Icaronycteris
Encyclopedia
Icaronycteris is an extinct genus of microchiropteran (echolocating) bat
that lived in the early Eocene
, approximately 52.2 million years ago. Four exceptionally preserved specimens are known from the Green River Formation
of North America. There is only one thoroughly described species of bat in the genus, I. index, although fragmentary material from France has also been tentatively placed within Icaronycteris as the second species I. menui.
Icaronycteris measured about 14 centimetres (5.5 in) long and had a wingspan of 37 centimetres (14.6 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.
Bat
Bats are mammals of the order Chiroptera "hand" and pteron "wing") whose forelimbs form webbed wings, making them the only mammals naturally capable of true and sustained flight. By contrast, other mammals said to fly, such as flying squirrels, gliding possums, and colugos, glide rather than fly,...
that lived in the early Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
, approximately 52.2 million years ago. Four exceptionally preserved specimens are known from the Green River Formation
Green River Formation
The Green River Formation is an Eocene geologic formation that records the sedimentation in a group of intermountain lakes. The sediments are deposited in very fine layers, a dark layer during the growing season and a light-hue inorganic layer in winter. Each pair of layers is called a varve and...
of North America. There is only one thoroughly described species of bat in the genus, I. index, although fragmentary material from France has also been tentatively placed within Icaronycteris as the second species I. menui.
Icaronycteris measured about 14 centimetres (5.5 in) long and had a wingspan of 37 centimetres (14.6 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
Shrew
A shrew or shrew mouse is a small molelike mammal classified in the order Soricomorpha. True shrews are also not to be confused with West Indies shrews, treeshrews, otter shrews, or elephant shrews, which belong to different families or orders.Although its external appearance is generally that of...
. 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.