Lepidosauromorpha

Lepidosauromorphs Temporal range: Late Permian - Recent, 260–0 Ma PreЄ Є O S D C P T J K Pg N
A Plumed Basilisk
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Node:	Romeriida
Subclass:	Diapsida
Infraclass:	Lepidosauromorpha Benton, 1983
Orders
Thalattosauriformes † Placodontia † Nothosauroidea † Plesiosauria † Eolacertilia † Sphenodontia Squamata

Lepidosauromorpha is a group of reptiles comprising all diapsids closer to lizards than to archosaurs (including crocodiles and birds). The only living sub-group is the Lepidosauria: extant lizards, snakes, and tuatara. The extinct lepidosauropmorphans are thought to include the plesiosaurs.

Lepidosauromorpha are distinguishable from Archosauromorphs (archosaurs) by their primitive sprawling gait, which allows 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. In contrast, Archosauromorphs possess a parasagittal gait, a reduction in their dermal girdle, a reduction and/or loss of the sternum, and a more thecodont dentition.

It is also important to note that, because Lepidosauromorphs are sprawlers, they require less energy to maintain their stance and are thus allowed to remain cold-blooded.

Classification

• Subclass Diapsida
  • Infraclass Lepidosauromorpha
    • Acerosodontosaurus †^{[citation needed]}.
    • Superorder Sauropterygia - Plesiosaurs †
    • Lepidosauriformes
      • Order Eolacertilia †
      • Superorder Lepidosauria
        • Order Sphenodontia - Tuatara
        • Order Squamata
          • Suborder Amphisbaenia - Worm lizards
          • Suborder Lacertilia* - Lizards
            • Family Mosasauridae †
          • Suborder Serpentes - Snakes