''Nuralagus'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

leporid Leporidae is the family of rabbits and hares, containing over 60 species of extant mammals in all. The Latin word ''Leporidae'' means "those that resemble ''lepus''" (hare). Together with the pikas, the Leporidae constitute the mammalian order ...

, with a single

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

, ''N. rex'', described in 2011. It lived on

Menorca Menorca or Minorca (from la, Insula Minor, , smaller island, later ''Minorica'') is one of the Balearic Islands located in the Mediterranean Sea belonging to Spain. Its name derives from its size, contrasting it with nearby Majorca. Its capi ...

, one of the Balearic Islands in the western Mediterranean during the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58lagomorph The lagomorphs are the members of the taxonomic order Lagomorpha, of which there are two living families: the Leporidae (hares and rabbits) and the Ochotonidae (pikas). The name of the order is derived from the Ancient Greek ''lagos'' (λαγ� ...

to have ever existed, with an estimated weight of 12 kilograms, although some breeds of domestic rabbit, such as the Flemish Giant rabbit, approach it in size. It likely went extinct at the Pliocene-Pleistocene transition when Mallorca and Menorca were united as one island, letting the mammalian fauna of Mallorca, including the goat-like

ungulate Ungulates ( ) are members of the diverse clade Ungulata which primarily consists of large mammals with hooves. These include odd-toed ungulates such as horses, rhinoceroses, and tapirs; and even-toed ungulates such as cattle, pigs, giraffes, ...

Myotragus balearicus ''Myotragus'' (Neo-Latin, derived from the Greek: , and "Balearian mouse-goat"), is an extinct genus of goat-antelope in the tribe Caprini which lived on the Balearic Islands of Mallorca and Menorca in the western Mediterranean until its extin ...

,'' colonize ''Nuralagus'' habitat.

Discovery

So far, all of the fossils have been found in fissure fill deposits in the northwest of Menorca, dating to sometime in the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Alilepus.'' The genus and species ''Nuralagus rex'' were described in 2011 in a full description of the material, which included the front half of a

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...

, as well as numerous isolated postcranial bones corresponding to most of the skeleton.

Description

Nuralagus - Comparacion tamaños 1920x1080

With a height of half a meter and an estimated weight of , the species is the largest known

lagomorph The lagomorphs are the members of the taxonomic order Lagomorpha, of which there are two living families: the Leporidae (hares and rabbits) and the Ochotonidae (pikas). The name of the order is derived from the Ancient Greek ''lagos'' (λαγ� ...

, being six times the weight of the extant European rabbit (''

Oryctolagus cuniculus The European rabbit (''Oryctolagus cuniculus'') or coney is a species of rabbit native to the Iberian Peninsula (including Spain, Portugal, and southwestern France), western France, and the northern Atlas Mountains in northwest Africa. It has b ...

'')''.'' Its size was likely due to Foster's rule, also called the "island effect". It had a comparatively small skull relative to its body size and small sensory receptors, including

orbits In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a p ...

and tympanic bullae, suggesting reduced senses of hearing and eyesight. ''Nuralagus rex'' had a short and stiff spine which resulted in low mobility and an inability to jump like other leporids.

Evolution

''Nuralagus rex'' likely entered what is now Menorca during the

Messinian Salinity Crisis The Messinian salinity crisis (MSC), also referred to as the Messinian event, and in its latest stage as the Lago Mare event, was a geological event during which the Mediterranean Sea went into a cycle of partial or nearly complete desiccation (d ...

5.96-5.3 million years ago. During this event, the Strait of Gibraltar closed, leading to the desiccation of the Mediterranean Sea, resulting in the connecton of the islands to the Iberian Peninsula, letting ''Nuralagus'' ancestor colonize the area. The subsequent Zanclean flood 5.3 million years ago then returned the Mediterranean to its original sea levels, isolating ''Nuralagus'' ancestor on Menorca. There is a dearth of knowledge about the evolutionary history of ''Nuralagus rex'' in relation to other lagomorphs. However, similarities between the dental morphology of ''Nuralagus'' and Eurasian members of the extinct genus '' Alilepus'' have led to speculation that ''Alilepus'' is closely related to and, possibly, the ancestor of ''Nuralagus''. The only other mammal native to Menorca during the Pliocene was the extinct giant

dormouse A dormouse is a rodent of the family Gliridae (this family is also variously called Myoxidae or Muscardinidae by different taxonomists). Dormice are nocturnal animals found in Africa, Asia, and Europe. They are named for their long, dormant hibe ...

species ''Muscardinus cyclopeus,'' which belongs to the same genus as the living

hazel dormouse The hazel dormouse or common dormouse (''Muscardinus avellanarius'') is a small mammal and the only living species in the genus ''Muscardinus''. Distribution and habitat The hazel dormouse is native to northern Europe and Asia Minor. It is the ...

, with a

herpetofauna Herpetology (from Greek ἑρπετόν ''herpetón'', meaning "reptile" or "creeping animal") is the branch of zoology concerned with the study of amphibians (including frogs, toads, salamanders, newts, and caecilians (gymnophiona)) and rept ...

including the giant tortoise '' Solitudo gymnesica,'' snakes,

amphisbaenian Amphisbaenia (called amphisbaenians or worm lizards) is a group of usually legless squamates, comprising over 200 extant species. Amphisbaenians are characterized by their long bodies, the reduction or loss of the limbs, and rudimentary eyes. As ...

, lacertid and gekkonid lizards, and alytid frogs. ''Nuralagus'' probably became extinct around the end of the Pliocene and the beginning of the Pleistocene, corresponding with the colonisation of Menorca by the mammals that lived on Mallorca (comprising the goat-antelope ''

Myotragus ''Myotragus'' (Neo-Latin, derived from the Greek: , and "Balearian mouse-goat"), is an extinct genus of goat-antelope in the tribe Caprini which lived on the Balearic Islands of Mallorca and Menorca in the western Mediterranean until its extin ...

'', the shrew '' Nesiotites'' and the dormouse ''

Hypnomys ''Hypnomys'', otherwise known as Balearic giant dormice, is an extinct genus of dormouse (Gliridae) in the subfamily Leithiinae. Its species are considered examples of insular gigantism. They were endemic to the Balearic Islands in the western Me ...

'') due to the islands being connected during low sea level episodes as a result of

Quaternary glaciation The Quaternary glaciation, also known as the Pleistocene glaciation, is an alternating series of glacial and interglacial periods during the Quaternary period that began 2.58 Ma (million years ago) and is ongoing. Although geologists describ ...

. ''Nuralagus'' unique traits were most likely the product of an insular environment containing no natural predators. Physical similarities between ''Nuralagus rex'' and '' Pentalagus furnessi'' (an extant insular lagomorph which until recently also did not have natural predators) despite the phylogenetic and geographical distance between the two species further supports this inference.

References

{{Taxonbar, from1=Q55461848, from2=Q134112 Environment of Menorca Endemic fauna of the Balearic Islands Neogene mammals of Europe Pliocene mammals Messinian first appearances Pliocene extinctions Prehistoric lagomorphs Prehistoric placental genera Fossil taxa described in 2011