The arthropod leg
is a form of jointed appendage
, usually used for walking
. Many of the terms used for arthropod leg segments are of Latin
origin, and may be confused with terms for bones: coxa
(compare greater trochanter
and lesser trochanter
Homologies of leg segments between groups are difficult to prove and are the source of much argument. Some authors posit up to eleven segments per leg for the most recent common ancestor
of extant arthropods
that the ancestral leg need not have been so complex, and that other events, such as successive loss of function of a Hox-gene
, could result in parallel
gains of leg segments.
==Biramous and uniramous==<!-- This section is linked from Arthropod
-->The appendages of arthropods may be either biramous
. A uniramous limb comprises a single series of segments attached end-to-end. A biramous limb, however, branches into two, and each branch consists of a series of segments attached end-to-end.
The legs of insects and myriapods
are uniramous. In crustaceans, the first antennae are uniramous, but the second antennae are biramous, as are the legs in most species.
For a time, possession of uniramous limbs was believed to be a shared, derived character
, so uniramous... Read More