Does the refinement that created the modern worm snake specialize before or after the main radiation of crown snakes?

It arose after the major phylogenetic radiation of modern snakes

The establishment of the fundamental snake blueprint—the major phylogenetic radiation that followed the emergence of the common ancestor often nicknamed "one blind grandpa"—set the stage for later diversification. The specialization observed in modern worm snakes represents an evolutionary refinement that took place within this already established and successful group. This means the worm snake morphology, dedicated intensely to soil penetration and earthworm consumption, is a relatively recent evolutionary development, illustrating an intense period of adaptation to a highly specific ecological role within the broader snake family tree, rather than representing one of the earliest divergences from the reptilian line.