''Aegyptonycteris'' ("Egyptian bat") is a genus of

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

bat from the Late Eocene of North Africa. It is currently known from a single specimen ( holotype CGM 83740) from the Birket Qarun Formation in the

Fayum Depression The Faiyum Oasis ( ar, واحة الفيوم ''Waḥet El Fayyum'') is a depression or basin in the desert immediately to the west of the Nile, or just 62 miles south of Cairo in Egypt. The extent of the basin area is estimated at between 1,270 ...

in western Egypt. ''Aegyptonycteris'' is notable both its large size, comparable to the larger modern bat species, as well due to its omnivorous diet, as opposed to the mostly

insectivorous A robber fly eating a hoverfly An insectivore is a carnivorous animal or plant that eats insects. An alternative term is entomophage, which can also refer to the human practice of eating insects. The first vertebrate insectivores were ...

diets of other Eocene bats (and the majority of modern species). This makes it a remarkable example of early chiropteran speciation, having not only attained a rather large size but also specialised towards a drastically different ecological niche from its contemporaries.

Description

''Aegyptonycteris'' is currently known only from its holotype. Said specimen is composed of a right maxilla - including the posterior portion of the orbital door and base of the zygomatic arch - and two molar teeth. The anterior orbital door is broad and flat and the zygomatic arch is robust and well developed, characteristics seen in a variety of mammal groups including the contemporary

primates Primates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians (monkeys and apes, the latter including huma ...

, eulipotyphlans and metatherians, but the molars have classical chiropteran traits like dilambdodonty, lack of a mesostyle and a narrow protofossa, though it does differ from most other bats in the presence of a bulbous hypocone. Comparisons to other bat species show that the animal was probably similar in size to the modern '' Vampyrum spectrum'', if not larger. Currently, it is unknown whether it had echolocation, though its omnivorous habits might imply the use of other senses like smell, as in modern frugivorous and omnivorous bat species.

Classification

''Aegyptonycteris'' is recovered as a chiropteran on the basis of several dental characteristics (see above). It is considered rather aberrant, however, and is considered to be a fairly basal species.

Ecology

Based on its tooth morphology, ''Aegyptonycteris'' was most likely a generalistic

omnivore An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nutr ...

. Unlike other contemporary bats such as ''

Witwatia ''Witwatia'' (from the Egyptian Arabic ''Wit Wat'' meaning "large, flapping wings") is an extinct genus of giant bat that contained two species which lived in the Al Fayyum in Egypt during the late Eocene (Priabonian epoch) and one species which ...

'', it lacks speciations towards carnivory, as well as speciations in other extreme lifestyles displayed by modern bats, such as frugivory or

nectarivory In zoology, a nectarivore is an animal which derives its energy and nutrient requirements from a diet consisting mainly or exclusively of the sugar-rich nectar produced by flowering plants. Nectar as a food source presents a number of benefits a ...

. Instead, its molars are fairly generalised, with a few speciations towards crushing, suggesting a diet involving both animal and plant matter. In this, it is unique in being the earliest truly omnivorous bat ever known, and the largest omnivorous bat species (other similar sized species are either specialised carnivores, including the contemporary giant bat ''

'', or frugivores).

Paleoecology

The

is one of the richest Eocene fossil sites, depicting a wet tropical environment dominated by lagoons, dating around the

Priabonian The Priabonian is, in the ICS's geologic timescale, the latest age or the upper stage of the Eocene Epoch or Series. It spans the time between . The Priabonian is preceded by the Bartonian and is followed by the Rupelian, the lowest stage of t ...

. It is best renowned for its early whales like '' Basilosaurus'', but several other mammal groups, from

to early

elephants Elephants are the largest existing land animals. Three living species are currently recognised: the African bush elephant, the African forest elephant, and the Asian elephant. They are the only surviving members of the family Elephantidae and ...

and several extinct groups like embrithopods and hyaenodontids are also known. Several bat species are known from this locality, including the similarly large ''

'' species, which are directly contemporary to ''Aegyptonycteris'', suggesting that this environment supported several large sized chiropteran species. In particular, ''Aegyptonycteris'' is not directly related to these other giant bats, suggesting that it evolved

gigantism Gigantism ( el, γίγας, ''gígas'', "giant", plural γίγαντες, ''gígantes''), also known as giantism, is a condition characterized by excessive growth and height significantly above average. In humans, this condition is caused by ove ...

independently.

References

External links

Laelaps Paleo Profile: Knight's Egyptian Bat
{{Taxonbar, from1=Q25096543, from2=Q108068563, from3=Q33136897 Eocene bats Prehistoric bat genera Eocene mammals of Africa Priabonian life Fossils of Egypt Fossil taxa described in 2016 Enigmatic mammal taxa Species known from a single specimen