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Temporal range: Early Eocene
Icaronycteris index.jpg
Icaronycteris index, Green River Formation, in the ROM,
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Chiroptera
Family: Icaronycteridae
Genus: Icaronycteris
Jepsen 1966

Icaronycteris is an extinct genus of microchiropteran (echolocating) bat that lived in the early Eocene, approximately 52.2 million years ago, making it the earliest known definitive bat.[1] Four exceptionally preserved specimens, among the best preserved bat fossils, are known from the Green River Formation of North America.[1] There is only one thoroughly described species of bat in the genus, I. index,[2] although fragmentary material from France has also been tentatively placed within Icaronycteris as the second species I. menui.[3] I. sigei is based on well-preserved fragments of dentaries and lower teeth found in Western India.[4]

Icaronycteris index, Houston


Icaronycteris[5] 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.[6]


According to Simmons & Geisler 1998,[7] Icaronycteris is the first genus, followed by Archaeonycteris, Hassianycetris, and Palaeochiropteryx, in a series leading to extant microchiropteran bats.[8]










Microchiroptera (Echolocating bats)


See also[edit]



  1. ^ a b Gunnell & Simmons 2005, Fossil Bats, p. 214
  2. ^ Jepsen 1966
  3. ^ Simmons & Geisler 1998, p. 40[failed verification]
  4. ^ Smith et al. 2007, Abstract
  5. ^ The name relates the mythic flight of Icarus to Nycteris, the genus of "hollow-faced bats".
  6. ^ Palmer 1999, p. 211
  7. ^ Simmons & Geisler 1998, Abstract
  8. ^ Simmons & Conway 1998, Discussion of Phylogenetic Relationships
  9. ^ Simmons & Conway 1998


  • Gunnell, G. F.; Simmons, N. B. (2005). "Fossil evidence and the origin of bats" (PDF). Journal of Mammalian Evolution. 12 (1–2): 209–246. doi:10.1007/s10914-005-6945-2.
  • Jepsen, G. L. (1966). "Early Eocene bat from Wyoming". Science. 154 (3754): 1333–9. Bibcode:1966Sci...154.1333J. doi:10.1126/science.154.3754.1333. PMID 17770307.
  • Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. ISBN 978-1-84028-152-1.
  • Russell, D. E.; Louis, P.; Savage, D. E. (1973). "Chiroptera and Dermoptera of the French early Eocene". University of California Publications in Geological Sciences. 95: 1–57. OCLC 691130847.
  • Smith, T.; Rana, R. S.; Missiaen, P.; Rose, K. D.; Sahni, A.; Singh, H.; Singh, L. (2007). "High bat (Chiroptera) diversity in the Early Eocene of India". Naturwissenschaften. 94 (12): 1003–1009. Bibcode:2007NW.....94.1003S. doi:10.1007/s00114-007-0280-9. hdl:1854/LU-385394. PMID 17671774.
  • Simmons, N. B.; Conway, T. (1998). "Chiroptera". Tree of Life. Retrieved September 2014. Check date values in: |accessdate= (help)
  • Simmons, N. B.; Geisler, J. H. (1998). "Phylogenetic relationships of Icaronycteris, Archaeonycteris, Hassianycteris, and Palaeochiropteryx to extant bat lineages, with comments on the evolution of echolocation and foraging strategies in Microchiroptera" (PDF). Bulletin of the AMNH (235).

Further reading[edit]