Definition of Microsauria
1
: an order of extinct amphibians (suborder Lepospondyli) of the Pennsylvanian and Lower Permian that resemble salamanders, are sometimes considered ancestral to modern apodal and caudate amphibians, or are placed among the primitive reptiles
2
in some classifications
: an order or other group of amphibians equivalent to Lepospondyli (see Lepospondyli a)
