Lepidosauromorpha (in PhyloCode known as Pan-Lepidosauria[2][3]) is a group of reptiles comprising all diapsids closer to lizards than to archosaurs (which include crocodiles and birds).

The only living sub-group is the Lepidosauria, which contains two subdivisions, Squamata, which contains lizards and snakes, and Rhynchocephalia, the only extant species of which is the tuatara.

Lepidosauromorphs are distinguishable from archosauromorphs (reptiles closer to archosaurs) by their primitive sprawling gait (allowing for the same sinusoidal trunk and tail movement seen in fish), the sliding "joint" between the coracoids and the sternum (for a longer stride), and their pleurodont dentition.

Living lepidosauromorphs have retained an ectothermic ("cold blooded") metabolism, unlike the ancestral condition in archosauromorphs.

While some putative stem-lepidosauromorphs like Palaeagama are known from the Late Permian, the oldest definitive lepidosauromorphs, Sophineta and Paliguana, are known from the Early Triassic.