Icaronycteris

Name: Icaronycteris ‭(‬Icarus night flyer‭ ‬-‭ ‬after Icarus from Greek mythology‭)‬.

Phonetic: Ik-a-ro-nik-ter-is.

Named By: Jepsen‭ ‬-‭ ‬1966.

Classification: Chordata,‭ ‬Mammalia,‭ ‬Chiroptera,‭ ‬Microchiroptera,‭ ‬Icaronycteridae.

Species: I.‭ ‬index‭ (‬type‭)‬,‭ ‬I.‭ ‬menui,‭ ‬I.‭ ‬sigei.

Diet: Insectivore.

Size: Wingspan‭ ‬37‭ ‬centimetres across,‭ ‬body‭ ‬14‭ ‬centimetres long.

Known locations: USA,‭ ‬Europe.

Time period: Ypresian of the Eocene.

Fossil representation: Many specimens.

Towards the end of the Triassic a group of reptiles evolved wings so that they could fly after insects in the air,‭ ‬becoming the reptiles now known to us as pterosaurs.‭ ‬Over one hundred and sixty million years later and only around thirteen million years after the pterosaurs became extinct at the end of the Cretaceous,‭ ‬evolution repeated itself but this time with the mammals,‭ ‬specifically the bats.‭

Icaronycteris is one of the earliest known bats and already the modern bat form is clearly established.‭ ‬The inner ear bones strongly suggest that Icaronycteris was already using echolocation to hunt during this time and‭ ‬the ankles of the feet were arranged to face backward so that Icaronycteris could hang upside down.‭ ‬Some specimens have also been found with moth scales inside where the stomach area would have been,‭ ‬clearly revealing that Icaronycteris also had a similar prey preference to most modern bats.

Despite all this Icaronycteris was still primitive in some respects.‭ ‬Modern bats have a single claw on their first digit,‭ ‬but Icaronycteris had this plus another one on the second digit.‭ ‬Icaronycteris also lacked a uropatagium,‭ ‬the flap of skin in‭ ‬between the legs of modern bats that also includes the tail.‭ ‬Icaronycteris also had a less rigid skeletal structure.‭ ‬Finally even though Icaronycteris was an insectivore,‭ ‬it had a full set of teeth that were relatively unspecialised beyond the basic mammalian form.‭ ‬Later bats would develop more specialised teeth that were also fewer in number than Icaronycteris had.

Further reading

- Early Eocene bat from Wyoming. - Science 154(3754):1333-1339. - G. L. Jepsen - 1966.

- Chiroptera and Dermoptera of the French early Eocene. - University of California Publications in Geological Sciences 95:1-57. - D. E. Russel, P. Louis & D. E. Savage - 1973.

- Phylogenetic relationships of Icaronycteris, Archaeonycteris, Hassianycteris, and Palaeochiropteryx to extant bat lineages, with comments on the evolution of echolocation and foraging strategies in Microchiroptera. - Bulletin of the AMNH (235). - N. B. Simmons & J. H. Geisler - 1998.

- High bat (Chiroptera) diversity in the Early Eocene of India. - Naturwissenschaften 94(12):1003-1009. - T. Smith, R. S. Rana, P. Missiaen, K. D. Rose, A. Sahni, H. Singh & L. Singh - 2007.

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