Their wings were short but broad, indicating an adaptation for slow but highly maneuverable flight beneath forest canopies and among dense vegetation.

[4] The name Palaeochiropteryx means "Ancient hand-wing", from Greek παλαιός (palaios, "old"), χείρ (kheir, "hand"), and πτέρυξ (pteruks, "wing").

[5] There are two major reasons as to why the discovery of these fossils is of importance and value; (1) this discover alters perceived relationships among extant forms at a few poorly supported nodes; and (2) the newly found fossils affect some character polarities (slightly changing tree topology), and also changes the levels at which transformations appear to apply (altering perceived support for some clades).

[6] Like other fossils from the locality, they are often found in remarkable states of preservation, retaining traces of fur, stomach contents, wing membranes, and even ears.

[8] The two species belonging to the genus are the following: In 1980, their parent taxon, Palaeochiropterygidae, was merged with Archaeonycteridae by the paleontologists Björn Kurtén and Elaine Anderson.

Close relatives of Palaeochiropteryx include the Middle Eocene Cecilionycteris, Lapichiropteryx and Microchiropteryx, all recovered from partial remains from Germany, China, and India, respectively.

[5] Analysis of melanosomes preserved in the hairs of Palaeochiropteryx specimens suggests that they contained phaeomelanin, which would have given it a brown colour in life like many living bat species.

[7] The fossils recovered are usually of healthy adults with full stomachs, making the reasons why they ended up at the bottom of a lake a bit of a mystery.

They specialized in hunting close to the ground, beneath the jungle canopy and among vegetation unlike other bats found in Messel Pit which flew at higher altitudes (an early evidence of niche partitioning).

[7][8] The shape of their teeth and the stomach contents of the numerous extremely well preserved fossils of the Messel Pit indicate that Palaeochiropteryx were insectivorous.

Icaronycteris, Archaeonycteris, Hassianycetris, and Palaeochiropteryx, unlike most other fossil bats, have not been referred to any extant family or superfamily.

These Eocene taxa are known from exceptionally well-preserved fossils, and they have long formed a basis for reconstructing the early evolutionary history of Chiroptera.

In contrast, Van Valen (1979) argued that these fossil forms are representatives of Eochiroptera, a primitive grade ancestral to both Megachiroptera and Microchiroptera; modern researchers, however, consider this clade to be obsolete.

Most recently, Simmons and Geisler (1998) found that Icaronycteris, Archaeonycteris, Hassianycteris, and Palaeochiropteryx represent a series of consecutive sister-taxa to extant microchiropteran bats.

[24] Below is the phylogenetic tree from Simmons and Geisler (1998) showing the proposed relationships of Palaeochiropteryx (in bold) with other extinct genera and with extant bats.