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Summary for Semester Exam
Parazoa
Phylum: Porifera
 “Pore-bearers” - sponges
 Loose federation of cells in gelatinous matrix
 Freshwater or marine
 Filter/suspension feeders
 Distinct shapes in calm water, can modify structure
 Asexual and sexual reproduction
...
Polyp is sessile, while medusa is motile
...

 Gastrovascular cavity: feeding, respiration, and waste elimination
 Acoelomatic (no coelom)
 No brain (or head) or muscle tissues, but have nerve net and contractile filaments
 Nemocyst: barb on tentacles responsible for stinging
...
Life cycle simple: eggs laid, fall off host, hatch,
larva seeks new host
o Trematoda (flukes): flat leaf-like body; obligate parasite
...
Most
hermaphrodite
...
Veterinary importance:
condemnation of liver, disease and/or death in sheep and cattle, public health concerns
...
2nd most important parasite after malaria
...

o Cestoda (tapeworms): parasites of small intestine, tapelike body; no mouth, digestive tract or anus - nutrients
absorbed across body surface
...
In pigs, cysticerci stay in muscles
o Hydatid tapeworm: definitive host can be dog, dingo or fox
...
Final hsot infected by ingesting contents of hydatid cyst from
raw offal of intermediate host
...
Cystic form can undergo asexual
reproduction
Phylum: Mollusca
 Includes chitons, gastropods, bivalves and cephalopods
...
Coelom present, but greatly reduced
...
Anus over its head (torsion) as well as gills
...

 Segmentation allots better control of body sections, and diversification of functions
...
Coelomic fluid protects
internal organs
...
Use head
region to attach to intestinal wall
 Life cycle of Macracanthorhychus hirudinaceus (large spiny-headed leach-like worm)

Phylum: Nematoda
 Roundworms
o Most microscopic; interstitial dwellers (freshwater, marine, soil); decomposers, many
parasitic to plants and animals, some greater than 1m
o Non-segmented (rings in cuticle), cylindrical, tapered both ends; complete gut with mouth
and anus
o Most dioecious (both male and female), sexual reproduction with internal fertilisation
o Triploblastic (body lined by thick cuticle secreted by underlying epidermis; pseudocoelom;
longitudinal muscles only - run length of body; no respiratory or circulatory system
(transport via body fluid)
o Nerve fibres run to sensory receptors and connect at nerve ring; brain - series of nerves that
surround GI tract anteriorly
o Complex excretory system, canals drain body cavity through pores (osmoregulatory rather
than excretory)
o Moults exoskeleton to grow; associated with change of environment, reproduction,
behaviour; moulted worm smaller than cuticle because worm undergoes expansion after
moulting
o Cuticle: very effective barrier, non-permeable (can’t respire/excrete); can’t kill nematodes
with many chemicals; able to withstand pressure from inside, resilient, hard
o Muscles flex body in one plane - dorso-ventral (dolphin-like); muscles act on exoskeleton
(usually rigid, resilient and flexible); contraction of muscles along cuticle bend inside of
nematode, resulting in wriggling
o Caenorhabditis elegans: free-living soil nematode; few cell types, short generation; ancestry
of each cell established
...
Get into the blood
system, burrow out of the lungs, and crawl up the trachea and into the oesophagus)
 Ascarids:
o Large intestinal worms (mammals)
o Cause disease by occluding intestine and because of aberrant migration in host
o Eggs are desiccation-resistant

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Parascaris equorum: intestinal worm in horse; results in lung effects due to migrating larvae
(can lead to pneumonia), loss of energy, colic, intestinal perforation and obstruction
Pinworms: small worms in rectum of mammals

Heartworm: adult worms in right side of heart and pulmonary artery
...
Lifecycle: adult worms in pulmonary artery; produce microfilaria (infective stage);
microfilaria in blood, which is ingested by mosquito; mosquito vector transmits heartworm with
blood meal; microfilaria develop in muscle; migrate to salivary glands and mosquito mouthparts
Whip worm: common parasite of animals; in extreme cases of humans, causes invagination of
larger bowel
Lymphatic filariasis: Wuchereria bancrofti; enlargement of limbs and lymph nodes (mainly male
and female genital area); worms sit in lymph nodes, collection of lymph
Trichinella spiralis: parasite relies on predation; transmitted by predator/scavenger; larval stage
in skeletal muscle, transmitted through ingestion of muscle without proper preparation; thrives
by living in host’s muscle and muscles of subsequent hosts
Trichinella spiralis: intracellular parasite, induces muscle cell to become nurse cell: sole purpose
to feed worm; instead of larvae passing out with faeces, burrow out of intestinal wall, enter
blood stream and travel to another muscle cell; can burrow right through cells without
destroying them
Plant Parasitic nematodes: soil dwellers; attach to roots, some migrate to other regions; can be
devastating to agriculture: mechanical and chemical injury, secondary infection, enhance
secondary disease, plant lose ability to withstand water stress
Types of parasites:

Phylum: Nematomorpha
 Horsehair worms; parasitic larvae, adults mate in large aggregations - “Gordioidea”
 Infected when drinking water; when worms mature, induce host to go to water and burst from
body
Arthropods

Major factors of success:
 Very adaptable body plan
 Ability to thrive in terrestrial environments
 Body segmented - allow greater control- specialisation of regions
 Segments become fused for even greater control
Possess:
 Exoskeleton: made of chitin (protection); heavy/light, rigid/flexible, waxy/not waxy,
wings/wingless
o Ecdysis: moulting to grow - temporary vulnerability, energetically expensive
 Metamerism: composed of segments call somites
 Jointed appendages: modified into specialised organs for walking, eating and grasping
 Dorsal heart
 Ventral nervous system: ventral nerve cord with ganglia (swellings) in each segment
 Open circulatory system: brain located at front end, dorsal vessel directs blood to brain; blood
then circulates towards rest of body by bathing cells
...
Head, thorax, abdomen (e
...
grasshopper); head, trunk
(e
...
centipede); cephalothorax, abdomen (e
...
spider)
2 groups based on mouth parts:
 Chelicerate mouthparts: chelicerae for grasping food
...

Mouthparts: chelicerae (paired feeding appendages modified into fangs or pincers) and
pedipalps (feeding/sensory)
...
External parasite of mammals and birds, 1-3 hosts (different
species have different number)
...
Saliva transmits diseases-causing microorganisms and secrete neurotoxins
o Mites: most free living
...
Cause severe dermatitis: characterised by hair loss, scabs and keratinised skin
 Mandibulate mouthparts: mandibles for chewing
...
Terrestrial,
freshwater, marine
...
Beetles most abundant
...
3 pairs of legs, sometimes 2 pairs of wings
o Insects: evolution associated with plant evolution
...
Tracheae (tubules) ramify
through body - direct oxygen supply to tissues
 Advanced nervous system
 Advanced sensory system: antennae, compound eyes
 Internal fertilization
 Resistant eggs
History:
 Apterygotes: wingless insects, simple mouths (springtails and silverfish)
 Palaeoptera: evolution of wings (350mya) - simple development, wings did not fold over
abdomen (dragonflies and mayflies)
 Orthopteroida: development of wings that fold over abdomen (grasshopper, locusts,
praying mantis, stick insects, cockroaches)
 Enhanced Innervation: 2 lineages - those that maintain simple development; those with
complete metamorphosis
 Hemipteroida: maintain simple metamorphosis
...
Hosts: dogs,
cats, poultry, humans
...
Eggs: on host or in
nest
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Cause harm through direct (flea-bite
allergy), vector (bacteria or virus), intermediate
host (fleas ‘cucumber’ tapeworm of dogs and cats)
 Lice: permanent ectoparasites
...
Hooked tarsi - grip
hair
...
Host specific: different species
on cattle, sheep, goats, horses, etc
...
Myiasis: invasion of living tissue by
dipteran larvae - huge economic loss in sheep
industry (blowfly strike)
...
Mosquito highly adapted to
human habitation - transmits dengue-fever (fever,
headaches, muscle and joint pains) and yellow fever
(fever, liver damage, jaundice)
...
Extensively specialised appendages - 19
pairs in decapods (crayfish, lobster, prawns, shrimp)

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Copepods: important food source, some parasitic on fish, some predatory - has been
used to control dengue mosquito in SE Asia

Agricultural pests: moth, 2 species in Sth Queensland - native budworm and cotton bollworm
or corn earworm
...
Enter soil and pupate over winter
...
DNA indicates Echinoderms and
Chordates are related - endoskeleton made of calcareous plates, covered by epithelium
...

 Urochordata: sea squirts
Four features define chordates: notochord, pharyngeal slits, dorsal hollow nerve cord, and muscular
post-anal tail
...

 Notochord: slender rod, develops from mesoderm; lies dorsal to coelom - beneath and parallel
to central nervous system
...
In
bony fish and terrestrial vertebrates: present during embryonic development, replaced by
vertebral column, but persists as nucleus pulposus of intervertebral discs
 Pharyngeal slits: longitudinal series of openings in walls of pharynx
...
In aquatic vertebrates, gills develop adjacent
to slits, which allow for flow of water across gills
 Dorsal hollow nerve cord: derived from ectoderm, lives above got, surrounded fluid-filled
neurocoel
 Muscular post-anal tail: posterior elongation beyond anus, consists of segmental musculature
and notochord

Invertebrate chordates provide clues on evolution of vertebrate chordates
...
Present day
example:
 Brachiostoma - amphioxus: blade-like in shape, possesses all 4 chordate features in adults, lives
with posterior end buried in sand - anterior end exposed to water currents (filter feed, ciliated
pharynx, mucous nets across slits)
 Cephalochordata:
o Digestive system: may be precursor of vertebrate organs; midgut caecum probably gave rise
to liver and pancreas
o Circulatory system: same general pattern, with ventral aorta and dorsal aorta; afferent and
efferent vessels (returning and taking away blood); capillary networks, but no heart
o Brain: shares homology with vertebrate brain - do not have differentiated brain, but cluster
of cells at anterior end of nerve cord
...
Vertebrates brain is elaboration of
cephalochordate ‘brain’
 Urochodata: tunicates, all species marine
o Class Ascidiacea: sea squirts, adults sessile, larvae planktonic
...
Unique characteristic
is neural crest - population of cells that gave rise to many structures (teeth, bones, neurons)
...
Most basal of craniates are Hagfish
o Hagfish: cartilaginous skull, lack jaws and vertebrae, retain notochord in adult, 30 species (all
marine), feed on detritus, produce mucous as defence
 Vertebrata: during Cambrian, Craniates gave rise to vertebrates - most basal lineage of
vertebrates are lampreys
o Lampreys: cartilaginous skeleton, lack jaws but have rasping tongue and teeth, retain
notochord in adult, primitive vertebrae enclose notochord, 35 species (marine and
freshwater)
o Gnathostomes: primitive fish that have developed jaw - transition from suspension feeding
to selective feeding
...
Skeleton entirely cartilage,
cartilaginous vertebral column replaces notochord
...

 Placoid scales made of dentine and enamel, with surface denticles (“small teeth”)
developed from dermis - project through epidermis)
...
Buoyancy controlled by swim
bladder, with external fertilisation
...
Fins supported by numerous endoskeletal
rays; muscles control fins within body
...
Fleshy fins composed of soft muscles;
ancestors gave rise to terrestrial vertebrates - tetrapod limb evolved from
sarcopterygian fin
...
Can breathe air, have prominent notochord
o Coelacanth: thought to be extinct, specimen found of South Africa; tiny vertebrat,
well-developed notochord; possess swim bladder, but does not serve in
respiration; lobe fins used to support and position fish in currents

Evolution of Tetrapods
Tetrapod = four footed (amphibians, reptiles, birds and mammals
Vertebrates moved onto land during mid-Devonian; still mostly in water, used formative limbs to
ambulate in the shallows, with occasional land trips
...

Adaption to land followed metamorphosis - limbs, pelvic and pectoral girdles progressively stronger;
vertebral column more prominent
...
Arose from labyrinthodonts
 Acanthostega: “four-footed fish”; radial fin rays supporting a tail fin, limbs with 8 digits (arose
before transition to land), weight bearing girdles, internal gills
Three extant orders of amphibians:
 Anura: frogs and toads
 Urodela/Caudata: salamanders and newts
...

 Gymnophiona/Apoda: caecilians (legless, blind; aquatic or subterranean)
Modern amphibians: very thin stratum corneum - limited protection from abrasion and dehydration,
but cutaneous respiration (gas exchange across skin; capillary beds within epidermis, with large
surface area to body mass ratio)
...
Frogs and toads - external fertilisation, often in or near
water; amplexus; female releases eggs, male deposits sperm over eggs
...
Salamanders - internal fertilisation; male produces spermatophore (cap of sperm on
gelatinous stalk), which female picks up with cloaca
 Brain: shows little development from fish
Evolution of amniotic egg facilitated the success of vertebrates on land
...
Amniotic egg characterised by presence of several extraembryonic membranes:
 Amnion: encloses embryo - fluid-filled and so protects embryo from mechanical shock
 Allantois: contains foetal urine; contributes to placenta in eutherian mammals
 Chorion: outer envelope; contributes to placenta in eutherian mammals
 Yolk sac: source of nutrition for embryo
In birds and reptiles - embryo enclosed by calcareous or leathery shell - presents desiccation
allowing terrestrial reproduction
Eutherian and marsupial (therian) mammals lost shell - eutherians formed placenta, marsupials
deliver altricial young (gestation vs lactation)
Monotremes have retained egg shell
Cotylosauria - “stem reptiles”, basal group of amniotes
Two major lineages in the evolution of amniotes:
 Sauropsida: dinosaurs, modern reptiles, birds
 Synapsids: mammals
Evolution of amniotes - characteristics:
 Skull fenestration: amniotes can be grouped according to anatomy of temporal region of skull
(number of fenestrae, or holes)
o Anapsid: no fenestrae; ancestral amniotes, turtles and tortoises
o Synapsid: one fenestra, mammals
o Diapsids: two fenestrae; dinosaurs, lizards, snakes, crocodiles, tuatara and birds
Evolution of Reptiles
4 extant orders:
 Testudines: turtles, tortoises; largest is leatherback turtle (shell up to 2m in length, weighs
900kg)
...
Herbivorous and carnivorous,
but lack teeth - keratinous ridges for slicing and grinding
...
Native to NZ and surrounding islands
...
Considered most ancestral of amniotes
...
Double row on maxilla (upper
jaw) and single row on mandible (lower jaw)
...
Two species:
o Sphenodon punctatus
o Sphenodon guntheri - very rare
 Squamata: lizards, snakes
...
Venom early in
squamate radiation - 60% venomous, predominantly snakes but two lizards (gila monster and
Mexican beaded lizard)
...
Semi-sprawled posture, results in belly-walk, and high walk with legs under body
...
two main
lineages
 Ornithischia: ‘bird-hipped’; herbivorous
 Saurischia: ‘lizard hipped’; herbivorous and carnivorous - includes ancestral birds
Reptiles have adapted to drier environments - some readapted to aquatic environment, but must lay
eggs on land (except sea snakes - viviparous); distribution limited by being ectothermic (not in
subarctic and subantarctic habitats)
...

 Epidermal scales: keratin structures; scale morphology is species-specific
...
Species like crocodiles, testudines and some lizards
...
Ventrally, fusion of
osteoderms, called plastron
 Skeleton: stronger than amphibians; cervical vertebrae - specialised atlas and axis, and short
ribs; thoracic and lumbar vertebrae not clearly distinguished
...
Small
epipubic bones may be present - project from pubic symphysis (role unknown)
 Limb bones: very similar to mammals, 5 digits on each manus (forelimb) and pes (hindlimb)
 Skull: key features are fenestrae (openings in temporal region of skull, caudal to orbit - reflect
differences in jaw musculature)
...
Crocodiles have unidirectional flow
(air follows set pathway - doesn’t pass through same area twice - same as birds)
 Heart: evolved from amphibians - adapted to more terrestrial existence; higher metabolic rate
for greater oxygen demands
...

 Reproduction: sexual dimorphisms minimal or non-existent
...
Internal fertilisation, sperm can
survive for years
o Viviparous: 20% of extant snakes and lizards; fertilised eggs retained in oviduct - greater
protection
o Oviparous: oviduct deposits albumin, shell membrane and shell
...
Embryo derived solely from fusion of two
eggs
...
Evolved from reptiles 150mya - birds, crocs and
dinosaurs diverged from common reptilian ancestor during Triassic
 Amino acid analysis of collagen extracted from fossilised femur of T
...
In feathered areas, epidermis only 10
cells thick - 5 of these are stratum corneum
...
Loss of
feathers and heat transfer to eggs (blood vessels close to surface)
Beak: keratinised structure derived from skin; grows continuously to replace loss from wear may require clipping in caged birds
Spurs: bony core and keratinised sheath
...
Removal of bud in chicks
Scales: sections of highly keratinised epidermis
Uropygial gland: not in all species; dorsal surface of tail, two lobes that open to single papilla;
soft tuft of feathers (uropygial wick)
...
Waterproof birds have very large gland, preening distributes
secretion
Feathers: highly keratinised epidermal outgrowths; arranged in well-defined, linear tracts
(pterylae)
...
Types:
o Contour: cover most of body, aerodynamics and protection
o Flight: larger and stiffer than contour feathers
...

Invasion by diverticular of air sacs - pneumatic bones, can be large and strong without being
heavy; vertebrae, pelvis, sternum, costal bones, humerus and femur
...
Unlobed, dense (1/10 volume, but similar
weight - can’t expand)’ communicate with air sacs
o Air sacs: blind-ending, thin walled extensions of bronchi
...
Heart divided
...
At copulation, cloaca everted in both sexes (“cloacal kiss”)
...
Ovary very large yolk-filled oocytes
...
Optic lobes very large

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Intelligence: varying degree between species
...
Crows: make tools, problem solve and teach others
...
Retain reptilian characteristics (oviparity, meroblastic
cleavage of embryo, produce venom, electroreception)
...
Platypus exists in freshwater habitats, eastern
Australia
...
Located with skin
of beak/bill, more extensive in platypus
...
In male: at meiosis, form
alternating XY chains (X1Y1X2Y2…), then segregate into multiple X- and Y-bearing sperm
o Platypus: X1X2X3X4X5Y1Y2Y3Y4Y5 male
...
X1X2X3X4X5X6X7X8X9X10 female
o Sex Determination: monotremes lack SRY (marsupials and eutherian sex is determined by
this on Y chromosomes)
...

In echidna, both functional
...
When laid, echidna only 1 egg (incubated in
pouch), platypus 1-3 eggs (incubated in nest)
...

Mammary glands but no teats

Marsupials: named for marsupium - pouch (not all possess pouch)
...
Not primitive mammals - marsupials and eutherians diverged from common
ancestor ~100mya
 Reproduction: young born in very altricial state (underdeveloped); placenta is yolk rather than
allanto-chorial placenta - dependence on lactation rather than gestation (highly successful
alternative
...
In all
mammals, embryo has ureters and Müllerian ducts (forms oviducts, uterus and upper
portion of vagina)
...
In marsupials, ureters pass medially to Müllerian ducts distal ends cannot fuse (forms two lateral vaginae, with median vagina from connective
tissue)
...

 Medial vagina: becomes patent just before parturition - for giving birth
 Lateral vaginae: where sperm ascend
 Chromosomes: fewer, larger than eutherians - ~7-28 pairs
...
SRY testisdetermining
...

o XY - sctotum
o XO - female reproductive tract and scrotum
o XX - pouch
o XXY - testes, male reproductive tract, penis and pouch
 Pouch: encloses teats and young - young attached to teat constantly (periderm, which covers
eyes and ears of foetus, grows over teat to attach young to teat)
...
However, at birth, climbs from urogenital
sinus to pouch - well developed forelimbs and claws - and attaches to teat (well developed
mouth, tongue, nostrils and lungs
Gross Anatomy
Terminology:
A
...
MEDIAN: divides body into equal left and right
2
...
TRANSVERSE: cuts perpendicular to median plan, dividing body into caudal and cranial
(infinite number)
4
...
LONGITUDINAL: cuts parallel to long axis of organ or limb
B
...
DORSAL: away from ground
...
VENTRAL: towards the ground
3
...
CAUDAL: towards tail
5
...
PALMAR: surface directed caudally on foreleg
7
...
MEDIAL: towards the median plane
9
...
PROXIMAL: nearest the trunk or origin of limb
11
...
SUPERFICIAL: nearer the surface

13
...
PERIPHERAL: distant from point of origin; near surface of body
15
...
AXIAL: pertains to digits, side of digit closer to longitudinal axis (facing inside)
17
...
VISCERAL: associated with organs within body cavities
19
...
IPSILATERAL: same side of body as another structure
21
...
SUPRA-: prefix signifying above or over
23
...
Basic movement terminology:
1
...
RETRACTION: moving whole limb caudally (backwards)
3
...
FLEXION: joint where angle is being decreased
5
...
SUPINATION: medial rotation of forearm with results in palmar surface facing up
7
...
ADDUCTION: movement of a part towards median plane
D
...
Caudal - cd
...
Cranial - cr
...
External - ext
...
Internal - int
...
Lateral - lat
...
Medial - med
...
Central nervous system - CNS
8
...
Artery - a
...
Vein - v
...
Muscle - m
...
Nerve - n
...
Lymph nose - ln
...
Primary function:
movement and locomotion
...
Primary function: provide nutrition and oxygen
to cells
...
Primary function: sensing
environment and coordinating movement
...
Primary function: oxygenation of blood
...
Primary function: removal waste products &
regulation correct hydration levels
...
Primary
function: to reproduce! Secondary functions: manufacture of sex hormones responsible for
secondary sex traits & behaviour, shares some structures with urinary system and often
grouped together as urogenital system
Digestive System: mouth, teeth, tongue, pharynx, oesophagus, stomach, liver, small intestine,
pancreas, caecum, large intestine, rectum, anus
...
Secondary functions: excretion some waste
products, maintenance hydration, regulation & balance many essential substances, territorial
marking
Integument System: skin main organ; also horns, hooves, hair
...
Secondary functions: fighting & sexual selection, locomotion, territorial
marking, temperature regulation
Immune System: thymus, bone marrow, lymph nodes, spleen; T & B lymphocytes
...
Secondary functions: wound repair, fighting cancer
Endocrine System: glands that secrete hormones into blood inc
...
Primarily a signalling system, like nervous system
...
g
...
Both are intimately connected to the central nervous system
...
Follows a set order:
 Fertilisation: fusion of sperm and egg (zygote)
...
3 key events:
o Contact: spermatozoon makes contact with protective layer (jelly coat, zona pellucida)
surrounding egg
o Acrosomal reaction: enzymes dissolve jelly coat, molecules (hydrolytic enzymes from
acrosome) on sperm bind to receptors on egg - species specific i
...
one of the impediments
to interspecies breeding - causes fusion of plasma membranes
...

Longer lasting; vesicales (cortical granules) beneath plasma membrane of egg fuse with
plasma membrane
...
Layer lifts away and hardens to form fertilisation
envelope - receptors clipped off, no further binding
Cleavage: cell divisions (blastula/blastocyst)
...
First 5-7 division produce hollow ball of
cells - blastula (blastocyst in mammals)
...
2
types of cleavage patterns:

Four celled morula

o

Early blastula

Holoblastic: therian mammals, amphibians, echinoderms
...
Less yolk at opposite pole (animal pole where embryo developes)
...

During division, indentation forms the divides cell in half (cleavage furrow)
...

3rd division is equatorial to produce 8 cells
...
Lots of yolk - volume of yolk in
vegetal hemisphere so great that cleavage furrow cannot pass through (cleavage occurs in
animal hemisphere)
...

End result is a ball of cells - blastula (blastocyst): has a fluid filled space called blastocoel
...
Outer layer of cells called
trophoblast - does not contribute to embryo, but forms chorion

Gastrulation: blastula rearranges layers of cells (gastrula)
...
Gastrulation involves the reorganisation of the cells to form a
3-layered embryo - gastrula, embryonic germ layers:
o Ectoderm: forms layer of skin and derivatives
o Mesoderm: skeletal and muscular systems, circulatory and lymphatic systems, excretory and
reproductive systems, dermis of skin, adrenal cortex
o Endoderm: epithelial lining of digestive tract and associated organs, epithelial lining of
respiratory, excretory and reproductive tracts and ducts, and thymus, thyroid and
parathyroid glands
Frogs:
Groups of cells on dorsal surface of blastula invaginate to form small, indented crease
(blastopore)
...
Once inside, move towards animal pole - organised into endoderm and mesoderm; cells
remaining at animal hemisphere become ectoderm

Cells at animal pole continue to spread (ectoderm)
...

Blastopore surrounds a plug of yolk-filled cells
...
Cells of blastoderm divide to form 2 layers - epiblast
and hypoblast; blastocoel sits in between
...

Cells from epiblast move to centre of blastoderm and inwards towards yolk, producing a
thickening (primitive streak)
...

Others migrate laterally and form mesoderm
...


Trophoblast cells secrete enzymes that facilitate implantation into endometrium of uterus
...
Cells of epiblast move
inward via primitive streak to form mesoderm and endoderm



Organogenesis: rudimentary organs form
...
Important process is the development of central nervous system, neurulation
...
Ectoderm above
notochord becomes neural plate
...
Feathers appeared in Compsognathids short, hair-like on head, neck and body for insulation
...

 In oviraptorosaurs, several new types of feathers: branched, downy with central stalk and
unstructured brances
...

Oviraptorosaurs had comparatively short forelimbs but long feathers - protection and incubation of
eggs
...


Other characteristics uniquely adapted to flight: gradual reduction, loss and fusion of many skeletal
elements; reduction in overall size; outer cortex of bones thinner by more dense (for greater
strength and rigidity); bones hollow
...
Forelimbs became longer than hind limbs - main form of locomotion switched from
running to flight; teeth were lost repeatedly in various lineages
Domestication: process of developing a mutually useful relationship between animals and humans
...
Product of
breeding population is isolated from wild species (reproductive isolation) - economic advantage
...
Around 8,000 years ago
...
Origins in China, Laos, Burma and India
...
In Indus Valley ~2,000 BC; from
there spread to Europe and Africa
...
They have increased body weight and reach sexual maturity earlier - egg production
earlier, more frequent laying, larger eggs
Dog Domestication
Thought to have evolved from grey wolf
...

Common ancestory: 60 million years ago, small weasel-like mammal of genus Miacis
...

 Greek for ‘in-between dog’
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Evolutionary development of dogs characterised by the acquisition of these 3 physical features
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Progenitor of wolves and foxes
General consensus is that dogs evolved from Eurasian grey wolf ~100,000 years ago
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2% difference; between grey wolf and coyote 4% difference
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Genetic overlap observed between some modern dogs
and wolves is the result of interbreeding after dog domestication
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Earliest
dogs lived among hunter-gather societies and adapted to agricultural life later
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Did
humans choose wolves or did wolves choose humans (took advantage of leftover carcasses)? People
who had dogs in hunt had advantage over those who didn’t
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Human societies share similarities with wolf packs: hierarchical order (communicate status,
dominance, males physically dominant over females), work cooperatively, strong ties, suspicious of
outsiders, care for and protect young, refined ability to interpret moods
 Dogs have left gaze bias when looking only at human face - look to right side of face, as its
better at portraying moods
Dogs have ability to digest starch - multiple copies of gene for amylase (4-30) compared to wolf (2)
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8 regions contain genes governing brain
development: supports theory that dogs are really wolves that never grew up (retained a lot of wolf
pup-like traits)
 Sociability around strangers, curiosity, playfulness, liberal tail wagging and solicitation of
attention - seen in both wolf and dog pups, but retained in adult dogs
 Floppy ears, shorter muzzle and broader faces
 Retention of juvenile traits into adulthood - paedomorphosis
Cat Domestication
Order Carnivora, Family Felidae
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Extant felids belong to one of two
subfamilies: pantherinae (tiger, lion, jaguar and leopard) or felinae (cougar, cheetah, serval, lynxes,
caracal, ocelot and domestic cat)
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Had binocular
vision, highly specialised carnassial teeth for shearing, retractable claws, completely carnivorous
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Skeleton smiliar to extant ‘big cats’
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Approximately 60% of modern felids developed within last million years
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Share a genetic anomaly that prevents them from tasting
sweetness - taste buds are receptors that bind proteins; different receptors for sour, bitter, salty,
sweet and umami
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 In felids, Tas1r2 lacks 247 base pairs - truncated, non-functional Tas1r2 protein, and sweet
receptor does not form
Tend to have lithe flexible bodies with muscular limbs; in great majority, tail is between a third and a
half the length of the body
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All domestic cats descended from the Middle East wildcat Felis sylvestris lybica 12,000 years ago
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lybica - correlates with when first
agricultural societies began to flourish in Fertile Cresent (Egypt)
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lybica still found in Middle East - tawny brown coat, light stripes, ticking
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One of earliest and most important changes was development of tabby patterning (better
camouflage in forests)
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Both have come
about as results of matings with European wildcat
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Environmental adaptation through genetic mutation, geographical isolation and human preference
resulted in breeds
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Geographic isolation and natural selection resulted in Maine Coon cat
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Difficulties: cats can, and do, interbreed with wild cousins (Bengal cat - domestic cat and Asian
leopard cat)
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Cats came to human societies
after rats and mice - and so domesticated themselves
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Seen as
afflicted with witches and the devil
Livestock Domestication
All cattle discended from wild ox (aurochs)
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Can interbreed
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Bos acutifrons proposed ancestor of aurochs
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Co-existed with domesticated zebu until 4,000-5,000 years ago
 Eurasian aurochs: ranged steppes and taigas of Europe, Siberia and Central Asia
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Domesticated into modern
taurine cattle breeds around 8,000 years ago in Middle East
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By 13th century, aurochs existed only in small numbers in Poland, Lithuania,
Moldavia, Transylvania and East Prussia
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Last recorded live aurochs, died in 1627 in Poland
from natural causes
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 North African aurochs: lived in wood- and shrubland of North Africa
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Proportions and body shape different to modern breeds: legs considerable longer and more slender,
skull substantially larger and more elongated, large neck and shoulder musculature in bulls
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Resulted in two distinct lineages of domestic cattle with distinct traits
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Multiple events in Fertile Crescent 10,500
years ago
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Ancestor of sheep through to be Asiatic Mouflon
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Wild ancestors had several characteristics ideal for domestication: relative lack of aggression,
manageable size, early sexual maturity, social nature, high reproduction rates
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Initially, kept solely for meat, milk and skins
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Difference in fleece of ancient and modern sheep: ancient sheep plucked, not shorn
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During roman occupation of British Isles, a large wool processing factory established in 50AD in
England
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Spanish
produced merino sheep (fine quality, great wealth, financed Spanish rulers and voyages to the New
World)
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Sheep outnumber people 2:1
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Horse Domestication
Evolution reflected in limbs and teeth
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Earliest known horses evolved 55mya multiple species lived at same time
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Belong to genus Equus
(horse, zebra and donkey)
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Dentition typical of omnivore - 3 incisors, 1 canine, 4
premolars and 3 molars
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Padded feet, with small hoof-like structures instead of
nails
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Co-existed during Eocene
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Premolar 1 smaller, and premolar
4 assumed shape and function of molar; crests more pronounced for greater grinding ability
 Mesohippus: 37-32mya
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Still had 3 digits on fore and hind
feet - majority of weight borne on 3rd digit
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3
premolars more molar-like (cheek teeth): sharp crests, more efficient grinding, all descendant
Equidae
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Extra crest in upper molars - characteristic feature of equine teeth
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Evolutionary link between ancestral forest-dwelling
horses and derived plans-dwelling grazers
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Prolonged skull - resembles extant horses
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Milestone in evolution of horses
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 Pliohippus: 12-6mya
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3 digits, but medial and lateral bare
visible studs - ‘grandfather’ of modern horse
 Dinohippus: closest relative, 13-5mya
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One of oldest species is Equus simplicidens - zebralike with donkey-shaped head
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Last wild extant species is Przewalski’s Horse
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5mya
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Timeline for domestication still debated, partly because evidence itself is debatable
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 Thoroughbred gene: identified special allele of myostatin gene responsible for speed and
precocity
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Since 1860s, bred
for shorter, faster races and maturity (reached 2 years)
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Domestication around Botai culture; 3 strands of evidence - shin bones, milk
consumption (fatty lipids found inside pots), bit wear on teeth

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