''Necromantis'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

bat Bats are flying mammals of the order Chiroptera (). 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 birds, flying with their very long spread-out ...

that lived during the

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

. Its fossils are found in the

Quercy Phosphorites Formation The Quercy Phosphorites Formation (French language, French: ''Phosphorites du Quercy''; ) is a Formation (geology), geologic formation and lagerstätte in Occitania (administrative region), Occitanie, southern France. It preserves fossils dated to ...

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

and the

Djebel Chambi : ''For mountains or other uses, see: Jabal.'' Djebel (1937–1958) was a French Thoroughbred racehorse, who won 15 of 22 races during 1939–1942 including the Prix d'Essai, 2000 Guineas and Prix de l'Arc de Triomphe. He was later a leading sir ...

Tunisia Tunisia, officially the Republic of Tunisia, is a country in the Maghreb region of North Africa. It is bordered by Algeria to the west and southwest, Libya to the southeast, and the Mediterranean Sea to the north and east. Tunisia also shares m ...

. 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 flying mammals of the orde ...

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

. 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 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

, it suggests that ''Necromantis'' had large, well developed

masseter In 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 is the ...

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, great spectral bat, American false vampire bat or Linnaeus's false vampire bat, is a large, carnivorous leaf-nosed bat found in Mexico, Central America, and Sout ...

'' 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 is a term used for a taxonomy (biology), 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 comm ...

. 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 Rhinolophoidea is a superfamily (taxonomy), superfamily of bats. It contains the following families: Craseonycteridae, Hipposideridae, Megadermatidae, Rhinolophidae, Rhinonycteridae, and Rhinopomatidae. It is one of two superfamilies that compris ...

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 (biology), 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 fa ...

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. Desc ...

(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 into ...

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

References

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