Ascendonanus (meaning "climbing dwarf") is an extinct genus of varanopid amniote from the Early Permian of Germany. It is the earliest specialized arboreal (tree-living) vertebrate currently known and resembled a small lizard, although it was related to mammals. The fossils of Ascendonanus are of special scientific importance because they include remains of skin, scales, scutes, bony ossicles, and body outlines, indicating that some of the oldest relatives of mammals had a scaly "reptilian-type" appearance. The animal was about 40 cm long, with strongly curved claws, short limbs, a slender, elongated trunk, and a long tail. It would have preyed on insects and other small arthropods.