Onychonycteris

Onychonycteris
Onychonycteris
Temporal occurrence
Lower Eocene
52.5 million years
Locations
Wyoming , USA ( Green River Formation )
Systematics
Higher mammals (Eutheria) Laurasiatheria Bats (chiroptera) Onychonycteridae Onychonycteris
Scientific name of the  family
Onychonycteridae
Simmons , Seymour , Habersetzer & Gunnell , 2008
Scientific name of the  genus
Onychonycteris
Simmons, Seymour, Habersetzer & Gunnell, 2008
species
Onychonycteris finneyi

Onychonycteris is an extinct genus of bats that was foundin North America around 52 million years ago in the Eocene . Due to the anatomical peculiarities of the only scientifically described species , Onychonycteris finneyi , it was possible for the first time to reliably prove that the early ancestors of today's bats were initially able to fly and only then developed the ability to echolocation .

Naming

Onychonycteris is a made-up word . The name of the genus is derived from the Greek onycho (= with claws ) and nycteris (= bat); she points out that there were long claws on all five fingers of the animals. The epithet of the only scientifically described species so far, Onychonycteris finneyi , honors Bonnie Finney, who hid the holotype on August 21, 2003 in the Finney Quarry, Lincoln County , Wyoming . Onychonycteris finneyi therefore means "Finney's clawed bat ".

Initial description

The holotype of the genus and also the type species Onychonycteris finneyi is a roughly palm -sized, complete skeleton, which was first described in the journal Nature in 2008 and is kept in the Royal Ontario Museum under archive number ROM 55351A, B. The find comes from the Fossil Butte Member of the Green River Formation and, along with the remains of Icaronycteris from the same locality, is one of the oldest known fossils of a bat . In contrast to Icaronycteris , Onychonycteris was built more originally from a phylogenetic point of view .

features

An anatomical feature that cannot be found in the somewhat younger Messel bats Archaeonycteris and Hassianycteris, or in 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) on finger. Jörg Habersetzer from the Senckenberg Research Institute , one of the co-authors of the first description , therefore suspects that Onychonycteris was a skilled climber and - like his descendants today - could hang upside down in the branches at night. Onychonycteris finneyi had relatively short wings, very long hind legs compared to today's bats and a flight membrane between the hind legs and the caudal spine. The wing skeleton as well as the shape of the rib cage and tail clearly indicate that this species could fly over long distances, but probably more with strong flutter, with the flight membrane serving as a stabilizing "sail". A reconstruction of the aerodynamic properties of the wings revealed that the ancestors of the bats were glider pilots .

From the teeth of the approximately 40 gram heavy animals it can be deduced that Onychonycteris finneyi captured insects - presumably while hunting.

High-resolution x-ray images of the cochlea in the inner ear of Messel bats such as Archaeonycteris and Hassianycteris indicate - albeit less perfected than in most of today's bats - an echolocation with ultrasound sounds that was established 47 million years ago . The fossil food remains found in the stomach area of ​​the Messel bats also show that these ancestors of today's bats lived exclusively on insects. Even if the teeth of Onychonycteris finneyi also allow conclusions to be drawn about an insect eater , comparative micro-X-rays exclude echolocation of prey insects by ultrasound sounds for Onychonycteris . The knowledge gained - a very small cochlea - suggests that the bats developed flying before echolocation with ultrasound sounds. The size of the cochlea resembles that of bats , the fruit-eating relatives of bats that do not have the ability to echolocation.

This seems to have resolved a long-standing scientific question: the question of whether the echolocation system developed first in bats or the ability to fly. John Speakman, professor of zoology at the University of Aberdeen , reconstructs the evolution of bats in such a way that these animals were initially diurnal and only under the pressure of birds of prey increasingly shifted to catching prey at night. At the same time, echolocation developed.

Web links

Commons : Onychonycteris  - Collection of Images

• Image of the fossil on: Spektrum.de from February 13, 2008

Individual evidence

1. ^ Nancy B. Simmons, Kevin L. Seymour, Jörg Habersetzer and Gregg F. Gunnell: Primitive Early Eocene bat from Wyoming and the evolution of flight and echolocation. In: Nature . Volume 451, 2008, pp. 818-821, doi: 10.1038 / nature06549 , ISSN  0028-0836
2. ↑ News from the theory of evolution: Petrified bat solves puzzles. In: taz from February 15, 2008
3. ↑ Lucila I. Amador, Nancy B. Simmons and Norberto P. Giannini: Aerodynamic reconstruction of the primitive fossil bat Onychonycteris finneyi (Mammalia: Chiroptera). In: Biology Letters. Volume 15, No. 3, 2019, 20180857, doi: 10.1098 / rsbl.2018.0857
4. ↑ Disoriented: Fossil bat flew without an echo sounder. On: Spektrum.de from February 13, 2008
5. ^ John R. Speakman: The evolution of flight and echolocation in bats: another leap in the dark. In: Mammal Review . Volume 31, No. 2, 2001, pp. 111-130, doi: 10.1046 / j.1365-2907.2001.00082.x