Lepidosauria

The Lepidosauria navigation envelope uses the approximately 240 Ma Megachirella specimen and its tested stem-squamate placement as the older evidence anchor and living lepidosaurs at 0 Ma as the younger edge; this does not make Megachirella a direct ancestor or establish a global lepidosaur first appearance or divergence time.

The cited analyses place Megachirella on the squamate stem, Taytalura as an early-diverging stem lepidosauromorph, and Bellairsia on the squamate stem; these placements are sampled analytical results and do not resolve every lepidosaur relationship.

The profile's named lepidosaur samples come from the Middle Triassic Italian Alps (Megachirella), Late Triassic Ischigualasto Formation of Argentina (Taytalura), and the Middle Jurassic Kilmaluag Formation of Skye, Scotland (Bellairsia specimen NMS G.2022.1.1); these occurrences do not establish a global lepidosaur distribution.

High-resolution imaging exposes complementary early lepidosaur anatomy: Megachirella contributes cranial, wrist and shoulder characters, Taytalura preserves a three-dimensionally exposed CT-resolved skull, and Bellairsia provides synchrotron-resolved stem-lizard anatomy.

The cited Megachirella, Taytalura and Bellairsia studies provide locality, anatomy and phylogenetic analyses but do not establish a single Lepidosauria diet, habitat, locomotor mode, body-size distribution or ecological guild; those fields remain explicitly unassigned here.