  We consider a geometric zero-radius limit for strings on $AdS_5\times S^5$,
where the anti-de Sitter hyperboloid becomes the projective lightcone. In this
limit the fifth dimension becomes nondynamical, yielding a different
"holographic" interpretation than the usual "bulk to boundary" one. When
quantized on the random lattice, the fifth coordinate acts as a new kind of
Schwinger parameter, producing Feynman rules with normal propagators at the
tree level: For example, in the bosonic case ordinary massless $\phi^4$ theory
is obtained. In the superstring case we obtain new, manifestly ${\cal N}=4$
supersymmetric rules for ${\cal N}=4$ super Yang-Mills. These gluons are also
different from those of the usual AdS/CFT correspondence: They are the
"partons" that make up the usual "hadrons" of the open and closed strings in
the familiar QCD string picture. Thus, their coupling $g_{YM}$ and rank $N$ of
the "color" gauge group are different from those of the "flavor" gauge group of
the open string. As a result we obtain different perturbation expansions in
radius, coupling, and 1/N.
