What is "monstersauria"

Monstersauria is a clade of varanoid lizards, defined as all taxa more closely related to Heloderma than Varanus. It includes Heloderma, as well as several extinct genera, such as Estesia and Gobiderma, but it was found to be polyphyletic in the most recent and complete squamate phylogenetic analysis by Reeder et al. (2015).