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In-Depth Information
Legs that are upright are able to more efficiently support heavier weights and
result in most small mammals being noncursorial whereas larger mammals
over 3kg are cursorial.
As with other elements of animal anatomy, feet have evolved in different
forms to meet animals' needs. The shape of a foot, the number of toes,
and the manner in which the feet are used have all developed to aid
locomotion, often at speed. This has led to a further classification of
animals that applies to quadrupeds and others based on the way the foot
is used to support the animal and to aid locomotion. Let's look at these
classifications now.
Ungulate is a general term that describes mammals that have developed
either paws or hooves, with most of them standing on the tips of their toes,
such as horses, zebra, cattle, goats, pigs, moose, deer, gazelles, and giraffes.
There are three separate classifications of animals that describe the
manner in which they use their feet to stand: plantigrade, digitigrade, and
unguligrade.
FIG 4.12 Different foot types:
a: Unguligrade. b: Plantigrade.
c: Digitigrade.
Plantigrade describes animals that stand with the whole of the foot, from
the toes to the heel, placed flat down on the ground. Humans and bears
both fall into this category. The greater surface area that makes contact with
the ground allows for increased balance. Amphibians and reptiles are also
plantigrades.
Digitigrade denotes animals that stand and walk only on their toes, with the
heel lifted completely off the ground. Cats and dogs fall into this classification.
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