Miodentosaurus brevis (Cheng et al. 2007) Late Triassic ~210 mya, ~5 m in length, is a large thalattosauriform derived from a sister to Askeptosaurus and it phylogenetically preceded Vancleavea and Helveticosaurus.
Distinct from Askeptosaurus, the skull of Miodentosaurus had a much shorter rostrum and fewer teeth. The kink in the upper jawline was filled by a rise in the mandible. The upper temporal fenestra was a hairline opening.
The cervicals were shorter. The caudal spines were slightly taller distally and the chevrons were slightly deeper.
The limbs were larger. The forelimb was larger and more robust than the hind limb. The unguals were smaller. Manual digits 3-5 were virtually identical.
The pelvis was larger, with a robust anteriorly directed pubis. Metatarsals 1-4 were aligned. Pedal digit 5 added a fifth phalanx.
A family tree of the Enaliosauria is here. A more complete tree of the Reptilia is here.