Australian region,one of the zoogeographical realms
Zoogeographical realms : Based on the faunal peculiarity &
the pattern of animal distribution , the earth surface can be
divided into several megafaunal zones .
The term “realm” was first proposed by Lydekker
He divided earth’s surface into 3 realms
Arctogaea is the largest division which includes the
continuous land mass of northern hemisphere
Arctogaea is further subdivided into 4 regions
4. Oriental regions
Notogaea includes Australia
Neogaea includes South America
Sclater (1867) : six geographical region
based mainly distribution of birds
1. Palearctic region : consist Europe , temperate regions of Asia &
the northern temperate part of Africa lying north of atlas
2. Ethiopian or western palaeotropical region : consist of Africa &
southern Arabia .
3. Indian or middle palaeotropical region : consist of tropical Asia
& the associated continental islands.
4. Australian or eastern palaeotropical region : consist of
Australia , New Guinea & Tasmania.
5. Nearctic or North American regions : consist of north
America , north to central Mexico .
6. Neotropical or south American region : consist of south
& central America & southern Mexico.
Largely based on Wallace’s analysis of the ranges of families of mammals
Alfred Russel Wallace in his famous work “Geographical
Distribution of Animals (1876)
Today the widely accepted system of zoogeographical
classification is that of Wallace
1. Palaearctic region
2. Nearctic region
3. Neotropical region
4. Ethiopean region
5. Oriental region
6. Australian region
Neotropical Ethiopian Oriental Australian
Geographical & Climatic features
This region consist of Australia , New guinea , Tasmania &
Some authors include New Zealand also in this region and call
the region Australasia , instead of Australia
The region is a mixture of tropical and temperate zones.
Northern part --- large tropical region
Southern part---- temperate region
Australia , New Zealand & New Caledonia are all portions of the ancient
supercontinent of Gondwana
Which started to break into smaller continents in the Cretaceous era ,
130-65 million year ago
New Zealand broke away first , more than 80 million years ago
Australia finally broke apart from Antarctica about 45 million year ago.
Australia moved northward to desert latitude , the
continents become hotter & drier
As a result new drought – tolerant and fire resistant flora ,
dominated by Eucalyptus , Casuarina , Acacia , Grasses
Presently , Australia is the smallest , the driest and the
flattest ( lowest in elevation ) continent.
From a zoological point of view , Australia is a distinct region with
a common evolutionary history and very unique animals .
Some of these animals are common to the entire area , others
specific to particular parts but sharing a common ancestry .
Australia & New Guinea are distinguished by their marsupial
mammals , including Kangaroos , possums and Wombats .
The last remaining monotreme mammals , the echidnas & the
platypus are endemic to Australia .
Sub - regions
Australian region is further subdivided into three sub regions
1. Austro- Malayan sub region (islands of Malayan
Archipelago , New Guinea and Solomon islands )
2. Australian sub region ( Australia and Tasmania ) :
3. Polynesian sub region ( islands of Polynesia and
sandwich islands )