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Deutrostomia
Available at http://planet.uwc.ac.za/nisl/Eco_people/Presentations/
PHYLUM: CHORDATA


CLASS: SARCOPTERYGII (LOBE FINNED FISH AND
TERESTRIAL VERTEBRATES)
This class of fish are not well resolved and more information is
needed. At the moment there are seven clades
 Onychodontiformest X
 Coelacanthimorpha
 Porolepimorpha X
 Dipnoi
 Rhizodontimorpha X
 Osteolepimorpha X
 Terrestrial vertebrates
X = extinct
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
SUBCLASS: COELACANTHIMORPHA
 Coelacanth characteristics

Stub-nosed

Small jawed

Highly specialized deep sea fish

Lack internal nostrils

Heavy cosmoid scales

Fleshy fins

Lungs are large sac-like and filled with fat and connective
tissue

Bone has been reduced and replaced with cartilage

Heart is a simple series of linear chambers

Brain case is large, but the brain within is very small

No pineal foramen
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
SUBCLASS: COELACANTHIMORPHA
 Coelacanth characteristics

Loss of salts is prevented by maintaining a high osmotic
concentration achieved through retention of urea in the blood

Eggs are large (100 mm) and develop within the maternal
oviduct (ovoviviparous)
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
SUBCLASS: DIPNOI (Lungfish)
 Three living genera.

One in
South-America
South Africa
Australia
 Dipnoi Characteristics

Cosmoid scales

Fleshy fins

Reduction in ossification of bone

Functional lungs

Australian forms can survive in stagnant water by air-breathing.
The other genera can survive complete drying up of the water
by burrowing and aestivating (dormancy phase). The African
Lungfish are so dependent on air that if kept underwater they
will drown
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES

21,100 extant species

Distributed worldwide

Tetrapoda is now a crown group including the last common
ancestor of the lissamphibia and amniotes
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES

LISSAMPHIBIA

Early amphibians- subclass Lepospondyli


Small and similar to modern salamanders
Labyrinthodonts

Large

Probably ancestral to the amphibians of today. These animals
possessed a long fish-like tail and were very similar to the
Crossopterygian fish, except they were the first amphibian to
walk on land
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
LISSAMPHIBIA


Adaptations to terrestrial life

Legs

Lungs

Nostrils connecting to the mouth cavity

Sense organs that function in water and air
The transition from water to land involves the following:
Change in skin to facilitate respiration

Replace gills with lungs

Changes in the circulation

Sense organs that are land/water compatible
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
LISSAMPHIBIA

Respiration

Most number of techniques for respiration of all vertebrates

Used for respiration:

Gills

Skin

Lungs

Buccopharynx
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
LISSAMPHIBIA

The heart in frog larvae is fish like with one atrium and a ventricle: it
receives only unoxygenated blood which is pumped directly to the gills

Adults have two atria and one ventricle. The left atrium receives
oxygenated blood from the skin and lungs, the right, unoxygenated
blood from the general circulation

Three pairs of external gills occur in most embryos and larvae but
persist only in those adult forms that are strictly aquatic (e.g.
Salamanders)
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
LISSAMPHIBIA

In tadpoles water is drawn in through the mouth and nostrils and is
then forced over the gills and out through the spiracles

Salamanders aid respiration by moving their gills

Lungs have few internal partitions that are vascularised- lungs are
not very efficient

In aquatic species lungs serve as hydrostatic organs

Skin of all amphibians is highly vascularised

Many species have buccopharyngeal respiration
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
LISSAMPHIBIA

Reproduction

Mating usually occurs in the water

Frogs -external fertilization

The eggs are deposited and grow until they metamorphose
into the adult stages

The male enters the water, clasps the female, and as the
female extrudes her eggs the male discharges sperm over
them

The amphibian eggs are covered in a gelatinous coating
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
LISSAMPHIBIA

Reproduction

Salamanders have elaborate courtship where the male
deposits a gelatinous spermatophore on the bottom of the
stream. The spermatophore is taken into the female cloaca
where the spermatozoa are stored in the seminal receptacle
and are fertilized (internally) at a later stage
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
LISSAMPHIBIA

Larvae

Salamanders resemble their parents in general form.

Larvae of frogs initially has external gills, replaced by internal gills.
Limbs develop at a later stage. The mouth is horny with labial teeth
and is used to scrape food material. The intestine is long and
slender
 Metamorphosis involves

Growth of a wide mouth, loss of horny jaws and the development
of conical teeth

Loss of gills, closure of gill slits and development of lungs.

Development of the protrusible tongue

Emergence of the four limbs (paired appendages)

Reduction in length of the intestine from long herbivore type to
short carnivore type

Re-absorption of tail and median fins

Biochemical changes include a change in the excretory products
from toxic ammonia to less toxic urea.

A change in the capacity of the blood to release oxygen to the
tissues, an adaptation reflecting a more active life style
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
LISSAMPHIBIA
 SALENTIA (Frogs)

Highly vascularised skin with many mucous glands

Skeleton/ muscles
Vertebra: Up to 100 in the anurans
Pelvic girdle: Well developed in the anurans

Most amphibians have fine teeth (upper jaw and roof of mouth)
and a long prehensile tongue which is situated as far forward as
possible
 CAUDATA (Salamander and Newts)

Head and neck region distinct

trunk Long and either cylindrical or depressed dorsoventrally and
possess a long tail
 GYMNOPHONA (Caecilians)

Limbless and worm like, with a skin containing many small internal
scales


PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
 There are three extant clades

Synapsida (mammals)

Testudines (turtles etc.)

Diapsida (lizards and birds etc.)
 Along with ten extinct taxa
 Includes most of the land dwelling vertebrates alive at present
 There are over 20,000 species
 They are distributed across the globe
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
REPTILIA
 This group has two extant clades

Testudines- turtles and tortoises

Diapsida- lizards, crocodiles, birds and Sphenodon
 There are ten orders of reptiles that are extinct including the
dinosaurs and the pterosaurs (the flying forms)
 First group of vertebrates adapted for life in dry places
 Their dry horny skin and scales resist loss of moisture
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
REPTILIA
 GENERAL CHARACTERISTICS
 Body is covered with dry cornified skin with scales or scutes
 Few surface glands
 Two pairs of limbs each typically with five toes ending in horny
claws
 Suited for running, crawling or climbing
 Limbs may be paddle-shaped as in marine turtles and are reduced
in some lizards, and are absent in the snakes
 The skeleton is completely ossified
 The heart is imperfectly four chambered, there are two atria and a
partly divided ventricle
 Respiration is via lungs; pharyngeal and cloacal respiration occurs
in some aquatic turtles
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
REPTILIA
 GENERAL CHARACTERISTICS
 Twelve pairs of cranial nerves
 The body temperature in living forms is variable (poikilothermic)
 Fertilization is internal via copulatory organs
 The eggs are large with much yolk and have either a leathery or
limy shell
 Segmentation is meroblastic
 Eggs have an amnion, chorion, yolk sac and allantois
 The young when they hatch, resemble the adults with no
metamorphosis
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
REPTILIA
 ADVANCES OVER AMPHIBIANS

Dry skin

Limbs which permit rapid running locomotion

Greater separation of oxygenated and unoxygenated blood

Complete ossification of the skeleton

Eggs suited to development on land with membrane and
shells to protect the embryo
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
REPTILIA
 REPTILES ARE NOT AS ADVANCED AS MAMMALS

Lack insulated body coverings

No internal regulation of body temperature

True internal development of embryo does not occur (eggs are
simply retained in the oviduct)
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
REPTILIA
 TESTUDINES (TURTLES AND TORTOISES)
 These are not resolved in the Amniota group but are split into two
extant groups

Pleurodira (side neck turtles)

Polycryptodira (most living turtles)

With six extinct clades
 They have an oval shell composed of plate-like bones
 Dorsal surface - carapace
 Ventral surface –plastron
 Soft-shelled turtles have a leathery carapace
 The jaws lack teeth and bear cornified beak-like structures to
cut/tear/crush vegetation
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
REPTILIA
 DIAPSIDA
 This is split into two extant groups

Archosauromorpha (crocs and birds)

Lepidosauromorpha (lizards and sphenodon etc)
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
REPTILIA
 DIAPSIDA
 LEPIDOSAUROMORPHA

This is the group that contains the lizards, snakes, Sphenodon
and their extinct relatives
 ORDER SQUAMATA Lizards & snakes

These are scaled reptiles. The phylogeny is not resolved but
there are ten clades
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
REPTILIA
 DIAPSIDA
 LEPIDOSAUROMORPHA
 ORDER SQUAMATA Lizards & snakes
 LIZARDS

Varied body shapes

Limbs can be long, short, vestigial (reduced) or
absent
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
REPTILIA
 DIAPSIDA
 LEPIDOSAUROMORPHA

ORDER SQUAMATA Lizards & snakes

SNAKES

Characterized by a loss of appendages and extreme
elongation

Most snakes lack limb girdles, sternum, eyelids, external ear
openings and a bladder

Snakes have numerous vertebrae (200 to 400)

Locomotion without limbs is achieved by backward pressure of
the lateral loops of the body against surface irregularities

Snakes can travel in straight lines by hitching scales against
the ground surface
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
REPTILIA
DIAPSIDA
LEPIDOSAUROMORPHA
ORDER SQUAMATA Lizards &
snakes
 SNAKES

Can ingest whole, large-sized prey
items due to modifications to the
jaw
Two mandibles connected
with flexible connective tissue
Loose attachment of other
jaw bones
Movement of the bones of the
palate and slender backward
pointing teeth



PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
REPTILIA
DIAPSIDA
LEPIDOSAUROMORPHA
 ORDER SPHENODONTIDA Tuatara (Sphenodon)

Lizard-like animal but very much more primitive

Found only in New Zealand

Have a median pineal eye

No copulatory organs
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
REPTILIA
DIAPSIDA
 ARCHOSAUROMORPHA (Crocodiles and Birds)

Two extant clades
Dinosaura (dinosaurs and birds)
Crocodylomorpha (crocodiles and extinct relatives)


PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL
VERTEBRATES
AMNIOTA
REPTILIA
DIAPSIDA
 ARCHOSAUROMORPHA (Crocodiles and Birds)
 CROCODYLOMORPHA (Crocodiles & alligators)

External Features of the Crocodiles
Head, neck, trunk and tail are clearly discernable
Long mouth and conical teeth set in sockets
Tip of the snout has two small valvular nostrils
Eyes are large with a nictitating membrane
Opening to the ears behind the eye, under a moveable flap
The vent is a longitudinal slit behind the base of the hind
limbs






PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
REPTILIA
DIAPSIDA
 ARCHOSAUROMORPHA (Crocodiles
and Birds)

CROCODYLOMORPHA (Crocodiles &
alligators)
External Features of the CrocodilesBody Covering
Horny scales arranged in transverse
and lengthwise rows.
Adult crocodiles have an almost
“exoskeleton” of separate bony
dermal plates
There are two pairs of epidermal
musk glands




PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
REPTILIA
DIAPSIDA
 ARCHOSAUROMORPHA (Crocodiles and Birds)
 CROCODYLOMORPHA (Crocodiles & alligators)

Features of the Crocodiles- Skeleton

Massive skull

The long lower jaw articulates at each side of the posterior margin
of the skull on the quadrat bone

The ventral surface of the cranium is the long hard palate above
which are the respiratory passages

The vertebral column consists of





9 Cervical vertebrae (short and free ribs)
10 Thoracic vertebrae (connected to sternum)
5 Lumbar vertebrae
2 Sacral vertebrae
+39 Caudal vertebrae
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
REPTILIA
DIAPSIDA
 ARCHOSAUROMORPHA (Crocodiles and Birds)
 CROCODYLOMORPHA (Crocodiles & alligators)

Features of the Crocodiles- Skeleton
Between the sternum and the pubic bones there are seven
pairs of V shaped abdominal ribs

Features of the Crocodiles- Muscular System
Muscles of the head, neck and limbs are well differentiated


PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
REPTILIA
DIAPSIDA
 ARCHOSAUROMORPHA (Crocodiles and Birds)
 CROCODYLOMORPHA (Crocodiles & alligators)

Features of the Crocodiles- Digestive System

Buccal cavity, large mouth,unspecialized teeth

Flat tongue

Oesophagus: slender tube

Stomach: large spherical divided into fundus and pyloric
portions

Coiled small intestine

Larger rectum

Cloaca and vent

Accessory organs to the stomach are the liver and a pancreas
PHYLUM:
CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
REPTILIA
DIAPSIDA
 ARCHOSAUROMORPHA
(Crocodiles and Birds)
 CROCODYLOMORPHA
(Crocodiles
and alligators)

Features of the CrocodilesCirculatory System

Heart comprises a small sinus venosus, two atria and two
ventricles

From blood travelling in the veins it enters the sinus venosus 
right ventricle  pulmonary artery  lungs  pulmonary veins 
left atrium  Left ventricle  emerges as a pair of aortic arches.

Arterial System

Carotid arteries  neck & head

Subclavian  forelimbs

Aortic arch 8 dorsal aorta  body cavity
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
REPTILIA
DIAPSIDA
 ARCHOSAUROMORPHA (Crocodiles and Birds)
 CROCODYLOMORPHA (Crocodiles & alligators)

Features of the Crocodiles- Circulatory System

Venous System

Anterior vena cava  Collects from neck, head and forelimbs

Single mid dorsal posterior vena cava  reproductive organs
and kidney

Hepatic portal  digestive tract
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
REPTILIA
DIAPSIDA
 ARCHOSAUROMORPHA (Crocodiles and Birds)
 CROCODYLOMORPHA (Crocodiles & alligators)

Features of the Crocodiles- Respiratory System

Paired nostrils

Internal nares

Palatine valve, prevents water entering

Glottis

Larynx (cartilaginous with paired vocal cords)

Tubular trachea reinforced with cartilage

Divides into two short bronchi

Lungs spongy with greater partitioning
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
REPTILIA
DIAPSIDA
 ARCHOSAUROMORPHA (Crocodiles and Birds)
 CROCODYLOMORPHA (Crocodiles & alligators)

Features of the Crocodiles- Excretory System

Two flat lobular kidneys  ureter  cloaca

Features of the Crocodiles- Nervous System/ Sense Organs

Two olfactory Lobes connected to the large cerebral
hemisphere

Two oval optic Lobes

Median pear-shaped cerebellum

Medulla oblongata spread laterally

Narrows into a spinal cord

optic tracts/optic nerves, infundibulum and hypophysis, twelve
pairs of cranial nerves and paired spinal nerves
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
REPTILIA
DIAPSIDA
 ARCHOSAUROMORPHA (Crocodiles and Birds)
 CROCODYLOMORPHA (Crocodiles & alligators)

Features of the Crocodiles- Senses Include

Taste buds on the tongue

Olfactory cells in nose

Eyes (colour vision) with Lachrymal glands

Ears short external auditory canal, tympanic membrane,
middle ear houses one ear bone (stapes) and the inner ear
consists of three semicircular canals
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
REPTILIA
DIAPSIDA
 ARCHOSAUROMORPHA (Crocodiles and Birds)
 CROCODYLOMORPHA (Crocodiles & alligators)

Features of the Crocodiles- Reproductive
system

Paired gonads

Mature male has two round testes, a ductus
deferens and a single median penis

Mature female has two ovaries, an open
funnel of the oviduct running to the cloaca
PHYLUM: CHORDATA


CLASS: SARCOPTERYGII
 TERRESTRIAL VERTEBRATES
 AMNIOTA- REPTILIA- DIAPSIDA ARCHOSAUROMORPHA (Crocodiles and Birds)DINOSAURA –THEROPODA
AVES (BIRDS)- Characteristics
Body covered with feathers
Two pairs of limbs
Skeleton, thin-walled bones but possessing
great structural strength, fully ossified
Mouth possessing a projecting beak or bill
Teeth are absent
Skull with one occipital condyle
Neck very flexible
Pelvis fused
Sternum enlarged and usually possessing a median keel
Tail vertebrae fused and compressed posteriorly










PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA- REPTILIA- DIAPSIDA –
ARCHOSAUROMORPH (Crocodiles and Birds)DINOSAURA –THEROPODA
 AVES (BIRDS)- Characteristics

Heart four chambered

Red blood cells are nucleated, oval and biconvex

Respiration is by way of compact lungs attached to ribs and connected
to thin-walled air sacs extending between internal organs, voice formed
from the syrinx at the base of the trachea

No ordinary bladder, excretion in semi solid form uric acid

Females usually only have the left ovary and oviduct

Twelve pairs of cranial nerves

Body temperature internally regulated (homeothermy)

Fertilization internal, eggs with large yolk, covered with a hard limy shell
and deposited externally for incubation

Cell division is meroblastic, embryonic membranes present during
development. Young hatchlings are cared for by parents
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA- REPTILIA- DIAPSIDA - ARCHOSAUROMORPHA
(Crocodiles and Birds)- DINOSAURA –THEROPODA
 AVES (BIRDS) - significant advances

Insulated body coverings

Complete separation of venous and arterial circulation in the heart

Regulated body temperature

High rate of metabolic activity

Ability to fly

Specialized care for young
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA- REPTILIA- DIAPSIDA - ARCHOSAUROMORPHA
(Crocodiles and Birds)- DINOSAURA –THEROPODA
 AVES (BIRDS) - Birds are different from mammals in

Body covering not of hair

Mode of reproduction very different

Their ability to fly (limited to bats in the case of mammals)
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA- REPTILIA- DIAPSIDA - ARCHOSAUROMORPHA
(Crocodiles and Birds)- DINOSAURA –THEROPODA
 AVES (BIRDS) -External Features

Distinct head, long flexible neck, a stout spindle-shaped body or
trunk

The mouth is extended as a pointed bill/beak with a horny
covering

On the upper mandible are two slit-like nostrils

The eyes are large and lateral with an upper and lower eyelid

Possess a nictitating membrane

Below and behind each eye is an ear opening, hidden under
special feathers

The two forelimbs are modified into wings

The hind limbs are generally adapted to bipedal hopping, running,
climbing or swimming

The short tail bears a fan-like group of long tail feathers
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA- REPTILIA- DIAPSIDA - ARCHOSAUROMORPHA
(Crocodiles and Birds)- DINOSAURA –THEROPODA
 AVES (BIRDS) -Body Covering

The soft flexible skin is loosely attached to the muscles beneath

One oil gland above the base of the tail

The feathers grow from follicles in the skin

Feathers- Distinctive epidermal structures
Lightweight
Flexible but resilient body coverings
Create air pockets which insulate the body covering, protect
the skin
Create wings and tail for support in flight




PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA- REPTILIA- DIAPSIDA - ARCHOSAUROMORPHA
(Crocodiles and Birds)- DINOSAURA –THEROPODA
 AVES (BIRDS) -The Growth of a Feather

Begins like the scale of a reptile

The base of this feather bud sinks into a circular depression: the
future follicle
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA- REPTILIA- DIAPSIDA - ARCHOSAUROMORPHA
(Crocodiles and Birds)- DINOSAURA –THEROPODA
 AVES (BIRDS) -The Growth of a Feather

The outermost epidermal cells on the bud become a smooth
cornified sheath (periderm): other epidermal cells become
arranged in parallel ribs, a large median one forming the future
shaft, the others producing barbs

The central soft, dermal pulp (original dermal papilla) contains the
blood vessels and is wholly nutritive, drying on completion of
growth, so that the feather is purely an epidermal structure. The
pigments for coloration are deposited in cells when the growth is
completed, the sheath breaks and crumbles away or is removed by
preening
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA- REPTILIA- DIAPSIDA - ARCHOSAUROMORPHA
(Crocodiles and Birds)- DINOSAURA –THEROPODA
 AVES (BIRDS) -Contour Feathers

The external covering and includes the enlarged flight feathers of
the wings and tail

Consists of a vane, central shaft, a hollow quill attaching to the
follicle. Each half of the vane is composed of many narrow parallel
and closely spaced barbs joining the sides of the shaft

On the proximal and distal side of each barb are numerous smaller,
parallel barbules, these are provided with minute barbicels or
hooklets, serving to hold opposing rows of barbules loosely
together
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA- REPTILIA- DIAPSIDA - ARCHOSAUROMORPHA
(Crocodiles and Birds)- DINOSAURA –THEROPODA
 AVES (BIRDS) -Down Feathers

Young chicks and other hatchlings are covered with soft downy
plumage - providing excellent insulation

Down feathers have short quills, reduced shafts and a long flexible
barb with short barbules

Down is also present beneath the contour feathers on ducks and
other water birds
 Filoplumes

Minute, hairline feathers, sparsely distributed over the body.

Grow in clusters near the follicles of some contour feathers

Each has a long threadlike shaft with a few week barbs and
barbules at the tip
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA- REPTILIA- DIAPSIDA - ARCHOSAUROMORPHA
(Crocodiles and Birds)- DINOSAURA –THEROPODA
 AVES (BIRDS) –Bristles

Hair-like growths that are modified feathers

Short quill and a slender shaft

Few vestigial barbs at the base

Seen about the mouths





Feather Colouration/Patterning/ Moult
Feather's colour due to pigment deposition during growth
Iridescence is due to microscopic, thin plates on the surface structure
of feathers
Feathers only grow in defined areas called feather tracts
Feather replacement is called moult, and is usually an orderly gradual
process
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA- REPTILIA- DIAPSIDA –
ARCHOSAUROMORPHA (Crocodiles
and Birds - DINOSAURA –THEROPODA
 AVES (BIRDS) –Skeleton

Delicate compared to that of mammals

Many of the bones possess cavities

Skeleton is modified for flight, for bipedal locomotion, and the laying of
relatively large eggs with hard shells

Bones of the cranium are separate in young, but are fused in adults

The braincase is rounded, large orbits occur for the eye

Lower jaws hinge on the moveable quadrate connecting to the
squamosal bone

The skull articulates on a single occipital condyle with the first neck
vertebrae
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA- REPTILIA- DIAPSIDA - ARCHOSAUROMORPHA
(Crocodiles and Birds)- DINOSAURA –THEROPODA
 AVES (BIRDS) –Skeleton

16 cervical vertebrae are saddle shaped and permit free
movement of the neck for feeding and preening

The trunk vertebrae are closely fitting, they have rib articulations
that are lateral in the thorax region, but are otherwise fused into a
solid synsarcun to which the pelvis is attached

No lumbar region is evident

Four free caudal vertebrae

Compressed terminal pygostyle (fused) permits movement of the
tail

A large thoracic cavity formed from ribs which protects the internal
organs and provides a rigid support for flight and permits a slight
expansion/contraction for respiration
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA- REPTILIA- DIAPSIDA - ARCHOSAUROMORPHA
(Crocodiles and Birds)- DINOSAURA –THEROPODA
 AVES (BIRDS) –Skeleton

The ribs are lateral and the sternum is ventral with a large median
keel below which the pectoral muscles attach

Each thoracic rib has a distinct vertebral and sternal part, the two
joining nearly at a right angle. The first four or five thoracic ribs has
a posterior flat process overlapping the ribs behind to strengthen
the thorax

The pectoral girdle consists of a sword-like scapula lying parallel to
the vertebrae and over the ribs. The coracoid bone occurs between
the scapula and the sternum

Clavicle hanging ventrally from the scapula: the two clavicles are
fused at their ventral ends to form the “V” shaped furcula wishbone)
attaching to the sternum
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA- REPTILIA- DIAPSIDA - ARCHOSAUROMORPHA
(Crocodiles and Birds)- DINOSAURA –THEROPODA
 AVES (BIRDS) –Skeleton

The scapula, coracoid and clavicle meet dorsally to form a circular
canal as a pulley for the tendon

Each forelimb is attached high on the dorsal surface: the humerus
pivoting in the glenoid fossa on the coracoid

The fore-arm contains the radius and the ulna, other wing bones
are modified to promote a stable support for the flight feathers

There are two carpels and three digits

Other carpels are fused to the metacarpals to form the
carpometacarpus

The second digit bears the alula

The third digit is the longest (composed of two segments)

The fourth digit is the innermost (composed of a single segments)
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA- REPTILIA- DIAPSIDA –
ARCHOSAUROMORPHA (Crocodiles and Birds)DINOSAURA –THEROPODA
 AVES (BIRDS) –Skeleton

The principal flight feathers (primaries) are supported on digits three
and four and on the carpometacarpus

The secondary flight feathers are supported on the ulna

The tertiary flight feathers are supported on the humerus

The pelvic girdle is broad: united with a synsacrum that is widely
opened ventrally, permitting the passage of large eggs

The pelvic girdle consists of an anterior ileum, a posterior ischiun, a
slender ventral pubis where these three bones meet, and a socket
where the acetabulun receives the head of the femur

The Leg consists of a -Femur
Tibiotarsus
Slender/incomplete Fibula
Fused tarsometatarsus
Patella
Four toes: three in front and one behind
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA- REPTILIA- DIAPSIDA ARCHOSAUROMORPHA (Crocodiles and
Birds)- DINOSAURA –THEROPODA
 AVES (BIRDS) – Muscular System

Birds have a greater proportion of nonsegmented muscles

The contraction of the pectoral muscle
moves the wing downwards and lifts the
bird’s body in flight

Forlimb is raised using a ventral muscle
called the supracoracoideus

The muscles of the femur and the tibiotarsus
are used for running and perching

The shank and feet contain little muscle: an
adaptation to reduce heat loss

Toes are moved by tendons that are
connected to muscles in the upper segments
of the legs. Tendons move through spaces
lubricated by fluid
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA- REPTILIA- DIAPSIDA –
ARCHOSAUROMORPHA (Crocodiles and Birds)DINOSAURA –THEROPODA
 AVES (BIRDS) –Digestive System

Tongue, small and pointed with horny covering

Mouth cavity: roofed with long palatal folds

Short pharynx

Tubular/muscular oesophagus

Stomach: soft anterior proventriculus

Disk shaped ventriculus or gizzard and walls of thick, dense
musculature - Lined internally by epithelial secretion -, food ground up
by action of muscular wall and with gravel/stones etc which function as
teeth

Intestine is slender and consists of several coils of the large rectum at
the junction of the two caeca or blind pouches

Cloaca: dorsally bears an outgrowth: the Bursa of Fabricus

Large red liver is bi-lobed with a gall bladder and two bile ducts

Pancreas: three ducts discharge into the anterior loop of the intestine
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA- REPTILIA- DIAPSIDA - ARCHOSAUROMORPHA
(Crocodiles and Birds)- DINOSAURA –THEROPODA
 AVES (BIRDS) –Circulation

Heart
Four chambered, two thin-walled atria and two thick walled
ventricles
Completely separate venous/arterial bloodstreams
Sinus venosus is incorporated in the right atrium
Blood from two precaval and one post caval enters the right
atriumright ventricle pulmonary artery capillaries of the Lung
 “oxygenated” returns via pulmonary veins to left atrium left
ventricle single right aortic arch which gives off two innominate
arteries each with three large branches: the carotid to the
head/neck, the branchial to the wing and the pectoral to the breast.
The arch continues as the dorsal aorta supplying the rest of the
body
A hepatic-portal system exists
A renal portal system is reduced






PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA- REPTILIA- DIAPSIDA - ARCHOSAUROMORPHA
(Crocodiles and Birds)- DINOSAURA –THEROPODA
 AVES (BIRDS) –Respiratory System

Nostrils: connected to internal nares and a slit - like glottis

Trachea: reinforced with hoop-like cartilage that is partly calcified

Syrinx: possess vocal muscles

Bronchus: 4 lungs which are small interconnecting chambers that open
into larger chambers,Parabronchi, which communicate with the bronchi
and air sacs which extend between organs in the body cavity and
space around the neck vertebrae and into the larger bones

Air is brought in by movement of muscles between the ribs bowing
laterally and by abdominal muscle

Contraction of the thorax reverse the flow
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA- REPTILIA- DIAPSIDA –
ARCHOSAUROMORPHA (Crocodiles and
Birds)- DINOSAURA –THEROPODA
 AVES (BIRDS) –Excretory System

Paired kidneys: three-lobed and attached dorsally under the
pelvis

From each is a slender ureter which extends posteriorly to
the dorsal wall of the cloaca

No bladder

Semi-solid nitrogenous waste (uric acid) passes down the
greeters and out of the cloaca via the vent
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA- REPTILIA- DIAPSIDA - ARCHOSAUROMORPHA
(Crocodiles and Birds)- DINOSAURA –THEROPODA
 AVES (BIRDS) – Nervous System and Sense Organs

Proportionately larger than reptiles

Olfactory lobes are small (poor sense of smell)

Cerebral hemispheres are large and smooth

Optic lobes on the midbrain are well developed

Cerebellum has an increased surface with many superficial folds

Nerve cord and paired spinal nerves similar to other vertebrates

The thoracic or branchial plexus serves the large pectoral muscles for
flight

The eyes are proportionately very large

Hearing is not as acute as for mammals

Chemoreception (smell and taste) is unlikely to be well developed
except in a few cases
PHYLUM: CHORDATA
 CLASS: SARCOPTERYGII
 TERRESTRIAL VERTEBRATES
 AMNIOTA- REPTILIA- DIAPSIDA ARCHOSAUROMORPHA (Crocodiles and Birds)- DINOSAURA
–THEROPODA
 AVES (BIRDS) –Endocrine Gland
 Pituitary: below the base of the brain
 Thyroid: two lateral lobes beneath the jugular and at the origin
where the subclavian and carotid meet
 Adrenals: ventral surface of the kidneys
 Pancreas: with islets of Langerhans
 Endocrine secretions of the gonad regulate secondary sexual
characters (e.g. plumage)
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA- REPTILIA- DIAPSIDA ARCHOSAUROMORPHA (Crocodiles and Birds)DINOSAURA –THEROPODA
 AVES (BIRDS) –Reproductive System

Male

Two oval, whitish testes arising from a much
convoluted ductus deferens which extends
posteriorly parallel to the ureter. In many birds it
is dilated as seminal vesicles before entering
cloacal. Some birds have vestigial penis (nonfunctional)

During breeding testis becomes enlarged, sperm
accumulates in the ductus deferens and is
transferred to the cloaca of the male during
copulation
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA- REPTILIA- DIAPSIDA - ARCHOSAUROMORPHA
(Crocodiles and Birds)- DINOSAURA –THEROPODA
 AVES (BIRDS) –Reproductive System

Female

System develops only on the left side, the ovary is near the
left kidney: Close by is the open expanded funnel or
infundibulun of the oviduct. The duct extends posteriorly to the
cloaca

In non-laying birds, the ovary is small containing minute eggs
and the duct is small. In the season of egg-laying the ovary
enlarges, a mature ovum receives a full quota of yolk before
being released. The mature ovum escapes from the ovarian
follicle into the abdominal cavity and enters the funnel at the
top end of the oviduct (movement is by ciliated epithelium)

Fertilization occurs in the upper oviduct, albumen is added by
glands in the middle portion and the shell membranes are
secreted by glands in the posterior part
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA- REPTILIA- DIAPSIDA ARCHOSAUROMORPHA (Crocodiles and Birds)DINOSAURA –THEROPODA
 AVES (BIRDS) –Reproduction (birds in general)

Eggs are laid with much yolk and a hard limy shell. The
shell is incubated during growth of the embryo

The young hatchlings of chickens and ducks are
precocial

Chicks of song birds, canaries, pigeons are altricial

Birds generally have different and characteristic seasons
for breeding

Breeding commences with a courtship display, defence
of territories, followed by construction of nests, laying of
eggs, incubation of eggs and the caring of the hatchlings
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA- REPTILIA- DIAPSIDA - ARCHOSAUROMORPHA
(Crocodiles and Birds)- DINOSAURA –THEROPODA
 AVES (BIRDS) –Flight

The spindle-shaped stream-lined body results in minimal
resistance

The shape of the wings and the manner in which they are moved
results in forward propulsion with as little expenditure of energy as
possible

The wing is an air foil with a leading edge that is thick and a trailing
edge that is thin

The upper surface of the wing is curved convexly, whereas the
lower surface is slightly concave

Consequently air passing over the curved upper surface must
move faster than the air underneath the wing

This causes a slight negative (low) pressure on the upper surface
in relation to the lower surface
PHYLUM:
CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA- REPTILIA- DIAPSIDA - ARCHOSAUROMORPHA
(Crocodiles and Birds)- DINOSAURA –THEROPODA
 AVES (BIRDS) –Flight

These differences in pressure creates
an upward force called lift. Increasing
the angle of attack (raising the position
of the leading edge in relation to the
trailing edge) causes an increased
amount of lift until a stall is induced

A stall is where the smooth air flow
is disrupted and turbulence is induced,
the result is that no lift now occurs and
flying is no longer possible

The outer part of the major flight
feathers (trailing edge) are semi
flexible and can be separated,
creating slots which reduce the turbulence and avoid a stall
when there is a high angle of attack

The shape of the wing is related to the type of flight
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
 SYNAPSIDA (mammals and their extinct relatives)

These are the dominant large terrestrial animals and are also
found in the sea in the form in Whales and in the air in the form of
Bats

All synapsids have a hole in the lateral surface of the skull
although it is modified in modern day mammals
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
 CLASS MAMMALIA

This refers to animals possessing mammary glands

Possess body hair

Homeothermic

Endothermic

Majority of mammals are viviparous

There are approximately 4000 living species of mammals
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA- Evolution
 Evolved from mammal-like reptiles (synapsids)
 The synapsid line eventually leads to the therapsids, one line of
which was the theriodonts. The theriodonts were half-way between
a reptile and a mammal, and were small animals occupying similar
life-styles to the modern day shrews
 The distinctive mammalian characteristics that evolved with these
early mammals included

An endothermic physiology

Insulating hair

Increased circulation efficiency

More effective locomotion

Viviparity

Greater parental investment in their young
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA- Evolution
 Extinction of the dinosaurs opened up many "niches" on land, sea
and in the air and an explosive species radiation of mammals
followed during the Cenozoic period
 The mammals are divided into the

Monotremata (egg-laying primitive mammals)

Marsupialia (pouched animals)

Eutheria (placental mammals)
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 MOMOTREMATA (egg laying mammals)

These are the most primitive, surviving mammals of today

Before hatching the embryo lives on the yolk contained within the
pliable egg

After hatching the young are nourished by milk from the mother's
mammary glands

There are no teats; the young lap up milk as it oozes from the
tubular glands

There are five living species of spiny anteater (Echidna) and one
species of duck-billed platypus (Ornithorhynchus)
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 MOMOTREMATA

They left the main mammalian stock far back in the Mesozoic era.

The skull has many primitive and/or reptilian features

The vertebra are very like that of reptiles, especially the cervical
vertebrae which bear separate ribs as occurred in the synapsid reptiles

The differentiation of the atlas, axis and seven cervical vertebrae is the
least for any mammalian group

There are 17 and 16 thoracic vertebrae for the platypus and the spiny
anteater respectively

Limbs are supported on pectoral and pelvic girdles, and more similar to
those of a reptile, and have far less muscle than the average advanced
mammal

Both the platypus and spiny anteater are highly specialized animals
and have no teeth in their adult phase, therefore we cannot deduce the
primitiveness of these
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 MOMOTREMATA -reproduction

The pattern of reproduction is unique amongst mammals and involves
laying of eggs

They show the beginning of the process of substitution of post-natal
nutrition from ovarian nutrition

Eggs are incubated for 10 days. The female platypus makes long
burrows where the nest is made. At birth the young monotremes
possess an “egg tooth” a unique character for mammals

After incubation and hatching the young enter the pouch and are fed by
milk. Postnatal care obviously preceded the egg laying characteristic

Both the echidna and the platypus produce milk from about 120 large
specialized sweat glands on the ventral abdomen. There are no ducts
uniting this secretion. ALL other mammals have nipples which do unite
such secretions
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 MOMOTREMATA

Have hair suggesting that Mesozoic mammals and even synapsid
mammals had made progress with temperature regulation

Able to regulate their body temperatures at around 32 °C in an
ambient temperature range of 5 to 30 °C

A curious feature found in monotremes is a grooved erectile poison
spine on the tarsus of the male

The circulation system is relatively advanced

In conclusion the monotremes are mammals with respect to their
brain, hair (insulation), warm-bloodedness, heart, larynx and
diaphragm. However, they have obvious reptilian affinities with
respect to their ovoviviparous reproduction and their skeleton
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 MARSUPIALIA (Kangaroos, Wombats,
Metatheria etc)

These are the pouched animals

250 living species

Show a strong anatomical resemblance to placental animals

Marsupials diverged from an early stage in the evolution of the
mammals

The marsupials parallel the adaptive radiation accomplished elsewhere
by the placental mammals except for forms like bats, whales or seals

Their features are specialized suggesting not a single stage on the way
to the placental evolution, but a specialized side branch

There are 172 marsupial species in Australia

There are successful representatives in North and South America e.g.
opossums which have survived in competition with the placentals
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 MARSUPIALIA

Temperature control less well developed than in the placental animals

Learning skills, visual discrimination and problem solving is equal to
that of similar placental mammals

The skull is similar to that of the primitive placentals such as the
insectivores, with a rather small cranium

The teeth are not easy to interpret the primitiveness of the group.
The incisor teeth are more numerous than in placental mammals
There are three and four premolar and molar teeth respectively in
each side of the upper or lower jaw whereas in placental there are
four and three premolars and molars


PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 MARSUPIALIA

The skeleton is generally similar to that of the placentals and
has greatly changed from the monotremes and the reptiles

The thoracic region consists of 13 pairs of rib-bearing
vertebrae as in placentals and there are usually 7 lumbar
vertebrae

The pectoral girdle is similar to that of the placentals

The pelvic girdle differs with the presence of the epipubic
bones and is similar to that of the monotremes

The hands usually carry five digits and armed with claws, but
the number of toes is often reduced and may bear hoof-like
structures
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 MARSUPIALIA- Marsupial Reproduction

The pattern is very different to that of placentals.

Pregnancy is very short

Hormones normally associated with development during
pregnancy of placentals can be removed in marsupial animals
without terminating the pregnancy

There is no special immune suppressant system protecting the
foetus from the mother’s antibodies as has to occur in placental
mammals

The life of the mother is not interrupted by any dramatic birth

The marsupial mother risks less and retains more freedom

After birth the young have long protection in the pouch

These young can be easily abandoned if the mother is stressed
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 MARSUPIALIA- Marsupial Reproduction

The marsupial egg has a very unequal cleavage, there is virtually
no placental development and instead uterine milk may be taken
up by the yolk sac

The embryo may be born as young as 8 days from conception (e.g.
the opossums)

At birth the young embryo will leave the vaginal opening and crawl
to the pouch and become attached to the teat

The embryo has well-developed forelimbs and nervous system. Its
mouth and olfactory system are well developed and are highly
specialized for suckling

In the pouch the neonate attaches to the teat, and the sides of the
lips grow around the teat, making it almost impossible to remove
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 MARSUPIALIA- Marsupial Reproduction

Milk is then injected into the neonate

The length of time in the pouch is variable between marsupial
forms. A wallaby may remain some 8 to 9 months in its mother's
pouch

Marsupials also have delayed implantation

Copulation can take place within a day of birth, but an 80 cell
blastocyte can remain dormant for up to 11 months

Suspension of development is controlled by suckling of the young
in the pouch
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 EUTHERIA (PLACENTAL MAMMALS) – Origins

Earliest forms found in the cretaceous period and were all small
insect-eating forms

During the Palaeocene both carnivore and primates evolved, in the
Late Cretaceous/Palaeocene the ungulates had evolved
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 EUTHERIA - Characteristics of Placental Mammals

Possess neither marsupial bones nor a pouch

The foetus develops directly and entirely within the body of the female

The embryo is connected indirectly to the mother via a placenta to the
wall of a uterus

A placenta permits the embryo (called a foetus) to remain in contact
with its mothers uterus for a long time

A placenta is a flat disk that becomes attached to the wall of the uterus
and is connected to the foetus by an umbilical cord

The junction of the placenta with the uterine wall is highly convoluted
this is where the exchange takes place

Blood does not pass from the mother to its foetus, but oxygen from her
lungs and nutrients derived from her food diffuse across the junction to
the foetus

The waste products produced by the foetus are absorbed by the
mother’s blood and then excreted through her kidneys
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 EUTHERIA - Characteristics of Placental Mammals

The placental foetus promotes the secretion of hormones which
suppresses the mothers sexual cycle during pregnancy

The foetuses tissues are not the same genetically as the mother's
since it contains genetic material from the father. When it becomes
connected to the mother's body, it risks immunological rejection

Placental mammals can stay in the uterus until they are fully
mobile and care carries on after birth

The placental breeding technique spares the young the hazardous
journey outside their mother’s body at a very early age

Placentals are the most widespread and diverse modern mammals
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 EUTHERIA

INSECTIVORA - small, primitive insect-eating
Order insectivora includes are variety of insect-eating forms. The
moles which live in underground tunnels, hedgehogs which are
spiny and roll into a ball as a defence against predation, the
desmans which swim with webbed feet and have a long snout
which act as a snorkel and shrews which are small active
predators on insects. In Madagascar there is a group called the
tenrecs, which are extremely diverse being aquatic and terrestrial
and some even resemble hedgehogs
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 EUTHERIA

DERMOPTERA - flying lemurs
Order dermoptera (= skin-winged) evolved from insectivores and
are commonly called flying lemurs. These animals do not have true
wings, but a furred skin extending from behind the ears outwards
to the digits, along the sides of the body to the tail. These flaps of
skin only allow them to glide rather than to fly
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 EUTHERIA

MACROSCELIDA - elephant shrews
Order Macroscelidia are also closely allied to the insectivores and
are commonly called the elephant shrews which are highly
specialized for running with very large hind limbs. Their eyes are
better developed than the poorly sighted insectivores
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 EUTHERIA

SCANDENTIA - tree shrews

Order scandentia include animals called tree shrews (Tupaia)

They are an intermediate group between the insectivores and
the primates (apes and monkeys)
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 EUTHERIA

CHIROPTERA – bats
Order chiroptera includes the only true flying mammals the bats.
Although they have obvious insectivore origins, their entire bone
structure is modified for flight. The wings are formed by the elongated
finger bones over which is stretched a naked skin membrane. Bats can
be divided into small carnivore forms and large fruit eating forms. The
small carnivorous bats hunt using echolocation. These bats emit high
frequency clicking sounds, which strike objects and the echo is
returned to the bats using its large ears to receive them
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 EUTHERIA

PHOLIDOTA – pangolins
Order pholidota are commonly called pangolins or scaly anteaters.
They possess large scales which are modified hairs and shield the
animal form predators. They also have no teeth, but do have an
exceptionally long sticky tongue (anchored to the pelvis) which is
used to eat ants and termites
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 EUTHERIA

TUBULIDENTATA – aardvarks
Order tubulidentata are commonly called aardvarks and
specializes in eating ants and termites and only occur in southern
Africa. Like the pangolins they have long sticky tongues, but they
are not toothless and possess five upper and four lower cheek
teeth on each side of their jaws (incisor and canines are absent)
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 EUTHERIA

EDENTATA – ant eaters and sloths
Order edentata are a varied group that are confined to the new world
(North and South America) and includes anteaters, sloths and
armadilos. Anteaters are toothless and have similar adaptations to
pangolins and aardvarks for eating ants and termites (convergent
evolution). Sloths and armadillos lack incisors and canines, but do have
simple cheek teeth that lack enamel and grow continuously from their
roots. The armadillo has 100 such teeth. The armadillo has bony plates
on its back for protection against predators. Sloths are slow moving
furred animals that live up in the trees. The prehistoric ground sloths
reach immense sizes up to 5 metres (Megatherim) as did some
armadillos (Glyptodon) whose bony plates formed a carapace that was
about 1,6 m in length
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 EUTHERIA

PRIMATES - lemurs, tarsiers, monkeys, apes, humans
Order primates includes lemurs, monkeys, apes and man. They are
essentially tropical in distribution and evolved from ancient, arboreal
insectivores sometime in the late Cretaceous period. Their tree-dwelling
existence demanded dextrous limbs, hands and fingers (including an
opposable thumb), close set eyes with overlapping fields of vision for
depth perception, excellent eye-hand co-ordination and extended
parental care for their young. They are characterized by considerable
development of the brain, a process that eventually resulted in the
evolution of man. The earliest ape-man was Australopithecus Africans,
a small-brained formed, followed in sequence by the larger brained
Homo hails (who used tools) and Homo erectus (had use of tools and
fire) . From this stock two forms of modern man Homo sapiens evolved,
one called Neanderthal man survived in cold northern climates during
the ice ages, the other form survives today as Homo sapiens sapiens
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 EUTHERIA

RODENTIA - gnawing animals except rabbits and hyraxes
Order rodentia, is the most abundant of placental mammal forms
and includes, rats, mice, mole-rats, squirrels (including forms that
can glide like the flying lemurs), porcupines, prairie dogs. They are
all characterized by a long pair of prominent upper and lower
incisors. These teeth are kept sharp through differential wear of
their enamel and are very effective for gnawing. Canine teeth are
absent
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 EUTHERIA

LAGOMORPHA – rabbits
Order Lagomorpha includes rabbits and hares and all are strictly
ground dwelling forms. Despite their similarities to rodents they are
not closely related. Like rodents they do have continuously growing
incisors with a total of four in the upper jaw (two of which are
reduced) as opposed to only two in the rodents
PHYLUM:
CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 EUTHERIA

CETACEA - whales, dolphins and porpoises
Order Cetacea includes the most aquatic forms of mammals; the
whales, dolphins and porpoises. The blue-whale is the heaviest animal
ever to have lived on the earth. Their modifications for an aquatic
existence include loss of the hind-limbs, forelimbs have developed into
flippers, the tail is flattened and most have a dorsal fin, the nasal
opening (blow hole) is on the top of the head, no external ears, hair is
almost absent and insulation is by way of blubber. They can be divided
into toothed forms which are active predators, and toothless forms
which have long plates of stiff hair - like material that forms a baleen
which acts as a sieve to filter plankton. Cetaceans are intelligent ,
social animals, which can communicate with each other and use
echolocation to navigate the waters they swim in. They probably
evolved from insectivores in the early Cenozoic
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 EUTHERIA

CARNIVORA - modern meat-eating
Order Carnivora are meat eating placentals that have prominent
canine teeth. These are long, curved, pointed, very strong and
particularly effective for stabbing. Most carnivores are
predominantly meat-eaters and also have short, but sharp incisor
teeth for nipping. The fourth upper premolar and first lower molar
teeth have become specialized into shearing blades called
carnassial teeth (these are absent in aquatic carnivores such as
seals). Cats, dogs, lions leopards, cheetahs, hyenas mongooses,
bears, pandas (secondarily adapted to an herbivorous diet), seals,
walruses, sea lions and elephant seals are all members of
Carnivora
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 EUTHERIA

PROBOSClDEA – elephants
Order Proboscidea is represented by two species of elephant.
Elephants are characterized by an immense size, and a long trunk that
is really a highly modified nose. The tusks are elongated upper incisors.
Elephants have no canines or premolars and their molars are used to
grind up herbaceous food and are replaced successively from behind
as they wear down. They are naked skinned since they live in tropical
climates and their large ears act as radiators to dissipate excess heat.
Their extinct relatives, the mammoths, had fur and had colonized cold,
northern latitudes until they were hunted to extinction by prehistoric
man
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 EUTHERIA

HYRACOlDEA – hyraxes
Order Hyracoidea includes the hyrax or dassie, which although
superficially resemble rodents and lagomorphs, are actually more
closely related to elephants. They are herbivores with continuously
growing chisel-shaped incisors. There feet are completely distinctive,
there being four toes on the front feet, three on the hind, terminating in
small, hoof like nails
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 EUTHERIA

SIRENlA - seacows, manatees and dugongs
Order Sirenia are the aquatic dugongs and manatees (sometimes
called sea cows). They are large, hairless herbivores (possessing
only functional cheek teeth) that have their forelimbs modified into
paddles and no hind limbs. Possibly share a similar ancestry with
elephants
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 EUTHERIA

PERISSODACTYLA odd-toed ungulates
Order Perissodactyla are odd-toed, hoofed animals (=ungulates) and
include, horses, asses, zebras, tapirs (all having a single digit) and
rhinoceroses (having three digits). They are all large herbivorous
animals, and many have elongated limbs for faster running speeds
(horses and zebras). Their cheek teeth are massive, strong and
modified for grinding plant material
PHYLUM: CHORDATA
CLASS: SARCOPTERYGII
TERRESTRIAL VERTEBRATES
AMNIOTA
SYNAPSIDA
CLASS MAMMALIA
 EUTHERIA

ARTIODACTYLA - even-toed ungulates
Order Artiodactyla are the even-toed hoofed animals and include
antelope, deer, hippos, giraffes, camels, llamas, cattle, sheep, pigs and
goats. These are generally herbivorous, and with the exceptions of pigs
and hippos are ruminant animals (having a large fore-stomach called a
rumen in which plant fibres are initially digested). Many are grazing
animals and occur in enormous herds and also have elongated legs for
faster running and to avoid predation. Their cheek teeth are large,
complex and designed for grinding plant material (upper canine and
incisors are reduced or absent