We show how the extremal behavior of d-variate Archimedean copulas can
be deduced from their stochastic representation as the survival dependence
structure of an l1-symmetric distribution (see McNeil and
Nešlehová (2009)). We show that the extremal behavior of the
radial part of the representation is determined by its Williamson
d-transform. This leads in turn to simple proofs and extensions of
recent results characterizing the domain of attraction of Archimedean copulas,
their upper and lower tail-dependence indices, as well as their associated
threshold copulas. We outline some of the practical implications of their
results for the construction of Archimedean models with specific tail behavior
and give counterexamples of Archimedean copulas whose coefficient of lower tail
dependence does not exist.