The Monoceros Ring wraps 100 degrees of the outer disk at 15 to 20 kpc with 10⁸ solar masses of stars whose chemistry and near-circular kinematics read disk-like, not stream-like, while the corrugation family (Triangulum-Andromeda, A13) suggests a rung disk whose required bell-ringer, Sagittarius, keeps failing to reproduce the amplitudes without tuning. ΛCDM owns either an accretion event with no coherent progenitor or waves without an adequate cause.
The model's outer disk is smooth by default: structure there must be imported by accretion or excited by a recent perturber, because a quiescently assembled disk has no native ring-and-corrugation architecture. Both import routes carry bookkeeping the data refuse to balance.
SCT builds the outer disk structured: the Galaxy condensed from a rotating debris stream whose fragmentation left in-plane overdensities, and whose deposition carried wave patterns, density and bending corrugations frozen in from the collision geometry rather than excited afterward (P31, P32, P33). A ring-like band of disk-chemistry stars at the deposition edge, rotating with the disk and rippling vertically through the corrugation family, is the native architecture of a deposited disk: the Monoceros Ring's awkward hybrid signature, too disk-like for accretion, too structured for a smooth disk, is the expected face of structure that was never imported and never needed a bell.
The burden ΛCDM shuffles between progenitor and perturber simply dissolves: Sagittarius and other satellites perturb the disk as real secondary modulations, but the corrugation baseline is inherited, which is why perturber-only models keep coming up short on amplitude. The prediction is the same continuity test as Canis Major: ring stars share disk chemical gradients and the warp's J alignment, with corrugation phases coherent over scales set by deposition rather than by any single recent passage.
This is the same deposited-structure reading behind Canis Major and the warp, one rung further out. There is no need to choose between a phantom dwarf and an underpowered bell-ringer.
Both exits remain open and decisive: isolation of a coherent progenitor orbit family with stream chemistry would establish accretion and remove the deposition reading; conversely, a Sagittarius-mass-and-orbit model independently reproducing the full corrugation amplitudes and phases without tuning would establish the excitation account and leave inherited structure unneeded. SCT requires the middle outcome to persist: disk-continuous populations in deposition-coherent waves that neither import nor excitation bookkeeping closes.