[1] The genus was erected by Brongniart[2] under the name Nilsonia based on material from the Hettangian of Scania.

[3] The diagnosis of the genus, initially based on the pinnate Nilssonia brevis, was later amended to include entire-margined and irregularly segmented species as well as information on the cuticle.

The lamina or the leaflets are attached to the midrib or rachis on the 'upper' (adaxial) side of the leaf, unlike in other similar genera such as Taeniopteris.

Fossils of Nilssonia are found in Triassic, Jurassic and Cretaceous-aged terrestrial strata of East Asia, Australia, North and South America, and Europe.

[6][7][8] The distribution of this genus in the Northern Hemisphere extended to low latitudes in Europe and Asia during the Triassic to Middle Jurassic.