Microsauria

Microsauria is an extinct, possibly polyphyletic order of tetrapods from the late Carboniferous and early Permian periods. It is the most diverse and species-rich group of lepospondyls. Recently, Microsauria has been considered paraphyletic, as several other non-microsaur lepospondyl groups such as Lysorophia seem to be nested in it. Microsauria is now commonly used as a collective term for the grade of lepospondyls that were originally classified as members of Microsauria.

thumb|left|200px|Microbrachis The microsaurs all had short tails and small legs, but were otherwise quite varied in form. The group included lizard-like animals that were relatively well-adapted to living on dry land, burrowing forms, and others that, like the modern axolotl, retained their gills into adult life, and so presumably never left the water. Their skeleton was heavily ossified, and their development was likely gradual with no metamorphosis.