''Nuralagus'' 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 ...

leporid Leporidae () is the family of rabbits and hares, containing over 70 species of extant mammals in all. The family name comes from "Lepus", hare in Latin. Together with the pikas, the Leporidae constitute the mammalian order Lagomorpha. Leporidae ...

(the family of

rabbit Rabbits are small mammals in the family Leporidae (which also includes the hares), which is in the order Lagomorpha (which also includes pikas). They are familiar throughout the world as a small herbivore, a prey animal, a domesticated ...

s and

hares Hares and jackrabbits are mammals belonging to the genus ''Lepus''. They are herbivores and live solitarily or in pairs. They nest in slight depressions called forms, and their young are able to fend for themselves shortly after birth. The genu ...

), with a single

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

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

Menorca Menorca or Minorca (from , 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 Mallorca. Its capital is Maó, situated on the isl ...

, one of the

Balearic Islands The Balearic Islands are an archipelago in the western Mediterranean Sea, near the eastern coast of the Iberian Peninsula. The archipelago forms a Provinces of Spain, province and Autonomous communities of Spain, autonomous community of Spain, ...

in the western Mediterranean during the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58lagomorph The lagomorphs () are the members of the taxonomic order Lagomorpha, of which there are two living families: the Leporidae (rabbits and hares) and the Ochotonidae ( pikas). There are 110 recent species of lagomorph, of which 109 species in t ...

to have ever existed, with an estimated weight of , nearly double the weight of the average Flemish Giant rabbit. It likely went extinct at the Pliocene-Pleistocene transition when

Mallorca Mallorca, or Majorca, is the largest of the Balearic Islands, which are part of Spain, and the List of islands in the Mediterranean#By area, seventh largest island in the Mediterranean Sea. The capital of the island, Palma, Majorca, Palma, i ...

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 Euungulata ("true ungulates"), which primarily consists of large mammals with Hoof, hooves. Once part of the clade "Ungulata" along with the clade Paenungulata, "Ungulata" has since been determined ...

Myotragus ''Myotragus'' (Neo-Latin, derived from the Greek: , "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 extinction around 4 ...

,'' 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 (geology), epoch in the geologic time scale that extends from 5.33 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, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

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

Description

With a height of half a meter and an estimated weight of , or 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 (rabbits and hares) and the Ochotonidae ( pikas). There are 110 recent species of lagomorph, of which 109 species in t ...

, being ten times the weight of the average wild European rabbit (''

Oryctolagus cuniculus The European rabbit (''Oryctolagus cuniculus'') or coney is a species of rabbit native to the Iberian Peninsula (Spain, Portugal and Andorra) and southwestern France. It is the only extant species in the genus '' Oryctolagus''. The European ra ...

'') and around double the weight of the average Flemish Giant rabbit. Its size was likely due to

island gigantism Island gigantism, or insular gigantism, is a biological phenomenon in which the size of an animal species isolated on an island increases dramatically in comparison to its mainland relatives. Island gigantism is one aspect of the more general "is ...

. It had a comparatively small skull relative to its body size and small

sensory receptor Sensory neurons, also known as afferent neurons, are neurons in the nervous system, that convert a specific type of stimulus, via their receptors, into action potentials or graded receptor potentials. This process is called sensory transduc ...

s, including

orbits In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an physical body, object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an satellite, artificia ...

and

tympanic bulla The tympanic part of the temporal bone is a curved plate of bone lying below the squamous part of the temporal bone, in front of the mastoid process, and surrounding the external part of the ear canal. It originates as a separate bone (tympanic ...

e, 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. Bone

histology Histology, also known as microscopic anatomy or microanatomy, is the branch of biology that studies the microscopic anatomy of biological tissue (biology), tissues. Histology is the microscopic counterpart to gross anatomy, which looks at large ...

analysis suggests that the species was sexually dimorphic, with females being larger than males. The growth lines within the bones suggest that the large body size was the result of growing over a longer period of time, rather than the result of increasing growth rates. The age of sexual maturity was estimated at 3.6 years for females and 6.2 years for males, considerably higher than would be expected solely based on bodymass.

Evolution

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

Messinian Salinity Crisis In the Messinian salinity crisis (also referred to as the Messinian event, and in its latest stage as the Lago Mare event) the Mediterranean Sea went into a cycle of partial or nearly complete desiccation (drying-up) throughout the latter part of ...

around 5.96 to 5.3 million years ago. During this event, the

Strait of Gibraltar The Strait of Gibraltar is a narrow strait that connects the Atlantic Ocean to the Mediterranean Sea and separates Europe from Africa. The two continents are separated by 7.7 nautical miles (14.2 kilometers, 8.9 miles) at its narrowest point. Fe ...

closed, leading to the desiccation of the Mediterranean Sea, resulting in the connection of the islands to the Iberian Peninsula, letting ''Nuralagus'' ancestor colonize the area. The subsequent

Zanclean flood The Zanclean flood or Zanclean deluge is theorized to have refilled the Mediterranean Sea 5.33 million years ago. This flooding ended the Messinian salinity crisis and reconnected the Mediterranean Sea to the Atlantic Ocean, although it i ...

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 dormouse species native to Europe and the only living species in the genus ''Muscardinus''. Distribution and habitat The hazel dormouse is native to northern Europe ...

, with a

herpetofauna Herpetology (from Ancient Greek ἑρπετόν ''herpetón'', meaning "reptile" or "creeping animal") is a branch of zoology concerned with the study of amphibians (including frogs, salamanders, and caecilians (Gymnophiona)) and reptiles (incl ...

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

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

lacertid The Lacertidae are the family of the wall lizards, true lizards, or sometimes simply lacertas, which are native to Afro-Eurasia. It is a diverse family with at about 360 species in 39 genera. They represent the dominant group of reptiles found i ...

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 ''

'', the shrew ''

Nesiotites ''Nesiotites'' is an extinct genus of large red-toothed shrews belonging to the tribe Nectogalini that inhabited the Balearic Islands from the latest Miocene/Early Pliocene (from around 5.3 million years ago) up until the arrival of humans on the ...

'' 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 M ...

'') 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 period, glacial and interglacial, interglacial periods during the Quaternary period that began 2.58 Year#SI prefix multipliers, Ma (million ...

. ''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