Onychonycteris

Wyoming, USA ( Green River Formation )

Onychonycteris finneyi ( " clawed bat " ) is the name of a fossil, about palm-sized bat from the Eocene epoch, whose age has been dated to 52.5 million years. Due to the anatomical features of the holotype of detection could be performed for the first time ensure that the early ancestors of today's bats could fly first and only then developed the ability to echolocation. The Fund is considered the oldest known fossil of a bat.

Etymology

The name of the type described in the journal Nature, starting in 2008, is derived from Greek Onycho ( = provided with claws ) and Nycteris ( = bat ); he takes off that long claws are present on all five fingers of the animal. The Style epithet honors Bonnie Finney, the the holotype - barg on 21 August 2003 in Finney Quarry, Lincoln County, in the U.S. state of Wyoming - a complete skeleton. The site is part of the Green River Formation, the holotype Museum under the archive number ROM 55351A, B is kept in the Royal Ontario.

Special

An anatomical feature that is found neither in the slightly younger Messel bats Archaeonycteris and Hassianycteris even at later developed or present-day specimens, are the claws on all five fingers. Except Onychonycteris have all known bats, only one ( bats, Microchiropter ) to a maximum of two ( flying foxes, Megachiroptera ) finger on. Jörg Habersetzer of the Senckenberg Research Institute, one of the co -authors of the original description, therefore assumes that Onychonycteris was a skilled climber and - as his descendants today - at night could hang the branches upside down. Onychonycteris finneyi had relatively short wings, compared to today's bats very long hind legs and a wing membrane between the hind legs and tail of spine. The wing skeleton as well as the shape of the thorax and the tail can unequivocally conclude that this kind could fly over long distances, but more likely with strong flutter, where the wing membrane was used as a stabilizing " sail". From the dentition is also possible to derive that Onychonycteris finneyi has captured insects in flight hunting.

High resolution X-ray images of the ear worm in the inner ear of Messel bats as Archaeonycteris and Hassianycteris have - albeit less perfect than most of today's bats - on a already formed 47 million years ago echolocation with ultrasonic sounds down. Proven in the stomach area of ​​the Messel fossil bats food residues also show that these ancestors of today's bats have fed exclusively on insects. Although the dentition of Onychonycteris finneyi also allows conclusions to an insectivore, close comparative micro - radiographs from an echolocation of insect prey by echolocation calls for Onychonycteris. The findings - a very small cochlea - suggest that the bats have developed flying before echolocation with ultrasonic sounds. The size of the cochlea are similar to those of bats, the frugivorous relatives of bats that do not have the ability to echolocation.

So many years of scientific controversy seems to have been clarified: the question of whether first developed the echolocation system in bats or the ability to fly. John Speakman, Professor of Zoology at the University of Aberdeen, the evolution of bats reconstructed in such a way that these animals were initially active during the day and are increasingly installed only under the pressure by birds of prey on nocturnal prey capture. In parallel, the echolocation have developed.