Parrots are a
monophyletic group and share many unique characteristics not seen in
any other bird groups.
Characters / Anatomy
Zygodactyl feet- The method by which parrots feed
is to bring food to their mouth by the use of their feet, therefore they have
evolved high dexterous feet able to hold a vast array of objects. Although
other birds such as woodpeckers have zygodactyl feet, it is not known whether
this is due to convergent evolution or a shared ancestor. This is the
main characteristic used by palaeo-ornithologist to determine early fossilised
parrots as the distinctive beak is thought o be later development during the
Oligocene
Zygodactylic feet in comparison to other types
Image from wikipedia.org
Large cranium - Parrots possess a large
skull for mainly two reasons: First, many species of parrots' diet
consists mainly of fruit, seeds and nuts, requiring large amounts of space to
the side of the cranium for muscle attachment to the lower mandible. The
second reason is they possess very large brains, in fact it has been shown in studies that african greys (Psittacus erithacus)
are able to count and understand basic language. This could share some
similarities
to human evolution,e.g expensive tissue hypothesis, the brain
requires vast amounts of
energy all year round from nuts and fruit, restricting them to
sub/tropical regions where high energy food is available all year
round. Further more the Kea (Nestor
notabilis) parrot feeds on insects and live flesh picked from
livestock, this may not be a unique trait though as many captive bred parrots regularly
'beg' and steal cooked meat from their human companions' food.
Communication - Due to
the clumping and varying
seasonality of fruiting of food sources in the tropical and subtropical
forests
they inhabit, parrots have an extensive memory. This also explains
their
communication skills, which are second to none in the bird world.
Parrots will
teach there offspring where and when food is available and call to
other parrots (even sometimes different species) informing them of
where a food source is available.
Tongue - As stated above, parrots have developed great
dexterity in their feet, but they also have a highly developed tongue that is
able to manipulate objects affectively. It acts in a similar way to having an extra finger
and can rotate and move object within the beak by holding the objects against the
upper mandible tip.
Pigmentation of feathers - Parrots are one of the most colourful
birds in the world, this is because they have dyck pigmentation allowing for colours such as green and blue.
Reduced clavicle/furcula appears in parrots, this characteristic
has yet to be fully explained.
