Icaronicteris

• Icaronicteris is known from four exceptionally preserved specimens from the Green River Formation of North America, as well as some fragmentary material from France.

• Icaronicteris had a wingspan of about 37 centimetres (15 inches) and a body length of about 14 centimetres (5.5 inches).

• Icaronicteris is considered to be one of the earliest branches of the microchiropteran lineage, along with other genera such as Archaeonycteris, Hassianycteris, and Palaeochiropteryx.

Icaronicteris is an extinct genus of microchiropteran (echolocating) bats that lived in the early Eocene, approximately 52.2 million years ago.
It is the earliest known definitive bat.
The fossil remains of Icaronicteris have been found in the Green River Formation of North America and France.

Icaronycteris is an extinct genus of microchiropteran (echolocating) bats that lived in the early Eocene, approximately 52.2 million years ago.

It is the earliest bat genus known from complete skeletons, and the earliest known bat from North America.

Icaronycteris measured about 14 centimetres (5.5 in) long and had a wingspan of 37 centimetres (15 in).

It closely resembled modern bats, but had some primitive traits.

The tail was much longer and not connected to the hind legs with a skin membrane, the first wing finger bore a claw and the body was more flexible.

Similarly, it had a full set of relatively unspecialised teeth, similar to those of a modern shrew.

Its anatomy suggests that, like modern bats, Icaronycteris slept while hanging upside down, holding onto a tree branch or stone ridge with its hind legs.