The Evolution of

ORDER

DIPROTODONTIA

BIO 140 F

Group 1

September 14, 2011

CLASS MAMMALIA

SUBCLASS THERIA

INFRACLASS MARSUPIALIA

MARSUPIALS

With mammalian characteristics

Warm-blooded

(+) Mammary glands

(+) Fur

Viviparous

Dentition for mechanical digestion

Bear live,

imature

young in

their

marsupium.

MARSUPIALS

MARSUPIALS

First appeared during the Late

Cretaceous in North America

Most species

found in

Australia

PALEONTOLOGICALHISTORY

Sinodelphys szalayi

125mya (Early Cretaceous Period)

Believed to be an early

ancestor of marsupials

Alphadon

Earliest marsupial

recorded

Remains found in North

America 80 mya(Cretaceous Period)

Late Oligocene…

1st Diprotodontia fossil uncovered…

Hypsiprymnodon bartholomaii

Earliest

identified

species (Early Miocene)

Diprotodon

Extinct, giant

marsupial

Closely related

to kangaroos

Fossil found in

Australia

Diprotodon

Herbivorous

Used all four legs

for walking

About as big as a

Rhinoceros

Diprotodon australis

– only known

species

Nototherium

Also a giant

marsupial

Related to

Diprotodon

Bones often

found with

Diprotodon

SYSTEMATICS ANDPHYLOGENY

ORDER DIPROTODONTIA

Divided into 10 families; one extinct

ORDER DIPROTODONTIA

Family

Pseudocheiridae

(ringtails and gliders)

Family Acrobatidae

(feathertail gliders)

Family

Vombatidae

(wombats)

◦ With allantoic

placentae

◦ Well-developed

marsupium(posterior orientation)

ORDER DIPROTODONTIA

ORDER DIPROTODONTIA

Family

Macropodidae(kangaroos)

◦ Embryonic

diapause

Blastocyst suspends

implantation and

development

ORDER DIPROTODONTIA

F. Macropodidae…

Females support

young of 3 litters

◦ Uterus

◦ Full-time in pouch;

attached to nipple

◦ Out of pouch but

returning to nurse

F. Macropodidae…

Longest and

strongest toe

– 4th toe in

hind feet

ORDER DIPROTODONTIA

ORDER DIPROTODONTIA

Family

Potoridae(bettongs, pottoroos,

and rat-kangaroos)

◦ DIET: fungi

◦ Closely allied

with kangaroos

and wallabies

ORDER DIPROTODONTIA

Family

Phascolarctidae

(koalas)

◦ Only one

extant species

◦ Endemic in

Australia

ORDER DIPROTODONTIA

F. Phascolarctidae…

Briefly forms

placenta during

gestation of

embryo

Co-evolved with

Eucalyptus

ORDER DIPROTODONTIA

Family

Phalangeridae(Possums and Cuscuses)

◦ DIET: Tree leaves

◦ marsupium well-

developed

(anterior opening)

◦ Single young per

litter

Family

Tarsipedidae

(honey possums)

◦ DIET: Nectar

ORDER DIPROTODONTIA

Family

Burramyidae

(Pygmy Possums)

ORDER DIPROTODONTIA

MORPHOLOGYAND

DIVERSIFICATION

ORDER DIPROTODONTIA

Largest order of marsupials

Basic characteristics:

◦ Enlarged lower incisor that project forward

◦ Absence of canine teeth

◦ Integument that binds together 2nd and 3rd digits of hind feet

◦ Diverse in size, diet and method of locomotion.

ORDER DIPROTODONTIA

Gondwanaland – origin of

mammals with distinctive

marsupial reproduction

Marsupial ancestors and

placentals separated and became

isolated in South America and

Australia

Found in Australia, New Zealand,

New Guinea, and nearby islands

Inhabit a variety of terrestrial

habitats:

◦ Grasslands

◦ Forests

◦ mountains

ORDER DIPROTODONTIA

Evolved to suit or adapt to a wide

variety of environments

Homologous adaptations –

marsupials and placental mammals

Introduced placental mammals in

Australia poses a threat to the

marsupials

ORDER DIPROTODONTIA

FATE OFO. DIPROTODONTIA

AND OTHERMARSUPIALS

In a few years…

Human protection = no

marsupial extinction

Established induced placental

mammals = competition =

marsupial extinction

Co-existence between marsupials

and placentals possible

In the formation of a new super-

continent… (200 my from now)

Dispersal of marsupials to

new habitats

Possible marsupial evolution

for adaptation

Thank you!