Page 72 - Atlas Of The World's Strangest Animals

72 ATLAS OF THE WORLD’S STRANGEST ANIMALS

Being big doesn’t necessarily mean that you can’t get
Emu habitats
airborne – it just makes it a lot harder! The extinct
Argentavis magnificens, for instance, weighed up to 110kg
(242.5lb). It was the largest bird that ever flew and
needed massive flight muscles and an 8m (26.2ft)
wingspan to get into the air. So, a bird the size of an emu
would certainly be able to fly, if its body was designed to
do so. Unfortunately, it isn’t.
Flight is about more than just feathers and wings – it’s
dependent also on the design of the body – and most birds
have a number of physical adaptations that aid flight.Their
skeletons, for instance, are lightweight.They have fewer
bones than other vertebrates and many of these are hollow.
They have circulatory and respiratory systems that have to
work at an incredibly high rate to power flight.They have
wings that are specially shaped to reduce drag and increase
lift. But it’s the birds’ sternum (breastbone) that is
particularly important.This large bone lies beneath the
body and, in those species that fly, it has an enormous,
projecting keel, to which the flight muscles are attached.
This keeled shape adds strength and enables the sternum replaced with finely preened flight feathers, they still
to bear the stresses of flight. wouldn’t be able to fly.
Some flightless birds retain many physical features that
tell us that their ancestors once flew. Some even have a Bird wars
keeled sternum, although their wings are too small, and In the past, birds like New Zealand’s quirky kakapo
their bodies too big, for them to get airborne. However, (Strigops habroptila) didn’t have to worry about getting
emus are members of a strange group of flightless birds airborne because the islands on which lived had no
called ratites, which have flat keels. So, even if their stubby ground-dwelling predators. So, as time progressed, they lost
wings were bigger and their shabby, hairlike plumage was the ability to fly. It was only when humans arrived in the

Comparisons

Emus may be Australia’s biggest bird, but they’re not the world’s only
big birds. South America has its own giants, known as greater rheas
(Rhea americana).The biggest of these impressive birds weigh in at
40kg (88.2lb) and stand over 1.5m (4.9ft) tall. Like the ‘antipodean’
emus, they’re flightless, with long, powerful legs and a long neck
designed for foraging on the ground.

Greater rhea

Emu

(c) 2011 Marshall Cavendish. All Rights Reserved.