Subterranean Dragon by nezumi
Subterranean dragons are one of the hardest species to study.
Their wing and fin membranes have evolved mostly away and are useless for flight but still serve an important function. The membranes are sensitive to airflow and temperature which help the dragons navigate in their lightless world by using air currents as landmarks. Some people even believe that these membranes are sensative enough to triangulate a primitive form of echolocation. This theory was first put forth by scientists who observed these dragons tucking their wings in tight to their bodies when passing withing a fairly long range of underground waterfalls. They took this to mean the dragons were protecting their membranes from something other than water spray.
Their diet consists mostly of the insect life that thrives on the guano of bats and harpies. The dragons will scavenge meat when it becomes available.