''Necromantis'' is an

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 ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

bat Bats are mammals of the order Chiroptera.''cheir'', "hand" and πτερόν''pteron'', "wing". With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight. Bats are more agile in flight than most ...

that lived during the

Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

. Its fossils are found in the

Quercy Phosphorites Formation The Quercy Phosphorites Formation ( French: ''Phosphorites du Quercy'') is a geologic formation and Lagerstätte in Occitanie, southern France. It preserves fossils dating back to the Paleogene period ( latest Bartonian to Late Oligocene),

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

and the Djebel Chambi in

Tunisia ) , image_map = Tunisia location (orthographic projection).svg , map_caption = Location of Tunisia in northern Africa , image_map2 = , capital = Tunis , largest_city = capital , ...

. Specimens of ''Necromantis'' are notable for their large size and specialization towards a predatory lifestyle.

History

The type species, ''N. adichaster'', was first described by A. Weithofer in 1887 on the basis of fragmentary fossils from the Eocene deposits of the

. Weithofer did not designate a type specimen, simply describing a lower jaw. This material was later described in more detail by

Pierre Revilliod Pierre Revilliod (1883–1954) was a Swiss naturalist. From 1927–1953 Revilliod was a curator and researcher at the Natural History Museum of Geneva. He is best known for his work on fossil bats Bats are mammals of the order Chiro ...

in 1920, offering the holotype the number QW627. He described additional material, and classified it within five species: ''N. adichaster'', ''N. gerzei'', ''N. marandati'', ''N. planifrons'' and ''N. grandis''. More recently, E. Maitre has described the fossils in more detail. ''N. grandis'' and ''N. planifrons'' have been considered indistinguishable from ''N. adichaster'', but ''N. gerzei'' and ''N. marandati'' may be distinct enough to retain their respective statuses as distinct species. Several indeterminate bat fossils in France may belong to ''Necromantis''. Currently, only jaws and skulls are known, with a single humerus known as a postcranial remain. More recently, ''Necromantis fragmentatum'' has been found in the Late Eocene deposits of Djebel Chambi,

Tunisia ) , image_map = Tunisia location (orthographic projection).svg , map_caption = Location of Tunisia in northern Africa , image_map2 = , capital = Tunis , largest_city = capital , ...

. This north African species is known from several isolated teeth.

Description

''Necromantis adichaster'' has a skull length of about 32 mm and an estimated weight of 47 g, making it one of the largest bats in the Quercy Formation. Due to the lack of postcranial remains aside from a humerus, its exact wingspan is unclear. The other two species are smaller in size, and possess several differences in regards to the trigon and cingulum. As noted by most researchers, ''Necromantis'' is unique among extinct and extant bats due to the sheer robustness of its jaws and skull. Its jaws are rather short and broad, bearing proportionally large teeth. The mandible is deep and thick and bears deep fossae; combined with the presence of a wide zygoma and a high-positioned

condyle A condyle (;Entry "condyle"
in
masseter In human anatomy, the masseter is one of the muscles of mastication. Found only in mammals, it is particularly powerful in herbivores to facilitate chewing of plant matter. The most obvious muscle of mastication is the masseter muscle, since it ...

s. The teeth themselves are strongly convergent with those of carnivoran mammals, bearing

carnassial Carnassials are paired upper and lower teeth modified in such a way as to allow enlarged and often self-sharpening edges to pass by each other in a shearing manner. This adaptation is found in carnivorans, where the carnassials are the modified f ...

-like M1 and M2. The sagittal crest was tall, though less so than some other carnivorous bats like ''

Vampyrum spectrum The spectral bat (''Vampyrum spectrum''), also called the great false vampire bat or Linnaeus's false vampire bat, is a large, carnivorous leaf-nosed bat found in Mexico, Central America, and South America. It is the only member of the genus '' ...

'' or ''

Macroderma gigas The ghost bat (''Macroderma gigas'') is a species of bat found in northern Australia. The species is the only Australian bat that preys on large vertebrates – birds, reptiles and other mammals – which they detect using acute sight and heari ...

''.

Biology

''Necromantis'' has a strong negative tilting of the head, a characteristic thought to correlate with nasal-emission echolocation in bats, as seen in forms like megadermatids and phyllostomids, though it is not clear if ''Necromantis'' had a nose-leaf, too. Its powerful jaws, combined with the specialised dentition, strongly suggest that ''Necromantis'' was a carnivore, feeding primarily on other vertebrates. The shearing teeth and strong masseters suggest that it was more specialised to grind and crush flesh and bone than were other bat species. In particular, the angular process of the dentary implies that crushing force was much more important than the width of gape, unlike modern predatory bats. Due to its large eyes and expanded petrosals, ''Necromantis'' might have hunted like modern megadermatids and phyllostomids, relying on low frequency-echolocation and passive listening. Such bats inspect their surroundings from a perch, locate vertebrate prey like birds and mammals visually and by sound, and ambush it, killing it by biting at the back of the head.

Evolution and phylogeny

Currently, ''Necromantis'' is listed as ''

incertae sedis ' () or ''problematica'' is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertainty ...

''. Weithofer originally classified it as a megadermatid, and Riviliod later as a phyllostomid, but similarities to either clade were ultimately deemed to be inconclusive and likely derived from

convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last com ...

. More recently, a relationship with emballonurid bats has been proposed, possibly as a basal member descended from the early Eocene radiation of this clade, but currently this is inconclusive as well. The more recent consensus is a position in Rhinolophoidea.

Ecology

''Necromantis'' occurs in the Quercy Formation deposits estimated to date from the Middle to Late Eocene, 44-36 million years ago. The regional climate is thought to have been tropical in nature, marked by dense rainforests. Much like modern equatorial forests, the Quercy Formation bears a massive diversity of bat species; though the overall diversity of the region is thought to be incomplete, there are representatives of the still-extant

Vespertilionidae Vespertilionidae is a family of microbats, of the order Chiroptera, flying, insect-eating mammals variously described as the common, vesper, or simple nosed bats. The vespertilionid family is the most diverse and widely distributed of bat familie ...

, Molossidae,

Hipposideridae The Hipposideridae are a family of bats commonly known as the Old World leaf-nosed bats. While it has often been seen as a subfamily, Hipposiderinae, of the family Rhinolophidae, it is now more generally classified as its own family.Simmons, 20 ...

and

Emballonuridae Emballonuridae is a family of microbats, many of which are referred to as sac-winged or sheath-tailed bats. They are widely distributed in tropical and subtropical regions around the world. The earliest fossil records are from the Eocene. Descr ...

(the former three still occur in Europe), as well as the now extinct

Palaeochiropterygidae Palaeochiropterygidae is a family of extinct bats. It was originally erected by the Swiss naturalist Pierre Revilliod in 1917 after discoveries of ''Palaeochiropteryx'' fossils from the Messel Pit of Germany. Palaeochiropterygidae was merged int ...

and Mixopterygidae.Gunnell GF & Simmons NB, ''Evolutionary History of Bats: Fossils, Molecules and Morphology'', Cambridge University Press, 2012.

References

{{Taxonbar, from=Q20721996 Eocene bats Mammal enigmatic taxa Paleogene mammals of Europe Prehistoric bat genera Eocene mammals of Africa