New important transitional fossil for bats

[shunyadragon]

New transitional fossils provide a more complete picture of the evolution of bats.

[rogue06]

New transitional fossils provide a more complete picture of the evolution of bats.

Not exactly "new" since the discovery is over a decade old. Still Onychonycteris finneyi, which lived 52.5 mya (Eocene) is indeed a great example of a transitional.

Onychonycteris had an underdeveloped coclea of the inner ear associated with the radar-like echolocation abilities in most modern bats. The part of the skull where the cochlea is located was found intact^[1]. But the morphology of the dentition demonstrates that Onychonycteris was insectivorous, like other bats from the Eocene and not a frugivore (fruit eater).

Onychonycteris also reveals many characteristics that demonstrate its evolution from a arboreal (tree-dwelling) insectivore. For example, while all modern species of bat have at the most claws on only one or two digits Onychonycteris possessed claws on all five fingers and several of the earlier species that are now extinct still retained bumps at the ends of their other digits. This shows a transition from a creature with claws on the ends of all of its digits to what we see now, creatures that have lost most of the claws through time since it no longer has to scurry through the trees in search of a meal.

Onychonycteris and other early bats demonstrate that bats have been losing its claws as they are no longer necessary and confer no advantage, and may have been a hinderance, after they abandoned their previous arboreal existence.

But that's not all. There is more evidence for Onychonycteris' transitional nature from arboreal insectivore to a flying insectivore.

The proportion of its limbs which is unique among bats is another indication. This differing limb ratio places Onychonycteris somewhere between other bats and climbing mammals such as gibbons and sloths. IOW, this limb proportion is intermediate between all other known bats and forelimb-dominated non-flying mammals

http://web.archive.org/web/20100612045005/http://www.plantbio.uga.edu/~chris/batgraph.jpg

This, along with its claws, demonstrates a previous arboreal existence and is exactly what we would expect from a species located near the base of chiropteran evolution.

OnychonycterisOnychonycteris

[shunyadragon]

rogue6

Agreed that it is not new, new as far as the fossils, but the completion of the research is relatively new. I consider everything since 2000 new. Thank you for the extra reference material.

[The Pixie]

Onychonycteris had an underdeveloped coclea of the inner ear associated with the radar-like echolocation abilities in most modern bats. The part of the skull where the cochlea is located was found intact^[1]. But the morphology of the dentition demonstrates that Onychonycteris was insectivorous, like other bats from the Eocene and not a frugivore (fruit eater).

That fruit bats have no echolocation would seem to be to indicate echolocation came second. Or are they evolved from bats that did?