​ ​some​ ​species​ ​only​ ​metamorphose​ ​when
environmental​ ​conditions​ ​are​ ​poor​ ​(eg
...
​ ​autotomisation​ ​salamander​ ​loses​ ​tail,​ ​an​ ​important​ ​source​ ​of​ ​energy)
Anura​ ​(Salientia)
● Frogs​ ​and​ ​toads
● Mainly​ ​solitary,​ ​except​ ​when​ ​breeding
● Lots​ ​of​ ​different​ ​families
○ Eg
...
​ ​Rhanidae
○ Eg
...
​ ​Tungara​ ​frogs
● Give​ ​a​ ​whining​ ​call,​ ​sometimes​ ​followed​ ​by​ ​a​ ​few​ ​“chucks”
○ Females​ ​prefer​ ​males​ ​that​ ​“chuck”,​ ​so​ ​why​ ​don’t​ ​all
males​ ​do​ ​so?
■ Chucks​ ​attract​ ​predators
○ Males​ ​grab​ ​females​ ​by​ ​the​ ​amplexus,​ ​which​ ​stimulates​ ​them​ ​to​ ​release​ ​eggs,
then​ ​the​ ​male​ ​sprays​ ​sperm​ ​over​ ​the​ ​eggs​ ​(external​ ​fertilisation)
■ The​ ​eggs​ ​absorb​ ​moisture​ ​and​ ​swell,​ ​and​ ​development​ ​begins
immediately
○ Larvae
■ Only​ ​the​ ​larvae​ ​have​ ​tails
■ External​ ​and​ ​internal​ ​gills
■ Specialised​ ​mouthparts
Joanna​ ​Griffith​ ​(2017)

Most​ ​species​ ​have​ ​herbivorous​ ​larvae,​ ​but​ ​some​ ​have
carnivorous​ ​larvae
■ Undergo​ ​metamorphosis​ ​to​ ​become​ ​adults
○ Parental​ ​care​ ​seen​ ​in​ ​some​ ​species
■ Marsupial​ ​frogs​ ​push​ ​eggs​ ​into​ ​a​ ​pouch​ ​of​ ​skin
■ Gastric​ ​brooding​ ​frogs
● Female​ ​swallows​ ​fertilised​ ​eggs
○ The​ ​jelly​ ​of​ ​the​ ​eggs​ ​contains​ ​prostaglandin​ ​e2​​ ,​ ​which
stops​ ​acid​ ​production,​ ​prevents​ ​the​ ​gut​ ​from
discharging​ ​its​ ​contents,​ ​and​ ​relaxes​ ​the​ ​stomach​ ​wall
● Range​ ​of​ ​anti-predatory​ ​techniques
○ Aposematic​ ​colouration
■ Bright​ ​colours​ ​warn​ ​predators​ ​that​ ​they​ ​are​ ​toxic
■ Lots​ ​of​ ​different​ ​toxins,​ ​picked​ ​up​ ​from​ ​insect​ ​prey
● Eg
...
​ ​hallucinogens,​ ​found​ ​in​ ​Colorado​ ​River​ ​toads
○ Some​ ​species​ ​can​ ​swell​ ​up​ ​in​ ​the​ ​mouths​ ​of​ ​predators
● Surviving​ ​low​ ​temperatures
○ Some​ ​species​ ​undergo​ ​hibernation
○ Some​ ​species​ ​can​ ​survive​ ​the​ ​freezing​ ​of​ ​extracellular​ ​fluid
■ Produce​ ​antifreeze​ ​made​ ​of​ ​glycogen​ ​to​ ​prevent​ ​the​ ​formation​ ​of​ ​ice
crystals
■ Can​ ​survive​ ​up​ ​to​ ​4​ ​weeks​ ​of​ ​being​ ​65-70%​ ​frozen,​ ​and​ ​can​ ​be​ ​fully
functional​ ​hours​ ​after​ ​thawing
Conservation
● Rapid​ ​population​ ​decline​ ​over​ ​the​ ​last​ ​25​ ​years
● Habitat​ ​loss,​ ​climate​ ​change
● Fungi​ ​and​ ​viruses
○ Eg
...
​ ​pareiasaurs
■ Large,​ ​quadrupedal​ ​herbivores
■ Had​ ​anapsid​ ​skulls,​ ​which​ ​provides​ ​the​ ​main​ ​body​ ​of​ ​evidence​ ​for
turtles​ ​evolving​ ​from​ ​parareptiles​ ​as​ ​they​ ​are​ ​the​ ​only​ ​reptile​ ​group
with​ ​anapsid​ ​skulls
● However,​ ​molecular​ ​evidence​ ​suggests​ ​that​ ​turtles​ ​are
diapsids,​ ​and​ ​their​ ​anapsid​ ​skulls​ ​may​ ​simply​ ​be​ ​highly​ ​derived
diapsid​ ​skulls
■ Some​ ​had​ ​scutes​ ​and​ ​bony​ ​plates​ ​that​ ​may​ ​have​ ​been​ ​early​ ​shells
■ Sister​ ​group​ ​to​ ​the​ ​archosaurs,​ ​and​ ​possibly​ ​the​ ​lepidosaurs
○ O
...

○ Kinesis​ ​evolved​ ​many​ ​times
○ Allows​ ​some​ ​species​ ​to​ ​close​ ​the​ ​shell
○ Some​ ​species​ ​are​ ​able​ ​to​ ​retract​ ​their​ ​head
○ Vertebrae​ ​and​ ​ribs​ ​tend​ ​to​ ​be​ ​fused​ ​to​ ​the​ ​shell
■ Creates​ ​a​ ​“cage”​ ​for​ ​vital​ ​organs
○ No​ ​teeth,​ ​have​ ​a​ ​keratinised​ ​horny​ ​beak​ ​instead
respiration/circulatory​ ​system/excretion
○ Respiration
■ The​ ​lungs​ ​are​ ​attached​ ​to​ ​the​ ​upper​ ​shell,​ ​and​ ​the​ ​organs​ ​below
■ Inhalation​ ​and​ ​exhalation​ ​require​ ​muscular​ ​activity​ ​to​ ​expand​ ​and
contract​ ​the​ ​two​ ​halves​ ​of​ ​the​ ​shell​ ​in​ ​order​ ​to​ ​enable​ ​the​ ​lungs​ ​to
inflate​ ​and​ ​deflate
● When​ ​the​ ​transverse​ ​abdominis​ ​and​ ​pectoralis​ ​muscles
contract,​ ​the​ ​volume​ ​of​ ​the​ ​visceral​ ​cavity​ ​decreases,​ ​and​ ​the
turtle​ ​exhales
● ​ ​When​ ​the​ ​serratus​ ​and​ ​abdominal​ ​obliques​ ​contract,​ ​the
volume​ ​of​ ​the​ ​visceral​ ​cavity​ ​increases,​ ​and​ ​the​ ​turtle​ ​inhales
■ Some​ ​turtle​ ​species​ ​supplement​ ​breathing​ ​with​ ​gas​ ​exchange​ ​via​ ​the
epithelial​ ​surfaces​ ​of​ ​the​ ​mouth​ ​and​ ​anus
■ Some​ ​freshwater​ ​turtles​ ​hibernate​ ​at​ ​the​ ​bottom​ ​of​ ​ponds​ ​for​ ​up​ ​to​ ​6
months
○ Circulation
■ 3-chambered​ ​heart​ ​(2​ ​atria,​ ​1​ ​ventricle)
■ Muscular​ ​ridge​ ​running​ ​through​ ​the​ ​ventricle​ ​keeps​ ​oxygen-rich​ ​and
oxygen-poor​ ​blood​ ​more​ ​or​ ​less​ ​on​ ​the​ ​correct​ ​side
■ When​ ​the​ ​atria​ ​contract,​ ​the​ ​muscular​ ​ridge​ ​blocks​ ​blood​ ​flow,​ ​and​ ​the
AV​ ​valve​ ​blocks​ ​the​ ​interventricular​ ​canal
■ When​ ​the​ ​ventricle​ ​contracts,​ ​the​ ​muscular​ ​ridge​ ​splits​ ​the​ ​ventricle​ ​in
half,​ ​directing​ ​oxygen-poor​ ​blood​ ​to​ ​the​ ​pulmonary​ ​arteries​ ​and
oxygen-rich​ ​blood​ ​into​ ​the​ ​left​ ​and​ ​right​ ​aortic​ ​arches
■

●

Joanna​ ​Griffith​ ​(2017)

When​ ​underwater,​ ​turtles​ ​divert​ ​most​ ​of​ ​the​ ​blood​ ​to​ ​the​ ​systemic
circuit,​ ​away​ ​from​ ​the​ ​heart​ ​and​ ​lungs,​ ​as​ ​the​ ​lungs​ ​are​ ​not​ ​in​ ​use
reproduction/development
○ Oviparous
■ Soft​ ​or​ ​rigid​ ​eggshells
○ Incubation​ ​occurs​ ​over​ ​40-60​ ​days
■ No​ ​parental​ ​care,​ ​except​ ​when​ ​choosing​ ​a​ ​nest​ ​site
○ Diapause​ ​(development​ ​does​ ​not​ ​start​ ​until​ ​a​ ​certain​ ​environmental​ ​cue​ ​is
detected)
○ Temperature-dependent​ ​sex​ ​determination
■ Occurs​ ​in​ ​the​ ​middle​ ​third​ ​of​ ​the​ ​incubation​ ​period
■ Low​ ​temperature​ ​=​ ​males,​ ​high​ ​temperature​ ​=​ ​females
● The​ ​pivotal​ ​point​ ​is​ ​around​ ​29℃​ ​in​ ​marine​ ​species
■ Female-biased​ ​sex​ ​ratios​ ​are​ ​typical
● Climate​ ​change​ ​is​ ​predicted​ ​to​ ​increase​ ​female​ ​bias,​ ​which
may​ ​have​ ​implications​ ​for​ ​population​ ​size​ ​due​ ​to​ ​fewer​ ​males
contributing​ ​to​ ​genetic​ ​diversity
○ We​ ​need​ ​to​ ​do​ ​more​ ​research​ ​on​ ​mating​ ​systems​ ​and
the​ ​current​ ​sex​ ​ratio​ ​to​ ​understand​ ​the​ ​potential​ ​threats
of​ ​climate​ ​change
○ Mating​ ​occurs​ ​offshore​ ​(in​ ​marine​ ​turtles)
○ Polygyny​ ​is​ ​common
○ Hybrids​ ​are​ ​common,​ ​despite​ ​the​ ​three​ ​turtle​ ​lineages​ ​being​ ​separated​ ​for
over​ ​50​ ​million​ ​years
■ Slow​ ​rate​ ​of​ ​molecular​ ​evolution
■ Indiscriminate​ ​mating​ ​of​ ​males
■ Identical​ ​chromosome​ ​number​ ​and​ ​structure
○ Natal​ ​philopatry​ ​(females​ ​will​ ​return​ ​to​ ​the​ ​same​ ​area​ ​every​ ​breeding​ ​season
to​ ​lay​ ​eggs)
○ Females​ ​lay​ ​clutches​ ​of​ ​over​ ​100+​ ​eggs​ ​over​ ​10-14​ ​days
■ Dig​ ​nests​ ​up​ ​to​ ​1m​ ​deep
■ Often​ ​produce​ ​mass​ ​nestings​ ​called​ ​arribas
○ Fine-scale​ ​adaptations​ ​allow​ ​some​ ​eggs​ ​to​ ​do​ ​better​ ​in​ ​a​ ​certain​ ​environment
than​ ​others​ ​(eg
...
​ ​leatherback​ ​‘lost​ ​years’)
■ Return​ ​to​ ​neritic​ ​waters​ ​once​ ​grown,​ ​often​ ​to​ ​the​ ​same​ ​place​ ​as​ ​where
they​ ​hatched
Migration
○ Turtles​ ​are​ ​extremely​ ​good​ ​at​ ​finding​ ​their​ ​way​ ​back​ ​to​ ​where​ ​they​ ​hatched
○ May​ ​use​ ​smell,​ ​oceanic​ ​currents,​ ​and​ ​the​ ​earth’s​ ​magnetic​ ​field
Cryptodira
○ Trochlear​ ​process,​ ​on​ ​the​ ​surface​ ​of​ ​the​ ​otic​ ​capsule,​ ​has​ ​a​ ​jaw​ ​muscle
attachment​ ​bending​ ​around​ ​it
■

●

●

●

Joanna​ ​Griffith​ ​(2017)

○ Free-floating​ ​pelvis,​ ​not​ ​fixed​ ​to​ ​the​ ​shell​ ​or​ ​vertebrae
○ Retract​ ​neck​ ​in​ ​a​ ​vertical​ ​S-shape
○ Dominant​ ​group,​ ​except​ ​in​ ​Australia
● Pleurodira
○ Trochlear​ ​process​ ​extends​ ​over​ ​a​ ​lateral​ ​process​ ​of​ ​the​ ​pterygoid
○ Pelvis​ ​normally​ ​fused​ ​to​ ​skull
○ Retract​ ​neck​ ​in​ ​a​ ​horizontal​ ​S-shape
● Sea​ ​turtle​ ​conservation
○ Threatened​ ​by:
■ Fisheries
● Bycatch
■ Harvest​ ​for​ ​trade
● Often​ ​illegal
■ Habitat​ ​loss
■ Climate​ ​change
○ Solutions:
■ Protected​ ​hatcheries
■ Fishery​ ​mitigation
● Eg
...
​ ​ammonites)
■ Viviparous
○ Mosasaurs
■ Existed​ ​in​ ​the​ ​late​ ​Cretaceous
■ Found​ ​in​ ​warm,​ ​shallow​ ​seas
■ Looked​ ​like​ ​finned​ ​crocodiles
■ Grew​ ​to​ ​be​ ​3-17m​ ​long
■ Elongated​ ​skull,​ ​filled​ ​with​ ​numerous​ ​sharp​ ​teeth
■ Voracious​ ​hunters
■ Viviparous
Sphenodontia
○ Tuataras
○ Diverse​ ​in​ ​the​ ​Mesozoic​ ​era
○ Two​ ​living​ ​species,​ ​found​ ​on​ ​small​ ​islands​ ​in​ ​New​ ​Zealand
○ Body​ ​plan
■ Lizard-like
■ Primitive​ ​diapsid​ ​skull
■ Some​ ​have​ ​acrodont​ ​teeth​ ​(attached​ ​to​ ​the​ ​top​ ​surface​ ​of​ ​the
jawbone),​ ​others​ ​have​ ​pleurodont​ ​teeth​ ​(attached​ ​to​ ​the​ ​inner​ ​surface
of​ ​the​ ​jawbone)
● Teeth​ ​are​ ​not​ ​replaced,​ ​so​ ​older​ ​tuataras​ ​must​ ​find​ ​softer​ ​foods
■ Can​ ​operate​ ​at​ ​very​ ​low​ ​temperatures​ ​(5℃)
● Optimum​ ​temperature​ ​is​ ​much​ ​higher​ ​than​ ​this
● Hibernate​ ​in​ ​the​ ​winter
■ Slow​ ​metabolism
● Slow-growing
○ Take​ ​20​ ​years​ ​to​ ​mature
○ Long-lived
○ nutrition/digestion
■ Varied​ ​diet
● Often​ ​prey​ ​on​ ​seabird​ ​colonies,​ ​so​ ​they​ ​are​ ​most​ ​active​ ​at​ ​night
○ respiration/circulatory​ ​system/excretion
■ 3-chambered​ ​heart
○ Nervous​ ​system/sense​ ​organs
■ Eyes
● Eyes​ ​focus​ ​independently,​ ​so​ ​they​ ​can​ ​look​ ​in​ ​two​ ​different
directions
● Have​ ​a​ ​tapetum​ ​lucidum,​ ​reflects​ ​back​ ​light​ ​from​ ​the​ ​back​ ​of
the​ ​eye​ ​to​ ​see​ ​better​ ​in​ ​low​ ​light​ ​conditions
● Nictitating​ ​membrane​ ​rolls​ ​over​ ​the​ ​eye​ ​to​ ​protect​ ​it,​ ​eg
...

■ Site​ ​above​ ​the​ ​pineal​ ​gland
● Part​ ​of​ ​the​ ​endocrine​ ​system
○ May​ ​be​ ​detecting​ ​light​ ​levels​ ​to
provoke​ ​hormonal​ ​reactions
○ Also​ ​found​ ​in​ ​salamanders,​ ​where​ ​it​ ​is​ ​used​ ​to​ ​react​ ​to
polarised​ ​light
■ No​ ​eardrum,​ ​instead​ ​the​ ​middle​ ​ear​ ​is​ ​filled​ ​with​ ​fatty​ ​tissue
● Detection​ ​of​ ​sound​ ​is​ ​different​ ​to​ ​that​ ​of​ ​organisms​ ​with
eardrums
○ reproduction/development
■ 2-5​ ​year​ ​reproductive​ ​cycle
■ Sexes​ ​are​ ​territorial
■ Have​ ​temperature-sensitive​ ​sex​ ​determination
● Higher​ ​temperatures​ ​produce​ ​males
Squamata
○ Lizards​ ​and​ ​snakes
○ Make​ ​up​ ​95%​ ​of​ ​all​ ​non-bird​ ​reptiles
○ Body​ ​plan
■ Diapsid​ ​skull
■ Skull​ ​is​ ​kinetic​ ​(moveable)
■ Loss​ ​of​ ​dermal​ ​bone
■ Snout​ ​tips​ ​upwards
● Increases​ ​closing​ ​force,​ ​allows​ ​them​ ​to​ ​seize​ ​and​ ​manipulate
prey
○ respiration/circulatory​ ​system/excretion
■ 3-chambered​ ​heart
■ Primarily​ ​excrete​ ​uric​ ​acid
● Animal​ ​waste​ ​products:
○ Ammonia
■ Toxic,​ ​but​ ​cheap​ ​to​ ​produce
■ Mainly​ ​used​ ​by​ ​aquatic​ ​animals
○ Urea
■ Low​ ​toxicity,​ ​less​ ​water​ ​loss,​ ​but​ ​energetically
costly
■ Used​ ​by​ ​mammals,​ ​amphibians,​ ​some​ ​bony
fish,​ ​sharks,​ ​and​ ​turtles
○ Uric​ ​acid
■ Low​ ​toxicity,​ ​less​ ​water​ ​loss,​ ​but​ ​very
energetically​ ​costly
■ Used​ ​by​ ​insects,​ ​snails,​ ​birds,​ ​and​ ​many​ ​reptiles
○ Saurias
●

●

Joanna​ ​Griffith​ ​(2017)

■
■
■

■

■

■

Lizards,​ ​geckos,​ ​skinks,​ ​iguanas,​ ​and​ ​chameleons
Occupy​ ​a​ ​wide​ ​range​ ​of​ ​habitats,​ ​niches​ ​and​ ​lifestyles
Body​ ​plan
● Some​ ​limbless​ ​forms​ ​(eg
...
​ ​horned​ ​lizards
○ Active​ ​foragers
■ Acquire​ ​and​ ​expend​ ​more​ ​energy
■ Slow​ ​sprinters,​ ​but​ ​good​ ​stamina
● Increased​ ​aerobic​ ​capacity
■ Brightly​ ​coloured
■ Long​ ​and​ ​thin​ ​bodies
■ Eg
...
​ ​komodo​ ​dragons
Predator​ ​avoidance
● Autonomy
○ Loss​ ​of​ ​tail,​ ​caused​ ​by​ ​fracture​ ​planes​ ​in​ ​caudal
vertebrae
■ Valves​ ​shut​ ​off​ ​caudal​ ​arteries
○ Tail​ ​twitches​ ​to​ ​distract​ ​predators
○ Tail​ ​regenerates
○ Costs:
■ Loss​ ​of​ ​energy/fat​ ​storage
■ Smaller​ ​clutches
■ Lower​ ​rank
● Draco​ ​lizards​ ​have​ ​flaps​ ​of​ ​skin​ ​to​ ​fly​ ​away​ ​from​ ​predators
● Frilled​ ​lizards​ ​hiss​ ​and​ ​lift​ ​frills​ ​to​ ​make​ ​themselves​ ​look​ ​bigger
Scleroglossa
● Geckos,​ ​skinks,​ ​snakes
● Amphisbaenians
○ Evolved​ ​in​ ​the​ ​late​ ​Cretaceous
○ Mainly​ ​limbless​ ​(early​ ​forms​ ​had​ ​limbs)
○ Highly​ ​specialised​ ​for​ ​living​ ​underground​ ​and​ ​burrowing
(fossorial​ ​lifestyle)
Joanna​ ​Griffith​ ​(2017)

Body​ ​sits​ ​inside​ ​tube​ ​of​ ​skin
● Annuli​ ​(rings​ ​in​ ​skin)​ ​anchor​ ​the​ ​body
against​ ​the​ ​tunnel​ ​wall​ ​and​ ​enable
movement)
■ Highly​ ​rigid​ ​skull
● Head​ ​can​ ​be​ ​blunt,​ ​keeled​ ​(wedged),​ ​or
spade-shaped​ ​depending​ ​on​ ​soil​ ​type
and​ ​depth​ ​of​ ​tunnelling
Single​ ​tooth​ ​in​ ​the​ ​upper​ ​jaw,​ ​two​ ​teeth​ ​in​ ​the​ ​lower​ ​jaw,
used​ ​to​ ​nip​ ​at​ ​prey​ ​(usually​ ​invertebrates)
■

○
■

○

Iguania
● Iguanas,​ ​agamids
● Chameleons​ ​(chamaeleonidae)
○ About​ ​160​ ​species
○ Most​ ​species​ ​are​ ​arboreal
○ Laterally​ ​compressed
○ Zygodactylous​ ​feet​ ​(three​ ​toes​ ​on​ ​the​ ​outside,​ ​two​ ​on
the​ ​inside)​ ​and​ ​prehensile​ ​tail
■ Useful​ ​in​ ​arboreal​ ​lifestyle
○ Able​ ​to​ ​change​ ​colour​ ​using​ ​pigments​ ​in​ ​layers​ ​of​ ​skin
(chromatophores)
■ Erythrophores​ ​(red)​ ​and​ ​xanthophores​ ​(yellow)
in​ ​upper​ ​layer​ ​of​ ​skin
■ Iridophores​ ​(blue)​ ​in​ ​lower​ ​layer​ ​of​ ​skin
■ The​ ​deepest​ ​layer​ ​of​ ​skin​ ​contains
melanophores​ ​(dark​ ​colours)
Serpentes
■ Snakes
■ First​ ​appeared​ ​as​ ​entirely​ ​limbless​ ​forms​ ​in​ ​the​ ​late​ ​Cretaceous
■ Many​ ​arboreal​ ​species
● Excellent​ ​binocular​ ​vision,​ ​for​ ​judging​ ​distances
■ Body​ ​plan
● Lack​ ​pelvic​ ​and​ ​pectoral​ ​girdles​ ​(except​ ​boas​ ​and​ ​pythons)
● Numerous​ ​vertebrae​ ​and​ ​ribs
● Highly​ ​kinetic​ ​skulls
● No​ ​moveable​ ​eyelids
● No​ ​external​ ​ears
● Big​ ​elastic​ ​jaw​ ​ligaments
○ Allow​ ​the​ ​jaw​ ​to​ ​expand​ ​to​ ​accommodate​ ​large​ ​prey
● Glottis
○ Windpipe​ ​can​ ​move​ ​out​ ​of​ ​the​ ​side​ ​of​ ​the​ ​mouth​ ​to
enable​ ​the​ ​snake​ ​to​ ​breathe​ ​while​ ​swallowing​ ​prey
■ Nervous​ ​system/sense​ ​organs
● Most​ ​employ​ ​a​ ​chemical​ ​sense
○ Jacobsen’s​ ​organ
■ On​ ​roof​ ​of​ ​mouth

Joanna​ ​Griffith​ ​(2017)

Full​ ​of​ ​olfactory​ ​cells
Forked​ ​tongue​ ​picks​ ​up​ ​particles​ ​and​ ​presses
them​ ​to​ ​the​ ​organ
Some​ ​species​ ​can​ ​detect​ ​infrared​ ​heat​ ​using​ ​pits​ ​beneath​ ​the
eyes
○ Eg
...
​ ​cobras
● Solenoglyphous
○ Hollow​ ​fangs,​ ​fold​ ​out​ ​when​ ​in​ ​use
● Opisthoglyphous
○ Venom​ ​delivered​ ​through​ ​teeth​ ​in​ ​the​ ​rear​ ​of​ ​the​ ​mouth
○ Either​ ​a​ ​solid​ ​tooth​ ​or​ ​groove
○ Eg
...
​ ​boas
● Sidewinding
○ Throw​ ​anterior​ ​body​ ​sideways,​ ​then​ ​posterior​ ​body​ ​is
brought​ ​into​ ​line
○ Enables​ ​fast​ ​movement​ ​on​ ​loose​ ​ground
○ Eg
...
​ ​ornithomimus
● Dromaeosaurs
Joanna​ ​Griffith​ ​(2017)

○
○

○
○
●

●

Very​ ​fast,​ ​took​ ​down​ ​large​ ​prey
Huge​ ​claw​ ​on​ ​hindlimb
■ 2nd​ ​toe​ ​in​ ​deinonychus,​ ​3rd​ ​toe​ ​in​ ​other​ ​species
■ 1st​ ​toe​ ​is​ ​backwards
■ Used​ ​to​ ​disembowel​ ​prey
Tail​ ​may​ ​have​ ​been​ ​used​ ​as​ ​a​ ​weapon
Eg
...
5m​ ​tall)
● Had​ ​elongated​ ​and​ ​robust​ ​diapsid​ ​skulls
■ All​ ​crocodilians​ ​evolved​ ​from​ ​non-aquatic​ ​ancestors
○ 21​ ​extant​ ​species
○ Mainly​ ​tropical​ ​and​ ​subtropical
○ Primarily​ ​aquatic
○ Body​ ​plan
■ Well-developed​ ​limbs
■ Thecodont​ ​teeth
● Sit​ ​in​ ​sockets​ ​in​ ​the​ ​jaw
■ Complete​ ​secondary​ ​palate
● Allow​ ​them​ ​to​ ​eat​ ​and​ ​breathe​ ​at​ ​the​ ​same​ ​time
● More​ ​advanced​ ​than​ ​in​ ​the​ ​phytosaurs
○ nutrition/digestion
■ Stealth​ ​hunters
■ Bulk​ ​feeders
○ respiration/circulatory​ ​system/excretion
■ 4-chambered​ ​heart
● Complete​ ​separation​ ​of​ ​oxygen-rich​ ​and​ ​oxygen-poor​ ​blood
● Separation​ ​of​ ​pressure
○ High​ ​pressure​ ​to​ ​the​ ​systemic​ ​system,​ ​low​ ​pressure​ ​to
the​ ​circulatory​ ​system
■ Greater​ ​in​ ​left​ ​ventricle
● Left​ ​ventricle​ ​disproportionately​ ​larger
● High​ ​pressure​ ​needed​ ​as​ ​the​ ​systemic
system​ ​(overall​ ​body​ ​size)​ ​can​ ​be​ ​large
■ Variable​ ​flow
Joanna​ ​Griffith​ ​(2017)

Allows​ ​the​ ​shunting​ ​of​ ​blood​ ​from​ ​one​ ​side​ ​of​ ​the​ ​heart​ ​to​ ​the
other,​ ​depending​ ​on​ ​the​ ​situation
■ Valves​ ​prevent​ ​backflow
■ Blood​ ​flows​ ​into​ ​the​ ​right​ ​atrium​ ​from​ ​the​ ​systemic​ ​system,​ ​into​ ​the
right​ ​ventricle,​ ​and​ ​either​ ​flows​ ​through​ ​the​ ​pulmonary​ ​artery​ ​(to
become​ ​reoxygenated)​ ​or​ ​through​ ​the​ ​left​ ​aortic​ ​arch​ ​(to​ ​the​ ​viscera,
where​ ​high​ ​CO​2​​ ​levels​ ​acidify​ ​the​ ​stomach​ ​and​ ​aid​ ​digestion)
● Blood​ ​from​ ​the​ ​lungs​ ​flows​ ​into​ ​the​ ​left​ ​atrium,​ ​into​ ​the​ ​left
ventricle,​ ​and​ ​either​ ​flows​ ​through​ ​the​ ​right​ ​aortic​ ​arch​ ​(to​ ​the
head​ ​and​ ​tail)​ ​or​ ​through​ ​the​ ​foramen​ ​of​ ​panizza​ ​(middle​ ​of​ ​the
heart)​ ​into​ ​the​ ​left​ ​aortic​ ​arch​ ​(to​ ​the​ ​viscera)
■ At​ ​rest​ ​on​ ​the​ ​surface:
● Oxygen-poor​ ​blood​ ​in​ ​the​ ​right​ ​ventricle​ ​goes​ ​to​ ​the​ ​viscera​ ​to
aid​ ​digestion,​ ​oxygen-rich​ ​blood​ ​in​ ​the​ ​left​ ​ventricle​ ​goes​ ​to​ ​the
head​ ​and​ ​tail
○ No​ ​flow​ ​through​ ​the​ ​foramen​ ​of​ ​panizza
■ When​ ​active:
● Oxygen-poor​ ​blood​ ​in​ ​the​ ​right​ ​ventricle​ ​goes​ ​to​ ​the​ ​lungs,
oxygen-rich​ ​blood​ ​in​ ​the​ ​left​ ​ventricle​ ​goes​ ​to​ ​the​ ​head​ ​and​ ​tail
via​ ​the​ ​right​ ​aortic​ ​arch,​ ​and​ ​the​ ​viscera​ ​via​ ​the​ ​foramen​ ​of
panizza​ ​into​ ​the​ ​left​ ​aortic​ ​arch
○ Systemic​ ​and​ ​pulmonary​ ​systems​ ​kept​ ​separate
■ When​ ​diving:
● Exhale​ ​then​ ​dive
● Oxygen-poor​ ​blood​ ​goes​ ​to​ ​the​ ​viscera,​ ​oxygen-rich​ ​blood
goes​ ​to​ ​the​ ​head​ ​and​ ​tail
○ Very​ ​little​ ​blood​ ​goes​ ​through​ ​the​ ​pulmonary​ ​system​ ​as
the​ ​shunt​ ​(cogged​ ​valve)​ ​is​ ​shut
reproduction/development
■ Vocalisations​ ​and​ ​courtship​ ​rituals​ ​to​ ​attract​ ​mates
■ Create​ ​mound​ ​nests
● Lay​ ​40-60​ ​eggs
■ Temperature-sensitive​ ​sex​ ​determination
● Females​ ​produced​ ​at​ ​lower​ ​temperatures,​ ​males​ ​at​ ​higher
temperatures
○ Intermediate​ ​temperatures​ ​produce​ ​males
○ Pivotal​ ​temperature​ ​of​ ​the​ ​Nile​ ​crocodile​ ​is​ ​32
...

○ Ectotherms​ ​have​ ​more​ ​“spare”​ ​energy
Temperature​ ​regulation
● Why​ ​is​ ​it​ ​important?
○ Metabolic​ ​rate​ ​and​ ​temperature​ ​are​ ​linked
■ Increase​ ​in​ ​temperature​ ​=​ ​increase​ ​in​ ​metabolic​ ​rate
■ For​ ​metabolic​ ​rate​ ​to​ ​be​ ​maintained​ ​at​ ​a​ ​suitable​ ​level,​ ​temperature
must​ ​also​ ​be​ ​at​ ​a​ ​suitable​ ​level
○ Protein​ ​conformation​ ​is​ ​linked​ ​to​ ​temperature
■ Proteins​ ​denature​ ​at​ ​high​ ​temperatures
■ Proteins​ ​fail​ ​to​ ​assimilate​ ​at​ ​low​ ​temperatures
○ Q10​ ​temperature​ ​coefficient
■ Rate​ ​of​ ​change​ ​of​ ​a​ ​biological​ ​or​ ​chemical​ ​system​ ​by​ ​increasing​ ​the
temperature​ ​by​ ​10℃
● Allows​ ​comparison​ ​between​ ​animals
● Mechanisms​ ​of​ ​heat​ ​exchange​ ​between​ ​an​ ​animal​ ​and​ ​the​ ​environment
○ Conduction
○ Convection
○ Radiation
○ Evaporation
● Regulation​ ​of​ ​body​ ​temperature
○ Controlled​ ​by​ ​the​ ​hypothalamus
Joanna​ ​Griffith​ ​(2017)

Psychological​ ​responses​ ​(in​ ​endotherms)
Behavioural​ ​responses
■ Eg
...

○ If​ ​body​ ​temperature​ ​drops​ ​below​ ​lower​ ​critical​ ​temperature
■ Metabolic​ ​rate​ ​increases​ ​to​ ​stabilise​ ​body​ ​temperature
● Temperature​ ​and​ ​metabolic​ ​rate​ ​are​ ​linked,​ ​so​ ​metabolic​ ​rate
would​ ​have​ ​decreased​ ​with​ ​temperature
■ Zone​ ​of​ ​chemical​ ​thermogenesis
○ If​ ​body​ ​temperature​ ​drops​ ​below​ ​lower​ ​lethal​ ​temperature
■ Metabolic​ ​rate​ ​is​ ​at​ ​maximum,​ ​but​ ​body​ ​temperature​ ​continues​ ​to​ ​fall
● Heat​ ​production​ ​falls,​ ​which​ ​has​ ​a​ ​feedback​ ​effect​ ​on​ ​metabolic
rate
■ Leads​ ​to​ ​hypothermia​ ​and​ ​death
○ If​ ​body​ ​temperature​ ​increases​ ​above​ ​upper​ ​critical​ ​temperature
■ Non-evaporative​ ​heat​ ​loss​ ​is​ ​at​ ​maximum​ ​(eg
...
​ ​hummingbirds​ ​shutting​ ​down​ ​overnight
○ Allows​ ​energetic​ ​costs​ ​to​ ​be​ ​reduced​ ​while​ ​an​ ​organism
can’t​ ​be​ ​foraging
● Hibernation
○ Avoiding​ ​the​ ​costs​ ​of​ ​maintaining​ ​body​ ​temperature
over​ ​an​ ​extended​ ​period​ ​of​ ​time
■ Burning​ ​brown​ ​adipose​ ​tissue
● Designed​ ​for​ ​rapid​ ​metabolism​ ​to​ ​heat​ ​the​ ​body
● Often​ ​stored​ ​in​ ​the​ ​neck/shoulder​ ​region
○ Prevalent​ ​in​ ​newborns
■ Muscle​ ​contraction
● Eg
...
​ ​North​ ​American​ ​wood​ ​frogs
■ Supercooling
● Eg
...
​ ​surface​ ​fish
○ Can​ ​synthesize​ ​glycoproteins​ ​that​ ​prevent​ ​the​ ​growth​ ​of
ice​ ​crystals
Were​ ​dinosaurs​ ​endothermic?
● Big​ ​debate​ ​in​ ​paleontology
● Cellular​ ​evidence
○ Haversian​ ​systems​ ​in​ ​bone
■ Canals​ ​that​ ​deliver​ ​blood​ ​and​ ​nutrients​ ​to​ ​growing​ ​bone
■ Endothermic​ ​characteristic
● Well-developed​ ​in​ ​fast-growing​ ​endotherms​ ​and​ ​dinosaurs,
poorly-developed​ ​in​ ​slow-growing​ ​reptiles
■ However:
● Bones​ ​are​ ​not​ ​reliable​ ​evidence​ ​for​ ​endothermy
○ Crocodiles,​ ​turtles,​ ​and​ ​tortoises​ ​also​ ​have
well-developed​ ​haversian​ ​systems
● Lines​ ​of​ ​arrested​ ​growth​ ​in​ ​dinosaur​ ​bones​ ​(similar​ ​to​ ​tree
rings)​ ​match​ ​those​ ​you​ ​would​ ​see​ ​in​ ​an​ ​ectotherm
○ However,​ ​lines​ ​of​ ​arrested​ ​growth​ ​are​ ​also​ ​seen​ ​in​ ​the
bones​ ​of​ ​hibernating​ ​endotherms​ ​(eg
...
​ ​migration,​ ​to​ ​remove​ ​damage,​ ​etc
...
​ ​penguins,​ ​mouse​ ​birds),​ ​feathers​ ​grow​ ​all​ ​over
○ Body-contour​ ​feathers
■ Base​ ​is​ ​fluffy​ ​as​ ​barbules​ ​lack​ ​hooks,​ ​but​ ​feather​ ​is​ ​pennaceous
(zipped)​ ​further​ ​up
■ Used​ ​for​ ​insulation
○ Flight​ ​feathers
■ Remiges
● Primaries,​ ​secondaries,​ ​coverts
■ Retrices
○
○
○
○
○

Joanna​ ​Griffith​ ​(2017)

● Tail​ ​feathers
■ All​ ​stiff​ ​and​ ​pennaceous
○ Semiplumes
■ Halfway​ ​between​ ​down​ ​and​ ​contour​ ​feathers
■ Plumalaceous​ ​(fluffy​ ​a
ll​ ​the​ ​way​ ​down​ ​the​ ​feather)
○ Down
■ Plumalaceous
○ Bristles
■ Around​ ​base​ ​of​ ​bill,​ ​eyes,​ ​mouth
■ Stiff​ ​rachis​ ​and​ ​only​ ​proximal​ ​barbs
■ Full​ ​of​ ​melanin​ ​for​ ​strength
■ Like​ ​whiskers
○ Filoplumes
■ Fine,​ ​hair-like
■ Barbs​ ​only​ ​at​ ​tip
■ Tend​ ​to​ ​be​ ​associated​ ​with​ ​primaries​ ​and​ ​secondaries
■ May​ ​feed​ ​back​ ​information​ ​about​ ​wing​ ​position​ ​so​ ​that​ ​the​ ​bird​ ​can
make​ ​adjustments​ ​during​ ​flight
● Skeleton​ ​and​ ​bones
○ Fused​ ​bones
○ Hollow​ ​bones
■ Exceptionally​ ​light​ ​and​ ​sturdy
■ Pneumatised​ ​(full​ ​of​ ​air​ ​cavities)
■ Trabeculae
● Supporting​ ​struts
● Prevent​ ​bones​ ​from​ ​bending)
○ Skull​ ​predominantly​ ​fused​ ​into​ ​one​ ​piece
■ Makes​ ​up​ ​0
...
​ ​hoatzin​ ​are​ ​foliovores,​ ​ceca​ ​are​ ​used​ ​for​ ​the​ ​breakdown​ ​of
cellulose
● Anus​ ​terminates​ ​in​ ​the​ ​cloaca
Joanna​ ​Griffith​ ​(2017)

Digestion​ ​is​ ​adapted​ ​for​ ​highly​ ​varied​ ​diets
○ Nectar,​ ​fruit,​ ​plants,​ ​carrion,​ ​small​ ​animals​ ​(vertebrates​ ​and​ ​invertebrates
● Huge​ ​diversity​ ​of​ ​beak​ ​shapes​ ​for​ ​different​ ​foraging​ ​strategies
○ Insect​ ​catchers,​ ​insect​ ​nets,​ ​fruit​ ​pluckers,​ ​generalised​ ​bills,​ ​flesh​ ​tearers,​ ​dip
nets,​ ​fish​ ​graspers,​ ​fish​ ​spears,​ ​mud-sifters,​ ​water-strainers,​ ​seed-crackers,
pine-seed-extractors
Respiration/circulatory​ ​system/excretion
● Avian​ ​circulatory​ ​system
○ Four-chambered​ ​heart
○ Pulmonary​ ​and​ ​systemic​ ​circuits
■ The​ ​left-hand​ ​side​ ​of​ ​the​ ​heart​ ​pumps​ ​oxygen-rich​ ​blood​ ​to​ ​the​ ​body,
the​ ​right-hand​ ​side​ ​of​ ​the​ ​heart​ ​pumps​ ​oxygen-poor​ ​blood​ ​to​ ​the​ ​lungs
○ Fast​ ​heartbeat,​ ​inversely​ ​related​ ​to​ ​body​ ​size
○ Have​ ​nucleated,​ ​biconvex​ ​red​ ​blood​ ​cells
● Immune​ ​system
○ Phagocytes​ ​and​ ​amoeboid​ ​cells​ ​repair​ ​and​ ​destroy​ ​microbes​ ​very​ ​efficiently
■ Birds​ ​have​ ​a​ ​very​ ​good​ ​ability​ ​to​ ​repair​ ​themselves​ ​(perhaps​ ​linked​ ​to
their​ ​fragility)
● Avian​ ​respiratory​ ​system
○ Adapted​ ​to​ ​meet​ ​high​ ​metabolic​ ​demands
○ Parabronchi
■ Enable​ ​continuous​ ​airflow
■ Highly​ ​vascularised​ ​(lots​ ​of​ ​blood​ ​vessels)
○ Made​ ​up​ ​of​ ​lungs,​ ​and​ ​many​ ​interconnecting​ ​air​ ​sacs​ ​in​ ​the​ ​thorax​ ​and
abdomen
■ Lung​ ​is​ ​continuous​ ​(open​ ​at​ ​both​ ​ends,​ ​not​ ​saclike)
○ Inhale,​ ​75%​ ​of​ ​air​ ​goes​ ​into​ ​posterior​ ​air​ ​sacs,​ ​25%​ ​to​ ​the​ ​lungs,​ ​exhale,
posterior​ ​air​ ​sac​ ​pushes​ ​air​ ​into​ ​lungs,​ ​inhale,​ ​air​ ​moves​ ​to​ ​anterior​ ​air​ ​sacs,
exhale,​ ​air​ ​leaves​ ​body
■ Takes​ ​two​ ​respiratory​ ​cycles​ ​for​ ​a​ ​single​ ​breath​ ​of​ ​air​ ​to​ ​complete​ ​the
circuit
■ Provides​ ​a​ ​continuous​ ​supply​ ​of​ ​oxygen
Nervous​ ​system/sense​ ​organs
● Important​ ​for​ ​reproduction
● Vision
○ Very​ ​good​ ​in​ ​some​ ​species
○ Large​ ​eyes
■ Large​ ​eye​ ​sockets​ ​in​ ​skull
○ Eyes​ ​meet​ ​in​ ​the​ ​middle​ ​of​ ​the​ ​skull
○ Tube-shaped​ ​eyes,​ ​instead​ ​of​ ​flattened​ ​spheres
○ Pecten​ ​at​ ​the​ ​back​ ​of​ ​the​ ​eye
■ Made​ ​up​ ​of​ ​capillaries,​ ​pigment,​ ​and​ ​a​ ​membrane
■ Huge​ ​blood​ ​supply,​ ​most​ ​likely​ ​used​ ​to​ ​remove​ ​metabolic​ ​waste
products​ ​from​ ​the​ ​eye
■ Linked​ ​to​ ​the​ ​retina​ ​and​ ​optic​ ​nerve
○ Cone​ ​cells​ ​contain​ ​droplets​ ​of​ ​coloured​ ​oil
●

Joanna​ ​Griffith​ ​(2017)

■
■
●

Act​ ​as​ ​filters,​ ​absorbing​ ​and​ ​reflecting​ ​certain​ ​wavelengths​ ​of​ ​light​ ​(eg
...
​ ​colour​ ​of​ ​pigments)​ ​conserved​ ​within​ ​groups
● Links​ ​with​ ​lifestyle​ ​and​ ​food​ ​acquisition

Hearing
○ Stapes​ ​transmits​ ​vibrations​ ​through​ ​the​ ​ear
■ Can​ ​detect​ ​the​ ​frequency​ ​and​ ​temporal​ ​patterns​ ​of​ ​sound​ ​vibrations
○ 10x​ ​the​ ​number​ ​of​ ​hair​ ​cells​ ​that​ ​mammals​ ​have
■ Allows​ ​it​ ​to​ ​separate​ ​many​ ​sound​ ​waves​ ​hitting​ ​a​ ​small​ ​skull
■ Better​ ​localisation​ ​of​ ​sound,​ ​from​ ​both​ ​internal​ ​and​ ​external​ ​sources
○ Reduction​ ​ratio​ ​change
■ The​ ​greater​ ​the​ ​ratio,​ ​the​ ​better​ ​the​ ​hering
○ Eg
...

● Learning​ ​period​ ​varies​ ​in​ ​different​ ​species
○ Experiences​ ​in​ ​early​ ​life​ ​create​ ​links​ ​in​ ​vocal​ ​muscles
○ Hormonal​ ​control​ ​in​ ​song​ ​control​ ​region
● Different​ ​bird​ ​populations​ ​have​ ​different​ ​dialects​ ​and
repertoires
○ Neighbour​ ​recognition
■ Mimicry
○ Visual
■ Body​ ​postures
■ Brightly​ ​coloured​ ​males
● Is​ ​bright​ ​plumage​ ​an​ ​honest​ ​signal?
■ Exaggerated​ ​sexual​ ​traits
■ Building​ ​of​ ​attractive​ ​structures​ ​(eg
...
​ ​red-billed​ ​buffalo​ ​weaver
■ Has​ ​a​ ​false​ ​penis,​ ​which​ ​is​ ​non-intromittent​ ​but​ ​may​ ​stimulate​ ​the
female​ ​during​ ​copulation

Joanna​ ​Griffith​ ​(2017)

Avian​ ​penis
■ Erectile​ ​expansion​ ​of​ ​the​ ​cloacal​ ​wall
● Full​ ​of​ ​lymph,​ ​not​ ​blood
■ Many​ ​waterfowl​ ​have​ ​huge​ ​cloacas
● Eg
...
​ ​Seychelles​ ​warbler)​ ​can​ ​determine​ ​the​ ​sex​ ​of​ ​the
first​ ​egg
○ Incubation
■ Different​ ​incubation​ ​strategies
● When​ ​the​ ​first​ ​egg​ ​is​ ​laid,​ ​or​ ​when​ ​the​ ​last​ ​egg​ ​is​ ​laid
○ Prolactin​ ​production​ ​synchronises​ ​when​ ​all​ ​eggs​ ​are
incubated​ ​at​ ​the​ ​same​ ​time,​ ​synchronises​ ​development
■ Survival​ ​chances​ ​are​ ​better​ ​when​ ​chicks​ ​hatch
together
■ Brood​ ​patch​ ​maintains​ ​eggs​ ​at​ ​33-35°C
■ Incubation​ ​is​ ​expensive​ ​as​ ​foraging​ ​time​ ​is​ ​lost
○

●

●

●

Joanna​ ​Griffith​ ​(2017)

●

●

Chicks
○ Precocial
■ Born​ ​downy
■ Nidifugous​ ​(leave​ ​the​ ​nest​ ​soon​ ​after​ ​hatching)
● Able​ ​to​ ​feed​ ​themselves
■ Often​ ​more​ ​yolk​ ​in​ ​egg
○ Altricial
■ Born​ ​naked
■ Nidiculous​ ​(stay​ ​in​ ​the​ ​nest​ ​for​ ​a​ ​while)
● Require​ ​prolonged​ ​care
○ Some​ ​types​ ​of​ ​chicks​ ​are​ ​between​ ​the​ ​two​ ​categories
Mating​ ​ ​systems
○ Determined​ ​by​ ​food​ ​availability,​ ​breeding​ ​site​ ​availability,​ ​and​ ​potential​ ​mates
■ Eg
...
​ ​adelie​ ​penguins​ ​will​ ​trade​ ​stones​ ​(used​ ​for
making​ ​nests)​ ​for​ ​copulations
■ Eg
...
​ ​cuckoos​ ​with​ ​dark
eggs​ ​lay​ ​in​ ​dark​ ​nests)
● Host​ ​parents​ ​cannot​ ​abandon​ ​the​ ​cuckoo​ ​chick​ ​as​ ​the​ ​costs​ ​of
being​ ​wrong​ ​(and​ ​maybe​ ​abandoning​ ​your​ ​own​ ​chick)​ ​are
greater​ ​than​ ​the​ ​benefits​ ​of​ ​abandoning​ ​a​ ​parasitic​ ​chick
● Chicks​ ​often​ ​match​ ​host​ ​chicks
Cooperative​ ​breeding
■ Occurs​ ​in​ ​about​ ​300​ ​species
■ Pair​ ​may​ ​have​ ​a​ ​helper,​ ​or​ ​in​ ​a​ ​group,​ ​many​ ​helpers
● Can​ ​lead​ ​to​ ​polygynandrous​ ​systems
■ Helpers​ ​may​ ​be​ ​retained​ ​offspring​ ​from​ ​the​ ​previous​ ​year
● Selective​ ​pressures​ ​may​ ​prevent​ ​juvenile​ ​dispersal
○ Too​ ​costly​ ​to​ ​find​ ​own​ ​mate
○ Kin-selected​ ​benefits
○ Access​ ​to​ ​benefits​ ​of​ ​group​ ​living
■ Increased​ ​group​ ​size​ ​=​ ​increased​ ​territory​ ​size​ ​=
independent​ ​breeding​ ​opportunities
■ Eg
...
​ ​diel​ ​vertical​ ​migration​ ​of​ ​zooplankton​ ​and​ ​phytoplankton
Avian​ ​migration:​ ​twice​ ​annual​ ​movement​ ​between​ ​a​ ​restricted​ ​breeding/wintering
area​ ​and​ ​a​ ​restricted​ ​wintering/breeding​ ​area
○ Movement​ ​to​ ​higher​ ​latitudes​ ​in​ ​spring
■ Suitable​ ​uncongested​ ​breeding​ ​sites
■ Abundant​ ​food​ ​(spring​ ​growth)
■ Long​ ​daylight​ ​hours
○ Movement​ ​to​ ​lower​ ​latitudes​ ​in​ ​autumn
■ Avoid​ ​cold,​ ​stormy​ ​weather
■ Avoid​ ​food​ ​shortages
■ Avoid​ ​short​ ​daylight​ ​hours
○ Altitudinal​ ​migration
■ Birds​ ​move​ ​up​ ​and​ ​down​ ​mountains,​ ​based​ ​on​ ​seasonal​ ​change
○ Austral​ ​migrants
■ About​ ​240​ ​species
■ Migrate​ ​both​ ​north​ ​and​ ​south​ ​to​ ​breed
Orientation​ ​and​ ​navigation
○ Routes
■ Innate​ ​in​ ​many​ ​species
● Eg
...
​ ​geese​ ​often​ ​have​ ​to​ ​migrate​ ​with​ ​their​ ​parents
○ Use​ ​various​ ​cues,​ ​not​ ​mutually​ ​exclusive
■ Local​ ​landmarks
■ Olfactory​ ​cues
■ Sun​ ​(sun​ ​azimuth​ ​orientation)
● Requires​ ​a​ ​good​ ​internal​ ​clock
■ Celestial​ ​cues
■ Electromagnetic​ ​fields
■ Can​ ​detect​ ​polarised​ ​light
● Polarised​ ​light​ ​used​ ​after​ ​sunset
○ Zugunruhe:​ ​migratory​ ​restlessness​ ​(triggered​ ​by​ ​day​ ​length​ ​and​ ​internal
circannual​ ​rhythms)
○ Zustimmung:​ ​migratory​ ​flight
○ Zugdisposition:​ ​preparing​ ​to​ ​migrate,​ ​heavy​ ​fattening​ ​and​ ​feeding
■ Can​ ​increase​ ​body​ ​mass​ ​by​ ​20-55%
■ Rapidly​ ​metabolised​ ​energy​ ​sources
● Night​ ​flying,​ ​day​ ​feeding​ ​or​ ​staggering​ ​flight​ ​and​ ​feeding
○ Stopover​ ​and​ ​staging​ ​sites
Physiological​ ​changes
○ Reduction​ ​of​ ​liver​ ​size
○ Reduction​ ​of​ ​kidney​ ​size
○ Reduction​ ​of​ ​intestine​ ​length
Joanna​ ​Griffith​ ​(2017)

●

●

○ Reduction​ ​of​ ​stomach​ ​size
○ Hypertrophy​ ​of​ ​heart​ ​muscles
○ Hypertrophy​ ​of​ ​pectoral​ ​muscles
Flyways
○ Well-established​ ​routes​ ​around​ ​the​ ​globe
○ Exploited​ ​by​ ​predators​ ​(eg
...
​ ​swainson’s​ ​thrush
■ Coastal​ ​and​ ​inland​ ​subspecies,​ ​with​ ​a​ ​hybrid​ ​zone​ ​in​ ​British​ ​Columbia
● Different​ ​migratory​ ​routes​ ​have​ ​led​ ​to​ ​speciation
○ Eg
...
​ ​greenland​ ​white-fronted​ ​goose
■ Fly​ ​UK-Iceland​ ​in​ ​one​ ​flight,​ ​stay​ ​for​ ​a​ ​few​ ​weeks,​ ​then
Iceland-Greenland​ ​in​ ​another​ ​continuous​ ​flight
Stopovers​ ​and​ ​staging
○ Migration​ ​is​ ​typically​ ​stop-start
■ Migration​ ​is​ ​constrained​ ​by​ ​how​ ​much​ ​fuel​ ​can​ ​be​ ​taken​ ​on​ ​in​ ​one​ ​go,
and​ ​how​ ​far​ ​a​ ​bird​ ​can​ ​continuously​ ​fly
■ Intermediate​ ​sites
○ Stopover
■ Sites​ ​where​ ​birds​ ​can​ ​refuel​ ​and​ ​rest​ ​for​ ​a​ ​couple​ ​of​ ​days​ ​en-route
○ Stage
■ Sites​ ​where​ ​birds​ ​stop​ ​for​ ​a​ ​longer​ ​period​ ​of​ ​time
■ Staging​ ​sites​ ​can​ ​have​ ​carry-over​ ​effects,​ ​where​ ​individual​ ​fitness​ ​can
be​ ​affected​ ​over​ ​several​ ​seasons​ ​depending​ ​on​ ​the​ ​quality​ ​of​ ​the​ ​site

Flight
● Categories​ ​of​ ​flight
○ Parachuting
■ Angle​ ​of​ ​descent​ ​>45°
○ Gliding
■ Angle​ ​of​ ​descent​ ​<45°
○ Powered
■ No​ ​angle​ ​of​ ​descent
● Flight​ ​is​ ​the​ ​characteristic​ ​mode​ ​of​ ​locomotion​ ​for​ ​three​ ​main​ ​groups​ ​of​ ​vertebrates
○ Pterosaurs
■ 100+​ ​species
■ Extinct
○ Bats
■ 830+​ ​species
○ Birds
■ Around​ ​10,000​ ​species
● Origin​ ​of​ ​avian​ ​flight
○ Feathers​ ​evolved​ ​before​ ​flight
■ Must​ ​have​ ​had​ ​other​ ​uses

Joanna​ ​Griffith​ ​(2017)

○

●

Trees-down
■ Arboreal​ ​animals​ ​leapt​ ​out​ ​of​ ​trees​ ​and​ ​glided​ ​down​ ​onto​ ​prey
● Some​ ​fossil​ ​evidence​ ​to​ ​suggest​ ​tree-climbers​ ​did​ ​exist
● Over​ ​time,​ ​gliding​ ​combined​ ​with​ ​weak​ ​flapping​ ​eventually
resulted​ ​in​ ​powered​ ​flight
○ Ground-up
■ The​ ​majority​ ​of​ ​dromaeosaurs​ ​(from​ ​which​ ​birds​ ​evolved)​ ​were
terrestrial​ ​(no​ ​tree-climbing)
● Bipedal​ ​and​ ​fast,​ ​may​ ​have​ ​initially​ ​used​ ​wings​ ​to​ ​bat​ ​prey​ ​out
of​ ​the​ ​air
● Archaeopteryx​ ​morphology
■ May​ ​have​ ​leapt​ ​into​ ​the​ ​air​ ​or​ ​forwards,​ ​this​ ​motion​ ​combined​ ​with
weak​ ​flapping​ ​motions​ ​may​ ​have​ ​led​ ​to​ ​powered​ ​flight
● Used​ ​to​ ​control​ ​movement​ ​and​ ​landing
● Wing-assisted​ ​incline​ ​running
Basic​ ​principles​ ​of​ ​flight
○ Animal​ ​needs​ ​to​ ​generate​ ​enough​ ​lift​ ​to​ ​overcome​ ​its​ ​body​ ​mass​ ​and​ ​the
force​ ​of​ ​gravity​ ​(weight),​ ​and​ ​thrust​ ​to​ ​propel​ ​it​ ​forward​ ​once​ ​in​ ​the​ ​air
■ Should​ ​also​ ​have​ ​features​ ​that​ ​minimise​ ​drag
○ Parachuting
■ Creating​ ​a​ ​drag​ ​force​ ​which​ ​acts​ ​in​ ​direct​ ​opposition​ ​to​ ​the​ ​pull​ ​through
the​ ​centre​ ​of​ ​gravity
■ Focus​ ​on​ ​maximising​ ​drag​ ​to​ ​slow​ ​the​ ​rate​ ​of​ ​descent
■ Angle​ ​of​ ​descent​ ​is​ ​greater​ ​than​ ​45°
■ V​ ​(speed​ ​you​ ​fall​ ​at)​ ​varies​ ​with​ ​the​ ​square​ ​root​ ​of​ ​WA​ ​(weight​ ​x​ ​area)
● Larger​ ​area​ ​=​ ​slower​ ​speed​ ​of​ ​falling
■ Function:
● Break​ ​a​ ​fall
● Cross​ ​gaps
● Escape​ ​from​ ​predators​ ​or​ ​competitors
● Move​ ​quickly​ ​between​ ​objects​ ​(eg
...
​ ​by​ ​waves,​ ​hills,​ ​and​ ​birds​ ​follow​ ​the​ ​rising​ ​air
○ Thermal​ ​soaring
■ Sun​ ​heats​ ​the​ ​ground,​ ​warm​ ​air​ ​rises,​ ​birds​ ​circle​ ​within​ ​the​ ​column​ ​of
rising​ ​air​ ​to​ ​gain​ ​height
■ Mainly​ ​used​ ​by​ ​large​ ​raptors​ ​and​ ​large​ ​water​ ​birds​ ​(eg
...
​ ​albatrosses)
● Wings​ ​are​ ​long​ ​and​ ​thin
Powered​ ​flight
○ Requirements:
■ Generate​ ​enough​ ​lift​ ​to​ ​counter​ ​gravity
■ Generate​ ​propulsive​ ​force​ ​to​ ​counter​ ​drag
■ Generate​ ​enough​ ​thrust​ ​for​ ​take-off
■ Absorb​ ​the​ ​shocks​ ​of​ ​landing
■ Minimise​ ​drag
■ Remain​ ​stable
Joanna​ ​Griffith​ ​(2017)

○

○

○

○

■ Maneuverable,​ ​and​ ​coordinated​ ​movements
■ Light​ ​and​ ​strong
Wing​ ​structure
■ Wing​ ​loading​ ​=​ ​body​ ​weight/wing​ ​area
● Small​ ​wing​ ​area​ ​=​ ​high​ ​wing​ ​loading​ ​(eg
...
​ ​albatrosses)
■ Wing​ ​shape​ ​and​ ​size​ ​differs​ ​with​ ​habits
● Elliptical​ ​wings
○ Eg
...
​ ​vultures
○ Suited​ ​for​ ​static​ ​soaring
○ Medium​ ​wing​ ​loading,​ ​low​ ​aspect​ ​ratio
● High​ ​speed​ ​wings
○ Eg
...
​ ​albatrosses
○ Suited​ ​for​ ​dynamic​ ​soaring
○ High​ ​wing​ ​loading,​ ​high​ ​aspect​ ​ratio
How​ ​is​ ​power​ ​for​ ​flight​ ​generated?
■ Pectoralis​ ​muscles
● Make​ ​up​ ​35%​ ​of​ ​body​ ​weight
● Attached​ ​to​ ​the​ ​sternum,​ ​and​ ​directly​ ​to​ ​the​ ​lower​ ​side​ ​of​ ​the
humerus
● Powers​ ​the​ ​down​ ​stroke
■ Supracoracoideus​ ​muscle
● Attached​ ​the​ ​the​ ​sternum,​ ​and​ ​to​ ​the​ ​upper​ ​side​ ​of​ ​the
humerus​ ​by​ ​a​ ​tendon
● Raises​ ​the​ ​wing​ ​on​ ​the​ ​upstroke
○ Rapid​ ​rotation​ ​at​ ​the​ ​top​ ​of​ ​the​ ​upstroke
Landing
■ Birds​ ​are​ ​bipedal
■ Short​ ​body​ ​axis​ ​and​ ​fused​ ​vertebrae​ ​help​ ​to​ ​absorb​ ​some​ ​of​ ​the
impact
■ Compressible​ ​and​ ​extensible​ ​hind​ ​limbs​ ​(like​ ​springs)
● Attached​ ​to​ ​synsacrum
Complementary​ ​adaptations
■ Streamlined​ ​body​ ​to​ ​reduce​ ​drag
■ Large​ ​cerebellum
● Responsible​ ​for​ ​coordination
■ Box-like​ ​thorax,​ ​fused​ ​bones​ ​for​ ​strength
Joanna​ ​Griffith​ ​(2017)

■
■
■

Skeleton​ ​is​ ​light,​ ​only​ ​7%​ ​of​ ​body​ ​mass
● Hollow​ ​bones
No​ ​teeth
Oviparity
● No​ ​retention​ ​of​ ​young
Gonadal​ ​recrudescence

■
Birds​ ​and​ ​humans
● Humans​ ​can​ ​have​ ​huge​ ​impacts​ ​on​ ​birds
○ Exploitation
○ Conservation
○ Extinction
■ Eg
...
​ ​St​ ​Stephen’s​ ​Island​ ​wren
○ Humans​ ​colonised​ ​the​ ​island,​ ​set​ ​up​ ​a​ ​lighthouse,​ ​and
brought​ ​a​ ​cat
■ Cat​ ​single-handedly​ ​wiped​ ​out​ ​these​ ​small
flightless​ ​birds
● Eg
...
​ ​Haast’s​ ​eagle
● Eg
...
​ ​ostriches,​ ​rheas,​ ​cassowaries,​ ​kiwis,​ ​emus
○ Non-keeled​ ​sternum
○ Some​ ​still​ ​have​ ​dinosaur-like​ ​back​ ​claws
● Tinamiformes
○ About​ ​47​ ​species
■ Eg
...
)
● Most​ ​diverse​ ​terrestrial​ ​group​ ​of​ ​vertebrates
○ 60%​ ​are​ ​passerines​ ​(perching​ ​songbirds)
○ Split​ ​into​ ​20+​ ​major​ ​groups
■ Eg
...
​ ​dicynodonts,​ ​therocephalians)​ ​went​ ​extinct​ ​in​ ​the​ ​P/T
extinction
● Cynodonts​ ​survived,​ ​became​ ​mammals
■ Cynodonts
● Mammal-like
● Small​ ​body​ ​size
● Multi-cusped​ ​teeth​ ​in​ ​the​ ​cheek
● Enlarged​ ​infraorbital​ ​foramen
○ Hole​ ​in​ ​the​ ​skull​ ​where​ ​nerves​ ​from​ ​nasal​ ​cavity​ ​pass​ ​to
brain
○ Suggests​ ​good​ ​sense​ ​of​ ​smell
■ Backed​ ​up​ ​by​ ​the​ ​presence​ ​of​ ​turbinate​ ​bones
● Probainognathan​ ​lineage​ ​gave​ ​rise​ ​to​ ​the​ ​mammals
○ Changes​ ​to​ ​the​ ​jaw​ ​and​ ​skull
■ Skull​ ​of​ ​an​ ​early​ ​synapsid
● Primitive​ ​jaw​ ​joint,​ ​found​ ​in​ ​other
tetrapods​ ​and​ ​fish
● In​ ​cynodonts,​ ​the​ ​size​ ​of​ ​the
post-dentary​ ​bones​ ​decreases,​ ​while​ ​the
size​ ​of​ ​the​ ​dentary​ ​bones​ ​increases
○ Trade-off​ ​between​ ​hearing​ ​and
eating
○ New​ ​jaw​ ​joint​ ​forms​ ​the​ ​quadrate
and​ ​articular​ ​bones,​ ​which​ ​create
the​ ​incus​ ​and​ ​malleus​ ​in​ ​the
inner​ ​ear
■ Brain​ ​enlargement
■ Post-canine​ ​teeth,​ ​with​ ​split​ ​roots
○ Small,​ ​shrew-like​ ​insectivores​ ​appeared​ ​in​ ​the​ ​early
Jurassic​ ​(possibly​ ​the​ ​late​ ​Triassic)
Earliest​ ​mammals
○ The​ ​Mesozoic​ ​contains​ ​2/3rds​ ​of​ ​mammalian​ ​history
○ Homogenous​ ​body​ ​plan,​ ​but​ ​highly​ ​diverse​ ​forms
○ Insectivores,​ ​omnivores,​ ​carnivores
○ Limited​ ​size
■ The​ ​largest​ ​mammal​ ​was​ ​about​ ​the​ ​size​ ​of​ ​a​ ​medium-sized​ ​dog
■ May​ ​have​ ​been​ ​a​ ​result​ ​of​ ​competition​ ​with​ ​dinosaurs
○ Predatory​ ​forms,​ ​gliders,​ ​diggers,​ ​swimmers
○ Boreospehnidans
■ Therian​ ​mammals
○ Australosphenidans
■ Monotremes
○ Development​ ​of​ ​lactation​ ​and​ ​suckling
Cenozoic​ ​mammal​ ​groups
○ Allotheria
■ Multituberculates​ ​(extinct)
■

●

●

Joanna​ ​Griffith​ ​(2017)

Multicusped​ ​teeth,​ ​used​ ​for​ ​grinding
● Shearing​ ​premolar,​ ​lower​ ​jaw​ ​moves​ ​backwards
■ Terrestrial,​ ​semi-arboreal
■ Narrow​ ​pelvis
● Gave​ ​birth​ ​to​ ​poorly​ ​developed​ ​offspring
Reproduction/development
● Lactation
○ Occlusion​ ​teeth
■ Contact​ ​between​ ​teeth
○ Mammary​ ​glands
■ Highly​ ​modified​ ​sebaceous​ ​glands
○ Evolved​ ​as​ ​a​ ​way​ ​to​ ​transfer​ ​antibodies​ ​from​ ​mother​ ​to​ ​offspring
■ Controlled​ ​inflammatory​ ​response
■ Colostrum​ ​contains​ ​anti-bacterial​ ​substances​ ​and​ ​antibodies
■ Other​ ​benefits​ ​(eg
...
5-16kg
■ Designed​ ​for​ ​a​ ​fossorial​ ​lifestyle
■ Covered​ ​in​ ​keratinous​ ​spines
● Attached​ ​to​ ​panniculus​ ​carnosus
○ Layer​ ​of​ ​muscle​ ​tissue​ ​under​ ​skin
■ Sticky​ ​and​ ​spiny​ ​tongue​ ​and​ ​palate
■ Have​ ​mechano-​ ​and​ ​electroreceptors
■ Can​ ​go​ ​into​ ​torpor​ ​when​ ​environmental​ ​conditions​ ​are​ ​unstable
● Reduce​ ​body​ ​temperature​ ​to​ ​3
...
4​ ​million​ ​years​ ​ago
● Discovered​ ​in​ ​1924
■ Australopithecus​ ​afarensis
● Lucy
○ Discovered​ ​in​ ​the​ ​Afar​ ​region​ ​of​ ​Ethiopia​ ​in​ ​1924
○ 3
...
​ ​afarensis​ ​skeletons
suggest​ ​an​ ​arboreal​ ​lifestyle
■ Lucy​ ​was​ ​a​ ​gracile​ ​form
○ Brain​ ​size​ ​of​ ​an​ ​equivalent-sized​ ​chimp
■ Ardipithecus​ ​ramidus
●
●
●
●

Joanna​ ​Griffith​ ​(2017)

●
●
●
●
●

○

○

Found​ ​in​ ​Aramis,​ ​Ethiopia
4
...
2m​ ​tall,​ ​52kg
Bipedal​ ​on​ ​the​ ​ground,​ ​quadrupedal​ ​in​ ​trees
○ Rigid​ ​foot​ ​structure,​ ​but​ ​outward-facing​ ​big​ ​toe
○ Sex​ ​suggested​ ​as​ ​reason​ ​for​ ​bipedalism
■ Pair​ ​bonds,​ ​parental​ ​care​ ​=​ ​no​ ​sexual​ ​selection
■ Standing​ ​upright​ ​makes​ ​provisioning​ ​offspring
easier
○ Partially​ ​arboreal​ ​life,​ ​in​ ​moist​ ​forests
○ Highly​ ​flexible​ ​wrists,​ ​like​ ​primitive​ ​apes/chimps

Gracile​ ​forms
■ More​ ​generalist
■ Less​ ​massively​ ​built​ ​(40kg,​ ​1
...
​ ​Paranthropus​ ​robustus
■ Strong​ ​jaws
■ Grinding​ ​teeth
■ Large​ ​body​ ​size
■ Specialised​ ​herbivores,​ ​ate​ ​nuts​ ​and​ ​seeds
■ Died​ ​out​ ​1​ ​million​ ​years​ ​ago

Bipedalism
● Climate​ ​was​ ​becoming​ ​cooler​ ​and​ ​drier,​ ​forests​ ​became​ ​restricted​ ​and
savannah/grassland​ ​began​ ​to​ ​take​ ​over
○ Two​ ​potential​ ​niches:
■ Low​ ​grade​ ​grasses,​ ​in​ ​large​ ​groups
■ High​ ​grade​ ​meat​ ​and​ ​nuts,​ ​in​ ​small,​ ​territorial​ ​groups
● Advantages:
○ Energetic​ ​(more​ ​efficient​ ​locomotion)
○ Height​ ​(able​ ​to​ ​see​ ​over​ ​long​ ​grass,​ ​detect​ ​predators)
○ Hunting​ ​prey
○ Thermal​ ​(less​ ​body​ ​surface​ ​exposed​ ​to​ ​sun,​ ​50%​ ​less​ ​water​ ​demand)
○ Front​ ​limbs​ ​freed​ ​for​ ​other​ ​uses​ ​(eg
...
5​ ​million​ ​years​ ​ago
○ Cooler​ ​and​ ​drier​ ​climate,​ ​reduced​ ​tree​ ​cover
● Homo​ ​habilis
○ “Handy​ ​man”
■ Produced​ ​stone​ ​tools
● Tools​ ​used​ ​multiple​ ​times​ ​and​ ​carried​ ​10-100km​ ​from​ ​the​ ​site
of​ ​manufacture
● May​ ​have​ ​been​ ​important​ ​for​ ​evolutionary​ ​change
○ Short​ ​jaw,​ ​large​ ​brain​ ​(600-750cm​3​)
Joanna​ ​Griffith​ ​(2017)

●

●

●

Tool​ ​use
○ 2
...
​ ​ergaster
● Tall​ ​and​ ​slender,​ ​small​ ​teeth
● Fully​ ​bipedal
● Relatively​ ​large​ ​brain
● Short,​ ​straight​ ​fingers
○ Suggests​ ​that​ ​they​ ​were​ ​not​ ​arboreal​ ​in​ ​any​ ​way
● Used​ ​more​ ​sophisticated​ ​stone​ ​tools
● Reduced​ ​sexual​ ​dimorphism
○ Suggests​ ​more​ ​pair-bonding​ ​and​ ​parental​ ​care,​ ​less
male-male​ ​competition
● Widespread​ ​distribution
■ H
...
​ ​ergaster
● First​ ​to​ ​colonise​ ​Asia​ ​(reached​ ​East​ ​Asia​ ​1​ ​million​ ​years​ ​ago)
● Slightly​ ​larger​ ​brain​ ​than​ ​H
...
​ ​ergaster
■ Small​ ​H
...
​ ​antecessor​ ​in​ ​Spain,​ ​H
...
​ ​sapiens​ ​fossils​ ​found​ ​in​ ​Zambia
○ Neanderthals
■ Found​ ​in​ ​Europe​ ​and​ ​Western​ ​Asia
■ Thick-boned
■ Prominent​ ​brow
■ Brain​ ​as​ ​large​ ​as​ ​those​ ​of​ ​modern​ ​humans
■ More​ ​robust,​ ​and​ ​possessed​ ​various​ ​adaptations​ ​for​ ​living​ ​in​ ​cold
conditions
■ Scavengers,​ ​hunters
Joanna​ ​Griffith​ ​(2017)

○

○

○

● Largely​ ​carnivorous​ ​(possibly​ ​cannibalistic)
■ Lived​ ​in​ ​caves,​ ​cold​ ​steppe,​ ​conifer​ ​forests
■ Wore​ ​furs,​ ​used​ ​fire
■ Used​ ​stone​ ​and​ ​wooden​ ​tools
■ May​ ​have​ ​been​ ​able​ ​to​ ​communicate
■ Buried​ ​their​ ​dead
■ Died​ ​out​ ​28,000​ ​years​ ​ago
Homo​ ​sapiens
■ 100,000-50,000​ ​years​ ​old
■ Lived​ ​side-by-side​ ​with​ ​Neanderthals​ ​in​ ​the​ ​Middle​ ​East
● Possible​ ​cultural​ ​exchange
● Possible​ ​genetic​ ​mixing
○ Some​ ​genes​ ​are​ ​so​ ​old,​ ​they​ ​are​ ​speculated​ ​to​ ​have
come​ ​from​ ​Neanderthals
■ Recent​ ​genetic​ ​studies​ ​suggest​ ​that​ ​this​ ​is
unlikely
■ Studies​ ​of​ ​mitochondrial​ ​DNA​ ​and​ ​y​ ​chromosomes​ ​suggest​ ​that
modern​ ​humans​ ​evolved​ ​in​ ​east​ ​Africa​ ​80,000​ ​years​ ​ago,​ ​then​ ​moved
rapidly​ ​across​ ​the​ ​world
● Rapid​ ​expansion​ ​possibly​ ​due​ ​to​ ​changes​ ​in​ ​cognition
■ Very​ ​little​ ​variation​ ​in​ ​humans
Weaponry
■ Neanderthal​ ​weapons
● Handheld
● Had​ ​to​ ​be​ ​in​ ​close​ ​contact​ ​with​ ​the​ ​animal
○ Lots​ ​of​ ​evidence​ ​of​ ​skeletal​ ​damage
■ H

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