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.