  We examine p-branes in AdS(D) in two limits where they exhibit partonic
behavior: rotating branes with energy concentrated to cusp-like solitons;
tensionless branes with energy distributed over singletonic partons on the
Dirac hypercone. Evidence for a smooth transition from cusps to partons is
found. First, each cusp yields D-2 normal-coordinate bound states with
protected frequencies (for p>2 there are additional bound states); and can
moreover be related to a short open p-brane whose tension diverges at the AdS
boundary leading to a decoupled singular CFT at the ``brane at the
end-of-the-universe''. Second, discretizing the closed p-brane and keeping the
number N of discrete partons finite yields an sp(2N)-gauged phase-space sigma
model giving rise to symmetrized N-tupletons of the minimal higher-spin algebra
ho_0(D-1,2)\supset so(D-1,2). The continuum limit leads to a 2d chiral
sp(2)-gauged sigma model which is critical in D=7; equivalent a la
Bars-Vasiliev to an su(2)-gauged spinor string; and furthermore dual to a WZW
model in turn containing a topological \hat{so}(6,2)_{-2}/(\hat{so}(6)\oplus
\hat\so(2))_{-2} coset model with a chiral ring generated by singleton-valued
weight-0 spin fields. Moreover, the two-parton truncation can be linked via a
reformulation a la Cattaneo-Felder-Kontsevich to a topological open string on
the phase space of the D-dimensional Dirac hypercone. We present evidence that
a suitable deformation of the open string leads to the Vasiliev equations based
on vector oscillators and weak sp(2)-projection. Geometrically, the bi-locality
reflects broken boundary-singleton worldlines, while Vasiliev's intertwiner
kappa can be seen to relate T and R-ordered deformations of the boundary and
the bulk of the worldsheet, respectively.
