Palaeochiropteryx

Fossils of both species of Palaeochiropteryx were first recovered from the Messel Pit, near the village of Messel, Germany in 1917. They were described and named by the Swiss naturalist Pierre Revilliod. He placed them under their own family – Palaeochiropterygidae. They are quite common and account for three quarters of all bat fossils found there, Authorities specializing in bat fossils, however, maintain the distinction between the two families. The Messel Pit formation dates from the Lutetian age of the Middle Eocene. Between 48.6 ± 0.2 and 40.4 ± 0.2 million years ago. Along with Onychonycteris, Icaronycteris, Hassianycetris, and Archaeonycteris; members of Palaeochiropteryx are among the oldest known bats. ==Taxonomy and phylogeny==

The fossil record of bats extends back at least to the early Eocene, and chiropteran fossils are known from all continents except Antarctica. Icaronycteris, Archaeonycteris, Hassianycetris, and Palaeochiropteryx, unlike most other fossil bats, have not been referred to any extant family or superfamily. These Eocene taxa are known from exceptionally well-preserved fossils, and they have long formed a basis for reconstructing the early evolutionary history of Chiroptera. Novacek (1987) reanalyzed morphology of Icaronycteris and Palaeochiropteryx and concluded that they are more closely related to Microchiroptera than to Megachiroptera. Most recently, Simmons and Geisler (1998) found that Icaronycteris, Archaeonycteris, Hassianycteris, and Palaeochiropteryx represent a series of consecutive sister-taxa to extant microchiropteran bats. ==Description==

Palaeochiropteryx differed little from modern bats, a surprising fact given their relative age. Palaeochiropteryx had wings formed from enlarged hands, even though their wings were less advanced than the modern bats. For example, they still possessed a claw in the index finger. Both P. tupaiodon and P. spiegeli were small bats. P. spiegeli is slightly larger than P. tupaiodon. P. tupaiodon had an estimated body mass of and a forearm length of . P. spiegeli was slightly larger and heavier, with an estimated body mass of and a forearm length of . They had wingspans between in length. The complete dentition of Palaeochiropteryx is known. They had 38 teeth, composed of four upper and six lower incisors, four canine teeth, twelve premolars, and twelve molars. Their dental formula is the same as at least three living families of bats, such as bats from the genus Myotis. Analysis of melanosomes preserved in the hairs of Palaeochiropteryx specimens suggests that they contained phaeomelanin, which would have given it a brown colour in life like many living bat species. ==Paleobiology and paleoecology==

Messel Pit (known in German as Grube Messel) is one of the most famous and richest fossil sites of the world. The site is renowned for the quality of preservation in the fossils found. Preserved in very fragile bituminous shale, they often retain exquisite details of the soft parts of animals and plants. As its name suggests, the pit is a dry depression about deep; the surface is around above sea level. It covers an area approximately by . 48 million years ago, the pit was a small but very deep lake, originally at least deep. It was located around 10° south of its current location in a tropical and subtropical Eocene Europe. Messel Pit was volcanic in origin, probably a caldera created by a massive volcanic eruption. It remained geologically and tectonically active during the Eocene, intermittently releasing puffs of poisonous volcanic gases. A virtually stagnant lake, its low oxygen levels enabled the types of preservation found in its fossils. Messel pit was surrounded by a lush tropical jungle ecosystem teeming with wildlife. Among these were several bat species, including Palaeochiropteryx. Fossils of Palaeochiropteryx (particularly Palaeochiropteryx tupaiodon) occur in great abundance in the pit. They account for three-fourths of all recovered bat fossils in the area. This fact may have made them especially vulnerable to the poisonous gases of the former Messel lake, explaining the abundance of their fossils. Echolocation From the results of radiographic analysis, Palaeochiropteryx (as well as Archaeonycteris and Icaronycteris) all have enlarged cochleae relative to the size of their skulls.{{cite journal|author=Michael J. Novacek|year=1987|title=Auditory Features and Affinities of the Eocene Bats Icaronycteris and Palaeochiropteryx (Microchiroptera, incertae sedis) ==See also==