2. “This theory demands the presence of bridges of continental
size spreading under deep water, serving as means of
communication from one continent to the other”
2
These land bridges were present in Cenozoic era leaving behind no trace of
their existence.
They were supposed to have sunk beneath the oceans leaving no trace of
their existence.
They are restricted to regions where the seas were shallow.
3. Land bridges
Atlantic Land Bridge
Africa and South
America
Lemuria Land Bridge
Madagascar and India
Antarctica Land Bridge
Australia and South
America
4. Between Africa and South
America
Atlantic Land
Bridge
4 Monkeys
Porcupines
Ostriches
Pipid toads Side-necked turtles
Lungfishes
6. 6
Hypothesis rejected
Zoological evidence indicates that such land bridge is
unlikely to have existed.
In South America Edentates is endemic order of
mammals which includes armadillos, sloths and this
order is not present in Africa.
Monkeys, porcupines and ostriches of Africa and South
America are no longer closely related to each other and
belong to different families.
Hypothesis rejected
7. Between Madagascar and
India
Lemuria Land
Bridge
It was named 'Lemuria' because it was designed to explain the distribution
of lemurs.
Lemurs
•These are arboreal, nocturnal primates. The
representatives of lemurs are present in the oriental
Madagascar.
Lorises
•Lorises are lemur like animals present in the oriental
and Indian regions.
10. The lemurs were thought to have evolved on Lemuria
towards the end of Mesozoic and spread to Africa and
the Oriental region where they are represented today
by Lorises.
The original lemurs were left on Madagascar and
Comoro Island when rest of the Lemuria sank below
the sea in the Cenozoic period.
11. 11
Hypothesis rejected
Hypothesis rejected
Hypothesis rejected
Firstly, the recent studies have shown that although both lemurs and
lorises have evolved from the same early primate stock, they are
otherwise not related to each other.
Secondly, a number of fossils of this early primate stock or the so
called ancestors of lemurs and lorises have been found in Palacocene
and Eocene rocks in north (i.e. in Europe and North America).
Many zoologists suggest that Madagascar has been separated from the
rest of the world during the Cenozoic era due to some drastic climatic
and environmental conditions
So Lemuria land bridge is unlikely to have existed
14. 14
Hypothesis ejected
Hypothesis rejected
Hypothesis rejected
Flightless birds of S. America (Rhea) and the Emus Australia are not
closely related to one another and are classified in separate as such their
distribution need not be discussed in this context.
Lungfishes and side-necked turtles were widespread in all continents
during Cretaceous period and their discontinuous distribution is therefore
better accounted for by the extinction in the north of formerly worldwide
groups.
As for marsupials and the hybrid tree frogs are concerned, it may be
interesting to note that there are no fossil records nor living marsupials
and tree frogs in the Oriental region.
